JP2016189447A - Solar cell element, method of manufacturing the same, and solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a solar cell element, having low resistivity, excellent ohmic contact between an electrode and a semiconductor substrate, and, furthermore, excellent adhesion force to the semiconductor substrate.SOLUTION: A method of manufacturing a solar cell element includes in the following order: an imparting step for imparting a composition for electrode formation containing metal particles including phosphorus-tin-nickel-containing copper alloy particles, solvent and resin on at least one surface of a semiconductor substrate to form a composition layer for electrode formation; a drying step for performing heat treatment for one second to fifteen minutes at a temperature of less than 300°C to evaporate the solvent; a dewaxing step for performing heat treatment for five seconds to two minutes at the temperature of 300°C or more and less than 600°C to thermally decompose the resin; and an electrode forming step for performing heat treatment for five seconds to one minute at the temperature of 600°C or more and 1000°C or less to form a copper-containing electrode which is a heat-treated product of the composition for electrode formation.SELECTED DRAWING: None

Description

  The present invention relates to a solar cell element, a manufacturing method thereof, and a solar cell.

  In general, electrodes are formed on the light receiving surface and the back surface of the solar cell. In order to efficiently extract the electric energy converted in the solar cell 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 It is necessary to form a good ohmic contact with the semiconductor substrate and to be in close contact with the semiconductor substrate with high strength. Regarding the electrode on the light receiving surface, from the viewpoint of minimizing the loss of incident sunlight, the wiring width tends to be reduced and the aspect ratio of the electrode tends to be increased.

  As a solar cell, a silicon-based solar cell using a silicon substrate is generally used, and an electrode on a light receiving surface of the silicon-based solar cell is usually formed as follows. That is, a texture (unevenness) is formed on the light receiving surface side of the p-type silicon substrate. Next, a conductive composition is applied by screen printing or the like on the n-type diffusion layer formed by thermally diffusing phosphorus or the like at a high temperature on the surface of the p-type silicon substrate. The electrode on the light receiving surface is formed by heat treatment (baking) at 0 ° C. The back electrode is formed in the same manner as the electrode on the light receiving surface except that it is formed on the surface opposite to the light receiving surface. The conductive composition forming the electrode on the light receiving surface and the electrode on the back surface contains conductive metal particles, glass particles, various additives, and the like.

In particular, silver particles are generally used as the conductive metal particles for the electrodes for taking out the output among the electrodes on the light receiving surface and the electrodes on the back surface. This is because the resistivity of the silver particles is as low as 1.6 × 10 ⁻⁶ Ω · cm, the silver particles are self-reduced and sintered under the heat treatment (firing) conditions, and the silicon substrate is in good ohmic contact. The electrode formed from the silver particles is excellent in the wettability of the solder material, and can be suitably bonded to a wiring material (such as a tab wire) that electrically connects the solar cell elements. .

  As described above, an electrode formed from a conductive composition containing silver particles exhibits excellent characteristics as an electrode of a solar cell. On the other hand, silver is a noble metal, and the bullion itself is expensive. From the viewpoint of resources, a conductive material that replaces silver is desired. An example of a promising conductive material that can replace silver is copper that is applied to semiconductor wiring materials. Copper is abundant in terms of resources, and the price 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 of copper, copper particles that have been given oxidation resistance using various techniques and are not easily oxidized even by high-temperature heat treatment (firing) have been reported (for example, Patent Document 1 and Patent Document 2).

JP 2005-314755 A Japanese Patent Laid-Open No. 2004-217952

  However, even the above copper particles of Patent Document 1 and Patent Document 2 have oxidation resistance at most up to 300 ° C. and are almost oxidized at a high temperature of 800 ° C. to 900 ° C., and thus are formed from copper particles. The electrode has not been put into practical use as an electrode for solar cells. Furthermore, the additive applied in order to provide oxidation resistance inhibits the sintering of the copper particles during the heat treatment (firing), and as a result, there is a problem that an electrode having a low resistivity such as silver cannot be obtained.

  As another method for obtaining an electrode by suppressing copper oxidation, there is a method through a special manufacturing process in which a conductive composition using copper as conductive metal particles is heat-treated (fired) in an atmosphere such as nitrogen. Can be mentioned. However, in the case of using the above method, in order to suppress the oxidation of copper particles, a sealed environment is required so as to have an atmosphere filled with nitrogen or the like, which is not suitable for mass production of solar cell elements in terms of manufacturing cost. .

Another problem for applying copper to a solar cell electrode is ohmic contact with a semiconductor substrate. That is, even if the copper-containing electrode can be formed without being oxidized during the high-temperature heat treatment (firing), the copper contacts the semiconductor substrate, thereby causing mutual diffusion between the copper and the semiconductor substrate. In some cases, a reactant phase of copper and a semiconductor substrate is formed at the interface between the two. For example, when a silicon substrate is used, copper is in contact with the silicon substrate, thereby causing mutual diffusion between copper and silicon, and a reaction phase of copper and silicon at the interface between the electrode and the silicon substrate. Cu ₃ Si may be formed.

