TW201308633A - Method and structure for protecting passivation layer - Google Patents

Abstract

The present invention relates to a method of fabricating a barrier layer between a passivation layer and a conductive electrode to protect a passivation layer comprising aluminum oxide and formed on a surface of the germanium substrate from being subjected to chemistry between the passivation layer and the conductive electrode The effect of the interaction caused by the interaction. Furthermore, the invention relates to corresponding structures and uses thereof.

Description

Method and structure for protecting passivation layer

The present invention relates to a method of protecting a passivation layer and a structure comprising the barrier layer constituting the protective passivation layer and its use.

Photovoltaic cells are gradually becoming an important device for generating electrical energy. In particular, solar cells, which are photovoltaic cells designed to convert sunlight into electricity, are recognized as one of the most promising candidates for renewable energy production.

An important issue in mitigating the commercial potential of solar cells is the low effect of solar cells relative to their cost, that is, the cost per solar watt of installed solar power is high. Novel technologies and novel solar cell structures have been developed to reduce manufacturing costs and increase the efficiency of solar cells. One of the improvements in twin crystal (c-Si) solar cells is surface passivation after introduction to reduce charge carrier recombination on the back side of the germanium wafer.

Surface recombination in semiconductors is the result of many different mechanisms that result in the possibility of capturing specific energy states or charge carriers close to the semiconductor surface. These energy states (or commonly referred to as surface states) can originate from different sources, such as impurities on the surface or inevitable disruption of the periodicity of the semiconductor crystals on the surface. In photovoltaic cells, when the charge carriers generated by photons absorbed in the semiconductor are combined with the surface state, the quantum efficiency and thus the overall efficiency are reduced, so that it cannot be collected in the battery electrodes to contribute to the battery current.

A variety of ways to passivate the surface of a semiconductor (or conductively doped semiconductor) have been developed to reduce surface recombination of charge carriers. Used to passivate the surface A promising candidate for the material is alumina. In particular, alumina for ALD growth (atomic layer deposition) has been shown to exhibit good passivation on the back surface of p-type germanium solar cells. In the fabrication of solar cells, the back electrode on the alumina passivation layer can be made of screen printed aluminum (i.e., aluminum paste). However, the problem is the relatively weak chemical resistance of amorphous alumina in the case of using such a process. This method of manufacturing the back electrode contains a firing step which is completed at an elevated temperature of about 700 to 800 °C. The aluminum paste contains chemicals that etch a passivation layer comprising alumina, and thus causes at least some removal of the alumina, thereby weakening or destroying surface passivation.

The inventors of the present invention have identified a need for an effective technique for protecting the passivation layer from the chemical interaction between the passivation layer and the electrode comprising aluminum.

It is an object of the present invention to provide a novel method and structure for protecting a passivation layer comprising aluminum oxide and formed on a surface of a germanium substrate from the effects of chemical interaction between the passivation layer and the conductive electrode. Furthermore, it is an object of the present invention to provide a novel use of the structure.

The method according to the invention is characterized by what is presented in item 1 of the independent item.

Features of the structure according to the invention are those presented in item 8 of the independent item.

Features of the use according to the invention are those presented in item 16 of the independent item.

The present invention relates to a method for protecting a passivation layer from being between a passivation layer and a conductive electrode by fabricating a barrier layer between a passivation layer and a conductive electrode formed on the surface of the substrate including aluminum oxide. Effect of the effect of chemical interaction, wherein the method comprises depositing the passivation layer on the passivation layer by exposing the passivation layer to alternating repeated surface reactions of two or more different precursors in the reaction space. a barrier layer of titanium and oxygen, cerium and oxygen, zirconium and oxygen, cerium and oxygen, or a combination of any of these materials, or any combination of these materials and aluminum and oxygen, wherein at least one of the precursors is an oxygen precursor; And forming a conductive electrode on the barrier layer deposited on the passivation layer by fabricating a layer comprising an aluminum paste on the barrier layer.

