WO2015115567A1 - Solar cell, solar cell module, electrode-provided component, semiconductor device, and electronic component - Google Patents

Abstract

Provided are a solar cell and solar cell module having superior connection reliability and superior adhesion between an electrode and a wiring member. The solar cell has a wiring connection section in which are laminated, in the given order: a semiconductor substrate having a p-n junction; a conductor layer containing a resin section and an electrode section containing a metal section and glass section; and a wiring member. A section is contained such that when a region is observed in which the length in a direction perpendicular to the lamination direction in a cross-section parallel to the lamination direction of the conductor layer in the wiring connection section is 100 μm, the proportion of the total length of the section at which the electrode section overlaps a wire (X) to the overall length of the wire (X) equally dividing the thickness of the electrode section is no greater 95%.

Description

Solar cell, solar cell module, electrode-equipped component, semiconductor device and electronic component

The present invention relates to a solar cell, a solar cell module, a component with an electrode, a semiconductor device, and an electronic component.

Generally, electrodes are formed on a light receiving surface and a back surface of a solar cell element provided with a semiconductor substrate such as a silicon substrate. In order to efficiently extract the electric energy converted in the solar cell element by the incidence of light to the outside, the electrode has a sufficiently low volume resistivity (hereinafter also simply referred to as “resistivity”), and the electrode is a semiconductor. It is necessary to form a good ohmic contact with the substrate.

The electrodes used in the solar cell element include a light receiving surface current collecting electrode, a light receiving surface output extraction electrode, a back surface current collecting electrode and a back surface output extraction electrode, and are usually formed as follows. When an electrode is formed using a p-type silicon substrate which is a kind of semiconductor substrate, a texture (unevenness) is formed on the light-receiving surface side of the p-type silicon substrate, and then phosphorus or the like is thermally diffused at a high temperature. A composition for an electrode (sometimes referred to as an electrode paste composition) is applied on the n ⁺ -type diffusion layer by screen printing or the like and fired at 800 ° C. to 900 ° C. in the atmosphere. An electrode is formed. The electrode composition forming these electrodes contains conductive metal powder, glass particles, various additives and the like.

Among the electrodes, silver particles are generally used as the conductive metal powder other than the back surface collecting electrode. The silver particles have a low resistivity of 1.6 × 10 ⁻⁶ Ω · cm, the silver particles are self-reduced and sintered under the above firing conditions, and have good ohmic contact with the semiconductor substrate. There is an advantage that (electrical connection) can be formed.

As described above, the electrode composition containing silver particles exhibits excellent characteristics as an electrode of a solar cell element. On the other hand, since silver is a precious metal and the bullion itself is expensive, and because of the problem of resources, a proposal for a material to replace silver is desired.
A promising material that can replace silver is copper that is applied to semiconductor wiring materials. Copper is abundant in terms of resources, and the cost of bullion is as low as about 1/100 of silver. However, copper is a material that is easily oxidized at a high temperature of 200 ° C. or higher in the atmosphere, and it is difficult to form an electrode in the above process.

In order to solve the above-mentioned problems that copper has, copper particles have been reported that give oxidation resistance to copper using various methods and are not easily oxidized even when subjected to high-temperature firing (for example, Japanese Patent Application Laid-Open No. 2005-2005). No. 314755 and Japanese Patent Application Laid-Open No. 2004-217952). In addition, as a method for suppressing the oxidation of copper during firing, a method using an electrode paste composition (electrode composition) containing copper-containing particles and glass particles has also been reported (for example, JP-A 2011 -171272).

Here, the structure of general solar cells and solar cell modules will be described. A general solar cell element has a size of, for example, 125 mm × 125 mm or 156 mm × 156 mm, and produces a small amount of power alone. Therefore, actually, a plurality of solar cell elements are collectively used as a solar cell and a solar cell module. In many cases, solar cells and solar cell modules have a plurality of solar cell elements connected in series and / or in parallel via wiring members electrically connected to the output extraction electrodes on the light receiving surface and the back surface. It has a structure. In addition, since the solar cell module is used in an outdoor environment, the solar cell module includes a plurality of solar cell elements connected via a wiring member as a sealing material in order to ensure resistance to temperature change, wind and rain, snow accumulation, and the like. And sealed. Usually, sealing is performed by a vacuum laminator after a sealing material including tempered glass, an ethylene vinyl acetate (EVA) sheet, a back sheet, and the like is laminated and sandwiched between solar cells having wiring members. In addition, a solar cell element means here what has a semiconductor substrate which has a pn junction, and the electrode formed on the semiconductor substrate. A solar cell means the thing of the state by which the wiring member was provided on the solar cell element and the several solar cell element was connected through the wiring member as needed. A solar cell module means what sealed the solar cell provided with the wiring member with the sealing material so that a part of wiring member in a solar cell may be located in the outer side of a sealing part.

When connecting the electrode of the solar cell element and the wiring member, it is necessary to reduce the electrical contact resistance between the electrode and the wiring member in order to efficiently extract the electric energy converted in the solar cell element to the outside. is there. Furthermore, when producing a solar cell module, in order to prevent the solar cell element from falling off the wiring member in the step of transporting the solar cell in a state where a plurality of solar cell elements are connected by the wiring member, It is necessary to firmly maintain the adhesion between the electrode and the wiring member.

Generally, solder is used to connect the electrode of the solar cell element and the wiring member (see, for example, Japanese Patent Application Laid-Open Nos. 2004-204256 and 2005-050780). Solder is widely used because it is excellent in connection reliability such as conductivity and fixing strength, is inexpensive and versatile. In recent years, lead-free solder has also become widespread as a solder used for connection between the electrode of the solar cell element and the wiring member from the environmental viewpoint.

On the other hand, as a connection method not using solder, a connection method using a conductive paste is disclosed (see, for example, Japanese Patent Laid-Open Nos. 2000-286436, 2001-357897, and 3448924).

However, when lead-free solder is used, since the melting temperature of the solder is usually about 230 ° C. to 260 ° C., the high temperature associated with the connection or the volumetric shrinkage of the solder affects the semiconductor structure of the solar cell element. It may cause deterioration of the performance of the element.
Further, as described in JP-A-2000-286436, JP-A-2001-357897 and JP-A-3448924, there is a method for connecting an electrode of a solar cell element and a wiring member using a conductive paste. The power generation performance may deteriorate significantly with time under high temperature and high humidity conditions, and sufficient connection reliability has not always been obtained.
On the other hand, when the connection between the copper-containing electrode and the wiring member as described in JP 2011-171272 A is performed with solder or a conductive paste, the adhesion between the copper-containing electrode of the solar cell element and the wiring member is insufficient. There was a tendency to.

The present invention has been made in view of the above problems, and has a solar cell, a solar cell module, a component with an electrode, a semiconductor device, and an electronic device having excellent adhesion between the electrode and the wiring member and excellent connection reliability. The purpose is to provide parts.

The present invention is as follows.
<1> a semiconductor substrate having a pn junction;
An electrode part including a metal part and a glass part, and a conductive layer including a resin part;
A wiring member and a wiring connection portion laminated in this order;
The total length of the line X that equally divides the thickness of the electrode portion when observing a region in which the length in the direction perpendicular to the laminating direction of the cross section parallel to the laminating direction of the conductive layer in the wiring connection portion is 100 μm The solar cell in which the portion where the total length of the portion where the electrode portion and the line X overlap with each other is 95% or less is present in at least a part of the wiring connection portion.
<2> The solar cell according to <1>, wherein the metal part includes copper.
<3> The solar cell according to <1> or <2>, wherein the metal part includes a Cu—Sn—Ni alloy phase, and the glass part includes a Sn—PO glass phase.
<4> The solar cell according to <3>, wherein at least a part of the Sn—PO glass phase is disposed between the Cu—Sn—Ni alloy phase and the semiconductor substrate.
<5> The solar cell according to any one of <1> to <4>, wherein the conductive layer includes a heat-treated product of an electrode composition including phosphorus-tin-containing copper alloy particles and glass particles. .
<6> The solar cell according to <5>, wherein the electrode composition further contains nickel particles.
<7> The solar cell according to <5> or <6>, wherein the phosphorus-tin-containing copper alloy particles further contain nickel.
<8> The solar cell according to any one of <5> to <7>, wherein the electrode composition further contains a dispersion medium.
<9> The solar cell according to any one of <1> to <8>, wherein the resin portion includes a cured product of an adhesive.
<10> A solar cell module comprising the solar cell according to any one of <1> to <9> and a sealing material that seals the solar cell.
<11> a support;
An intermediate layer including an inorganic material portion and a resin portion;
The adherend, and a connection portion laminated in this order,
The total length of the line X that equally divides the thickness of the inorganic material portion when observing a region in which the length in the direction perpendicular to the stacking direction of the cross section of the intermediate layer parallel to the stacking direction in the connecting portion is 100 μm The part with an electrode which exists in the part in which the ratio of the total length of the part with which the said inorganic material part and the line | wire X overlap with respect to is 95% or less, and at least one part of the said connection part.
<12> a semiconductor substrate;
An intermediate layer including an inorganic material portion and a resin portion;
The adherend, and a connection portion laminated in this order,
The total length of the line X that equally divides the thickness of the inorganic material portion when observing a region in which the length in the direction perpendicular to the stacking direction of the cross section of the intermediate layer parallel to the stacking direction in the connecting portion is 100 μm The semiconductor device in which a portion where the total ratio of the length of the portion where the inorganic material portion and the line X overlap with each other is 95% or less exists in at least a part of the connection portion.
<13> a support;
An intermediate layer including an inorganic material portion and a resin portion;
The adherend, and a connection portion laminated in this order,
The total length of the line X that equally divides the thickness of the inorganic material portion when observing a region in which the length in the direction perpendicular to the stacking direction of the cross section of the intermediate layer parallel to the stacking direction in the connecting portion is 100 μm An electronic component in which a portion in which the total ratio of the length of the portion where the inorganic material portion and the line X overlap with each other is 95% or less exists in at least a part of the connection portion.

According to the present invention, it is possible to provide a solar cell, a solar cell module, a component with an electrode, a semiconductor device, and an electronic component having excellent adhesion between the electrode and the wiring member and excellent connection reliability.

It is a figure which shows an example of the cross section of the electrode of the solar cell of this invention. It is a figure which shows an example of the cross section of the electrode of the solar cell of this invention. It is a schematic sectional drawing which shows an example of the solar cell element used for the solar cell of this invention. It is a schematic plan view which shows an example of the light-receiving surface side electrode structure of the solar cell element used for the solar cell of this invention. It is a schematic plan view which shows an example of the light-receiving surface side electrode structure of the solar cell element used for the solar cell of this invention. It is a schematic plan view which shows an example of the back surface side electrode structure of the solar cell element used for the solar cell of this invention. It is a schematic plan view which shows an example of the light-receiving surface of the solar cell of this invention. It is a schematic plan view which shows an example of the back surface of the solar cell of this invention. It is a schematic sectional drawing which shows an example of the structure which connected the two solar cells of this invention. It is a figure for demonstrating an example of the manufacturing method of the solar cell module of this invention.

In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. . “˜” indicates a range including numerical values described before and after that as a minimum value and a maximum value, respectively. The amount of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. The term “layer” includes a configuration formed in a part in addition to a configuration formed in the entire surface when observed as a plan view. The term “stacked” indicates that the layers are stacked, and two or more layers may be bonded, or two or more layers may be detachable.

[Solar cell]
The solar cell of the present invention has a wiring connection portion in which a semiconductor substrate having a pn junction, an electrode portion including a metal portion and a glass portion, a conductive layer including a resin portion, and a wiring member are stacked in this order. When the region of the cross section parallel to the stacking direction of the conductive layer in the wiring connection portion having a length of 100 μm in the direction perpendicular to the stacking direction is observed, the line X dividing the thickness of the electrode portion equally A portion where the total ratio of the length of the portion where the electrode portion and the line X overlap with respect to the total length is 95% or less exists in at least a part of the wiring connection portion. By satisfying the above conditions, the solar cell of the present invention is excellent in adhesion between the electrode formed on the semiconductor substrate and the wiring member, and excellent in reliability.

In the present specification, the “wiring connection portion” means a portion in which a semiconductor substrate, a conductive layer, and a wiring member are laminated in this order in a solar cell. The “conductive layer” means an electrode part including a metal part and a glass part, and a resin part, and a part located between the semiconductor substrate and the wiring member. The “cross section parallel to the stacking direction of the conductive layers” means a surface obtained by cutting the solar cell perpendicular to the surface direction of the semiconductor substrate, and is also simply referred to as “cross section” below. The “thickness” of the electrode portion means a distance between the line X1 and the line X2 calculated by a method described later.

The solar cell of the present invention will be described with reference to FIGS. 1A and 1B. FIG. 1A is an observation cross section 100 as an example of the cross section of the electrode of the solar cell of the present invention. As shown in the observation cross section 100, a gap portion 106 exists inside the electrode portion 104 formed on the semiconductor substrate 102, and a part of the gap portion 106 is a central portion in the thickness direction of the electrode portion 104. Exists. For this reason, the ratio of the sum total of the length of the part which the said electrode part and the line X overlap with respect to the full length of the line X which equally divides the thickness of the said electrode part is 95% or less.

It is considered that a part of the gap 106 existing inside the electrode 104 forms open pores and the gap 106 communicates with the electrode surface. For this reason, when the connecting material and the wiring member are arranged on the electrode 104 and pressed, the connecting material enters at least a part of the gap 106 to form a resin portion. In this case, the shape of the interface between the electrode part 104 and the resin part becomes complicated and the contact area between the electrode part 104 and the resin part increases compared to the case where the gap part 106 does not exist inside the electrode part 104, and It is considered that the adhesion between the electrode portion 104 and the wiring member is improved by the expression of the anchor effect. As a result, it is considered that the reliability of the solar cell is improved and further stable power generation performance is exhibited. The gap portion 106 may include a portion that does not form a resin portion without entering the connection material and exists in a void state.

The ratio of the total length of the portion where the electrode portion 104 and the line X overlap with respect to the total length of the line X is 95% or less, preferably 90% or less, and more preferably 85% or less. If the ratio exceeds 95%, the ratio of the voids 106 existing inside the electrode part 104 is insufficient, and good adhesion may not be obtained. The ratio of the total length of the portion where the electrode portion and the line X overlap with respect to the total length of the line X can be obtained by a normal method such as image analysis. For example, image processing software such as “ImageJ” (National Institutes of Health) can be used.

