KR20090132541A - Manufacturing method of substrate type solar cell - Google Patents

Abstract

The present invention is a step of etching the upper surface of the semiconductor substrate in an uneven structure; And forming a semiconductor substrate having a first semiconductor layer and a second semiconductor layer doped with the dopant on the first semiconductor layer by doping a dopant on the semiconductor substrate. The etching process and the doping process relates to a method of manufacturing a substrate-type solar cell, characterized in that performed in one chamber,

According to the present invention, the problem of environmental pollution is reduced compared to the etching process by the conventional wet etching method, and the dopant is doped only on the upper portion of the semiconductor substrate, so that a separate dopant removal process is not required, thereby simplifying the etching process and the doping process. Since it is performed on one piece of equipment, the equipment configuration is simplified, and manufacturing cost can be reduced.

Description

Method for manufacturing substrate type solar cell {Method for manufacturing Wafer type Solar Cell}

The present invention relates to a solar cell, and more particularly to a substrate type solar cell.

Solar cells are devices that convert light energy into electrical energy using the properties of semiconductors.

The structure and principle of the solar cell will be described briefly. The solar cell has a PN junction structure in which a P (positive) type semiconductor and an N (negative) type semiconductor are bonded to each other. Holes and electrons are generated in the semiconductor by the energy of the incident solar light. At this time, the holes (+) are moved toward the P-type semiconductor by the electric field generated in the PN junction. Negative (-) is moved toward the N-type semiconductor to generate a potential to produce power.

Such solar cells may be classified into thin film solar cells and substrate solar cells.

The thin film solar cell is a solar cell manufactured by forming a semiconductor in the form of a thin film on a substrate such as glass, the substrate solar cell is a solar cell manufactured by using a semiconductor material such as silicon itself as a substrate.

The substrate type solar cell has a disadvantage in that a thicker and expensive material is used as compared to the thin film type solar cell, but the cell efficiency is excellent.

Hereinafter, a conventional substrate type solar cell will be described with reference to the drawings.

1 is a schematic cross-sectional view of a conventional substrate-type solar cell.

As can be seen in Figure 1, the conventional substrate type solar cell is a P-type silicon layer (1), an N-type silicon layer (2), an antireflection layer (3), a P ⁺ type silicon layer (4), the front electrode (5) And a back electrode (6).

The P-type silicon layer 1 and the N-type silicon layer 2 formed on the upper surface of the P-type silicon layer 1 form a PN junction structure of a solar cell, and the upper surfaces of the P-type silicon layer 1 and the N-type silicon layer 2 are It is formed in an uneven structure so that sunlight can be absorbed into the solar cell as much as possible.

The anti-reflection layer 3 is formed on the upper surface of the N-type silicon layer 2 to minimize reflection of incident light.

The P ⁺ -type silicon layer 4 is formed on the lower surface of the P-type silicon layer 1 to prevent electrons formed by sunlight from being recombined and extinguished.

The front electrode 5 extends from the top of the antireflection layer 3 to the N-type silicon layer 2, and the back electrode 6 is formed on the bottom surface of the P ⁺ type silicon layer 4. .

2a to 2e is a cross-sectional view showing a manufacturing process of the conventional substrate-type solar cell as shown in FIG.

First, as shown in FIG. 2A, after preparing the P-type silicon substrate 1a, the upper surface of the P-type silicon substrate 1a is etched into an uneven structure. The etching process is performed by a wet etching method using an alkaline solution or an acid solution.

Next, as shown in FIG. 2B, the N-type dopant is diffused onto the P-type silicon substrate 1a to dope the N-type silicon 2a to the surface of the P-type silicon substrate 1a.

The doping process is performed through a so-called high temperature diffusion process. Specifically, the N-type dopant gas such as POCl ₃ is supplied by supplying an N-type dopant gas such as POCl ₃ while the P-type silicon substrate 1a is placed in a diffusion furnace having a temperature of about 800 ° C. or more. The dopant is diffused to the surface of the P-type silicon substrate 1a.