The formation of such a reactant phase such as Cu ₃ Si may reach a depth of several μm from the interface of the semiconductor substrate, which may cause cracks in the semiconductor substrate. In addition, the reactant phase may penetrate an n-type diffusion layer formed in advance on the semiconductor substrate and deteriorate the semiconductor performance (pn junction characteristics) of the solar cell. In addition, the formed reactant phase may raise the copper-containing electrode, thereby hindering the adhesion between the electrode and the semiconductor substrate, resulting in a decrease in the mechanical strength of the electrode.

  The present invention has been made in view of the above problems, and has a low resistivity, a good ohmic contact with a semiconductor substrate, and a solar cell element having a copper-containing electrode with excellent adhesion to the semiconductor substrate. It aims at providing the manufacturing method, the solar cell element manufactured by this manufacturing method, and the solar cell which has this solar cell element.

  As a result of earnest research to solve the above problems, the present invention has been achieved. That is, the present invention is as follows.

<1> An electrode-forming composition layer is provided by applying a composition for forming an electrode containing metal particles containing phosphorus-tin-nickel-containing copper alloy particles, a solvent, and a resin on at least one surface of a semiconductor substrate. An application step to form;
A drying step of heat-treating the electrode-forming composition layer at a temperature of less than 300 ° C. for 1 second to 15 minutes to evaporate the solvent;
A degreasing step in which the electrode forming composition layer is heat-treated at a temperature of 300 ° C. or higher and lower than 600 ° C. for 5 seconds to 2 minutes, and the resin is thermally decomposed;
An electrode forming step of heat-treating the electrode-forming composition layer at a temperature of 600 ° C. or higher and 1000 ° C. or lower for 5 seconds to 1 minute to form a copper-containing electrode that is a heat-treated product of the electrode-forming composition;
The manufacturing method of the solar cell element which contains these in this order.
<2> The method for producing a solar cell element according to <1>, wherein the degreasing step and the electrode forming step are continuously performed.
<3> The method for producing a solar cell element according to <1> or <2>, wherein the phosphorus-tin-nickel-containing copper alloy particles have a phosphorus content of 2.0% by mass to 15.0% by mass.
<4> The solar cell element according to any one of <1> to <3>, wherein the phosphorus-tin-nickel-containing copper alloy particles have a tin content of 3.0% by mass to 30.0% by mass. Manufacturing method.
<5> The solar cell element according to any one of <1> to <4>, wherein the phosphorus-tin-nickel-containing copper alloy particles have a nickel content of 3.0% by mass to 30.0% by mass. Manufacturing method.
<6> The method for producing a solar cell element according to any one of <1> to <5>, wherein the electrode-forming composition further includes glass particles.
<7> Before the electrode formation step, the method further includes a step of applying an aluminum electrode formation composition to a portion of the semiconductor substrate to which the electrode formation composition is not applied, The method for producing a solar cell element according to any one of <1> to <6>, wherein the containing electrode and the aluminum electrode are collectively formed.
<8> Before the electrode formation step, further includes a step of applying a composition for forming a silver electrode to a portion of the semiconductor substrate where the composition for forming an electrode and the composition for forming an aluminum electrode are not applied, The method for manufacturing a solar cell element according to <7>, wherein in the electrode formation step, the copper-containing electrode, the aluminum electrode, and the silver electrode are collectively formed.
<9> The sun according to any one of <1> to <8>, wherein the copper-containing electrode includes an alloy phase containing copper, tin, and nickel and a glass phase containing tin, phosphorus, and oxygen. A battery element manufacturing method.
<10> A solar cell element produced by the production method according to any one of <1> to <9>.
<11> A solar cell having the solar cell element according to <10> and a wiring material disposed on an electrode of the solar cell element.

  According to the present invention, a method for manufacturing a solar cell element having a low resistivity, a good ohmic contact with a semiconductor substrate, and further having a copper-containing electrode having excellent adhesion to the semiconductor substrate, and the manufacturing method It is possible to provide a solar cell element and a solar cell having this solar cell element.

It is a schematic sectional drawing which shows an example of a solar cell element. It is a schematic plan view which shows an example of the light-receiving surface of a solar cell element. It is a schematic plan view which shows an example of the back surface of a solar cell element. It is a schematic plan view which shows an example of the back surface side electrode structure of a back contact type solar cell element. It is a schematic perspective view which shows an example of AA cross-section structure of a back contact type solar cell element. It is a schematic perspective view which shows another example of the cross-sectional structure of a back contact type solar cell element. It is a schematic perspective view which shows another example of the cross-sectional structure of a back contact type solar cell element. It is the schematic which shows an example of the time change of the temperature of the semiconductor substrate in the degreasing process and electrode formation process of the manufacturing method of this invention.