The line X in the observation cross section can be obtained as follows. The solar cell is cut at the wiring connection portion with a diamond cutter or the like, and an electron micrograph of the obtained cross section is taken. Next, a region where the length in the surface direction of the semiconductor substrate in the electron micrograph is 100 μm is taken as an observation cross section. In the observation cross section, the position in the stacking direction of the line X1 parallel to the surface direction of the semiconductor substrate is set such that the area of the electrode portion located on the wiring member side from the line X1 and the line X1 of the portion other than the electrode portion. Further, the area of the portion located on the electrode part side is determined to be equal within a range obtained from the observation cross section. Further, the position in the stacking direction of the line X2 parallel to the surface direction of the semiconductor substrate in the observation cross section is set such that the area of the portion of the semiconductor substrate located on the electrode part side of the line X2 and the line of the portion other than the semiconductor substrate. The area of the portion located closer to the semiconductor substrate than X2 is determined to be equal within a range obtained from the observation cross section. A distance between the line X1 and the line X2, that is, a line that equally divides the thickness of the electrode is defined as a line X. The positional relationship between the line X, the line X1, and the line X2 is shown in FIG. 1B. The positions of the lines X1 and X2 can be determined by a normal method such as image analysis. The size of the electron micrograph shown in FIG. 1B is 100 μm × 38 μm.

The solar cell of the present invention has an electrode portion that occupies the total area of the conductive layer when observing a region whose length in the direction perpendicular to the stacking direction of the cross section parallel to the stacking direction of the conductive layer in the wiring connection portion is 100 μm. It is preferable that a portion where the total area is 90% or less exists in at least a part of the wiring connection part, and it is more preferable that a part where the total area is 85% or less exists in at least a part of the wiring connection part. When a portion where the total area of the electrode portions in the region is 90% or less is present in at least a part of the wiring connection portion, there is a sufficient gap inside the electrode, and there is a gap between the electrode and the wiring member. There is a tendency that good adhesion between them is obtained. The area of the electrode portion in the conductive layer can be determined by an ordinary method such as image analysis from an electron micrograph obtained by photographing a cross section obtained by cutting the solar cell with a diamond cutter or the like at the wiring connection portion.

The solar cell of the present invention is opposed to the wiring member of the electrode part when observing a region where the length in the direction perpendicular to the laminating direction of the cross section parallel to the laminating direction of the conductive layer in the wiring connecting part is 100 μm. It is preferable that a portion where the total length of the contour line on the side to be connected is 105 μm or more is present in at least a part of the wiring connection part, and a part where the total length is 110 μm or more is present in at least a part of the wiring connection part. preferable. In the solar cell of the present invention, when the portion where the total length of the contour line is 105 μm or more is present in at least a part of the wiring connection portion, the surface of the electrode has sufficient unevenness and good adhesion. Tends to be obtained. The total length of the contour line can be obtained by an ordinary method such as image analysis from an electron micrograph of a cross section obtained by cutting the solar cell with a diamond cutter or the like at the wiring connection portion.

The observation cross section can be obtained at any position of the wiring connection part of the solar cell. For example, a cross section in which the conductive layer, the wiring member, and the semiconductor substrate are all continuously observed at least 100 μm in length in the surface direction of the semiconductor substrate is selected.

The solar cell of the present invention can be obtained using, for example, an electrode composition to be described later, a connection material capable of forming a resin portion, and a wiring member. For example, a solar cell can be manufactured by a method including the following steps.

(1) An electrode composition is applied onto the semiconductor substrate and heat-treated (fired) to form an electrode having voids therein.
(2) A connecting material and a wiring member are arranged on the formed electrode and subjected to heat and pressure treatment, and at least a part of the connecting material enters at least a part of the gap of the electrode, and includes a metal part and a glass part. A conductive layer including an electrode portion and a resin portion is formed, and the electrode and the wiring member are bonded.

On the other hand, when the connection between the electrode and the wiring member is made with solder or conductive paste, the adhesion between the electrode and the wiring member is inferior to the case where the connection material is used. This is presumably because even if there is a gap inside the electrode, solder or conductive paste does not enter the gap and the anchor effect cannot be obtained.

The solar cell of the present invention is considered to be capable of expressing a reduction in electrical contact resistance as well as improving adhesion. This can be considered as follows, for example.

As described above, when the connecting material and the wiring member are arranged on the electrode having a gap inside and heated and pressurized, at least a part of the connecting material enters at least a part of the gap. At this time, the amount (volume) of the connection material that enters the void portion is increased as compared with an electrode having a small void portion, such as a silver electrode. As a result, it is considered that the thickness of the resin portion derived from the connection material interposed between the electrode and the wiring member is reduced, and the conductivity is improved.

Furthermore, the conductive layer in the wiring connection part of the solar cell of the present invention includes a part where the electrode part including the metal part and the glass part and the wiring member are in contact, and a part where the resin part and the wiring member are in contact. , May be included. When the conductive layer includes a portion where the electrode portion and the wiring member are in contact with each other, the conductivity tends to be improved. The conductive layer including a portion where the electrode portion and the wiring member are in contact can be obtained, for example, by forming an electrode having a shape having irregularities on the surface. When connecting material and wiring member are placed on such an electrode and heat-pressed, the connecting material flows from the convex part of the electrode surface to the concave part, resulting in a part where the electrode and wiring member are in direct contact There is. As a result, the conductivity is improved and the electrical contact resistance between the electrode and the wiring member is reduced. In the portion where the electrode and the wiring member are in contact, the glass portion may be interposed between the metal portion and the wiring member, or the metal portion and the wiring member may be in direct contact. Furthermore, when the metal part and the wiring member are in direct contact, conductive components such as metal in the electrode and the wiring member are diffused from the contact part, so that the contact part is alloyed and the contact resistance is further reduced. This is also considered as one factor for improving the conductivity.

In the solar cell of the present invention, the electrode (electrode part) preferably contains copper, more preferably contains copper and tin, and further preferably contains copper, tin and nickel. The metal part in the electrode (electrode part) preferably contains a Cu—Sn—Ni alloy phase, and the glass part preferably contains a Sn—PO glass phase, and at least a part of the Sn—PO glass phase. Is preferably disposed between the Cu—Sn—Ni alloy phase and the semiconductor substrate.

<Electrode composition>
Examples of the electrode composition that can be used in the production of the solar cell of the present invention include an electrode composition containing metal-containing particles, glass particles, and a dispersion medium. Hereafter, each component contained in the composition for electrodes used for manufacture of the solar cell of this invention is demonstrated in detail.

(Metal-containing particles)
The composition for electrodes used for manufacturing the solar cell of the present invention contains metal-containing particles. The type of metal-containing particles is not particularly limited, and can be selected from those that can form an electrode having voids inside by heat treatment (firing).

The metal-containing particles preferably contain copper. Copper is excellent in conductivity and inexpensive compared to gold, silver and the like. Since copper is oxidized at a high temperature of 200 ° C. or higher in the atmosphere, it is preferable that copper be given oxidation resistance. Examples of the copper particles imparted with oxidation resistance include copper alloy particles containing phosphorus. By using copper alloy particles containing phosphorus in the electrode composition, it is possible to form an electrode having excellent oxidation resistance and low resistivity by utilizing the reducibility of phosphorus to copper oxide. Further, the electrode can be fired at a low temperature, and the effect that the process cost can be reduced can be obtained. As a copper alloy containing phosphorus, a brazing material used as a bonding agent between copper and copper, which is called phosphorus copper brazing (phosphorus content: about 7% by mass or less), is known.

More preferably, the metal-containing particles are phosphorus-tin-containing copper alloy particles containing phosphorus, tin and copper. By using copper alloy particles further containing tin in addition to phosphorus, an electrode having voids inside can be easily formed. When the electrode composition containing particles containing copper, tin and phosphorus is used as the electrode composition containing metal-containing particles for forming an electrode, the present inventors have made a Cu—Sn alloy by heat treatment (firing). A metal part containing copper and tin such as a phase, a metal part containing copper and tin such as a Cu—Sn alloy phase, and a glass part containing tin, phosphorus and oxygen such as a Sn—PO glass phase are formed respectively. It was found that voids were formed in which neither the metal part nor the glass part was formed. The reason for the generation of voids is not clear, but is thought to be due to the rapid progress of sintering when the Cu—Sn alloy phase forms a dense bulk metal part. That is, it is considered that one of the factors affecting the shape of the electrode on which the behavior during sintering of the metal contained in the metal-containing particles used in the electrode composition is formed. Therefore, it is considered that an electrode having voids therein can be formed by selecting the type or composition of the metal-containing particles used in the electrode composition.

Furthermore, by using an electrode composition containing phosphorus-tin-containing copper alloy particles, oxidation of copper during firing in the atmosphere is suppressed, and an electrode having a low resistivity can be formed. Furthermore, formation of a reactant phase between copper and the semiconductor substrate is suppressed, and a good ohmic contact can be formed between the formed electrode and the semiconductor substrate. This can be considered as follows, for example.

When an electrode composition containing phosphorus-tin-containing copper alloy particles is heat-treated (fired), a Cu—Sn alloy phase is formed by the reaction of copper and tin in the phosphorus-tin-containing copper alloy particles, thereby reducing the resistivity. An electrode can be formed. Since the Cu—Sn alloy phase is produced at a relatively low temperature (for example, about 500 ° C.), the electrode can be fired at a low temperature, and the effect of reducing the process cost can be expected.

Further, when the electrode composition including the phosphorus-tin-containing copper alloy particles is heat-treated (fired), the Cu—Sn alloy phase is maintained while the resistivity is kept low due to the reaction between copper and tin in the phosphorus-tin-containing copper alloy particles. And a Sn—PO glass phase are formed. For example, the Sn—PO glass phase functions as a barrier layer for preventing mutual diffusion of copper and silicon contained in the semiconductor substrate, so that a reactant phase is formed between the electrode containing copper and the semiconductor substrate. Thus, a good ohmic contact is formed between the electrode containing copper and the semiconductor substrate. It can be considered that these two characteristic mechanisms can be realized collectively in a heat treatment (firing) step.

This can be considered as follows, for example.
Copper and tin in the phosphorus-tin-containing copper alloy particles react with each other in the firing step to form an electrode including a Cu—Sn alloy phase as a metal part and a Sn—PO glass phase as a glass part. To do. The Cu—Sn alloy phase forms a dense bulk metal portion between the Cu—Sn alloy phases. This bulk metal portion is formed in the electrode, and functions as a conductive layer, thereby forming an electrode having a low resistivity. The dense bulk body here means a structure in which massive Cu—Sn alloy phases are in close contact with each other and are continuously formed in three dimensions.
On the other hand, the Sn—PO glass phase is formed between the Cu—Sn alloy phase and the silicon substrate. Thus, it can be considered that adhesion of the Cu—Sn alloy phase to the silicon substrate can be obtained.

In addition, since the Sn—PO glass phase functions as a barrier layer for preventing mutual diffusion between copper and silicon, a good ohmic contact between the electrode formed by heat treatment (firing) and the silicon substrate can be obtained. It can be considered that it can be achieved. That is, the formation of a reactant phase (Cu ₃ Si) formed when an electrode containing copper and silicon are directly contacted and heated is suppressed, and silicon performance (for example, pn junction characteristics) is not deteriorated. It is considered that good ohmic contact can be expressed while maintaining adhesiveness with the substrate.
Conventionally, ohmic contact with a silicon substrate has been cited as a problem for applying copper to an electrode of a solar cell element. The formation of Cu ₃ Si may extend to several μm from the interface of the silicon substrate, which may cause cracks on the silicon substrate side and cause performance deterioration of the solar cell element. In addition, the formed Cu ₃ Si lifts the electrode containing copper, and thus the adhesion between the electrode and the silicon substrate may be hindered, resulting in a decrease in the mechanical strength of the electrode. According to the electrode composition, since formation of the reactant phase (Cu ₃ Si) can be suppressed, good ohmic contact properties can be exhibited.

More preferably, the metal-containing particles contain copper, phosphorus, tin, and nickel. Specifically, the combination of phosphorus-tin-containing copper alloy particles and nickel-containing particles, the use of phosphorus-tin-nickel-containing copper alloy particles alone, the combination of phosphorus-tin-nickel-containing copper alloy particles and nickel-containing particles Combinations can be mentioned.

It is considered that when the metal-containing particles contain copper, phosphorus, tin, and nickel, the Cu—Sn alloy phase further reacts with nickel to form a Cu—Sn—Ni alloy phase. Since this Cu—Sn—Ni alloy phase is formed even at a relatively high temperature (for example, 800 ° C.), it is possible to form an electrode having a low resistivity while maintaining oxidation resistance even in a firing process at a higher temperature. Conceivable. That is, by using metal-containing particles containing copper, phosphorus, tin, and nickel, the electrode composition can be heat-treated (fired) at a high temperature.

Further, by using an electrode formed from a composition for an electrode containing metal-containing particles containing copper, phosphorus, tin, and nickel, good ohmic contact between the electrode and the semiconductor substrate while maintaining adhesion to the semiconductor substrate Can be achieved. The Cu—Sn—Ni alloy phase obtained when the electrode composition contains copper, phosphorus, tin, and nickel is similar to the Cu—Sn alloy phase, or between the Cu—Sn—Ni alloy phases, or Cu—Sn. A dense bulk metal portion is formed together with the alloy phase. Note that even if the Cu—Sn alloy phase and the Cu—Sn—Ni alloy phase coexist in the electrode, it is considered that the function (for example, resistivity) of the electrode is not lowered.

Specifically, the electrode composition contains metal-containing particles containing copper, phosphorus, tin, and nickel, so that first, the reducing ability of phosphorus atoms in the copper-particles containing phosphorus-tin-nickel to copper oxide is reduced. , An electrode having excellent oxidation resistance and low resistivity is formed. In addition, by including tin and nickel, a Cu—Sn alloy phase, or a Cu—Sn—Ni alloy phase and a Sn—PO glass phase are formed while the resistivity is kept low. For example, the Sn—P—O glass phase is formed in a three-dimensional continuous structure of a Cu—Sn alloy phase or a Cu—Sn—Ni alloy phase, so that the electrode itself has a dense structure, and as a result, the electrode An improvement in strength is obtained. In addition, since the Sn—PO glass phase functions as a barrier layer for preventing mutual diffusion between copper and silicon, a good ohmic contact is formed between the copper-containing electrode and the silicon substrate. It can be considered that such a characteristic mechanism can be realized collectively in the heat treatment (firing) step.