On the other hand, since the high temperature diffusion process is performed at a high temperature of more than 800 ℃ may be a by-product such as PSG (Phosphor-Silicate Glass) on the surface. Since the PSG causes a problem of shielding current from the solar cell, a process of removing the PSG is further performed to increase the efficiency of the solar cell.

Next, as shown in FIG. 2C, the N-type silicon 2a formed on the side and the bottom of the P-type silicon substrate 1a is removed to form the P-type silicon layer 1 and the N-type silicon layer formed on the upper surface thereof ( A PN junction layer consisting of 2) is formed.

Next, as can be seen in Figure 2d, the anti-reflection layer 3 is formed on the upper surface of the N-type silicon layer (2).

Next, as shown in FIG. 2E, a front electrode 5 extending from the anti-reflection layer 3 to the N-type silicon layer 2 is formed, and P ⁺ is formed on the bottom surface of the P-type silicon layer 1. The type silicon layer 4 and the back electrode 6 are formed, completing a substrate type solar cell as shown in FIG.

However, the conventional method of manufacturing a substrate-type solar cell has the following problems.

First, since the upper surface of the P-type silicon substrate 1a is etched through the wet etching method, there is a problem of environmental pollution due to the etchant.

Second, since the N-type silicon 2a is doped onto the surface of the P-type silicon substrate 1a through a high temperature diffusion process, to obtain a PN junction layer, the side and bottom portions of the P-type silicon substrate 1a are as shown in FIG. 2C. There is a further need for a process for removing the doped N-type silicon 2a, and a further process for removing by-products such as PSG (Phosphor-Silicate Glass) is required.

Third, since the etching process and the doping process are performed through separate equipment, there is a problem in that the composition of the equipment becomes complicated and the manufacturing cost increases accordingly.

The present invention is devised to solve the conventional problems as described above, the present invention is to prevent the environmental pollution problem by performing the etching process without using the wet etching method, so that dopants are not doped on the side and bottom of the semiconductor substrate. By performing the doping process, a separate dopant removal process is not required, which simplifies the process and enables the etching process and the doping process to be performed in a single device, thereby simplifying the composition of the substrate-type solar cell. It is an object to provide a manufacturing method.

In order to achieve the above object, the present invention comprises the steps of etching the upper surface of the semiconductor substrate with an uneven structure; And forming a semiconductor substrate having a first semiconductor layer and a second semiconductor layer doped with the dopant on the first semiconductor layer by doping a dopant on the semiconductor substrate. The etching process and the doping process provide a method of manufacturing a substrate-type solar cell, characterized in that performed in one chamber.

The forming of the semiconductor substrate including the first semiconductor layer and the second semiconductor layer may be performed by forming a semiconductor substrate including a P-type semiconductor layer and a PN junction layer of an N-type semiconductor layer.

The etching process may be performed by etching an upper surface of the P-type semiconductor substrate, and the doping process may be performed by doping an N-type dopant on the P-type semiconductor substrate.

The etching process may be performed by etching an upper surface of the N-type semiconductor substrate, and the doping process may be performed by doping a P-type dopant on the N-type semiconductor substrate.

The etching process may include a process of generating a plasma after supplying a predetermined etching gas into the chamber, and the doping process may include a process of generating a plasma after supplying a predetermined doping gas into the chamber. After supplying the mixed gas of the etching gas and the doping gas into the chamber, plasma may be generated to simultaneously perform the etching process and the doping process.

In the etching process and the doping process, a mixture of a predetermined etching gas and a doping gas is supplied into the chamber and a plasma is generated to simultaneously perform the etching process and the doping process, wherein the mixed gas is Cl ₂ , SF _6. And an etching gas consisting of O ₂ , and a mixed gas of 1 to 5% PH ₃ gas and a doping gas consisting of 95 to 99% H ₂ or He gas.

When the etching process and the doping process are performed at the same time, the pressure in the chamber may be adjusted to a range of 0.1 to 1 Torr, and RF power may be applied to the chamber at a range of 5 to 20 KW.