  In this specification, the term “process” is not limited to an independent process, and is included in this term if the purpose of the process is achieved even when it cannot be clearly distinguished from other processes. In the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. In addition, in the present specification, the content of each component in the composition is such that when there are a plurality of substances corresponding to each component in the composition, the plurality of substances present in the composition unless otherwise specified. Means the total amount. In the present specification, the particle diameter of each component in the composition is such that when there are a plurality of particles corresponding to each component in the composition, the plurality of particles present in the composition unless otherwise specified. The value for a mixture of In addition, in the present specification, the term “layer” includes a configuration of a shape formed in part in addition to a configuration of a shape formed on the entire surface when observed as a plan view.

<Method for producing solar cell element>
The method for producing a solar cell element of the present invention is a composition for forming an electrode (hereinafter referred to as “electrode-forming composition”) containing metal particles containing phosphorus-tin-nickel-containing copper alloy particles, a solvent, and a resin on at least one surface of a semiconductor substrate. An application step of forming an electrode forming composition layer by applying a “specific electrode forming composition”, and heat-treating the electrode forming composition layer at a temperature of less than 300 ° C. for 1 second to 15 minutes, A drying process for evaporating, a degreasing process for thermally decomposing the resin by heat-treating the electrode forming composition layer at a temperature of 300 ° C. or higher and lower than 600 ° C. for 5 seconds to 2 minutes, and an electrode forming composition layer at 600 ° C. or higher. And an electrode forming step of forming a copper-containing electrode, which is a heat-treated product of the electrode-forming composition, in this order at a temperature of 1000 ° C. or lower for 5 seconds to 1 minute.
When the semiconductor element manufacturing method has the above-described configuration, oxidation of copper during heat treatment (firing) in the atmosphere is suppressed, and an electrode having a low resistivity tends to be formed. Furthermore, when an electrode-forming composition is applied to a semiconductor substrate to form an electrode, the formed electrode and the semiconductor substrate can form a good ohmic contact, and an electrode having excellent adhesion to the semiconductor substrate can be formed. There is a tendency to form.

(Granting process)
In the applying step, an electrode forming composition containing phosphorus-tin-nickel-containing copper alloy particles, a solvent, and a resin is applied on at least one surface of the semiconductor substrate to form an electrode forming composition layer (hereinafter referred to as “specific”). Also referred to as “electrode-forming composition layer”.
Examples of the method for applying the composition for forming a specific electrode to a semiconductor substrate include a screen printing method, an ink jet method, a dispenser method, and the like. From the viewpoint of productivity, the screen printing method is preferable.

  When the specific electrode forming composition is applied to the semiconductor substrate by a screen printing method, the specific electrode forming composition is preferably a paste-like composition. The paste-like composition for forming a specific electrode preferably has a viscosity in the range of 20 Pa · s to 1000 Pa · s. In addition, the viscosity of the composition for specific electrode formation is measured at 25 degreeC using a Brookfield HBT viscometer.

The amount of the specific electrode forming composition applied to the semiconductor substrate can be appropriately selected according to the size of the electrode to be formed. For example, the application amount of the specific electrode-forming composition ^may be a ^{2g / m 2 ~10g / m 2} , it is preferably ^{4g / m 2 ~8g / m 2} .

  Further, an electrode forming composition other than the specific electrode forming composition (for example, an aluminum electrode forming composition, a silver electrode forming composition) is used to make an electrode other than a copper-containing electrode (for example, an aluminum electrode, a silver electrode). ) May be applied to the semiconductor substrate by using a method similar to the method for applying the specific electrode forming composition.

(Drying process)
In the drying step, the specific electrode forming composition layer is heat-treated at a temperature of less than 300 ° C. for 1 second to 15 minutes to evaporate the solvent. A drying process is performed after the said provision process. The drying step suppresses the solvent contained in the specific electrode forming composition from being evaporated and remaining as a residue in the specific electrode forming composition layer. Therefore, in an electrode formation process, it is suppressed that reaction and sintering of phosphorus-tin-nickel containing copper alloy particles are inhibited by the residue of a solvent, and a low resistance electrode can be formed. In addition, since a Sn—PO glass phase, which will be described later, can be generated effectively, the formation of a Cu ₃ Si reaction phase at the interface between the electrode and the semiconductor substrate (for example, a silicon substrate) can be suppressed.
The conditions for the drying step can be appropriately set according to the type of solvent, the coating amount of the composition for forming a specific electrode, and the like. From the viewpoint of productivity, for example, the drying step is preferably performed at a temperature of 280 ° C. or lower for 2 seconds to 3 minutes, more preferably at a temperature of 250 ° C. or lower for 5 seconds to 2 minutes.