The invention further relates to a structure comprising a barrier layer between a passivation layer and a conductive electrode, wherein the barrier layer is configured to protect a passivation layer comprising aluminum oxide and formed on a surface of the germanium substrate from a passivation layer and The effect of the chemical interaction between the conductive electrodes, including titanium and oxygen, helium and oxygen, zirconium and oxygen, helium and oxygen, or a combination of any of these materials, or any of these materials with aluminum and A combination of oxygen, and the conductive electrode comprises a layer comprising an aluminum paste. According to one embodiment of the present invention, the barrier layer is deposited on the passivation layer by exposing the passivation layer to alternating surface reactions of two or more different precursors in the reaction space, wherein at least One of the precursors is an oxygen precursor; and a conductive electrode is formed on the barrier layer deposited on the passivation layer by fabricating a layer comprising an aluminum paste on the barrier layer.

The aluminum paste used in the present invention may be any aluminum paste commonly used in the production of photovoltaic cells.

The method and structure of the present invention provides an efficient way to protect the passivation layer from the effects of chemical interaction between the passivation layer and the conductive electrodes. Surprisingly, it is noted that the barrier layer formed by exposing the passivation layer to alternating surface reactions of two or more different precursors in the reaction space effectively suppresses the passivation layer and the conductive electrode A chemical reaction occurs to protect the passivation layer. It is noted that when a barrier layer comprising titanium and oxygen, germanium and oxygen, zirconium and oxygen, germanium and oxygen, or any combination of these materials, or a combination of any of these materials and aluminum and oxygen is fabricated between the passivation layer and the conductive electrode The detrimental effect of reducing the passivation properties of the passivation layer is significantly reduced compared to the otherwise identical structure without the barrier layer.

In the present specification, the expression "passivating", "passivation", "surface passivation" or other corresponding expression is understood to mean reducing the passivation of the surface composite surface, ie, reducing passivation. A composite of charge carriers on or near the surface of the passivated surface.

The passivation layer according to the invention comprises alumina. According to a specific embodiment of the invention, the passivation layer comprises a mixture comprising alumina.

According to one embodiment of the invention, the barrier layer is deposited on the passivation layer in the reaction space by an atomic layer deposition (ALD) type process.

The atomic layer deposition (ALD) or ALD type method is a method of depositing uniform and conformal films, for example, films on substrates of various shapes, even films on complex 3D (three-dimensional) structures. In the ALD type process, the deposit is grown by surface reaction between alternating repeating (substantially self-limiting) precursors and the surface to be coated. Therefore, the growth mechanism in the ALD type program is generally not as sensitive as other coating methods, for example, the flow dynamics in the reaction chamber can be non- The source of uniformity, especially in coating methods relying on gas phase reactions or in physical deposition methods, such as metal-organic chemical vapor deposition (MOCVD) or physical vapor deposition (PVD).

In an ALD type procedure, two or more different chemicals (precursors) can be introduced into the reaction space in a sequential, alternating manner, and the precursors are adsorbed onto a desired surface within the reaction space. This sequential, alternating introduction of precursors is commonly referred to as a pulse (pulse of precursor). There is usually a rinse period between the pulses of each precursor during which a gas stream that does not react with the precursor used in the procedure is introduced through the reaction space. Thus, this gas (commonly referred to as the carrier gas) is inert to the precursors used in the process, and the remaining precursors and by-products resulting from the adsorption reaction of pulses such as previous precursors are flushed from the reaction space. This flushing can also be arranged by other means.

An essential feature of the ALD type process is the sequential exposure of the deposition surface to the precursor and the growth reaction of the precursor substantially on the deposition surface. Alternate and sequential exposure of the deposition surface to different precursors can be performed in different ways. In a batch type ALD process, the substrate to be deposited is placed in a reaction space in which the precursor and the purge gas are introduced into a predetermined cycle. In a continuous ALD type procedure, the invariant gas flow zones are spatially separated and the moving substrate is used for time-ordered exposure. The continuous coating process is accomplished by moving the substrate in the reaction space by providing a precursor exposure and a fixed area of the rinse zone, and roll-to-roll coating of the substrate can be performed. In the continuous ALD type program, the cycle time depends on the moving speed of the substrate between the gas flow regions in the reaction space.

The thickness of the deposit, coating or layer produced by the ALD type procedure may It is increased by repeating the pulse sequence including the aforementioned pulse containing the precursor material and the rinsing period multiple times. The number of repetitions of this sequence (referred to as "ALD cycle") depends on the target thickness of the layer.