Forming an anti-reflection layer on the second semiconductor layer; And forming a front electrode electrically connected to the second semiconductor layer and a back electrode electrically connected to the first semiconductor layer, wherein the front electrode and the back electrode are formed. The step of forming a front electrode material on the anti-reflection layer; Forming a back electrode material on the first semiconductor layer; And heat treating the front electrode material so that the front electrode material penetrates the anti-reflection layer and penetrates to the second semiconductor layer, and heat-treats the back electrode material to form a P ⁺ type semiconductor layer between the first semiconductor layer and the back electrode. It can be made to the process of forming.

The present invention also includes a chamber, a susceptor located in the chamber, an RF electrode located above the chamber, a plurality of gas injection holes, and a gas distribution plate connected to a lower portion of the RF electrode, through the RF electrode. Preparing a device including a gas inlet tube formed, and an etching gas storage unit and a doping gas storage unit connected to the gas inlet tube; Loading a tray containing at least one semiconductor substrate onto the susceptor; The semiconductor substrate is formed by supplying the etching gas stored in the etching gas storage part and the doping gas stored in the doping gas storage part through the gas injection hole of the gas distribution plate through the gas inlet pipe, and then generating a plasma. Etching the upper surface of the semiconductor substrate and doping the upper portion of the semiconductor substrate with a dopant; And unloading a tray containing at least one substrate having the etching process and the doping process out of the chamber.

The step of supplying the etching gas and the doping gas into the chamber includes a step of supplying the mixed gas of the etching gas and the doping gas into the chamber through the gas injection hole of the gas distribution plate, and simultaneously performing the etching process and the doping process. can do.

The mixed gas is an etching gas consisting of Cl ₂ , SF ₆ , and O ₂ stored in the etching gas storage unit and 1-5% PH ₃ gas and 95-99% H ₂ or He stored in the doping gas storage unit. A mixed gas of a doping gas made of gas may be used, and the pressure in the chamber may be adjusted in the range of 0.1 to 1 Torr during the etching process and the doping process, and RF power of 5 to 20 KW may be applied to the RF electrode. In addition, the distance between the gas distribution plate and the semiconductor substrate may be in the range of 10 to 40 mm.

According to the present invention as described above has the following effects.

First, since the etching process is performed by supplying an etching gas into the chamber and then generating a plasma, the problem of environmental pollution is reduced as compared with the wet etching method.

Second, since the doping process is performed by supplying the doping gas into the chamber and then generating a plasma, the dopant is not doped on the side and bottom of the semiconductor substrate, and the dopant is doped only on the upper portion of the semiconductor substrate. No removal process is required, which simplifies the process.

Third, since the present invention performs the etching process and the doping process in one equipment, the equipment configuration can be simplified, and manufacturing cost can be reduced.

Fourth, the present invention can reduce the process time because the etching process and the doping process can be performed simultaneously in a single equipment.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic view of a manufacturing apparatus of a substrate-type solar cell according to an embodiment of the present invention, Figures 4a to 4e is a cross-sectional view showing a manufacturing process of the substrate-type solar cell according to an embodiment of the present invention.

First, after describing the manufacturing equipment of the substrate-type solar cell according to an embodiment of the present invention, a process of manufacturing the substrate-type solar cell according to an embodiment of the present invention using the same will be described.

As can be seen in Figure 3, the manufacturing apparatus 10 of the substrate-type solar cell according to an embodiment of the present invention, the chamber 20, the susceptor 30, the RF electrode 40, the gas distribution plate 50, It comprises a gas inlet pipe 60, gas storage unit 70, 70a, and the exhaust port (80).

The chamber 20 defines a reaction zone and is connected to a predetermined pumping device (not shown) to maintain a vacuum therein.

The susceptor 30 supports the tray T, which is located in the chamber 20 and accommodates a plurality of substrates S.

The RF electrode 40 is positioned above the chamber 20 and is insulated from the chamber 20 by the insulating member 45. In addition, the RF electrode 40 is connected to the RF power source 42.