  As an apparatus used for the drying step, any apparatus that can be heated to the above temperature can be used as appropriate, and examples thereof include a blower dryer, a hot plate, and a tunnel furnace.

  Further, an electrode forming composition other than the specific electrode forming composition (for example, an aluminum electrode forming composition, a silver electrode forming composition) is used to make an electrode other than a copper-containing electrode (for example, an aluminum electrode, a silver electrode). ) May be applied by applying the above conditions of the drying step of the composition for forming a specific electrode. For example, after applying a composition for forming a specific electrode and performing a drying process, applying and drying at least one selected from a composition for forming an aluminum electrode and a composition for forming a silver electrode; It is preferable to carry out the drying steps alternately.

(Degreasing process)
In the degreasing step, the specific electrode forming composition layer is heat-treated at a temperature of 300 ° C. or higher and lower than 600 ° C. for 5 seconds to 2 minutes to thermally decompose the resin. The degreasing process is performed after the drying process. The degreasing step prevents the resin contained in the specific electrode forming composition from being thermally decomposed and remaining as a residue in the specific electrode forming composition layer. Therefore, in an electrode formation process, it is suppressed that reaction and sintering of phosphorus-tin-nickel containing copper alloy particles are inhibited by the residue of a solvent, and a low resistance electrode can be formed. In addition, since a Sn—PO glass phase, which will be described later, can be generated effectively, the formation of a Cu ₃ Si reaction phase at the interface between the electrode and the semiconductor substrate (for example, a silicon substrate) can be suppressed.

  The conditions for the degreasing step are not particularly limited as long as heat treatment can be performed at a temperature of 300 ° C. or higher and lower than 600 ° C. for 5 seconds to 2 minutes. The conditions for the degreasing step can be appropriately set according to the type of solvent, the coating amount of the composition for forming a specific electrode, and the like. The degreasing process is preferably performed at a temperature of 350 ° C. or higher and 550 ° C. or lower for 5 seconds to 2 minutes, and at a temperature of 350 ° C. or higher and 500 ° C. or lower for 10 seconds to 2 from the viewpoint of productivity and electrode resistivity. It is more preferable to perform a heat treatment.

  As an apparatus used for the degreasing step, any apparatus that can be heated to the above temperature can be used as appropriate, and examples thereof include a blow dryer, a hot plate, and a tunnel furnace. From the viewpoint of productivity, in particular, from the viewpoint of continuity with the subsequent electrode formation step, it is preferable to use a tunnel furnace.

  Further, an electrode forming composition other than the specific electrode forming composition (for example, an aluminum electrode forming composition, a silver electrode forming composition) is used to make an electrode other than a copper-containing electrode (for example, an aluminum electrode, a silver electrode). ) May be degreased by applying the above conditions of the degreasing step of the composition for forming a specific electrode. For example, after applying a specific electrode forming composition and performing a drying step, applying at least one selected from an aluminum electrode forming composition and a silver electrode forming composition and drying, then forming each electrode The composition layer may be degreased all at once.

(Electrode formation process)
In the electrode forming step, the specific electrode forming composition layer is heat-treated (fired) at a temperature of 600 ° C. to 1000 ° C. for 5 seconds to 1 minute to form a copper-containing electrode that is a heat-treated product of the specific electrode forming composition. . An electrode formation process is performed after a degreasing process. You may perform a degreasing process and an electrode formation process continuously. In the electrode forming step, the reaction and sintering of the phosphorus-tin-nickel-containing copper alloy particles contained in the composition for forming a specific electrode is performed, and a low-resistance electrode is formed.

  In the present specification, “degreasing step and electrode forming step are performed continuously” means performing the electrode forming step after the degreasing step without performing other processes between the degreasing step and the electrode forming step. Means. For example, after the semiconductor substrate on which the composition layer for forming a specific electrode is formed is placed in an apparatus used for the degreasing process and the heat treatment in the degreasing process is performed, the semiconductor substrate is taken out, without performing processing such as cooling, You may perform the said heat processing (baking) in an electrode formation process within the same apparatus.

  The conditions for the electrode forming step are not particularly limited as long as heat treatment (firing) can be performed at a temperature of 600 ° C. to 1000 ° C. for 5 seconds to 1 minute. The conditions for the electrode forming step can be appropriately set according to the type of metal particles, the coating amount of the specific electrode forming composition, and the like. The electrode forming step is preferably performed at a temperature of 650 ° C. to 950 ° C. for 5 seconds to 50 seconds from the viewpoint of productivity and electrode resistivity, and is preferably 700 ° C. to 950 ° C. It is more preferable to perform heat treatment (firing) for 5 seconds to 40 seconds.