The alternating introduction of precursors is a feature of this deposition procedure, which is commonly referred to as atomic layer deposition (ALD). Other names than ALD have also been employed for these procedures of the type of alternating introduction of two or more different precursors resulting in the growth of the layer, which is typically by a substantially self-limiting surface reaction. These other name or program variants include atomic layer epitaxy (ALE), atomic layer chemical vapor deposition (ALCVD), and corresponding plasma enhanced variants. Unless otherwise stated, in the present specification, these programs will be collectively referred to as an ALD type program.

According to a specific embodiment of the invention, depositing the barrier layer comprises depositing a layer comprising titanium and oxygen or a layer comprising germanium and oxygen. According to a specific embodiment of the invention, the barrier layer comprises titanium and oxygen, or germanium and oxygen. According to a specific embodiment of the invention, depositing the barrier layer comprises depositing a layer comprising an oxide. According to a specific embodiment of the invention, the barrier layer comprises an oxide. According to a specific embodiment of the invention, depositing the barrier layer comprises depositing a layer comprising titanium oxide or cerium oxide. According to a specific embodiment of the invention, the barrier layer comprises titanium oxide or cerium oxide. According to one embodiment of the invention, depositing the barrier layer comprises depositing a layer comprising a combination of any of the foregoing materials. According to a specific embodiment of the invention, the barrier layer comprises a combination of any of the above materials.

According to one embodiment of the invention, depositing the barrier layer comprises depositing titanium oxide, hafnium oxide, zirconium oxide, hafnium oxide, or a combination of any of these materials, or a combination of any of these materials and an aluminum oxide layer. According to one of the present invention By way of example, the barrier layer comprises titanium oxide, cerium oxide, zirconium oxide, cerium oxide, or a combination of any of these materials, or a combination of any of these materials and aluminum oxide.

According to a specific embodiment of the invention, depositing the barrier layer comprises depositing a layer comprising a nano sandwich structure. According to a specific embodiment of the invention, the barrier layer comprises a nano sandwich structure.

According to one embodiment of the invention, the nano sandwich structure comprises alternating layers of different oxide materials.

According to a specific embodiment of the invention, depositing the barrier layer comprises depositing a layer of a nano sandwich structure comprising aluminum oxide and an inert material. According to a specific embodiment of the invention, the barrier layer comprises a nano sandwich structure of alumina and an inert material. According to a specific embodiment of the invention, the inert material is selected from the group consisting of titanium oxide, cerium oxide, zirconium oxide and cerium oxide.

According to a specific embodiment of the invention, depositing the barrier layer comprises depositing a layer comprising a nanostructure of alumina and titania, yttria, zirconia or yttria. According to a specific embodiment of the present invention, the barrier layer comprises a nano sandwich structure of alumina and titania, yttria, zirconia or yttria.

According to one embodiment of the invention, a nano sandwich structure is formed in an ALD type process using 2 to 50 cycles to deposit alumina and 1 to 10 cycles to deposit an ALD cycle ratio of the inert material. According to a specific embodiment of the invention, the inert material is selected from the group consisting of titanium oxide, cerium oxide, zirconium oxide and cerium oxide.

The surprising barrier effect achieved by the present invention is due to the compatibility of the barrier layer between the passivation layer and the conductive electrode. The present invention is not limited to any particular mechanism for achieving the aforementioned advantages of effective protection, and the assumptions include Titanium and oxygen, niobium and oxygen, zirconium and oxygen, niobium and oxygen, or combinations of any of these materials, or any of these materials in combination with aluminum and oxygen are stable materials (eg, chemically inert) The passivation layer comprising aluminum oxide is protected, for example, during the firing step of the photovoltaic cell manufacturing process. An ALD type method for forming a barrier layer between a passivation layer and a conductive electrode provides advantageous properties to form a barrier layer that can effectively protect the passivation layer. When the barrier layer is formed on the passivation layer in an ALD type process, excellent conformality and uniformity are achieved in the barrier layer. In a similar manner, when a passivation layer is formed on the surface of the tantalum substrate in an ALD type process, excellent conformality and uniformity are achieved in the barrier layer. In addition to the advantageous protective properties of the barrier layers described above, the present invention provides these additional advantages.

According to a specific embodiment of the invention, the conductive electrode comprises a metal. According to a specific embodiment of the invention, the conductive electrode comprises aluminum.