The gas distribution plate 50 includes a plurality of gas injection holes 52 and is connected to the lower portion of the RF electrode 40.

The gas inlet pipe 60 is formed through the RF electrode 40 to introduce a reaction gas into the chamber 20.

The gas storage units 70 and 70a store the reaction gas and are connected to the gas inlet pipe 60 to supply gas to the gas inlet pipe 60. The gas storage units 70 and 70a may include an etching gas storage unit 70 and a doping gas storage unit 70a.

The exhaust port 80 is formed on the lower surface of the chamber 20 to discharge residual gas.

Referring to the manufacturing apparatus 10 of the substrate-type solar cell as described above will be described a manufacturing process of the substrate-type solar cell according to an embodiment of the present invention.

First, as shown in FIG. 4A, the P-type semiconductor substrate 100a is prepared.

The P-type semiconductor substrate 100a may use single crystal silicon or polycrystalline silicon. Since single crystal silicon has high purity and low crystal defect density, solar cell efficiency is high, but the price is too high, and thus economical efficiency is low. Although relatively inefficient, they are inexpensive and are suitable for mass production due to their low production costs.

Next, as can be seen in Figure 4b, by etching the upper surface of the P-type semiconductor substrate 100a with an uneven structure and doping the N-type dopant on the upper portion of the P-type semiconductor substrate 100a, P having an upper surface of the uneven structure The PN junction layer of the type semiconductor layer 100 and the N type semiconductor layer 200 is formed.

The etching process and the doping process are performed by using the manufacturing equipment 10 according to FIG.

Specifically, referring to FIG. 3, at least one P-type semiconductor substrate S is seated on a tray T, and then the tray T is loaded on the susceptor 30 of the manufacturing apparatus 10. do. Thereafter, the etching gas stored in the etching gas storage unit 70 and the doping gas stored in the doping gas storage unit 70a are introduced into the gas inlet pipe 60 to open the gas injection hole 52 of the gas distribution plate 50. Feed into the chamber through. Here, the etching gas is composed of Cl ₂ , SF ₆ , and O ₂ , the doping gas may be composed of 1 to 5% PH ₃ gas and 95 to 99% H ₂ or He gas. Thereafter, RF power is applied to the RF electrode 40 to generate a plasma. Then, an upper surface of the P-type semiconductor substrate S is etched by the plasma of the etching gas, and an N-type dopant is doped on the P-type semiconductor substrate S by the plasma of the doping gas. A semiconductor substrate having a PN junction structure such as 4b is obtained.

As described above, since the present invention performs the etching process by the plasma of the etching gas, the problem of environmental pollution is reduced as compared with the conventional wet etching method. In addition, the present invention has the following advantages over the conventional high temperature diffusion process because the doping process is performed by the plasma of the doping gas.

First, since the doping concentration and the doping depth can be precisely controlled by adjusting the flow rate or the RF power of the doping gas, more precise and reproducible doping can be realized compared to the high temperature diffusion process, and the processing time is shortened.

Second, since the doping by the plasma proceeds in the vertical direction, the N-type dopant is doped only on the upper portion of the P-type semiconductor substrate S, and the N-type dopant is formed on the side and the bottom of the P-type semiconductor substrate S as in the high temperature diffusion process. Is not doped.

Third, since the plasma doping process is performed at a relatively low temperature compared to the high temperature diffusion method, by-products (for example, PSG) generated in the high temperature diffusion process are not generated, and thus an additional process for removing the by-products is not required.

Meanwhile, the etching process and the doping process may be performed simultaneously by supplying the mixed gas of the etching gas and the doping gas into the chamber 20.

That is, the etching gas consisting of Cl ₂ , SF ₆ , and O ₂ stored in the etching gas storage unit 70 flows into the gas inlet pipe 60, and at the same time, 1 to 5 stored in the doping gas storage unit 70a. By introducing a doping gas consisting of% PH ₃ gas and 95 ~ 99% H ₂ or He gas into the gas inlet pipe 60, the mixed gas of the etching gas and the doping gas through the gas inlet pipe 60 The etch process and the doping process may be performed at the same time by being supplied into the chamber through the gas injection hole 52 of the gas distribution plate 50.