(Phosphorus particles containing phosphorus-tin)
The phosphorus content contained in the phosphorus-tin-containing copper alloy constituting the phosphorus-tin-containing copper alloy particles is not particularly limited. From the viewpoint of oxidation resistance and electrode resistivity, the phosphorus content is, for example, preferably 2% by mass to 15% by mass, more preferably 3% by mass to 12% by mass, and more preferably 4% by mass. It is more preferable that it is 10% by mass or more. When the phosphorus content in the phosphorus-tin-containing copper alloy is 15% by mass or less, a lower electrode resistivity can be achieved, and the productivity of the phosphorus-tin-containing copper alloy particles tends to be excellent. is there. Moreover, it exists in the tendency which can achieve the outstanding oxidation resistance because it is 2 mass% or more.

The tin content contained in the phosphorus-tin-containing copper alloy constituting the phosphorus-tin-containing copper alloy particles is not particularly limited. From the viewpoint of oxidation resistance and reactivity with copper and phosphorus, for example, it is preferably 5% by mass or more and 30% by mass or less, more preferably 6% by mass or more and 25% by mass or less, and more preferably 7% by mass or more. More preferably, it is 20 mass% or less. When the tin content in the phosphorus-tin-containing copper alloy particles is 30% by mass or less, a sufficient volume of the Cu—Sn alloy phase can be formed, and the resistivity of the electrode tends to decrease. Moreover, it exists in the tendency which can produce reaction with copper and phosphorus uniformly by making tin into 5 mass% or more.

The combination of phosphorus content and tin content contained in the phosphorus-tin-containing copper alloy constituting the phosphorus-tin-containing copper alloy particles is from the viewpoint of oxidation resistance, electrode resistivity and reactivity with copper and phosphorus. For example, the phosphorus content is preferably 2% by mass to 15% by mass and the tin content is preferably 5% by mass to 30% by mass, and the phosphorus content is 3% by mass to 12% by mass. More preferably, the tin content is 6% by mass or more and 25% by mass or less, the phosphorus content is 4% by mass or more and 10% by mass or less, and the tin content is 7% by mass or more and 20% by mass or less. More preferably.

The phosphorus-tin-containing copper alloy is a copper alloy further containing at least one metal atom (hereinafter also referred to as a specific metal atom) selected from the group consisting of silver, manganese and cobalt in addition to phosphorus and tin. It is also preferable. By further including a specific metal atom, a low resistance electrode tends to be formed.
The content rate of the specific metal atom in the copper alloy containing phosphorus, tin, and the specific metal atom can be appropriately selected according to the type and purpose of the specific metal atom. For example, it can be 0.05% by mass to 20% by mass, preferably 0.1% by mass to 15% by mass, and more preferably 1% by mass to 10% by mass. When the content of the specific metal atom is 0.05% by mass or more, the melting point of the alloy particles can be further reduced, and the sintering reaction of the alloy particles in the firing process tends to proceed. Further, when the content of the specific metal atom is 20% by mass or less, the oxidation resistance is improved and an electrode having a low resistivity tends to be formed.

The phosphorus-tin-containing copper alloy may further contain other atoms inevitably mixed other than silver, manganese and cobalt. Other atoms that are inevitably mixed include, for example, Sb, Si, K, Na, Li, Ba, Sr, Ca, Mg, Be, Zn, Pb, Cd, Tl, V, Al, Zr, W, and Mo. Ti, Ni and Au can be mentioned.
The content of other unavoidably mixed atoms contained in the phosphorus-tin-containing copper alloy particles can be, for example, 3% by mass or less in the phosphorus-tin-containing copper alloy particles. From the viewpoint of the resistivity of the electrode, it is preferably 1% by mass or less.

Phosphorus-tin-containing copper alloy particles may be used singly or in combination of two or more. “Use in combination of two or more types of phosphorus-tin-containing copper alloy particles” means that two or more types of phosphorus-tin-containing copper alloys having the same particle shape such as particle diameter and particle size distribution described later, although the component ratio is different When using a combination of particles, two or more types of phosphorus-tin containing two or more types of phosphorus-tin-containing copper alloy particles having the same component ratio but different particle shapes are used. The case where it uses combining copper alloy particle | grains etc. is mentioned.

The particle diameter of the phosphorus-tin-containing copper alloy particles is not particularly limited, but the particle diameter (D50%) when the integrated volume is 50%, for example, is preferably 0.4 μm to 10 μm, and preferably 1 μm to More preferably, it is 7 μm. When the D50% of the phosphorus-tin-containing copper alloy particles is set to 0.4 μm or more, the oxidation resistance tends to be effectively improved. In addition, when the D50% of the phosphorus-tin-containing copper alloy particles is 10 μm or less, the contact area between the phosphorus-tin-containing copper alloy particles in the electrode increases, and the resistivity of the electrode tends to decrease more effectively. It is in. The particle size (D50%) of the phosphorus-tin-containing copper alloy particles is measured by a laser diffraction particle size distribution analyzer (for example, Beckman Coulter, Inc., LS 13 320 type laser scattering diffraction particle size distribution analyzer). The Specifically, phosphorus-tin-containing copper alloy particles are added in a range of 0.01 mass% to 0.3 mass% to 125 g of a solvent (terpineol) to prepare a dispersion. About 100 ml of this dispersion is poured into a cell and measured at 25 ° C. The particle size distribution is measured as a solvent refractive index of 1.48.
The shape of the phosphorus-tin-containing copper alloy particles is not particularly limited, and examples thereof include a substantially spherical shape, a flat shape, a block shape, a plate shape, and a scale shape. From the viewpoint of oxidation resistance and electrode resistivity, it is preferably substantially spherical, flat, or plate-shaped.

When the electrode composition contains phosphorus-tin-containing copper alloy particles, the content of phosphorus-tin-containing copper alloy particles in the electrode composition is not particularly limited, but from the viewpoint of oxidation resistance and electrode resistivity, In the electrode composition, for example, the content is preferably 45% by mass or more and 94% by mass or less, and more preferably 50% by mass or more and 90% by mass or less.

The phosphorus-tin-containing copper alloy can be produced by a commonly used method. Also, the phosphorus-tin-containing copper alloy particles should be prepared using a normal method of preparing metal powder using a phosphorus-tin-containing copper alloy prepared so as to have a desired phosphorus content and tin content. Can do. For example, it can be manufactured by a conventional method using a water atomizing method. For details of the water atomization method, the description of Metal Handbook (Maruzen Co., Ltd. Publishing Division) can be referred to.
Specifically, a desired phosphorus-tin-containing copper alloy particle is produced by dissolving a phosphorus-tin-containing copper alloy, pulverizing this by nozzle spraying, and drying and classifying the obtained powder. Can do. In addition, phosphorus-tin-containing copper alloy particles having a desired particle diameter can be produced by appropriately selecting the classification conditions.

(Phosphorus particles containing phosphorus-tin-nickel)
The phosphorus content contained in the phosphorus-tin-nickel-containing copper alloy constituting the phosphorus-tin-nickel-containing copper alloy particles is not particularly limited. From the viewpoint of oxidation resistance (electrode resistivity) and Sn—PO glass phase-forming ability, the phosphorus content is preferably 2.0% by mass to 15.0% by mass, for example. It is more preferably 5% by mass to 12.0% by mass, and further preferably 3.0% by mass to 10.0% by mass. Since the phosphorus content in the phosphorus-tin-nickel-containing copper alloy is 15.0% by mass or less, the resistivity of the electrode can be reduced, and the production of phosphorus-tin-nickel-containing copper alloy particles It tends to be excellent. When the content is 2.0% by mass or more, an Sn—PO glass phase can be effectively formed, and an electrode having excellent adhesion to a semiconductor substrate and ohmic contact tends to be formed.

The tin content contained in the phosphorus-tin-nickel-containing copper alloy constituting the phosphorus-tin-nickel-containing copper alloy particles is not particularly limited. From the viewpoint of oxidation resistance, reactivity with copper and nickel, and the ability to form a Sn—PO glass phase, the tin content is preferably 3.0% by mass to 30.0% by mass, for example. The content is more preferably 4.0% by mass to 25.0% by mass, and still more preferably 5.0% by mass to 20.0% by mass. When the tin content in the phosphorus-tin-nickel-containing copper alloy is 30.0% by mass or less, a Cu—Sn—Ni alloy phase having a low resistivity tends to be formed. Further, by setting the tin content to 3.0% by mass or more, the reactivity with copper and nickel and the reactivity with phosphorus are improved, and the Cu—Sn—Ni alloy phase and the Sn—PO glass phase respectively. Tends to be formed effectively.

The nickel content in the phosphorus-tin-nickel-containing copper alloy constituting the phosphorus-tin-nickel-containing copper alloy particles is not particularly limited. From the viewpoint of oxidation resistance, for example, it is preferably 3.0% by mass to 30.0% by mass, more preferably 3.5% by mass to 25.0% by mass, and 4.0% by mass to More preferably, it is 20.0 mass%. When the nickel content in the phosphorus-tin-nickel-containing copper alloy is 30.0% by mass or less, a Cu—Sn—Ni alloy phase having a low resistivity tends to be formed effectively. Moreover, it exists in the tendency which can improve the oxidation resistance in a high temperature area | region especially 500 degreeC or more by making nickel content rate 3.0 mass% or more.

The combination of phosphorus content, tin content, and nickel content contained in the phosphorus-tin-nickel-containing copper alloy constituting the phosphorus-tin-nickel-containing copper alloy particles includes oxidation resistance, electrode resistivity, copper From the viewpoint of reactivity with phosphorus and phosphorus, ability to form a Sn—PO glass phase, and adhesion between the electrode and the silicon substrate, the phosphorus content is, for example, 2.0 mass% to 15.0 mass%. And the tin content is preferably 3.0% by mass to 30.0% by mass, and the nickel content is preferably 3.0% by mass to 30.0% by mass, for example. The ratio is 2.5% by mass to 12.0% by mass and the tin content is, for example, 4.0% by mass to 25.0% by mass, and the nickel content is 3.5% by mass. More preferably, it is 25.0% by mass, and the phosphorus content is 3.0% by mass. To 10.0 mass%, tin content is 5.0 mass% to 20.0 mass%, and nickel content is 4.0 mass% to 20.0 mass% Further preferred.

The phosphorus-tin-nickel-containing copper alloy particles are copper alloy particles containing phosphorus, tin, and nickel, but may further contain other atoms inevitably mixed therein. Examples of other atoms inevitably mixed include Ag, Mn, Sb, Si, K, Na, Li, Ba, Sr, Ca, Mg, Be, Zn, Pb, Cd, Tl, V, Al, and Zr. , W, Mo, Ti, Co, Au and Bi.
The content of other atoms inevitably mixed in the phosphorus-tin-nickel-containing copper alloy particles can be, for example, 3% by mass or less in the phosphorus-tin-nickel-containing copper alloy particles. From the viewpoints of oxidation resistance and low electrode resistivity, it is preferably 1% by mass or less.

Phosphorus-tin-nickel-containing copper alloy particles may be used singly or in combination of two or more. “Use in combination of two or more types of phosphorus-tin-nickel-containing copper alloy particles” means that two or more types of phosphorus-tin-containing different particle ratios but the same particle shape such as particle diameter and particle size distribution described later. When nickel-containing copper alloy particles are used in combination, the component ratio is the same, but when two or more types of phosphorus-tin-nickel-containing copper alloy particles having different particle shapes are used in combination, the component ratio and particle shape are both different. A case where a combination of at least one kind of phosphorus-tin-nickel-containing copper alloy particles is used.

The particle diameter of the phosphorus-tin-nickel-containing copper alloy particles is not particularly limited, but the particle diameter (D50%) when the volume integrated from the small diameter side in the particle size distribution is 50% is, for example, 0.4 μm to 10 μm. It is preferably 1 μm to 7 μm. When the D50% of the phosphorus-tin-nickel-containing copper alloy particles is 0.4 μm or more, the oxidation resistance tends to be more effectively improved. By setting the D50% of the phosphorus-tin-nickel-containing copper alloy particles to 10 μm or less, the contact area between the phosphorus-tin-nickel-containing copper alloy particles in the electrode is increased, and the resistivity of the electrode is more effectively reduced. Tend to.

The particle diameter of the phosphorus-tin-nickel-containing copper alloy particles is the same as the method for measuring the particle diameter of the phosphorus-tin-containing copper alloy particles.

The shape of the phosphorus-tin-nickel-containing copper alloy particles is not particularly limited, and may be any of a substantially spherical shape, a flat shape, a block shape, a plate shape, a scale shape, and the like. From the viewpoint of oxidation resistance and reduction in the resistivity of the electrode, the shape of the phosphorus-tin-nickel-containing copper alloy particles is preferably substantially spherical, flat, or plate-shaped.

The phosphorus-tin-nickel-containing copper alloy can be produced by a commonly used method, and the phosphorus-tin-nickel-containing copper alloy particles have a desired phosphorus content, tin content, and nickel content. The phosphor-tin-nickel-containing copper alloy prepared as described above can be used in the same manner as the phosphor-tin-containing copper alloy particles.

(Nickel-containing particles)
The nickel-containing particles are not particularly limited as long as the particles contain nickel. Among these, at least one selected from nickel particles and nickel alloy particles is preferable, and at least one selected from nickel particles and nickel alloy particles having a nickel content of 1% by mass or more is preferable.
The purity of nickel in the nickel particles is not particularly limited. For example, the purity of the nickel particles can be, for example, 95% by mass or more, preferably 97% by mass or more, and more preferably 99% by mass or more.

The nickel alloy particles are not limited as long as they are alloy particles containing nickel. Among these, from the viewpoint of the melting point of the nickel alloy particles and the reactivity with the Cu—Sn alloy phase, the nickel content is preferably, for example, nickel alloy particles having a content of 1% by mass or more, and the nickel content is 3% by mass. % Of nickel alloy particles, more preferably nickel alloy particles having a nickel content of 5% by mass or more, and nickel alloy particles having a nickel content of 10% by mass or more. It is particularly preferred. There is no particular limitation on the upper limit of the nickel content.