According to a specific embodiment of the present invention, the deposition barrier layer is terminated before the barrier layer reaches a thickness of 100 nm. According to a specific example of the present invention, the barrier layer has a thickness of 100 nm or less.

According to a specific embodiment of the invention, the barrier layer has a thickness of from 2 to 50 nm, and preferably from 1 to 10 nm.

According to a specific embodiment of the present invention, the passivation layer has a thickness of 2 to 50 nm, and preferably 5 to 10 nm.

According to a specific example of the present invention, a passivation layer is deposited on the surface of the germanium substrate in the reaction space by an atomic layer deposition (ALD) type process, and a passivation layer is formed on the surface of the germanium substrate.

By repeatedly exposing the deposition surface to the precursor in the reaction space And causing a portion of the precursor to adsorb on the exposed surface in the reaction space (i.e., adsorbed on the deposition surface), which may increase the thickness of the barrier layer in some embodiments of the invention. In this manner, the protection of the passivation layer can be enhanced in certain embodiments of the invention. In a similar manner, the thickness of the passivation layer can also be increased during the ALD type process.

According to one embodiment of the invention, the germanium substrate is in the form of a conductive layer for the arrangement of photovoltaic cells.

According to a specific embodiment of the invention, the growth layer of the passivation layer and/or the barrier layer in the ALD type process is substantially thermally activated. For example, the passivation effect is enhanced when the ALD type process is substantially thermally activated (i.e., without plasma activation).

The deposition process for the barrier layer and/or the passivation layer may be selected from a large group of chemicals. According to a specific embodiment of the present invention, the titanium precursor is selected from the group consisting of titanium tetrachloride (TiCl ₄ ), titanium isopropoxide (Ti(OCH(CH ₃ ) ₂ ) ₄ ), titanium titanium (Ti(OCH ₂ CH ₃ )). ₄ ), a group consisting of titanium tetramethoxide (Ti(OCH ₃ ) ₄ ) and titanium iodide (TiI ₄ ). According to a particular embodiment of the present invention, tantalum precursor thereof selected from the group consisting of five tantalum chloride (TaCl _5), tantalum pentaiodide (TaI _5), tantalum pentaethoxide (Ta (OEt) _5), penta (dimethyl XI A group consisting of an amine group Ta(Ta(NMe ₂ ) ₅ ) and 钽(V) diethyl decylamine TA(NEt ₂ ) ₅ . According to a specific embodiment of the present invention, the zirconium precursor is selected from the group consisting of ZrCl ₄ , ZrCl ₂ [N(SiMe ₃ ) ₂ ] ₂ , ZrI ₄ , Zr(OtBu) ₄ , Zr(OtBu) ₂ (mmp) ₂ , Zr (mmp) ₄ , Zr(ONEt ₂ ) ₄ , Zr(NMe ₂ ) ₄ , Zr(NEt ₂ ) ₄ and Zr(NEtMe) ₄ are grouped. According to a specific embodiment of the present invention, the ruthenium precursor is selected from the group consisting of HfCl ₄ , HfCl ₂ [N(SiMe ₃ ) ₂ ] ₂ , HfI ₄ , Hf(OtBu) ₄ , Hf(OtBu) ₂ (mmp) ₂ , Hf (mmp) ₄ , Hf(ONEt ₂ ) ₄ , Hf(NMe ₂ ) ₄ , Hf(NEt ₂ ) _4, and Hf(NEtMe) ₄ are grouped.

According to a specific embodiment of the present invention, the aluminum precursor is selected from the group consisting of TMA (trimethylaluminum), TEA (triethylaluminum), AlCl ₃ , AlBr ₃ , AlMe ₂ Cl, AlMe ₂ OiPr, AlOnPr ₃ and AlOnPr. The group that makes up. According to a specific embodiment of the present invention, the oxygen precursor is selected from the group consisting of H ₂ O, O ₂ , O ₃ , ROHd, AlOEt ₃ , AlOiOr ₃ , H ₂ O ₂ , N ₂ O, and N ₂ O ₄ . group. For those skilled in the art, it will be apparent that other process parameters are selected in accordance with the present specification to deposit a barrier layer and a passivation layer prior to selection.

According to a specific example of the present invention, the ruthenium substrate has a thickness of 200 μm or less.