At this time, the pressure in the chamber 20 is preferably adjusted to 0.1 ~ 1 Torr range, it is preferable to apply RF power of 5 ~ 20 KW range to the RF electrode (40). In addition, the distance between the gas distribution plate 50 and the semiconductor substrate (S) is preferably in the range of 10 to 40 mm.

Next, as can be seen in Figure 4c, to form an anti-reflection layer 300 on the N-type semiconductor layer (200).

As the upper surface of the N-type semiconductor layer 200 is formed in the concave-convex structure, the anti-reflection layer 300 is also formed in the concave-convex structure.

The anti-reflection layer 300 may be formed of silicon nitride or silicon oxide using plasma CVD.

4D, the front electrode material 500a is formed on the top surface of the anti-reflection layer 300 in a predetermined pattern, and the back electrode material 600a is formed on the bottom surface of the P-type semiconductor layer 100. Form. The back electrode material 600a may be formed in a predetermined pattern similar to the front electrode material 500a.

The front electrode material 500a may be formed first, and then the back electrode material 600a may be formed, and the back electrode material 600a may be formed first, and then the front electrode material 500a may be formed. have.

The front electrode material 500a includes Ag, Al, Ag + Al, Ag + Mg, Ag + Mn, Ag + Sb, Ag + Zn, Ag + Mo, Ag + Ni, Ag + Cu, Ag + Al + Zn and It may be made of the same metal material, the back electrode material 600a is made of a material that can function as a P-type dopant, such as Al, for example, Al, Al + Ag, Al + Mo, Al + Ni And metal materials such as Al + Cu, Al + Mg, Al + Mn, Al + Zn, and the like.

The front electrode material 500a and the back electrode material 600a may include screen printing, inkjet printing, gravure printing, or microcontact printing. It can form using.

Next, as can be seen in Figure 4e, by performing a heat treatment process to form a front electrode 500, a P ⁺ type semiconductor layer 400, and a back electrode 600, to manufacture a substrate-type solar cell according to the present invention Complete

In detail, when the heat treatment is performed at a high temperature of 850 ° C. or more, the front electrode material 500a penetrates the anti-reflection layer 300 and penetrates to the N-type semiconductor layer 200. ) And a front electrode 500 that is electrically connected. In addition, when the heat treatment is performed at a high temperature of 850 ° C. or higher, the back electrode material 600a penetrates into the lower surface of the P-type semiconductor layer 100 to form a P ⁺ type semiconductor layer 400. Therefore, the back electrode 600 is finally electrically connected to the P-type semiconductor layer 100 through the P ⁺ -type semiconductor layer 400.

The method of manufacturing a substrate-type solar cell by forming a PN junction structure by doping an N-type dopant to a P-type semiconductor substrate based on the P-type semiconductor substrate and then forming a front electrode and a back electrode is described. However, the present invention is not necessarily limited thereto, and a PN junction structure is formed by doping a P-type dopant to an N-type semiconductor substrate based on an N-type semiconductor substrate, and then forming a front electrode, a back electrode, and the like. It also includes a method of manufacturing a solar cell.

1 is a schematic cross-sectional view of a conventional substrate-type solar cell.

2A through 2E are cross-sectional views illustrating a manufacturing process of a conventional substrate type solar cell.

Figure 3 is a schematic diagram of the manufacturing equipment of the substrate-type solar cell according to an embodiment of the present invention.