Examples of the nickel alloy constituting the nickel alloy particles include a Ni—Fe alloy, a Ni—Cu alloy, a Ni—Cu—Zn alloy, a Ni—Cr alloy, and a Ni—Cr—Ag alloy. In particular, nickel alloy particles containing Ni-58Fe, Ni-75Cu, Ni-6Cu-20Zn, etc. can react uniformly with phosphorus-tin-containing copper alloy particles or phosphorus-tin-nickel-containing copper alloy particles. Can be preferably used. For example, in the case of Ni-AX-BY-CZ, the nickel alloy contains A mass% of element X, B mass% of element Y, and C mass% of element Z in the nickel alloy. It shows that.
In the electrode composition, these nickel-containing particles may be used singly or in combination of two or more.
In the present invention, “use in combination of two or more kinds of nickel-containing particles” means that two or more kinds of nickel-containing particles having the same particle shape such as particle diameter and particle size distribution described later are used in combination although the component ratio is different. In this case, there are cases where two or more kinds of nickel-containing particles having the same component ratio but different particle shapes are used in combination, and two or more kinds of nickel-containing particles having different component ratios and particle shapes are used in combination. .

The nickel-containing particles may further contain other atoms that are inevitably mixed. Examples of other atoms inevitably mixed include Ag, Mn, Sb, Si, K, Na, Li, Ba, Sr, Ca, Mg, Be, Zn, Pb, Cd, Tl, V, Al, and Zr. , W, Mo, Ti, Co, Sn, and Au.
The content of other atoms inevitably mixed in the nickel-containing particles can be, for example, 3% by mass or less in the nickel-containing particles, the melting point, and the phosphorus-tin-containing copper alloy particles or phosphorus-tin. -From the viewpoint of reactivity with nickel-containing copper alloy particles, it is preferably 1% by mass or less.

The particle diameter of the nickel-containing particles is not particularly limited, but as D50%, for example, it is preferably 0.5 μm to 20 μm, more preferably 1 μm to 15 μm, and even more preferably 3 μm to 15 μm. . By setting the particle diameter to 0.5 μm or more, the oxidation resistance of the nickel-containing particles and the nickel-containing particles themselves tends to be improved. Further, the contact area with the phosphorus-tin-containing copper alloy particles or the phosphorus-tin-nickel-containing copper alloy particles is increased by being 20 μm or less, and the phosphorus-tin-containing copper alloy particles or the phosphorus-tin-nickel-containing copper alloy particles The reaction tends to proceed effectively. The method for measuring the particle diameter (D50%) of the nickel-containing particles is the same as the method for measuring the particle diameter of the phosphorus-tin-containing copper alloy particles.
The shape of the nickel-containing particles is not particularly limited, and examples thereof include a substantially spherical shape, a flat shape, a block shape, a plate shape, and a scale shape. From the viewpoint of oxidation resistance and electrode resistivity, it is preferably substantially spherical, flat, or plate-shaped.

In the case where the electrode composition contains nickel-containing particles, the content of nickel-containing particles is not particularly limited. Among them, the content of the nickel-containing particles when the total content of the phosphorus-tin-containing copper alloy particles or the phosphorus-tin-nickel-containing copper alloy particles and the nickel-containing particles is 100% by mass is, for example, 10% by mass or more It is preferably 70% by mass or less, more preferably 12% by mass or more and 55% by mass or less, further preferably 15% by mass or more and 50% by mass or less, and 15% by mass or more and 35% by mass or less. It is particularly preferred.
By setting the content of the nickel-containing particles to 10% by mass or more, the Cu—Sn—Ni alloy phase tends to be formed more uniformly. Further, when the content of the nickel-containing particles is 70% by mass or less, a Cu—Sn—Ni alloy phase having a sufficiently large volume can be formed, and the resistivity of the electrode tends to decrease.

The total content of phosphorus-tin-containing copper alloy particles (or phosphorus-tin-nickel-containing copper alloy particles) and nickel-containing particles added as necessary in the electrode composition is oxidation resistance and electrode resistivity. From this viewpoint, for example, it is preferably 60% by mass or more and 94% by mass or less, and more preferably 64% by mass or more and 88% by mass or less.

(Glass particles)
The composition for electrodes used for manufacturing the solar cell of the present invention contains glass particles. When the electrode composition contains glass particles, adhesion between the electrode and the silicon substrate is improved during heat treatment (firing). Further, particularly in the formation of the electrode on the light-receiving surface side of the solar cell, the silicon nitride layer as the antireflection layer is removed by so-called fire-through during heat treatment (firing), and an ohmic contact between the electrode and the silicon substrate is formed.

The glass particles are preferably glass particles containing glass having a softening temperature of 650 ° C. or lower and a crystallization start temperature exceeding 650 ° C. from the viewpoint of adhesion to a silicon substrate and electrode resistivity. The softening temperature and the crystallization start temperature are measured by a usual method using a differential thermal-thermogravimetric analyzer (TG-DTA).

When the electrode composition is used as an electrode on the light-receiving surface side of the solar cell, the glass particles are softened and melted at the electrode forming temperature to oxidize the silicon nitride contained in the contacted antireflection layer, thereby oxidizing silicon dioxide. As long as the antireflection layer can be removed by incorporating, glass particles that are usually used in the art can be used without particular limitation.

The glass particles contained in the electrode composition preferably contain lead from the viewpoint that silicon dioxide can be efficiently taken up. Examples of the glass containing lead include those described in Japanese Patent No. 3050064. In the present invention, it is also preferable to use lead-free glass that does not substantially contain lead in consideration of the influence on the environment. Examples of the lead-free glass include lead-free glass described in paragraphs 0024 to 0025 of JP-A-2006-313744 and lead-free glass described in JP-A-2009-188281.

When the electrode composition is used as an electrode other than the electrode on the light-receiving surface side of the solar cell, for example, a back surface output extraction electrode, a glass containing a glass having a softening temperature of 650 ° C. or lower and a crystallization start temperature exceeding 650 ° If it is a particle | grain, the glass particle which does not contain the component required for fire through like lead can be used.

As a glass component which comprises the glass particle used for the composition for electrodes, for example, silicon oxide (SiO or SiO ₂ ), phosphorus oxide (P ₂ O ₅ ), aluminum oxide (Al ₂ O ₃ ), boron oxide (B ₂ O ₃ ), vanadium oxide (V ₂ O ₅ ), potassium oxide (K ₂ O), bismuth oxide (Bi ₂ O ₃ ), sodium oxide (Na ₂ O), lithium oxide (Li ₂ O), barium oxide ( BaO), strontium oxide (SrO), calcium oxide (CaO), magnesium oxide (MgO), beryllium oxide (BeO), zinc oxide (ZnO), lead oxide (PbO), cadmium oxide (CdO), tin oxide (SnO) , zirconium oxide _(ZrO 2), tungsten oxide _(WO 3), molybdenum oxide _(MoO 3), lanthanum oxide (La _{2 3),} niobium oxide _{(Nb 2 O} 5), tantalum oxide _{(Ta 2 O} 5), yttrium oxide _{(Y 2 O} 3), titanium oxide _(TiO 2), germanium oxide _(GeO 2), tellurium oxide _(TeO 2) , Lutetium oxide (Lu ₂ O ₃ ), antimony oxide (Sb ₂ O ₃ ), copper oxide (CuO), iron oxide (FeO, Fe ₂ O ₃ or Fe ₃ O ₄ ), silver oxide (AgO or Ag ₂ O) And manganese oxide (MnO).

Among them, it is preferable to use glass particles containing at least one selected from SiO ₂ , P ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , V ₂ O ₅ , Bi ₂ O ₃ , ZnO and PbO, More preferably, glass particles containing at least one selected from SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ and PbO are used. Since such glass particles have improved wettability with metal-containing particles, sintering between the particles proceeds in the firing process, and an electrode with low resistivity can be formed. Moreover, it is possible to obtain the glass particle which has a sufficiently low softening temperature by using the glass particle containing 2 or more types from the above-mentioned.

From the viewpoint of reducing the contact resistivity after electrode formation, glass particles containing phosphorous oxide (phosphate glass, P ₂ O ₅ glass particles) are preferable, and vanadium oxide is further contained in addition to phosphorus oxide. More preferred are glass particles (P ₂ O ₅ —V ₂ O ₅ based glass particles). By further containing vanadium oxide, the oxidation resistance is improved and the resistivity of the electrode is lowered. This can be attributed to, for example, that the softening temperature of the glass is lowered by further containing vanadium oxide. When using phosphorus oxide-vanadium oxide glass particles (P ₂ O ₅ —V ₂ O ₅ glass particles), the vanadium oxide content is preferably 1% by mass or more based on the total mass of the glass, It is more preferably 1% by mass to 70% by mass.

The particle diameter of the glass particles is not particularly limited. For example, the particle diameter (D50%) when the integrated volume is 50% is preferably 0.5 μm or more and 10 μm or less, and more preferably 0.8 μm or more and 8 μm or less. When the thickness is 0.5 μm or more, the workability during production of the electrode composition tends to be improved. Moreover, when it is 10 μm or less, it can be uniformly dispersed in the electrode composition, fire-through can be efficiently generated in the heat treatment (firing) step, and the adhesion to the semiconductor substrate tends to be improved. The method for measuring the particle size (D50%) of the glass particles is the same as the method for measuring the particle size of the phosphorus-tin-containing copper alloy particles.
The shape of the glass particles is not particularly limited, and examples thereof include a substantially spherical shape, a flat shape, a block shape, a plate shape, and a scale shape. From the viewpoint of oxidation resistance and electrode resistivity, it is preferably substantially spherical, flat, or plate-shaped.

The content of the glass particles is, for example, preferably 0.1% to 12% by mass, more preferably 0.5% to 10% by mass, based on the total mass of the electrode composition. More preferably, the content is from 9% to 9% by mass. By including glass particles with a content in such a range, oxidation resistance, low electrode resistivity, and low contact resistance can be achieved effectively, and the reaction between metal-containing particles is effectively promoted. There is a tendency.

In the electrode composition, the ratio (mass ratio) of the content of the glass particles to the total content of the metal-containing particles is preferably 0.01 to 0.18, for example, 0.03 to 0.15. It is more preferable that By including glass particles in such a range of content, oxidation resistance, low electrode resistivity and low contact resistance are effectively achieved, and the reaction between metal-containing particles is effectively promoted. It is in.

(Dispersion medium)
The composition for electrodes used for manufacturing the solar cell of the present invention may contain a dispersion medium. Thereby, the liquid physical property (for example, a viscosity, surface tension) of the composition for electrodes can be adjusted to the required liquid physical property according to the provision method at the time of providing to a semiconductor substrate etc. Examples of the dispersion medium include at least one selected from the group consisting of a solvent and a resin.

The solvent is not particularly limited, and hydrocarbon solvents such as hexane, cyclohexane, and toluene, halogenated hydrocarbon solvents such as dichloroethylene, dichloroethane, and dichlorobenzene, tetrahydrofuran, furan, tetrahydropyran, pyran, dioxane, 1,3-dioxolane, and trioxane. Cyclic ether solvents such as N, N-dimethylformamide, amide solvents such as N, N-dimethylacetamide, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone and cyclohexanone, ethanol, 2 Alcohol solvents such as propanol, 1-butanol, diacetone alcohol, 2,2,4-trimethyl-1,3-pentanediol monoacetate, 2,2,4-trimethyl 1,3-pentanediol monopropionate, 2,2,4-trimethyl-1,3-pentanediol monobutyrate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2, Esters of polyhydric alcohols such as 2,4-triethyl-1,3-pentanediol monoacetate, ethylene glycol monobutyl ether acetate and diethylene glycol monobutyl ether acetate, ethers of polyhydric alcohols such as butyl cellosolve, diethylene glycol monobutyl ether and diethylene glycol diethyl ether Solvent, terpinene such as α-terpinene, terpineol such as α-terpineol, pinene such as α-pinene and β-pinene, myrcene, allocymene, limonene, dipentene, carvone, osimene And terpene solvents such as chelandren, and mixtures thereof.

As the solvent, a polyhydric alcohol ester solvent, a terpene solvent, and the like from the viewpoint of imparting characteristics (coating property, printability, etc.) when the electrode composition is applied onto a semiconductor substrate to form an electrode biolayer. It is preferably at least one selected from the group consisting of polyhydric alcohol ether solvents, and more preferably at least one selected from the group consisting of polyhydric alcohol ester solvents and terpene solvents.
Moreover, in the composition for electrodes used by this invention, a solvent may be used individually by 1 type or in combination of 2 or more types.

As the resin, any resin that can be thermally decomposed by heat treatment (firing) can be used without particular limitation, and a resin that is a natural polymer compound is a synthetic polymer compound. Also good. Specifically, cellulose resins such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and nitrocellulose, polyvinyl alcohol resins, polyvinyl pyrrolidone resins, acrylic resins such as polyethyl acrylate (EPA), vinyl acetate-acrylate copolymers, polyvinyl Examples include butyral resins such as butyral, alkyd resins such as phenol-modified alkyd resin, castor oil fatty acid-modified alkyd resin, epoxy resin, phenol resin, and rosin ester resin.

In the case where the electrode composition contains a resin, it is preferably at least one selected from the group consisting of a cellulose resin and an acrylic resin from the viewpoint of disappearance in heat treatment (firing) treatment. The resins may be used alone or in combination of two or more.

The weight average molecular weight of the resin when the resin is contained in the electrode composition is not particularly limited. Among these, the weight average molecular weight of the resin is, for example, preferably from 5,000 to 500,000, and more preferably from 10,000 to 300,000. It exists in the tendency which can suppress that the viscosity of the composition for electrodes increases that the weight average molecular weight of resin is 5000 or more. If the weight average molecular weight of the resin is 5000 or more, it is considered that the particles can hardly aggregate each other due to the steric repulsion when adsorbed to the metal particles in the electrode composition. On the other hand, when the weight average molecular weight of the resin is 500,000 or less, the resin is suppressed from aggregating in the solvent, and the viscosity of the electrode composition tends to be suppressed from increasing. Further, when the weight average molecular weight of the resin is 500,000 or less, it is suppressed that the combustion temperature of the resin becomes high, and the resin is not burned and remains as a foreign substance when the electrode composition is heat-treated (fired). There is a tendency that an electrode having a low resistivity can be formed.