As an apparatus used for the electrode forming step, any apparatus that can be heated to the above temperature can be adopted as appropriate, and examples thereof include an infrared heating furnace and a tunnel furnace. The infrared heating furnace is highly efficient because electric energy is input to the heat treatment material in the form of electromagnetic waves and converted into heat energy, and rapid heating is possible in a short time. Furthermore, since there are few products by combustion and non-contact heating, it is possible to suppress contamination of the generated electrodes. Since the tunnel furnace automatically and continuously conveys the sample from the entrance to the exit and heat-treats (firing), it is possible to suppress unevenness of the heat-treatment (firing) by controlling the furnace body classification and the conveyance 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.
In addition, it is preferable to use a tunnel furnace also from a viewpoint which can perform a degreasing process and an electrode formation process continuously. For example, a semiconductor substrate on which a composition layer for forming a specific electrode is formed is put into a tunnel furnace, heat-treated under the above degreasing conditions, and then the setting of the temperature of the tunnel furnace is changed without removing the semiconductor substrate from the tunnel furnace. Thus, a copper-containing electrode that is a heat-treated product of the composition for forming a specific electrode may be formed by heat treatment (firing) under the above electrode formation conditions.

(Other processes)
The manufacturing method of a solar cell element may include other steps as desired in addition to the above-described application step, drying step, degreasing step, and electrode forming step. For example, the process for forming other electrodes, such as an aluminum electrode and a silver electrode, may be included other than the copper containing electrode which is the heat processing thing of the composition for specific electrode formation. As such a step, a step of applying a composition for forming other electrodes (hereinafter, also referred to as “other electrode forming composition”) onto the semiconductor substrate, and the other formed electrode forming composition The process of drying a physical layer, the process of degreasing, the process of heat-processing the other composition layer for electrode formation, and the process of forming another electrode, etc. are mentioned.
The conditions for the application process, the drying process, the degreasing process, and the electrode forming process of the other electrode forming composition were the same as those in the application process, the drying process, the degreasing process, and the electrode forming process using the specific electrode forming composition. It's okay.
In addition, the drying process of a composition for electrode formation, a degreasing process, and an electrode formation process can also be performed collectively with the drying process for forming a copper containing electrode, a degreasing process, and an electrode formation process, respectively. Thereby, the number of processes can be suppressed and manufacturing efficiency can be improved.

For example, when manufacturing a solar cell element further having an aluminum electrode, the method for manufacturing a solar cell element applies a composition for forming a specific electrode on a semiconductor substrate before an electrode formation step for forming a copper-containing electrode. In the electrode forming step for forming the copper-containing electrode, the step of applying the composition for forming an aluminum electrode to a portion that is not formed can be further formed.
Moreover, when manufacturing the solar cell element which further has a silver electrode in addition to an aluminum electrode, the manufacturing method of a solar cell element is for the specific electrode formation on a semiconductor substrate before the electrode formation process for forming a copper containing electrode. In the electrode formation process for forming a copper containing electrode further including the process of providing the composition for silver electrode formation in the part which has not provided the composition and the composition for aluminum electrode formation, a copper containing electrode, an aluminum electrode, A silver electrode can be formed at a time.

<Electrode forming composition>
The electrode forming composition used in the present invention contains metal particles including phosphorus-tin-nickel-containing copper alloy particles, a solvent, and a resin. By being a structure which the composition for electrode formation concerns, it exists in the tendency for the oxidation of copper in the heat processing (baking) in air | atmosphere to be suppressed, and for an electrode with low resistivity to be formed. Furthermore, when an electrode-forming composition is applied to a semiconductor substrate to form an electrode, the formed electrode and the semiconductor substrate can form a good ohmic contact, and an electrode having excellent adhesion to the semiconductor substrate can be formed. There is a tendency to form.

(Metal particles)
The composition for specific electrode formation contains at least one of phosphorus-tin-nickel-containing copper alloy particles as metal particles. The composition for specific electrode formation may contain at least one selected from the group consisting of phosphorus-containing copper alloy particles, tin-containing particles, and nickel-containing particles as metal particles, and silver particles, if necessary. Good.

  The content rate of the metal particles in the composition for forming a specific electrode is not particularly limited. The content of the metal particles in the composition for forming a specific electrode is preferably, for example, 65.0% by mass to 94.0% by mass, and more preferably 68.0% by mass to 92.0% by mass. Preferably, it is 70.0 mass%-90.0 mass%. When the content of the metal particles is 65.0% by mass or more, it tends to be adjusted to a suitable viscosity when the composition for forming a specific electrode is applied. Moreover, it exists in the tendency for generation | occurrence | production of the blurring at the time of providing the composition for specific electrode formation to be suppressed effectively because the content rate of a metal particle is 94.0 mass% or less.

-Phosphorus-tin-nickel-containing copper alloy particles-
The composition for specific electrode formation contains at least one of phosphorus-tin-nickel-containing copper alloy particles as metal particles. In general, as a copper alloy containing phosphorus, a brazing material called phosphorus copper brazing (phosphorus concentration: about 7% by mass or less) is known. Phosphor copper brazing is also used as a bonding material between copper and copper. By using copper alloy particles containing phosphorus as metal particles in the composition for forming a specific electrode, it is possible to form an electrode having excellent oxidation resistance and low resistivity by utilizing the reducibility of phosphorus to copper oxide. .