According to one embodiment of the invention, the method includes protecting the passivation layer from the effects of chemical interaction between the passivation layer and the conductive electrodes in the photovoltaic cell. According to a specific embodiment of the present invention, the barrier layer group constitutes a protective passivation layer from the effect of the chemical interaction between the passivation layer and the conductive electrode in the photovoltaic cell.

The invention further relates to the use of a structure according to the invention for protecting a passivation layer comprising aluminum oxide and formed on a surface of a germanium substrate from chemical interaction between the passivation layer and a conductive electrode in a photovoltaic cell Effect effect.

An advantage of the present invention is that it protects the passivation layer from the chemicals contained in the back electrode, i.e., the layer comprising the aluminum paste, the chemicals of which cause etching of the passivation layer. The barrier layer according to the invention prevents etching of the passivation layer, which results in at least partial removal of the aluminum oxide and thus weakening or destroying Surface passivation.

An advantage of the present invention is that the barrier layer (which is fabricated in an ALD type process and includes, for example, titanium oxide) is stable and has the ability to protect a passivation layer comprising aluminum oxide during the firing step of the fabrication method of the back electrode. .

An advantage of the present invention is that both the passivation layer and the barrier layer including aluminum oxide can be fabricated in the same ALD process and apparatus, thus eliminating the need to use any additional deposition equipment.

An advantage of the barrier layer is that it can be formed to include, for example, a combination of two different oxide materials, for example, a tighter structure of the nano sandwich structure, as compared to the use of individual layers or films.

The present invention is not limited to any particular mechanism by which a barrier layer comprising a nano-sandwich structure can provide effective protection of the passivation layer, assuming that a barrier layer having a nano-layered structure can reduce grain boundaries in the depth direction of the film or layer Existence. The gap between the grains can be a potential route across the barrier layer. In a nano sandwich structure of two or more oxide materials, the second material will fill the grain boundaries of the first deposited material, thereby preventing excess material from traversing the barrier film.

The specific examples of the invention described above may be used in any combination with each other. A number of specific examples can be combined to form further specific examples of the invention. The invention relates to a method, structure or use that can include at least one specific embodiment of the invention described above.

The embodiments will now be explained in the appended drawings, with reference to the specific embodiments of the invention.

For simplicity, in the case of a repeating component, the number of components will be maintained in the following illustrative examples.

As presented above, atomic layer deposition (ALD) or ALD type procedures are methods of depositing a uniform and conformal film or layer on substrates of various shapes. Further, as presented above, in the ALD type program, deposits are grown by alternately repeating (substantially self-limiting) the surface reaction between the precursor and the surface to be coated. The prior art discloses a wide range of materials in the ALD type process that can be synthesized and deposited on a substrate by alternately exposing the surface of the substrate to different precursors. The prior art also discloses many different devices suitable for performing ALD type programs. For example, U.S. Patent No. 6,824,816 discloses a procedure for depositing a metal thin film by ALD, and a deposition tool for ALD described in U.S. Patent No. 6,174,377.

For those skilled in the art, it will be apparent from this disclosure that a processing tool suitable for carrying out the methods in the following specific examples will be apparent. The tool can be, for example, a conventional ALD tool suitable for processing chemical processing. ALD tools (i.e., reactors) are disclosed, for example, in U.S. Patent No. 4,389, 973, the disclosure of which is incorporated herein by reference. Many steps in handling this tool, such as transferring the substrate into the reaction space, evacuating the reaction space to low pressure, or adjusting the gas flow in the tool if the program is completed at atmospheric pressure, and heating the substrate and reaction space, etc. It will be apparent to those skilled in the art. Furthermore, many other known operations or features are not described or referenced in detail herein in order to emphasize the aspects of the various embodiments of the invention.

The following detailed description discloses certain specific examples of the invention, resulting in familiarity The skilled artisan can utilize the present invention based on this disclosure. Many steps or components will be apparent to those skilled in the art from this description, and therefore, all steps or components of the specific examples are not described in detail.

The method of Fig. 1 and the structure of Fig. 2 respectively illustrate a method according to a specific example of the present invention and a correspondingly produced structure. The method of FIG. 1 shows how to perform a method of passivating the germanium substrate 1 with a passivation layer 2 comprising aluminum oxide, and protecting the passivation layer 2 from the passivation layer 2 and deposited on the other side of the barrier layer 3 with the barrier layer 3 The chemical interaction of the conductive electrode 4 is affected.