The content of the dispersion medium in the case where the dispersion medium is contained in the electrode composition can be selected according to the desired liquid properties and the type of the dispersion medium to be used. For example, the content of the dispersion medium is preferably 3% by mass or more and 40% by mass or less, more preferably 5% by mass or more and 35% by mass or less, based on the total mass of the electrode composition, and 7% by mass. More preferably, it is 30 mass% or less.
When the content of the dispersion medium is within the above range, the application suitability when applying the composition for an electrode to a semiconductor substrate is improved, and an electrode having a desired width and height can be easily formed. There is a tendency.
The kind of each of the solvent and the resin in the dispersion medium and the content ratio in the dispersion medium can be selected in consideration of the application method of the electrode composition and the like.

(flux)
The composition for electrodes used for manufacturing the solar cell of the present invention may contain a flux. By including the flux, the oxide film formed on the surface of the metal-containing particles can be removed, and the reduction reaction of the metal-containing particles during the heat treatment (firing) can be promoted. Furthermore, the effect that the adhesiveness of an electrode and a silicon substrate improves is also acquired.

The flux is not particularly limited as long as the oxide film formed on the surface of the metal-containing particles can be removed and the melting of the nickel-containing particles added as necessary is promoted. For example, fatty acids, boric acid compounds, fluorinated compounds, and borofluorinated compounds can be mentioned as preferred fluxes.

Specific examples of the flux include lauric acid, myristic acid, palmitic acid, stearic acid, sorbic acid, stearic acid, propionic acid, boron oxide, potassium borate, sodium borate, lithium borate, potassium borofluoride, borofluoride Sodium, lithium borofluoride, acidic potassium fluoride, acidic sodium fluoride, acidic lithium fluoride, potassium fluoride, sodium fluoride, lithium fluoride and the like can be mentioned.
Among these, potassium borate and potassium borofluoride are preferable from the viewpoint of complementing the heat resistance during electrode heat treatment (firing) (the characteristic that the flux does not volatilize at low temperatures during heat treatment (firing)) and the oxidation resistance of the metal-containing particles. Each of these fluxes may be used alone or in combination of two or more.

As the flux content when the electrode composition contains a flux, the viewpoint of effectively expressing the oxidation resistance of the metal-containing particles and reducing the porosity of the portion where the flux is removed at the completion of the firing of the electrode From the total mass of the electrode composition, for example, it is preferably 0.1% by mass to 5% by mass, more preferably 0.3% by mass to 4% by mass, and 0.5% by mass. It is more preferably from 3.5% by weight, particularly preferably from 0.7% by weight to 3% by weight, and particularly preferably from 1% by weight to 2.5% by weight.

(Other ingredients)
In addition to the above-described components, the electrode composition used in the production of the solar cell of the present invention can further contain other components usually used in the technical field as necessary. Examples of other components include plasticizers, dispersants, surfactants, inorganic binders, metal oxides, ceramics, and organometallic compounds.

The manufacturing method of the composition for electrodes used for manufacturing the solar cell of the present invention is not particularly limited, and metal-containing particles, glass particles, and a dispersion medium or other components added as necessary are usually used for dispersion. It can manufacture by disperse | distributing or mixing using a method or a mixing method. The dispersion method and the mixing method are not particularly limited, and can be selected and applied from commonly used dispersion methods and mixing methods.

<Semiconductor substrate>
The semiconductor substrate used for manufacturing the solar cell of the present invention is not particularly limited. Semiconductor substrates include silicon substrates, gallium phosphide substrates, gallium nitride substrates, diamond substrates, aluminum nitride substrates, indium nitride substrates, gallium arsenide substrates, germanium substrates, zinc selenide substrates, zinc telluride substrates, cadmium telluride substrates. , A cadmium sulfide substrate, an indium phosphide substrate, a silicon carbide substrate, a germanium silicide substrate, a copper indium selenium substrate, and the like.

<Connection material>
The connection material used for manufacturing the solar cell of the present invention includes an adhesive.
As long as the connection material includes an adhesive capable of connecting an electrode formed of the electrode composition and a wiring member described later in the manufacturing process of the solar cell, the shape, material, component content, and the like are particularly limited. Not. Examples of the state of the connecting material include a film form, a paste form, and a solution form. The state of the connection material can be adjusted by the type and content of the components contained in the connection material. From the viewpoints of solar cell production efficiency, handleability, power generation performance stability, etc., the connecting material is preferably in the form of a film.

In the case of forming a film-like connection material, the connection material preferably includes an adhesive, a curing agent, and a film forming material. As such a connection material, for example, a conductive adhesive film described in JP-A-2007-214533 can be exemplified, and these can be suitably used in the present invention. By using such a connection material, it is possible to provide a solar cell and a solar cell module that exhibit stable power generation performance. This can be considered as follows, for example.

When connecting the electrode of the solar cell element and the wiring member using a film-like connection material, since it is possible to connect in a low temperature region around 200 ° C., even when a thin solar cell element is used, the wiring Generation | occurrence | production of the curvature or crack in the case of a connection with a member can be suppressed. Moreover, since no solder seepage occurs during solder connection, the light receiving area of the solar cell element can be increased, and as a result, improvement in power generation performance can be expected.
By using the connection material, it is possible to expect effects such as improvement in power generation performance as described above.

Incidentally, the conductive adhesive film described in JP-A-2007-214533 and the like contains conductive particles, and can exhibit conductivity between the substrates through the conductive particles during thermocompression bonding. The connection material used in the present invention is not limited to this composition, and may not contain conductive particles. That is, when the connection material does not contain conductive particles, the copper-containing electrode and the wiring member can obtain conductivity by directly contacting the connection material at a portion where the connection material is flow-excluded by pressurization.

The connecting material preferably has a viscosity of, for example, 40000 Pa · s or less under conditions of thermocompression bonding of the wiring member. When the viscosity is 40,000 Pa · s or less, the wiring member tends to easily enter the void formed in the electrode during thermocompression bonding. The viscosity of the connecting material is preferably 20000 Pa · s or less, and more preferably 15000 Pa · s or less. In addition, it is preferable that the viscosity of a connection material is 5000 Pa * s or more from the point of the handling in the manufacturing process of a solar cell.
The viscosity of the connecting material can be confirmed using a shear viscometer measuring device (ARES, TA Instruments Japan Co., Ltd.) at 25 ° C. and a frequency of 10 Hz.

(adhesive)
The adhesive preferably exhibits insulating properties. The adhesive exhibiting insulating properties is not particularly limited, but it is preferable to use a thermosetting resin from the viewpoint of adhesion reliability. A well-known thing can be used as a thermosetting resin, For example, an epoxy resin, a phenol resin, a melamine resin, and an alkyd resin are mentioned. Among these, an epoxy resin is preferable from the viewpoint of obtaining sufficient connection reliability.

The content of the adhesive is not particularly limited. From the viewpoint of film formability before curing or adhesive strength after curing, for example, it is preferably 20% by mass or more and 70% by mass or less, and more preferably 30% by mass or more and 60% by mass or less in the connection material. Preferably, it is 40 mass% or more and 50 mass% or less.

(Curing agent)
Examples of the curing agent that can be contained in the connecting material include an anion polymerizable catalyst type curing agent, a cationic polymerizable catalyst type curing agent, and a polyaddition type curing agent. These can be used alone or as a mixture of two or more. Of these, anionic or cationic polymerizable catalyst-type curing agents are preferred because they are excellent in rapid curability and do not require chemical equivalent considerations.

Examples of anionic or cationic polymerizable catalyst-type curing agents include tertiary amine derivatives, imidazole derivatives, hydrazide compounds, boron trifluoride-amine complexes, onium salts (sulfonium salts, ammonium salts, etc.) amine imides, diamino maleonitriles. , Melamine and its derivatives, salts of polyamines, and dicyandiamide, and these modifications can also be used. Examples of the polyaddition type curing agent include polyamines, polymercaptans, polyphenols, and acid anhydrides.
As the anionic or cationic polymerizable catalyst-type curing agent, a tertiary amine derivative or an imidazole derivative is preferably used, and an imidazole derivative is more preferably used in terms of adhesive strength.

As the curing agent, a latent curing agent is preferred because the active point of reaction initiation by thermocompression bonding is relatively clear and suitable for a connection method involving a thermocompression bonding process. Here, the latent curing agent is a substance that exhibits a curing function under certain specific conditions (such as temperature). Examples of the latent curing agent include those obtained by protecting a normal curing agent with microcapsules and the like, and those having a structure in which a curing agent and various compounds form a salt.
For example, when the latent curing agent exceeds a specific temperature, the curing agent is released from the microcapsules or the salt into the system, and exhibits a curing function.

Examples of the latent curing agent include a reaction product of an amine compound and an epoxy compound (amine-epoxy adduct system), a reaction product of an amine compound and an isocyanate compound or a urea compound (urea type adduct system), and the like. Commercial products of latent curing agents include Amicure (Ajinomoto Co., Inc., registered trademark), NovaCure (Asahi Kasei E-Materials Co., Ltd., registered trademark) in which microencapsulated amine is dispersed in phenolic resin, etc. It is done.

The content of the curing agent in the connection material is not particularly limited, but from the viewpoint of adhesive strength, the content of the curing agent when the total content of the adhesive and the curing agent is 100% by mass is, for example, 10% by mass. The content is preferably 50% by mass or less and more preferably 20% by mass or more and 40% by mass or less.

(Film forming material)
Examples of the film forming material include phenoxy resin, acrylic resin, polycarbonate resin, acrylic rubber, polyimide resin, polyamide resin, polyurethane resin, polyester resin, polyester urethane resin, and polyvinyl butyral resin, and are phenoxy resin or acrylic rubber. Is preferred.

The weight average molecular weight of the film forming material is, for example, preferably from 5,000 to 2,000,000, more preferably from 8,000 to 1,000,000, and still more preferably from 10,000 to 1,000,000. The weight average molecular weight of the film forming material can be measured according to a conventional method using a gel permeation chromatography method (GPC).

The content of the film-forming material is not particularly limited, but the total content of the adhesive, the curing agent, and the film-forming material is set to 100 from the viewpoint of the hardness of the produced connection material, ease of peeling from the release film described later, and the like. For example, the content of the film-forming material when it is set to mass% is preferably 20% by mass or more and 80% by mass or less, and more preferably 30% by mass or more and 70% by mass or less.

(Conductive particles)
The connection material can further contain conductive particles. By containing the conductive particles, the power generation performance of the solar cell module can be improved.
The conductive particles are not particularly limited, and examples thereof include gold particles, silver particles, copper particles, nickel particles, gold-plated nickel particles, gold / nickel-plated plastic particles, copper-plated particles, and nickel particles. It is done. When conductive particles are contained, the particle size (D50%) of the conductive particles is, for example, preferably 1 μm to 50 μm, more preferably 1 μm to 30 μm, and preferably 1 μm to 25 μm. Further preferred. The method for measuring the particle size (D50%) of the conductive particles is the same as the method for measuring the particle size of the phosphorus-tin-containing copper alloy particles.
The content of the conductive particles in the connection material is preferably 1% by volume or more and 15% by volume or less, for example, from the viewpoint of conductivity, with the total volume of the connection material being 100% by volume. It is more preferably 12% by volume or less and further preferably 3% by volume or more and 10% by volume or less.

(Other ingredients)
In addition to the components described above, the connecting material can contain a modifying material such as a silane coupling agent, a titanate coupling agent, and an aluminate coupling agent in order to improve adhesion or wettability. Moreover, when adding electroconductive particle, in order to improve the dispersibility, a chelating material etc. for suppressing dispersing agents, such as calcium phosphate and a calcium carbonate, silver, or copper migration, etc. can be contained.

The connecting material can be produced, for example, by applying a coating solution obtained by dissolving or dispersing the above-described various materials in a solvent onto a release film such as a polyethylene terephthalate film and removing the solvent.

<Wiring member>
The wiring member used for manufacturing the solar cell of the present invention is not particularly limited. For example, a solder-coated copper wire (tab wire) for solar cells can be suitably used. Examples of the solder composition include Sn—Pb, Sn—Pb—Ag, and Sn—Ag—Cu. Considering the influence on the environment, it is preferable to use Sn—Ag—Cu based solder which does not substantially contain lead.

The thickness of the copper wire inside the tab wire is not particularly limited. However, from the viewpoint of the difference in thermal expansion coefficient or connection reliability with the solar cell element during the heat and pressure treatment and the resistivity of the tab wire itself, for example, 0. The thickness can be from 05 mm to 0.5 mm, and preferably from 0.1 mm to 0.5 mm.

The cross-sectional shape of the tab line is not particularly limited, and any of the rectangular cross-sectional shape (flat tab) and the elliptical shape (round tab) can be applied. From the viewpoints of penetration into the gap and uniformity of pressure during thermocompression bonding, it is preferable to use tab wires (flat tabs) having a rectangular cross-sectional shape.

The total thickness of the tab wire is not particularly limited, but is preferably 0.1 mm to 0.7 mm, and preferably 0.15 mm to 0.5 mm, for example, from the viewpoint of uniformity of pressure during thermocompression bonding. More preferred.

[Method for manufacturing solar cell]
The manufacturing method of the solar cell of the present invention is not particularly limited as long as the solar cell satisfying the conditions of the present invention can be manufactured. For example, a step of applying the electrode composition onto a semiconductor substrate having a pn junction (referred to as an electrode composition application step) and a heat treatment (firing) of the semiconductor substrate to which the electrode composition is applied form an electrode. A manufacturing process of a solar cell element including a process (referred to as an electrode forming process), a process of stacking a connection material and a wiring member on the electrode of the solar cell element in this order to obtain a stacked body (referred to as a stacking process), and the stacking process. It can be manufactured by a method including a step of heating and pressurizing a body (referred to as a heating and pressing step) and a manufacturing step of a solar cell.
Hereinafter, an example of the manufacturing method of the solar cell of this invention is demonstrated.

(Solar cell element manufacturing process)
A solar cell element is obtained by the electrode composition applying step and the electrode forming step.
In the electrode composition application step, the electrode composition is applied to a region on the semiconductor substrate where the electrode is to be formed. Examples of the method for applying the electrode composition include a screen printing method, an ink jet method, and a dispenser method. From the viewpoint of productivity, application by screen printing is preferable.