  The phosphorus-tin-nickel-containing copper alloy particles used in the present invention are copper alloy particles further containing tin and nickel in addition to phosphorus. When the copper alloy particles contain tin and nickel, it is possible to form an electrode with low resistivity and excellent adhesion in the electrode forming step, and to further improve the oxidation resistance of the electrode.

  This can be considered as follows, for example. When the copper alloy particles contain phosphorus and tin, phosphorus, tin and copper in the phosphorus-tin-nickel-containing copper alloy particles react with each other in the electrode forming step, and the Cu-Sn alloy phase and Sn-PO glass Form a phase. By forming the Cu—Sn alloy phase, an electrode having a low resistivity can be formed. Here, the Cu—Sn alloy phase is generated at a relatively low temperature of about 500 ° C. It is considered that when the copper alloy particles used in the present invention contain nickel, the Cu—Sn alloy phase formed above reacts further with nickel to form a Cu—Sn—Ni alloy phase. This Cu—Sn—Ni alloy phase may be formed even at a high temperature of 500 ° C. or higher (for example, 800 ° C.). As a result, an electrode having a low resistivity can be formed while maintaining oxidation resistance even if heat treatment (firing) is performed at a high temperature in the electrode formation step.

  Further, the Cu—Sn—Ni alloy phase is a Cu—Sn—Ni alloy phase and forms a dense bulk body in the electrode. The bulk body functions as a conductive portion, so that the resistivity of the electrode can be reduced. As used herein, a dense bulk body means that massive Cu—Sn—Ni alloy phases are in close contact with each other and a three-dimensional continuous structure is formed. The formation of such a structure means that a scanning electron microscope (for example, Hitachi High-Technologies Corporation, TM-1000 type scanning) is used to scan an arbitrary cross section perpendicular to the electrode forming surface of the substrate on which the electrodes are formed. This can be confirmed by observing at a magnification of 100 to 10,000 times using a scanning electron microscope. Here, the cross section for observation is taken as a cross section when cut by an RCO-961 type diamond cutter manufactured by Refine Tech Co., Ltd. In addition, since the cross section for observation after cutting may still have cutting flaws or the like due to a cutting machine, it is preferable to polish it with abrasive paper or the like to remove surface irregularities on the observation cross section, and then buff, etc. More preferably, mirror polishing is used.

  In addition, when an electrode is formed on a semiconductor substrate using the composition for forming a specific electrode, an electrode having high adhesion to the semiconductor substrate can be formed, and the ohmic contact between the electrode and the semiconductor substrate is improved. This can be considered as follows by taking a semiconductor substrate containing silicon (hereinafter also simply referred to as “silicon substrate”) as an example.

  The Sn—PO glass phase formed by the reaction of phosphorus and tin in the phosphorus-tin-nickel-containing copper alloy particles in the electrode forming step is a three-dimensional bulk body of the Cu—Sn—Ni alloy phase in the electrode. And between the Cu—Sn—Ni alloy phase and the silicon substrate. Since the Cu-Sn-Ni alloy phase and the Sn-PO glass phase are three-dimensionally continuous with each other and are not mixed after being formed by heat treatment (firing), the strength of the electrode itself is kept high. . In addition, since the Sn—PO glass phase is interposed at the interface between the silicon substrate and the electrode, the adhesion between the electrode and the silicon substrate is improved.

Further, the Sn—PO glass phase functions as a barrier layer for preventing mutual diffusion between copper and silicon, so that an ohmic contact between the electrode formed by heat treatment (firing) and the silicon substrate can be achieved. It can be considered that the contact becomes good. That is, by using the composition for forming a specific electrode, the reaction between copper and silicon is suppressed, the formation of a reactant phase (Cu ₃ Si) is suppressed, and the semiconductor performance (for example, pn junction characteristics) is not deteriorated. It is considered that good ohmic contact between the electrode and the silicon substrate can be exhibited while maintaining the adhesion of the formed electrode to the silicon substrate.

  Such an effect is generally manifested when an electrode is formed using a composition for forming a specific electrode on a silicon-containing substrate, but the same applies to other semiconductor substrates. An effect can be expected, and the type of the semiconductor substrate 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. Especially, it can use suitably for a silicon substrate. In addition, it is not limited to the semiconductor substrate for solar cell formation, The said composition for electrode formation can be used also for the semiconductor substrate etc. which are used for manufacture of semiconductor devices other than a solar cell.