The tantalum substrate 1 can be prepared by, for example, depositing a tantalum film on a substrate of its microcrystalline, nanocrystalline or polycrystalline phase. The specific example of Fig. 1 is started by bringing the ruthenium substrate 1 into a reaction space of a typical reactor tool (for example, a tool suitable for performing an ALD type program) (step 1)).

The reaction space is subsequently evacuated to a pressure suitable to form a passivation layer 2 comprising alumina. The reaction space can be evacuated to a suitable pressure using, for example, a mechanical vacuum pump, or under atmospheric pressure ALD systems and/or procedures, the gas flow can be set to protect the deposition zone from the atmosphere. The tantalum substrate 1 is also heated to a temperature suitable for forming the passivation layer 2 by the method used. The crucible substrate 1 can be introduced into the reaction space by, for example, a hermetic load-fastening system or only through a loading hatch. The crucible substrate 1 can be heated by, for example, an electric resistance heating element that can also heat the entire reaction space.

After the tantalum substrate 1 and the reaction space have reached the target temperature and other conditions suitable for deposition, the surface of the crucible can be conditioned such that the passivation deposit can be deposited substantially directly on the crucible surface. The tone of the surface on which the passivation layer 2 is to be deposited The surface of the chemically purified ruthenium film may be chemically removed to remove impurities and/or oxidize. In particular, the removal of oxides is beneficial when the surface of the crucible has been introduced into the reaction space by an oxidizing environment, for example, when the exposed crucible surface is transported from one deposition tool to another. For those skilled in the art, the details of the procedure for removing impurities and/or oxides from the surface of the ruthenium film will be apparent in light of the present specification. In some embodiments of the invention, the conditioning can be performed ex-situ, i.e., outside of the tool suitable for the ALD type procedure. An example of a remote conditioning procedure is etching in a 1% HF solution for 1 minute followed by rinsing in deionized water.

After the tantalum substrate 1 has been conditioned, alternating exposure of the deposition surface with different precursor chemicals is initiated to form a passivation layer 2 comprising alumina directly on the tantalum substrate 1 ((step a) in Fig. 1). The result of the adsorption reaction of the corresponding precursor and deposition surface is that the deposition surface causes additional deposits on the deposition surface for each exposure of the precursor.

A typical reactor suitable for ALD type deposition includes a system for introducing a carrier gas such as nitrogen or argon into the reaction space so that the reaction space can remove the remaining space from the reaction space before introducing the next precursor chemical into the reaction space. Chemicals and reaction by-products. This feature, in conjunction with controlling the dose of the vaporized precursor, enables the substrate surface to be alternately exposed to the precursor in the reaction space or in different precursors in other portions of the reactor without significant intermixing. In practice, the carrier gas stream typically passes continuously through the reaction space throughout the deposition process, and various precursors are introduced into the reaction space only alternately with the carrier gas.

The thickness of the passivation layer 2 on the germanium substrate 1 can be exposed by the deposition surface Controlled by the number of different precursors. The thickness of the passivation layer 2 is increased until the target thickness is reached, and then the barrier layer 3 is deposited on the passivation layer 2 ((step b) Fig. 1).

In one embodiment of the present invention, after the deposition of the passivation layer 2 has been completed, an ALD type process is directly performed with the same deposition tool to deposit the barrier layer 3. In this case, the barrier layer 3 can be deposited by changing the precursor chemicals before they are used to deposit the passivation layer 2 to those suitable for depositing the barrier layer 3.

The following embodiment details how the barrier layer 3 of titanium oxide (TiO ₂ ) can be deposited on the passivation layer 2 remaining on the tantalum substrate 1.

Example

The barrier layer 3 is formed on the passivation layer 2 of alumina (Al ₂ O ₃ ), and the passivation layer 2 is deposited on the surface of the tantalum substrate 1; Fig. 1 shows the step b) of a specific example of the present invention. After depositing the passivation layer 2 on the tantalum substrate 1 as described above, the barrier layer 3 is deposited directly in the reaction space of the P400ALD batch tool (available from Beneq OY Finland). The crucible substrate 1 is a photovoltaic cell structure. This structure is positioned within the reaction space, causing the passivation layer 2 to be exposed to the reaction environment.