When the electrode composition is applied by a screen printing method, the electrode composition preferably has a viscosity in the range of 20 Pa · s to 1000 Pa · s, for example. The viscosity of the electrode composition is measured using a Brookfield HBT viscometer at a temperature of 25 ° C. and a rotation speed of 5.0 rpm (rotation / min, min ⁻¹ ).

The application amount of the electrode composition can be appropriately selected according to the size of the electrode to be formed. For example, the application amount of the electrode composition can be 2 g / m ² to 10 g / m ^2, and preferably 4 g / m ² to 8 g / m ² .

In the electrode forming step, the semiconductor substrate to which the electrode composition has been applied is heat-treated (fired) after drying. Thereby, heat processing (baking) of the composition for electrodes is performed, an electrode is formed in a desired region on the semiconductor substrate, and a solar cell element can be obtained. By using a composition containing metal-containing particles containing at least phosphorus and copper as an electrode composition, a copper-containing electrode having a low resistivity even when heat treatment (firing) is performed in the presence of oxygen (for example, in the air). Can be formed.

As heat treatment (firing) conditions for forming an electrode on a semiconductor substrate using the electrode composition, commonly used heat treatment (firing) conditions can be applied.
In general, the heat treatment (firing) temperature is 800 ° C. to 900 ° C., but when an electrode composition containing metal-containing particles containing at least phosphorus and copper is used, a general heat treatment is performed from a low temperature heat treatment (firing) condition. It can be applied to a wide range up to (firing) conditions. For example, a copper-containing electrode having good characteristics can be formed by heat treatment (firing) performed in a wide temperature range of 450 ° C. to 900 ° C.
The heat treatment (firing) time can be selected according to the heat treatment (firing) temperature and the like, and can be, for example, 1 second to 20 seconds.

The heat treatment apparatus is not particularly limited as long as it can be heated to the above temperature, and examples thereof include an infrared heating furnace and a tunnel furnace. An infrared heating furnace is highly efficient because electric energy is directly input to a heating material in the form of electromagnetic waves and is converted into thermal energy, and rapid heating is possible in a short time. Furthermore, since there is no product due to combustion and non-contact heating, it is possible to suppress contamination of the formed electrode. In the tunnel furnace, the sample is automatically and continuously transferred from the entrance to the outlet and is heat-treated (fired). Therefore, the tunnel furnace can be uniformly heat-treated (fired) by dividing the furnace body and controlling the transfer speed. From the viewpoint of the power generation performance of the solar cell element, it is preferable to perform heat treatment (firing) with a tunnel furnace.

Hereinafter, although the specific example of the solar cell element of this invention and its manufacturing method are demonstrated, referring drawings, this invention is not limited to this. Moreover, the magnitude | size of the member in each figure is notional, The relative relationship of the magnitude | size between members is not limited to this.
A sectional view showing an example of a typical solar cell element, and outlines of a light receiving surface and a back surface are shown in FIGS.
As shown in a schematic cross-sectional view in FIG. 2, an n ⁺ -type diffusion layer 2 is formed near the surface of one surface of the semiconductor substrate 1, and the light-receiving surface output extraction electrode 4 and the reflection are formed on the n ⁺ -type diffusion layer 2. A prevention layer 3 is formed. A p ⁺ type diffusion layer 7 is formed in the vicinity of the surface of the other surface, and a back surface output extraction electrode 6 and a back surface current collecting electrode 5 are formed on the p ⁺ type diffusion layer 7. Usually, single crystal or polycrystalline silicon is used for the semiconductor substrate 1 of the solar cell element. This semiconductor substrate 1 contains boron or the like and constitutes a p-type semiconductor. Irregularities (also referred to as texture, not shown) are formed on the light receiving surface side by an etching solution containing NaOH and IPA (isopropyl alcohol) in order to suppress reflection of sunlight. Phosphorus or the like is diffused (doped) on the light receiving surface side, the n ⁺ -type diffusion layer 2 is provided with a thickness on the order of submicrons, and a pn junction is formed at the boundary with the p-type bulk portion. . Further, on the light-receiving surface side, an antireflection layer 3 such as silicon nitride is provided on the n ⁺ type diffusion layer 2 with a thickness of about 90 nm by plasma-enhanced chemical vapor deposition (PECVD) or the like. .

Next, the light receiving surface output extraction electrode 4 and the light receiving surface current collecting electrode 8 provided on the light receiving surface side schematically shown in FIG. 3, and the back surface collecting electrode 5 and back surface formed on the back surface schematically shown in FIG. A method for forming the output extraction electrode 6 will be described.
The light receiving surface output extraction electrode 4, the light receiving surface current collecting electrode 8 and the back surface output extraction electrode 6 are formed from an electrode composition. The back current collecting electrode 5 is formed of an aluminum electrode composition containing glass powder. As a first method of forming the light receiving surface output extraction electrode 4, the light receiving surface current collecting electrode 8, the back surface output extraction electrode 6 and the back surface current collecting electrode 5, an electrode composition and an aluminum electrode composition are screen printed. And a desired pattern, followed by drying, followed by heat treatment (firing) at about 750 ° C. to 900 ° C. in the air.

At that time, on the light receiving surface side, the glass particles contained in the electrode composition forming the light receiving surface output extraction electrode 4 and the light receiving surface current collecting electrode 8 react with the antireflection layer 3 (fire through). The light receiving surface output extraction electrode 4 and the light receiving surface current collecting electrode 8 and the n ⁺ type diffusion layer 2 are electrically connected (ohmic contact).
In the case where the light receiving surface output extraction electrode 4 and the light receiving surface current collecting electrode 8 are formed using an electrode composition containing metal-containing particles containing at least phosphorus and copper, copper is oxidized while containing copper as a conductive metal. Is suppressed, and a copper-containing electrode having a low resistivity is formed with good productivity.
Further, it is preferable that the copper-containing electrode includes a Cu—Sn alloy phase and / or a Cu—Sn—Ni alloy phase and a Sn—PO glass phase, and the Sn—PO glass phase is Cu— More preferably (not shown) between the Sn alloy phase or the Cu—Sn—Ni alloy phase and the semiconductor substrate. As a result, the reaction between copper and the semiconductor substrate is suppressed, and an electrode having low resistivity and excellent adhesion can be formed.

On the back surface side, aluminum in the aluminum electrode composition that forms the back current collecting electrode 5 during heat treatment (firing) diffuses to the back surface of the semiconductor substrate 1 to form the p ⁺ -type diffusion layer 7. Thus, an ohmic contact can be obtained between the semiconductor substrate 1 and the back surface collecting electrode 5 and the back surface output extraction electrode 6.

As a second method for forming the light receiving surface output extraction electrode 4, the light receiving surface current collecting electrode 8 and the back surface output extracting electrode 6, the aluminum electrode composition for forming the back surface collecting electrode 5 is first printed and dried. After heat treatment (baking) at about 750 ° C. to 900 ° C. in the atmosphere to form the back current collecting electrode 5, the electrode composition is applied to the light receiving surface side and the back surface side, and after drying, 450 ° C. to 650 in the air after drying. A method of forming the light receiving surface output extraction electrode 4, the light receiving surface current collecting electrode 8, and the back surface output extraction electrode 6 by heat treatment (firing) at about 0 ° C. is exemplified.

This method is effective in the following cases, for example. That is, when the aluminum electrode composition for forming the back surface collecting electrode 5 is heat-treated (fired), at a heat treatment (baking) temperature of 650 ° C. or less, the aluminum particles are fired depending on the composition of the aluminum electrode composition. As a result, the amount of aluminum diffused into the semiconductor substrate 1 may be insufficient, and the p ⁺ -type diffusion layer may not be sufficiently formed. In this state, an ohmic contact cannot be sufficiently formed between the semiconductor substrate 1 on the back surface, the back surface collecting electrode 5 and the back surface output extraction electrode 6, and the power generation performance as a solar cell element may be lowered. Therefore, after forming the back current collecting electrode 5 at an optimum heat treatment (firing) temperature (for example, 750 ° C. to 900 ° C.) for the aluminum electrode composition, the electrode composition is applied, and after drying, a relatively low temperature (for example, The light receiving surface output extraction electrode 4, the light receiving surface current collecting electrode 8, and the back surface output extraction electrode 6 are preferably formed by heat treatment (baking) at 450 ° C. to 650 ° C.
Regardless of which method is selected, the thickness of the light receiving surface collecting electrode 8 and the back surface output extraction electrode 6 obtained after the heat treatment (firing) is, for example, 3 μm to 50 μm, preferably 5 μm to 30 μm. Can do. In addition, the thickness of the layer or laminated body in this invention measures the thickness of 5 points | pieces of the layer or laminated body used as object, and is taken as the value given as the arithmetic mean value. The thickness of a layer or a laminated body shall be measured using the micrometer.

As shown in the plan view of FIG. 4, the solar cell element can take a form in which the light receiving surface output extraction electrode 4 is not formed. The solar cell element shown in FIG. 4 can be manufactured in the same manner as the solar cell element having the structure shown in FIGS. This can be considered as follows, for example.

In the present invention, since the connection material is used, the object to which the wiring member is connected does not need solder wettability as described above. In the present invention, by using the connection material, the antireflection layer 3 formed on the semiconductor substrate 1 and the wiring member can be firmly adhered. In addition, since the connection material enters at least a part of the voids existing inside the electrode, the wiring member can be firmly adhered. Further, when the electrode portion and the wiring member are in contact with each other or the connecting material contains conductive particles, electrical connection between the light receiving surface current collecting electrode 8 and the wiring member is made. Will improve.

(Solar cell manufacturing process)
By using the solar cell element obtained as described above, a solar cell including the solar cell element is obtained through a stacking step and a heat and pressure treatment step.
The solar cell of the present invention has a structure in which an electrode part including a metal part and a glass part and a conductive layer including a resin part are interposed between a semiconductor substrate and a wiring member. In the conductive layer, the resin part is formed by entering at least a part of the connecting material into the gap part existing inside the electrode part, and thus the adhesion between the electrode part and the wiring member is excellent.

Next, a specific example of the solar cell of the present invention and a manufacturing method thereof will be described with reference to FIGS. 6 to 8, but the present invention is not limited to this. Moreover, the magnitude | size of the member in each figure is notional, The relative relationship of the magnitude | size between members is not limited to this.
As shown in FIGS. 6 to 8, a connection body 10 and a wiring member 9 are arranged in this order on the light receiving surface output extraction electrode 4 and the back surface output extraction electrode 6 to obtain a laminate (lamination process). By subjecting the laminated body to heat pressure treatment (thermocompression treatment), the light receiving surface output extraction electrode 4 and the wiring member 9 are pressure bonded, and the back surface output extraction electrode 6 and the wiring member 9 are pressure bonded to form a solar cell. Is done. When connecting a plurality of solar cells, the wiring member 9 has one end of the light receiving surface output extraction electrode 4 of the solar cell element and the other end of the wiring member 9 and the back surface output extraction electrode 6 of another solar cell element. It may be arranged so as to be connected through the. In the case of manufacturing a solar cell, a solar cell element in which the light receiving surface output extraction electrode 4 is not formed can be used as shown in FIG.

When manufacturing a solar cell, as a condition for thermocompression bonding of the electrode and the wiring member, a heat and pressure treatment condition usually used in the technical field can be applied.
In general, the heating temperature is preferably 150 ° C. or higher and 200 ° C. or lower, and more preferably 150 ° C. or higher and 190 ° C. or lower. The pressure during pressure bonding is preferably 0.1 MPa or more and 4.0 MPa or less, and more preferably 0.5 MPa or more and 3.5 MPa or less. The time for the heat and pressure treatment is preferably 3 seconds or longer and 30 seconds or shorter, and more preferably 4 seconds or longer and 20 seconds or shorter. By heating and pressurizing under the above conditions, the connection material can easily enter the voids of the copper-containing electrode, the adhesive force between the electrode and the wiring member is improved, and the connection material is efficiently flow-excluded. The electrode and the wiring member can be easily in direct contact with each other, and as a result, the electrical contact resistance between the electrode and the wiring member can be reduced.
The direction of pressurization may be any direction as long as pressure is applied at least in the stacking direction of the electrode and the wiring member to bond the electrode and the wiring member.

As the thermocompression bonding apparatus, any apparatus capable of applying the above temperature and pressure can be used as appropriate. For example, a thermocompression bonding machine including a pressure bonding head having a heating mechanism can be suitably used. In this case, it is particularly preferable that the pressure of the pressure-bonding head ((target pressure) × (adhesion area)) can be appropriately set from the target pressure and the adhesion area.

[Solar cell module]
The solar cell module of the present invention includes the solar cell of the present invention, and a sealing material that seals the solar cell so that a part of the wiring member in the solar cell is located outside the sealing portion, Have In the solar cell module, for example, a plurality of solar cells are connected in series and / or in parallel as necessary, sandwiched with tempered glass for environmental resistance, and the gap is filled with a transparent resin and sealed The thing provided with the wiring member located in the outer side of the part as an external terminal is included.

As a manufacturing method of a solar cell module, for example, as shown in FIG. 9, a glass plate 11, a sealing material 12, a solar cell 14 provided with a wiring member 9, a sealing material 12, and a back sheet 13 are used. A general method including a sealing step that is arranged in this order and is sealed with a vacuum laminator or the like can be suitably used. Lamination conditions are determined depending on the type of sealing material, but are preferably maintained at 130 ° C. to 160 ° C. for 3 minutes or more, more preferably 135 ° C. to 150 ° C. for 3 minutes or more.

Examples of the glass plate 11 include white plate tempered glass with dimples for solar cells. Examples of the sealing material 12 include an EVA sheet containing ethylene vinyl acetate (EVA). Examples of the back sheet 13 include polyethylene terephthalate (PET) -based or Tedlar-PET laminated material, metal foil-PET laminated material, and the like.

[Parts with electrodes]
The component with an electrode according to the present invention has a connection part in which a support, an intermediate layer including an inorganic material part and a resin part, and an adherend are stacked in this order, and the intermediate layer in the connection part When observing a region having a length of 100 μm in a direction perpendicular to the stacking direction in a cross section parallel to the stacking direction, the inorganic material portion and the line X with respect to the total length of the line X equally dividing the thickness of the inorganic material portion A portion where the total length of the overlapping portions is 95% or less is present in at least a part of the connecting portion.