  That is, in the present invention, by containing phosphorus-tin-nickel-containing copper alloy particles as metal particles in the composition for forming a specific electrode, first, copper oxidation of phosphorus atoms in the phosphorus-tin-nickel-containing copper alloy particles An electrode having excellent oxidation resistance and low resistivity is formed by utilizing the reducing property of the product. In addition, since the alloy particles contain tin and nickel, the resulting electrode maintains a low resistivity while the Cu—Sn alloy phase, or the Cu—Sn—Ni alloy phase and the Sn—PO glass phase. Formed in the electrode. 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, thereby making the electrode itself a dense structure, resulting in an electrode An improvement in strength is obtained. In addition, since the Sn—PO glass phase functions as a barrier layer for preventing mutual diffusion of copper and silicon, a good ohmic contact is formed between the electrode containing copper and the silicon substrate. It can be considered that such a characteristic mechanism can be realized in the electrode forming process.

  The effects as described above can be obtained even when, for example, phosphorus-containing copper alloy particles, tin-containing particles, and nickel-containing particles are combined without using phosphorus-tin-nickel-containing copper alloy particles in the composition for forming a specific electrode. can get. However, by using phosphorus-tin-nickel-containing copper alloy particles in the composition for forming a specific electrode, for example, the obtained electrode is compared with the case where phosphorus-containing copper alloy particles, tin-containing particles and nickel-containing particles are used in combination. Further, the resistivity is further reduced and the adhesion with the silicon substrate is improved.

  This can be considered as follows, for example. In the case where, for example, phosphorus-containing copper alloy particles, tin-containing particles and nickel-containing particles are used in combination without using phosphorus-tin-nickel-containing copper alloy particles in the composition for forming a specific electrode, heat treatment (firing) ) And the metal particles react with each other to form a Cu—Sn—Ni alloy phase and a Sn—PO glass phase. However, while the reaction between the metal particles proceeds, voids are formed in the electrode due to the separate metal particles, or the Sn—PO glass phase is locally thickly formed. There is. Thereby, the adhesion area of the electrode to the silicon substrate tends to be small. Furthermore, due to the difference in thermal expansion coefficient between the Sn—PO glass phase and the Cu—Sn—Ni alloy phase in the temperature lowering process in the electrode formation step, the Sn—PO glass phase and the Cu—Sn—Ni alloy phase There is a tendency that cracks between them or cracks in the Sn-PO glass phase tend to occur. As a result, there is a possibility that the strength in the electrode is lowered, and the connection strength when the wiring material is connected to the electrode cannot be maintained.

  On the other hand, in the present invention, since the phosphorus-tin-nickel-containing copper alloy particles are used in the composition for forming a specific electrode, the element forming the electrode is contained in one alloy particle, so that Cu-Sn-Ni The network formation of the alloy phase tends to occur uniformly, and the resistivity of the formed electrode is further reduced. Further, since the Sn—PO glass phase is produced from the individual phosphor-tin-nickel-containing copper alloy particles, the Sn—PO glass phase is easily distributed uniformly in the electrode. Thereby, it is suppressed that the Sn—PO glass phase is locally formed thick, and generation of cracks due to the Sn—PO glass phase is suppressed. As a result, the strength in the electrode can be improved.

The copper content contained in the phosphorus-tin-nickel-containing copper alloy constituting the phosphorus-tin-nickel-containing copper alloy particles in the present invention is not particularly limited. The copper content is preferably 50.0% by mass to 92.0% by mass, for example, from the viewpoint of reducing the resistivity of the electrode and forming ability of the Sn—PO glass phase, and is preferably 55.0% by mass. It is more preferable that it is -88.0 mass%, and it is still more preferable that it is 60.0 mass%-85.0 mass%.
Since the copper content contained in the phosphorus-tin-nickel-containing copper alloy is 92% by mass or less, an Sn—PO glass phase can be effectively formed, and adhesion to a silicon substrate and ohmic contact can be achieved. An excellent electrode can be formed. When the copper content is 50.0% by mass or more, more excellent acid resistance can be achieved and the resistivity of the formed electrode can be reduced. Further, when the copper content is 60.0% by mass or more, the structure of the formed electrode is densified, and as a result, the strength in the electrode and the adhesion to the semiconductor substrate are improved.

The phosphorus content contained in the phosphorus-tin-nickel-containing copper alloy constituting the phosphorus-tin-nickel-containing copper alloy particles in the present invention is not particularly limited. From the viewpoint of improving oxidation resistance (reducing the resistivity of the electrode) and forming ability of the Sn—PO glass phase, for example, the phosphorus content is preferably 2.0% by mass to 15.0% by mass. It is more preferable that it is 2.5 mass%-12.0 mass%, and it is still more preferable that it is 3.0 mass%-10.0 mass%.
It is possible to obtain an electrode having a low resistivity because the phosphorus content contained in the phosphorus-tin-nickel-containing copper alloy is 15.0% by mass or less, and phosphorus-tin-nickel-containing copper alloy particles Excellent productivity. Moreover, Sn-PO glass phase can be effectively formed by making the phosphorus content rate contained in a phosphorus-tin-nickel containing copper alloy 2.0 mass% or more, and the adhesiveness with respect to a silicon substrate. An electrode excellent in ohmic contact can be formed. Phosphorus-tin-nickel-containing copper alloy particles satisfying the above-described content can be suitably used as electrode-forming alloy particles.