During the deposition of the barrier layer 3, the pressure and temperature in the reaction space are about 1 mbar (1 hPa) and about 300 ° C, respectively. In this embodiment, the carrier gas as described above and which is responsible for rinsing the reaction space is nitrogen (N ₂ ). The processing temperature is sufficient to cause heat activated ALD type growth, and plasma activation is not employed in this embodiment.

After depositing the passivation layer 2 of alumina, the precursor is changed to start depositing titanium oxide on the passivation layer 2 as the barrier layer 3. Titanium tetrachloride (TiCl ₄ ) is introduced into the reaction space to expose the passivation layer 2 to the first precursor. After the carrier gas is flushed into the reaction space to remove the remaining first precursor and reaction byproducts, the surface of the resulting substrate is likewise exposed to the second precursor, oxygen precursor and water (H ₂ O). After this, the reaction space was rinsed again. This pulse sequence was performed once before the end of the program, followed by 299 repetitions, and the substrate was discharged from the reaction space and the ALD tool. These 300 "ALD cycles" result in a titanium oxide barrier layer 3 having a thickness of about 25 nm on the passivated aluminum oxide layer 2.

More specifically, the surface of the substrate is exposed to a particular precursor by turning on a pulse valve that controls the flow of precursor chemicals into the reaction space of the P400 ALD tool. The rinsing of the reaction space is carried out by closing the valve that controls the flow of the precursor into the reaction space so that only a continuous stream of carrier gas passes through the reaction space. The pulse sequence in this example is detailed below: exposure to titanium tetrachloride for 0.6 seconds, rinsing for 1.5 seconds, exposure to water for 0.4 seconds, and rinsing for 2.0 seconds. The exposure time and rinse time in this sequence represent the time that a particular pulse valve of a particular precursor remains open and the time that all of the pulse valves of the precursor remain closed.

In the above embodiments, the first precursor is titanium tetrachloride and the second precursor is water, but other precursors may be used depending on the desired barrier material and composition. The present invention is not particularly limited to the use of the foregoing precursors, and those skilled in the art can also obtain the advantages of the present invention from other precursors in accordance with the present specification.

After the barrier layer 3 on the passivation layer 2 and the passivation layer 2 has been deposited in a single procedure as described above, a conductive electrode 4 (for example, aluminum) is formed on the barrier layer 3. The structure of Fig. 2 is completed by the electrode). Next, the aluminum electrode 4 is fabricated on the barrier layer 3 by a screen printing method, which comprises, for example, printing the aluminum paste on the barrier layer using a method step, drying at a high temperature and curing the slurry, which is familiar to the art. The one is obvious.

In the structure of FIG. 2, the barrier layer 3 effectively protects the underlying aluminum oxide passivation layer 2 of the surface of the passivation substrate 1, thereby minimizing surface recombination on the interface between the germanium substrate 1 and the passivation layer 2.

The test results have been shown in the structure of Fig. 2 manufactured by the method of Fig. 1 above, and the titanium oxide barrier layer 3 particularly protects the alumina passivation layer 2 from chemical interaction with the aluminum electrode 4. This surprisingly enables the passivation layer 2 to retain a passivation effect on the surface of the tantalum substrate 1 without significant decomposition over time, even under severe environmental conditions such as high temperatures. According to the specific example of Fig. 1, as presented above, an additional benefit of the method is that the passivation layer 2 and the barrier layer 3 can be fabricated on the germanium substrate 1 in a single ALD type process. The layer structure of Figure 2 is commonly used, for example, in solar cells and other photovoltaic devices.

In the above embodiments, the barrier layer comprises titanium oxide, but the barrier layer may also comprise other materials such as yttria, zirconia, yttria or a combination of any of these materials, or a combination of any of these materials and alumina, and It will be apparent to those skilled in the art from this disclosure. Accordingly, the present invention is not limited to the particular use of the aforementioned barrier layers, and those skilled in the art can readily obtain the advantages of the present invention from the above-described other materials in accordance with the present specification.

For those skilled in the art, as the technology advances, various The basic idea of implementing the invention is obvious. Therefore, the present invention and the specific examples thereof are not limited to the above embodiments, but may be changed within the scope of the patent application.