4A to 4E are cross-sectional views illustrating a process of manufacturing a substrate-type solar cell according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: manufacturing equipment 20: chamber

30: susceptor 40: RF electrode

50: gas distribution plate 60: gas inlet pipe

70: etching gas storage unit 70a: doping gas storage unit

100: P-type semiconductor layer 200: N-type semiconductor layer

300: antireflection layer 400: P ⁺ type semiconductor layer

500: front electrode 600: rear electrode

Claims (13)

Etching the upper surface of the semiconductor substrate into an uneven structure; And Forming a semiconductor substrate having a first semiconductor layer and a second semiconductor layer doped with the dopant on the first semiconductor layer by doping a dopant on the semiconductor substrate, In this case, the etching process and the doping process is a substrate-type solar cell manufacturing method, characterized in that performed in one chamber. The method of claim 1, The step of forming a semiconductor substrate having the first semiconductor layer and the second semiconductor layer comprises a step of forming a semiconductor substrate having a PN junction layer of a P-type semiconductor layer and an N-type semiconductor layer. Manufacturing method of solar cell. The method of claim 1, The etching process is a step of etching the upper surface of the P-type semiconductor substrate, the doping process is a method of manufacturing a substrate-type solar cell, characterized in that the step of doping the N-type dopant on the upper portion of the P-type semiconductor substrate. . The method of claim 1, The etching process is a step of etching the upper surface of the N-type semiconductor substrate, the doping process is a method of manufacturing a substrate-type solar cell, characterized in that the step of doping the P-type dopant on the upper portion of the N-type semiconductor substrate. . The method according to any one of claims 1 to 4, The etching process is a step of generating a plasma after supplying a predetermined etching gas in the chamber, the doping step is characterized in that the step of generating a plasma after supplying a predetermined doping gas into the chamber Method of manufacturing a substrate-type solar cell. The method of claim 5, And supplying the mixed gas of the etching gas and the doping gas into the chamber and generating a plasma to simultaneously perform the etching process and the doping process. The method of claim 3, In the etching process and the doping process, a mixture of a predetermined etching gas and a doping gas is supplied into the chamber and a plasma is generated to simultaneously perform the etching process and the doping process, wherein the mixed gas is Cl ₂ , SF _6. And an etching gas consisting of O ₂ , and 1 to 5% PH ₃ gas and 95 to 99% H ₂ Or a mixed gas of a doping gas consisting of He gas. The method according to claim 6 or 7, A method of manufacturing a substrate type solar cell, wherein the pressure in the chamber is adjusted to a range of 0.1 to 1 Torr, and RF power is applied to the chamber in a range of 5 to 20 KW. The method of claim 1, Forming an anti-reflection layer on the second semiconductor layer; And And forming a front electrode electrically connected to the second semiconductor layer and a back electrode electrically connected to the first semiconductor layer. A chamber, a susceptor located in the chamber, an RF electrode located above the chamber, a gas distribution plate having a plurality of gas injection holes and connected to a lower portion of the RF electrode, a gas inlet pipe formed through the RF electrode, And preparing an equipment including an etching gas storage part and a doping gas storage part connected to the gas inlet pipe. Loading a tray containing at least one semiconductor substrate onto the susceptor; The semiconductor substrate is formed by supplying the etching gas stored in the etching gas storage part and the doping gas stored in the doping gas storage part through the gas injection hole of the gas distribution plate through the gas inlet pipe, and then generating a plasma. Etching the upper surface of the semiconductor substrate and doping the upper portion of the semiconductor substrate with a dopant; And And unloading a tray containing the at least one substrate on which the etching process and the doping process have been completed, out of the chamber. The method of claim 10, The step of supplying the etching gas and the doping gas into the chamber includes a step of supplying the mixed gas of the etching gas and the doping gas into the chamber through the gas injection hole of the gas distribution plate, and simultaneously performing the etching process and the doping process. Method of manufacturing a substrate-type solar cell, characterized in that. The method of claim 11, The mixed gas is an etching gas consisting of Cl ₂ , SF ₆ , and O ₂ stored in the etching gas storage unit and 1-5% PH ₃ gas and 95-99% H ₂ or He stored in the doping gas storage unit. A method of manufacturing a substrate type solar cell, characterized in that the gas is a mixed gas of a doping gas. The method of claim 11, The method of manufacturing a substrate type solar cell, characterized in that during the etching process and the doping process, the pressure in the chamber is adjusted to a range of 0.1 to 1 Torr, and RF power of 5 to 20 KW is applied to the RF electrode.

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