The electrode-equipped parts of the present invention have excellent adhesion and excellent connection reliability between the inorganic material part and the adherend by having the above configuration. The support is not particularly limited and can be selected depending on the application. For example, the semiconductor substrate used for the solar cell mentioned above, a ceramic substrate, a glass substrate etc. can be mentioned. The adherend is not particularly limited and can be selected according to the application. For example, the wiring member used for the solar cell mentioned above, the circuit member which has a circuit, or an electrode part etc. can be mentioned. The composition in particular of the inorganic material part and resin part which comprise an intermediate | middle layer is not restrict | limited, For example, the composition of the electrode part and resin part in a solar cell mentioned above can be mentioned. The detailed description of the electrode-equipped component of the present invention can be applied by replacing the corresponding constituent requirement as the constituent requirement of the electrode-equipped component in the detailed description of the solar cell described above. The application of the electrode-equipped component of the present invention is not particularly limited, and can be used for various electronic devices.

[Semiconductor device]
The semiconductor device of the present invention has a connection portion in which a semiconductor substrate, an intermediate layer including an inorganic material portion and a resin portion, and an adherend are stacked in this order, and the stack of the intermediate layers in the connection portion When observing a region having a length of 100 μm in a direction perpendicular to the stacking direction of a cross section parallel to the direction, the inorganic material part and the line X with respect to the total length of the line X equally dividing the thickness of the inorganic material part are A part where the total length of the overlapping parts is 95% or less is present in at least a part of the connection part. The semiconductor device of the present invention has excellent adhesion and excellent connection reliability between the inorganic material portion and the adherend by having the above structure. The detailed description of the semiconductor substrate, the inorganic material part, the resin part, and the adherend constituting the semiconductor device of the present invention is the same as the above-described detailed description of the solar cell and the electrode-equipped component. It can be read and applied as a requirement. The application of the semiconductor device of the present invention is not particularly limited, and can be used for various electronic devices.

[Electronic parts]
The electronic component of the present invention has a connection part in which a support, an intermediate layer including an inorganic material part and a resin part, and an adherend are laminated in this order, and the lamination of the intermediate layer in the connection part When observing a region having a length of 100 μm in a direction perpendicular to the stacking direction of a cross section parallel to the direction, the inorganic material part and the line X with respect to the total length of the line X equally dividing the thickness of the inorganic material part are A part where the total length of the overlapping parts is 95% or less is present in at least a part of the connection part. The electronic component of the present invention has excellent adhesion between the inorganic material portion and the adherend and excellent connection reliability by having the above configuration. The detailed description of the support, the inorganic material part, the resin part, and the adherend constituting the electronic component of the present invention is the same as the detailed description related to the solar cell and the electrode-attached component described above. It can be read and applied as a requirement. The application of the electronic component of the present invention is not particularly limited, and can be used for various electronic devices.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these embodiments.

<Example 1>
(A) Preparation of electrode composition A phosphorus-tin-containing copper alloy containing 6% by mass of phosphorus and 15% by mass of tin was prepared by a conventional method, dissolved, powdered by a water atomization method, and then dried. And classified. For classification, a forced vortex classifier (turbo classifier; TC-15, Nissin Engineering Co., Ltd.) was used. The classified powders were mixed, deoxygenated and dehydrated to produce phosphorus-tin-containing copper alloy particles containing 6% by mass phosphorus and 15% by mass tin. The particle diameter (D50%) of the phosphorus-tin-containing copper alloy particles was 5.0 μm, and the shape thereof was substantially spherical.

Silicon _(SiO 2) 3 parts by weight dioxide, lead oxide (PbO) 60 parts by mass, 18 parts by weight of boron oxide _{(B 2} O 3), bismuth oxide _{(Bi 2 O} 3) 5 parts by weight, aluminum oxide _(Al 2 _{O 3} ) 5 parts by mass and 9 parts by mass of zinc oxide (ZnO) (hereinafter, sometimes abbreviated as “G01”) were prepared. The obtained glass G01 had a softening temperature of 420 ° C. and a crystallization start temperature of over 650 ° C. By using the obtained glass G01, glass G01 particles having a particle diameter (D50%) of 2.5 μm were obtained. The shape was substantially spherical.

The shapes of the phosphorus-tin-containing copper alloy particles and the glass particles were determined by observing with a scanning electron microscope (Hitachi High-Technologies Corporation, TM-1000 type). The particle diameters of the phosphorus-tin-containing copper alloy particles and glass particles were calculated using a laser scattering diffraction particle size distribution analyzer (Beckman Coulter, LS 13, 320 type, measurement wavelength: 630 nm). The glass softening temperature and crystallization onset temperature were determined from a differential heat (DTA) curve using a differential thermal-thermogravimetric simultaneous measurement apparatus (Shimadzu Corporation, DTG-60H type). Specifically, in the DTA curve, the softening point can be estimated from the endothermic part, and the crystallization start temperature can be estimated from the heat generating part.

72.0 parts by mass of the phosphorus-tin-containing copper alloy particles obtained above, 8.0 parts by mass of glass G01 particles, 20.0 parts by mass of diethylene glycol monobutyl ether (BC), and polyethyl acrylate (EPA) Was mixed using an automatic mortar kneader to make a paste, and an electrode composition 1 was prepared. When the viscosity of the obtained composition 1 for electrodes was measured on the conditions of the temperature of 25 degreeC, and rotation speed 5.0rpm using the Brookfield HBT viscometer, it was 31 Pa.s.

(B) Preparation of connecting material Acrylic rubber (product name: KS8200H, Hitachi Chemical Co., Ltd.) obtained by copolymerizing 40 parts by mass of butyl acrylate, 30 parts by mass of ethyl acrylate, 30 parts by mass of acrylonitrile, and 3 parts by mass of glycidyl methacrylate. Co., Ltd.), 125 g of weight average molecular weight: 850,000) and 50 g of phenoxy resin (product name: PKHC, Union Carbide, weight average molecular weight 45,000) are dissolved in 400 g of ethyl acetate to obtain a 30% by mass solution. It was. Next, 325 g of a liquid epoxy resin (Novacure HX-3941HP, Asahi Kasei E-Materials Co., Ltd., epoxy equivalent 185) containing a microcapsule type latent curing agent was added to this solution and stirred to obtain an adhesive composition. It was. Further, 56 g of Ni particles having a diameter of about 10 μm were added to the adhesive composition and stirred.

The adhesive composition obtained above was applied onto a polyethylene terephthalate film using an applicator (YOSHIMITSU SEIKI, Irie Shokai Co., Ltd.), and dried on a hot plate at a temperature of 70 ° C. for 10 minutes. A connection material 1 having a thickness of 25 μm was prepared. The thickness of the connection material was measured using a micrometer (Mitutoyo Corporation, ID-C112). The viscosity of the connecting material 1 was 9800 Pa · s when measured under the conditions of 25 ° C. and a frequency of 10 Hz using a shear viscometer (ARES) (TA Instruments Japan Co., Ltd.). It was.

(C) Production of Solar Cell Element The electrode composition 1 and the connection material 1 obtained in the above (a) and (b) were prepared as an electrode connection set.
Further, in addition to the electrode connection set, as a wiring member, a solder-plated rectangular wire for a solar cell (product name: SSA-TPS L 0.2 × 1.5 (10), thickness 0.2 mm × width 1.5 mm) Hitachi Metals Co., Ltd., which has a specification in which Sn—Ag—Cu-based lead-free solder is plated on a single side to a thickness of 10 μm, was prepared on a copper wire.
Using these, solar cell elements were produced as follows.

First, a p-type silicon substrate having a thickness of 190 μm in which an n ⁺ -type diffusion layer, a texture, and an antireflection layer (silicon nitride layer) were formed on the light receiving surface was prepared, and two pieces were cut into a size of 125 mm × 125 mm. The electrode composition 1 was printed on the light receiving surface by screen printing so as to form an electrode pattern as shown in FIG. The electrode pattern is composed of a light receiving surface collecting electrode having a width of 150 μm and a light receiving surface output extraction electrode having a width of 1.5 mm, and the thickness of each of the light receiving surface collecting electrode and the light receiving surface output extraction electrode after heat treatment (firing) is 20 μm. The printing conditions (screen plate mesh, printing speed, printing pressure, etc.) were adjusted so that This was placed in an oven heated to 150 ° C. for 15 minutes, and the solvent was removed by evaporation.

Subsequently, an electrode composition 1 as an electrode composition and an aluminum electrode composition (PVG Solutions Inc., PVG-AD) on a surface opposite to the light-receiving surface (hereinafter also referred to as “back surface”). −02) was printed by screen printing in the same manner as described above so as to obtain an electrode pattern as shown in FIG.
The pattern of the back surface output extraction electrode formed using the electrode composition 1 was composed of 123 mm × 5 mm, and was printed in two places in total. The printing conditions (screen plate mesh, printing speed, printing pressure, etc.) were adjusted so that the thickness of the back surface output extraction electrode after heat treatment (firing) was 20 μm. Moreover, the composition for aluminum electrodes was printed on the whole surface except the back surface output extraction electrode, and the back surface current collection electrode pattern was formed. The printing conditions (screen plate mesh, printing speed, printing pressure, etc.) of the aluminum electrode composition were adjusted so that the thickness of the back surface collecting electrode after heat treatment (firing) was 20 μm. This was placed in an oven heated to 150 ° C. for 15 minutes, and the solvent was removed by evaporation.

Subsequently, using a tunnel furnace (Noritake Co., Ltd., single row W / B tunnel furnace), heat treatment (firing) was performed at a maximum temperature of 800 ° C. and a holding time of 10 seconds (firing) in an air atmosphere. Thus, two solar cell elements 1 on which desired electrodes were formed (one for peel strength evaluation and one for power generation performance evaluation) were produced.

The connection material 1 is cut into the width (1.5 mm) of the light receiving surface output extraction electrode of the solar cell element 1, and between the prepared wiring member and the light receiving surface output extraction electrode and the back surface output extraction electrode of the solar cell element 1. In each, the cut connection material 1 was disposed. Next, using a thermocompression bonding machine (device name: MB-200WH, Hitachi Chemical Co., Ltd.), thermocompression bonding is performed under the conditions of 180 ° C., 2 MPa, 10 seconds, and the electrode and the wiring member are connected via the connection material 1. Two solar cells 1 having the above structure were produced.

(D) Production of solar cell module About one of the obtained solar cells 1 (one for power generation performance evaluation), tempered glass (product name: white plate tempered glass 3KWE33, Asahi Glass Co., Ltd.), ethylene vinyl acetate (EVA) and back sheet, as shown in FIG. 9, glass (glass plate 11) / EVA (sealing material 12) / solar cell 1 (solar cell 14) / EVA (sealing material 12) / back The sheets (back sheet 13) were laminated in this order. Using this laminate, a vacuum laminator (device name: LM-50 × 50, NPC Corporation) was used for 5 minutes at a temperature of 140 ° C. so that a part of the wiring member was located outside the sealed portion. The solar cell module 1 was produced by vacuum lamination.

The composition of the electrode composition 1 is shown in Table 1, and the configurations of the solar cell 1 and the solar cell module 1 are shown in Table 2 and Table 3, respectively. The same applies hereinafter.
In Table 2 and Table 3, “◯” in the column of “Applied electrode” means that the target electrode is used, and “-” means that the target electrode is not used. Means that. “-” In the other columns means that there is no corresponding item.

<Examples 2 to 5>
In Example 1, phosphorus content of copper alloy particles, tin content and nickel content, particle size (D50%) and content thereof, composition of nickel-containing particles, particle size (D50%) and content thereof, glass Composition 1 for electrodes except having changed the kind of particle | grain, particle diameter (D50%) and its content, the kind and content of a solvent, and the kind and content of resin as shown in Table 1. In the same manner, electrode compositions 2 to 5 were prepared.
The glass G02 is, ₍₂ O 5 V) 45 parts by weight of vanadium oxide, 24.2 parts by weight of phosphorus oxide _{(P 2} O 5), barium oxide (BaO) 20.8 parts by mass, antimony oxide _(Sb 2 _{O 3} ) 5 parts by mass and tungsten oxide (WO ₃ ) 5 parts by mass. The softening temperature of this glass G02 was 492 ° C., and the crystallization start temperature exceeded 650 ° C.

Then, using the obtained electrode compositions 2 to 5, respectively, except that the heat treatment (firing) conditions (maximum temperature and holding time) and the like were changed to the conditions shown in Tables 2 and 3, respectively. Thus, solar cell elements 2 to 5, solar cells 2 to 5 and solar cell modules 2 to 5 were produced, respectively.

<Example 6>
In Example 1, a solar cell 6 and a solar cell module 6 were produced in the same manner as in Example 1 except that the connection material was changed from the connection material 1 to the connection material 2. The connection material 2 was produced in the same manner as the connection material 1 except that it did not contain Ni particles as conductive particles. The viscosity of the connecting material 2 was 9500 Pa · s as measured in the same manner as the connecting material 1.

<Example 7>
In Example 1, the electrode composition 1 was applied to form the light receiving surface current collecting electrode and the light receiving surface output extraction electrode, and the back surface output extraction electrode was formed as follows. Except having applied the electrode composition 6, it carried out similarly to Example 1, and produced the solar cell element 7, the solar cell 7, and the solar cell module 7, respectively.

The electrode composition 6 was prepared in the same manner as the electrode composition 5 except that the composition of the glass particles was changed from the glass G01 to the glass G03 shown below.
The glass G03 is composed of 13 parts by mass of silicon dioxide (SiO ₂ ), 58 parts by mass of boron oxide (B ₂ O ₃ ), 38 parts by mass of zinc oxide (ZnO), 12 parts by mass of aluminum oxide (Al ₂ O ₃ ), and It prepared so that it might consist of 12 mass parts of barium oxide (BaO). The obtained glass G03 had a softening temperature of 583 ° C. and a crystallization start temperature of over 650 ° C.

<Example 8>
In Example 7, a solar cell element 8, a solar cell 8, and a solar cell were formed in the same manner as in Example 7 except that the electrode composition 7 shown below was applied to form the back surface output extraction electrode. Modules 8 were produced respectively.