1‧‧‧矽 substrate

2‧‧‧ Passivation layer

3‧‧‧Barrier layer

4‧‧‧Conductive electrode

The accompanying drawings, which are incorporated in the claims of the claims In the drawings: FIG. 1 is a flow chart of a method according to a specific example of the present invention.

Fig. 2 is a schematic view showing the structure of a specific example of the present invention.

Claims (16)

One method is to protect the passivation layer from chemical interaction between the passivation layer and the conductive electrode (4) by fabricating a barrier layer (3) between the passivation layer (2) and the conductive electrode. Effect of the effect, the passivation layer (2) comprises aluminum oxide and is formed on the surface of the germanium substrate (1), characterized in that the method comprises: - exposing the passivation layer to two or more in the reaction space Alternating repeated surface reactions of different precursors, and depositing on the passivation layer (2) includes titanium and oxygen, helium and oxygen, zirconium and oxygen, helium and oxygen, or a combination of any of these materials, or any of these materials The barrier layer (3) in combination with aluminum and oxygen, wherein at least one of the precursors is an oxygen precursor; and - by depositing a layer comprising an aluminum paste on the barrier layer The conductive electrode (4) is formed on the barrier layer (3) on the passivation layer. The method of claim 1, wherein the barrier layer (3) is deposited on the passivation layer (2) in the reaction space by an atomic layer deposition (ALD) type process. The method of any one of claims 1 to 2, wherein depositing the barrier layer (3) comprises depositing a layer comprising a nano sandwich structure. The method of any one of claims 1 to 3, wherein the barrier layer (3) is terminated before the barrier layer reaches a thickness of 100 nm. The method of any one of claims 1 to 4, wherein the passivation layer (2) is deposited on the surface of the germanium substrate in the reaction space by an atomic layer deposition (ALD) type program. The passivation layer is formed on the surface of the tantalum substrate (1). The method of any one of claims 1 to 5, wherein the substrate (1) is in the form of a conductive layer of a photovoltaic cell. The method of any one of claims 1 to 6, wherein the method comprises protecting the passivation layer (2) from the passivation layer and the conductive electrode (4) in the photovoltaic cell The effect of the chemical interaction. A structure comprising a barrier layer (3) between the passivation layer (2) and the conductive electrode (4), wherein the barrier layer is formed to protect the surface including the aluminum oxide and formed on the surface of the germanium substrate (1) The passivation layer is protected from the effects of chemical interaction between the passivation layer and the conductive electrode, and is characterized in that the barrier layer (3) comprises titanium and oxygen, germanium and oxygen, zirconium and oxygen, germanium and Oxygen, or a combination of any of these materials, or any combination of these materials with aluminum and oxygen, and the conductive electrode (4) comprises a layer comprising an aluminum paste. The structure of claim 8, wherein the barrier layer (3) is an alternating repeated surface reaction by exposing the passivation layer to two or more different precursors in the reaction space. Depositing on the passivation layer (2), wherein at least one of the precursors is an oxygen precursor; and by making a layer comprising an aluminum paste on the barrier layer, The conductive electrode (4) is formed on the barrier layer deposited on the layer. The structure of any one of claims 8 to 9, wherein the barrier layer (3) is an atomic layer deposition (ALD) type process, and the passivation layer in the reaction space (2) ) deposited on it. The structure of any one of claims 8 to 10, wherein the barrier layer (3) comprises a nano sandwich structure. The structure according to any one of claims 8 to 11, wherein the barrier layer (3) has a thickness of 100 nm or less. The structure of any one of claims 8 to 12, wherein the passivation layer (2) is on the surface of the germanium substrate in the reaction space by an atomic layer deposition (ALD) type program The passivation layer is deposited and formed on the surface of the tantalum substrate (1). The structure of any one of claims 8 to 13 wherein the ruthenium substrate (1) is in the form of a conductive layer in the configuration of a photovoltaic cell. The structure of any one of claims 8 to 14, wherein the barrier layer (3) is configured to protect the passivation layer (2) from the passivation layer and the photovoltaic cell. The effect of the chemical interaction between the conductive electrodes (4). Use of the structure of any one of claims 8 to 15 for protecting a passivation layer (2) comprising alumina and formed on the surface of the ruthenium substrate (1) from the passivation layer ( 2) The effect of the chemical interaction between the conductive electrode (4) in the photovoltaic cell.