The electrode composition 7 was prepared in the same manner as the electrode composition 5 except that the composition of the glass particles was changed from the glass G01 to the glass G04 shown below.
Glass G04 was prepared so as to consist of 12.8 parts by mass of boron oxide, 8.7 parts by mass of silicon dioxide, and 78.5 parts by mass of bismuth oxide. The softening temperature of this glass G04 was 451 ° C., and the crystallization start temperature exceeded 650 ° C.

<Example 9>
In Example 1, an electrode composition 8 was prepared in the same manner as in Example 1 except that the solvent and the resin of the electrode composition 1 were changed as shown in Table 1. Subsequently, using this, a solar cell element 9, a solar cell 9, and a solar cell module 9 were respectively produced in the same manner as in Example 1.
The solvent Ter in the table represents terpineol, and the resin EC represents ethyl cellulose.

<Example 10>
A p-type silicon substrate having a thickness of 190 μm in which an n ⁺ -type diffusion layer, a texture, and an antireflection layer (silicon nitride layer) were formed on the light receiving surface was prepared, and two pieces were cut into a size of 125 mm × 125 mm. Thereafter, an aluminum electrode composition (PVG Solutions, PVG-AD-02) was printed on the back surface to form a back surface collecting electrode pattern. The back surface collecting electrode pattern was printed on the entire surface other than the back surface output extraction electrode as shown in FIG. Further, the printing conditions (screen plate mesh, printing speed, printing pressure, etc.) of the aluminum electrode composition were adjusted so that the thickness of the back surface collecting electrode after heat treatment (firing) was 30 μm. This was placed in an oven heated to 150 ° C. for 15 minutes, and the solvent was removed by evaporation.
Subsequently, using a tunnel furnace (Noritake Co., Ltd., single-row transport W / B tunnel furnace), heat treatment (firing) was performed at a maximum temperature of 800 ° C. and a holding time of 10 seconds (firing) in an air atmosphere. Then, a current collecting electrode on the back surface and a p ⁺ type diffusion layer were formed.

Thereafter, the electrode composition 1 obtained as described above was printed in a pattern of the light receiving surface current collecting electrode, the light receiving surface output extraction electrode, and the back surface output extraction electrode shown in FIGS. 3 and 5. The electrode pattern is composed of a light receiving surface collecting electrode having a width of 150 μm and a light receiving surface output extraction electrode having a width of 1.5 mm, and printing conditions (screen plate mesh, Printing speed, printing pressure, etc.) were adjusted. The pattern of the back surface output extraction electrode was 123 mm × 5 mm, and was printed in two places in total. The printing conditions (screen plate mesh, printing speed, printing pressure, etc.) were adjusted so that the thickness after heat treatment (firing) was 20 μm. This was placed in an oven heated to 150 ° C., and the solvent was removed by evaporation.

Next, using a tunnel furnace (Noritake Co., Ltd., 1-row transport W / B tunnel furnace), heat treatment (firing) was performed in an air atmosphere at a maximum heat treatment (firing) temperature of 650 ° C. and a holding time of 10 seconds. Two solar cell elements 10 on which desired electrodes were formed were produced. Thereafter, in the same manner as in Example 1, a solar cell 10 and a solar cell module 10 were produced.

<Example 11>
Example 10 is the same as Example 10 except that the electrode composition for forming the light receiving surface collecting electrode, the light receiving surface output extraction electrode, and the back surface output extraction electrode is changed to the electrode composition 5. Thus, two solar cell elements 11 were produced. Thereafter, in the same manner as in Example 10, a solar cell 11 and a solar cell module 11 were produced.

<Example 12>
In Example 5, the solar cell 12 and the solar cell module 12 were formed in the same manner as in Example 5 except that the light receiving surface output extraction electrode was not formed and the light receiving surface electrode pattern as shown in FIG. 4 was applied. Produced.

<Comparative Example 1>
In the production of the solar cell in Example 1, the solar cell C1 and the solar cell were obtained in the same manner as in Example 1 except that solder melting was used to connect the light receiving surface output extraction electrode and the back surface output extraction electrode to the wiring member. Battery module C1 was produced. Specifically, flux (product name: Deltalux, Senju Metal Industry Co., Ltd.) is applied to the electrode surface of the solar cell element 1, and then Sn—Ag—Cu based lead-free solder is melted at a temperature of 240 ° C. Then, wiring members were arranged and connected.

<Comparative example 2>
In the preparation of the electrode composition in Example 1, as shown in Table 1, an electrode composition C1 using silver particles was prepared without using copper alloy particles. Except having used the composition C1 for electrodes, it carried out similarly to Example 1, and produced the solar cell element C2, the solar cell C2, and the solar cell module C2.

<Comparative Example 3>
In the production of the solar cell in Example 1, the solar cell was formed in the same manner as in Example 1 except that the following conductive paste was used to connect the light receiving surface output extraction electrode and the back surface output extraction electrode to the wiring member. Battery C3 and solar cell module C3 were produced.
Specifically, 78.0 parts by mass of silver particles (particle diameter (D50%) 3.0 μm; purity 99.8% by mass), 3.5 parts by mass of polyethylenedioxythiophene, and 1.2 parts by mass of epoxy resin 17.3 parts by weight of N-methyl-2-pyrrolidone (NMP) were mixed and pasted using an automatic mortar kneader to prepare a conductive paste. Next, a conductive paste is applied to the electrode surface of the solar cell element, and a wiring member (SSA-TPS L 0.2 × 1.5 (10)) is disposed thereon, and this is heated at a temperature of 150 ° C. for 15 minutes. Then, the conductive paste was cured, and the solar cell element electrode and the wiring member were connected.
In Table 1, “part” represents “part by mass”, and “%” represents “% by mass”.

 

 

 

 

 

 

<Evaluation>
(Cross-sectional shape)
For one of the produced solar cells, a portion (wiring connection portion) to which the wiring member is connected is connected to the solar cell element 1 and the wiring member using a diamond cutter (Refinetech Co., Ltd., RCO-961 type). It cut | disconnected in parallel with respect to the lamination direction. An SEM photograph of the obtained cross section was obtained using SEM (Hitachi High-Technologies Corporation, TM-1000 scanning electron microscope).

The SEM photograph has a rectangular shape of 300 μm × 250 μm when the length in the cutting direction is the height and the length in the direction parallel to the cutting direction is the width, and the semiconductor substrate, the conductive layer, and the wiring material are all What was observed continuously over the whole 300 micrometer of the width direction was used. A region having a length in the width direction of 100 μm in the SEM photograph was taken as an observation cross section. In the observation cross section, the position in the height direction of the line X1 parallel to the width direction is set such that the area of the portion of the electrode portion located on the wiring member side from the line X1 and the portion of the portion other than the electrode portion than the line X1. The area of the portion located on the electrode part side was determined to be equal within the range obtained from the observation cross section. The position in the height direction of the line X2 parallel to the width direction is set so that the area of the portion of the semiconductor substrate located on the electrode portion side of the line X2 and the portion other than the semiconductor substrate closer to the semiconductor substrate side of the line X2 It was determined that the area of the portion to be positioned was equal within the range obtained from the observation cross section. A distance between the line X1 and the line X2, that is, a line that equally divides the thickness of the electrode was defined as a line X. Next, the total ratio of the length of the portion where the electrode portion and the line X ′ overlap with respect to the total length of the line X (electrode portion occupancy) was calculated using image processing software “ImageJ” (manufactured by National Institutes of Health). The results are shown in Table 4.

<Evaluation>
(Peel strength)
For one of the produced solar cells, the peel strength of the wiring member connected to the light receiving surface output extraction electrode and the back surface output extraction electrode was measured. The peel strength of the wiring member was determined by measuring the 90 ° peel adhesion strength of the wiring member using a desktop peel tester (device name: EZ-S, Shimadzu Corporation). The measurement was performed in accordance with JIS K 6854-1: 1999 (adhesive-peeling adhesion strength test method), and the tensile speed of the wiring member was 50 mm / min and the tensile distance of the wiring member was 100 mm. For each test, a wiring member tensile distance-test force curve was plotted, and the average value of the test force at tensile distances of 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm was taken as the peel adhesion strength. The obtained values are converted into relative values with the measured value of Comparative Example 1 (solar cell C1) as 100.0 and are shown in Table 4.

(Power generation performance)
About another one of the produced solar cells, a solar cell module was produced as described above, and the power generation performance was evaluated. Evaluation was made using simulated sunlight (device name: WXS-155S-10, Wacom Denso Co., Ltd.) and voltage-current (IV) evaluation measuring device (device name: IV CURVE TRACER MP-160, Hidehiro) The measurement device of Seiki Co.) was used in combination. Jsc (short-circuit current), Voc (open circuit voltage), FF (fill factor), and Eff (conversion efficiency), which indicate power generation performance as a solar cell, are JIS-C-8913: 2005 and JIS-C-8914: 2005, respectively. It was obtained by performing the measurement in conformity. The obtained measured values are shown in Table 4 in terms of relative values with the measured value of Comparative Example 1 (solar cell module C1) as 100.0.

 

 

In each of the solar cells produced in Examples 1 to 12, the electrode portion occupancy was 95% or less, and sufficient gaps were formed in the electrodes.
Further, the peel strength of the wiring member in Example 1 was higher than the measured value of Comparative Example 1 in which the same electrode composition as in Example 1 was used, but the wiring members were connected with solder. This is presumably because the connecting material efficiently enters the voids of the electrode formed in the present invention, and the dynamic adhesive strength is improved by the anchor effect.
In Comparative Example 2 in which the voids were not sufficiently formed inside the electrode, the peel strength of the wiring member was lower than the measured value of Comparative Example 1. This is presumably because there were almost no voids inside the electrode, and the anchor effect due to the connection material entering the voids was not sufficiently obtained.

The same electrode composition as in Example 1 was used, but also in Comparative Example 3 in which the wiring members were connected with a conductive paste, the peel strength of the wiring members was lower than the measured value of Comparative Example 1. This is thought to be because the mechanical strength could not be maintained because the electrode and the wiring member were connected with a conductive paste, and the conductive particles in the conductive paste were insufficiently sintered. . Moreover, the power generation performance was also degraded. For the same reason, since a large amount of contact resistance component between the conductive particles is contained, the resistivity at the wiring connection portion is also increased, and as a result, it is considered that the power generation performance is lowered.

The power generation performance of the solar cell modules produced in Examples 1 to 12 was almost the same as the measured value of Comparative Example 1. In particular, the solar cell module 12 showed high power generation performance even though the light receiving surface output extraction electrode was not formed. From this, the adhesive is flow-excluded by thermocompression bonding, and the wiring member has a portion that is in direct contact with not only the light receiving surface and the back surface output extraction electrode, but also the light receiving surface current collecting electrode. It is considered that conductivity is obtained.

In the observation cross section as a cross section parallel to the stacking direction of the wiring connection portion of the solar cell manufactured in Example 1, the electrode portions having a non-uniform shape are irregularly arranged on the silicon substrate. The boundary line with the portion was irregularly bent in the width direction of the observation cross section according to the contour of the electrode portion having an uneven shape. The total length of this boundary line was longer than the width of the observation cross section. Examples 2 to 12 were the same.

The entire disclosure of Japanese Patent Application No. 2014-017940 is incorporated herein by reference. All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims (13)

a semiconductor substrate having a pn junction;
An electrode part including a metal part and a glass part, and a conductive layer including a resin part;
A wiring member and a wiring connection portion laminated in this order;
The total length of the line X that equally divides the thickness of the electrode portion when observing a region in which the length in the direction perpendicular to the laminating direction of the cross section parallel to the laminating direction of the conductive layer in the wiring connection portion is 100 μm The solar cell in which the portion where the total length of the portion where the electrode portion and the line X overlap with each other is 95% or less is present in at least a part of the wiring connection portion. The solar cell according to claim 1, wherein the metal part includes copper. The solar cell according to claim 1 or 2, wherein the metal part includes a Cu-Sn-Ni alloy phase and the glass part includes a Sn-PO glass phase. 4. The solar cell according to claim 3, wherein at least a part of the Sn—P—O glass phase is disposed between the Cu—Sn—Ni alloy phase and the semiconductor substrate. The solar cell according to any one of claims 1 to 4, wherein the conductive layer includes a heat-treated product of an electrode composition including phosphorus-tin-containing copper alloy particles and glass particles. The solar cell according to claim 5, wherein the electrode composition further contains nickel particles. The solar cell according to claim 5 or 6, wherein the phosphorus-tin-containing copper alloy particles further contain nickel. The solar cell according to any one of claims 5 to 7, wherein the electrode composition further contains a dispersion medium. The solar cell according to any one of claims 1 to 8, wherein the resin portion includes a cured product of an adhesive. A solar cell module comprising: the solar cell according to any one of claims 1 to 9; and a sealing material that seals the solar cell. A support;
An intermediate layer including an inorganic material portion and a resin portion;
The adherend, and a connection portion laminated in this order,
The total length of the line X that equally divides the thickness of the inorganic material portion when observing a region in which the length in the direction perpendicular to the stacking direction of the cross section of the intermediate layer parallel to the stacking direction in the connecting portion is 100 μm A part with an electrode, wherein a part where the total ratio of the length of the part where the inorganic material part and the line X overlap with each other is 95% or less is present in at least a part of the connection part. A semiconductor substrate;
An intermediate layer including an inorganic material portion and a resin portion;
The adherend, and a connection portion laminated in this order,
The total length of the line X that equally divides the thickness of the inorganic material portion when observing a region in which the length in the direction perpendicular to the stacking direction of the cross section of the intermediate layer parallel to the stacking direction in the connecting portion is 100 μm The semiconductor device in which a portion where the total ratio of the length of the portion where the inorganic material portion and the line X overlap with each other is 95% or less exists in at least a part of the connection portion. A support;
An intermediate layer including an inorganic material portion and a resin portion;
The adherend, and a connection portion laminated in this order,
The total length of the line X that equally divides the thickness of the inorganic material portion when observing a region in which the length in the direction perpendicular to the stacking direction of the cross section of the intermediate layer parallel to the stacking direction in the connecting portion is 100 μm An electronic component in which a portion in which the total ratio of the length of the portion where the inorganic material portion and the line X overlap with each other is 95% or less exists in at least a part of the connection portion.

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