  Moreover, 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 viewpoints of oxidation resistance, reactivity with copper and nickel during heat treatment (firing) in the electrode forming step, and Sn-PO glass phase forming ability, the tin content contained in the phosphorus-tin-nickel-containing copper alloy Is, for example, preferably 3.0% by mass to 30.0% by mass, more preferably 4.0% by mass to 25.0% by mass, and more preferably 5.0% by mass to 20.0% by mass. More preferably. When the tin content contained in the phosphorus-tin-nickel-containing copper alloy is 30.0% by mass or less, a low resistivity Cu—Sn—Ni alloy phase can be formed. Moreover, the reactivity with copper and nickel at the time of the heat processing (baking) in an electrode formation process by making the tin content rate contained in a phosphorus-tin-nickel containing copper alloy 3.0 mass% or more, and with phosphorus The reactivity is improved, and a Cu—Sn—Ni alloy phase and a Sn—P—O glass phase can be effectively formed.

  Moreover, the nickel 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, the nickel content contained in the phosphorus-tin-nickel-containing copper alloy is preferably 3.0% by mass to 30.0% by mass, for example, and 3.5% by mass to 25.%. It is more preferably 0% by mass, and further preferably 4.0% by mass to 20.0% by mass. When the nickel content contained in the phosphorus-tin-nickel-containing copper alloy is 30.0% by mass or less, a low resistivity Cu—Sn—Ni alloy phase can be effectively formed. Further, by setting the nickel content contained in the phosphorus-tin-nickel-containing copper alloy to 3.0% by mass or more, oxidation resistance particularly in a high temperature region of 500 ° C. or more can be improved.

  Furthermore, as a 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, oxidation resistance, From the viewpoint of resistivity, the reactivity of copper, phosphorus, tin and nickel during heat treatment (firing), the ability to form a Sn-PO glass phase, and the adhesion between the electrode and the silicon substrate, for example, the phosphorus content is 2.0 mass% to 15.0 mass%, tin content is 3.0 mass% to 30.0 mass%, and nickel content is 3.0 mass% to 30.0 mass% %, The phosphorus content is 2.5% by mass to 12.0% by mass, the tin content is 4.0% by mass to 25.0% by mass, and the nickel content is Is more preferably 3.5% by mass to 25.0% by mass, The content is 3.0 mass% to 10.0 mass%, the tin content is 5.0 mass% to 20.0 mass%, and the nickel content is 4.0 mass% to 20 mass%. More preferably, it is 0.0 mass%.

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. 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, and is resistant to oxidation. From the viewpoint of reducing the resistivity and the electrode resistivity, it is preferably 1% by mass or less.

  In addition, the content rate of each element in the phosphorus-tin-nickel containing copper alloy which comprises phosphorus-tin-nickel containing copper alloy particle | grains can be measured by the quantitative analysis of an inductively coupled plasma mass spectrometry (ICP-MS) method. .

  Moreover, the content rate of each element in the phosphorus-tin-nickel containing copper alloy which comprises phosphorus-tin-nickel containing copper alloy particle | grains can also be measured by the quantitative analysis of an energy dispersive X ray spectroscopy (EDX) method. Specifically, the phosphorus-tin-nickel-containing copper composite particles were embedded in a resin, cured, and then cut with a diamond cutter or the like, and were obtained by polishing with water-resistant abrasive paper, polishing liquid or the like as necessary. It is preferable to analyze the cross section of the phosphorus-tin-nickel-containing copper composite particles in the cross section. The reason can be considered as follows, for example.

  Since the phosphorus-tin-nickel-containing copper alloy particles contain significant phosphorus, depending on the handling environment, moisture absorption of the phosphorus-tin-nickel-containing copper alloy particles occurs, and as a result, the surface of the particles is oxidized. there is a possibility. The film formed by this oxidation is formed on the very surface and is considered to have little influence on the quality of the phosphorus-tin-nickel-containing copper alloy particles. There may be a difference in the copper content of each metal element between the inside of the particles. Therefore, when measuring the content of each element in the phosphorus-tin-nickel-containing copper alloy particles, it is considered preferable to measure the particle cross section instead of the particle surface.

  Phosphorus-tin-nickel-containing copper alloy particles may be used singly or in combination of two or more. In the present invention, “use in combination of two or more types of phosphorus-tin-nickel-containing copper alloy particles” means that two or more types of phosphorus having the same particle shape such as the particle size and particle size distribution described later, although the component ratios are different. -When using tin-nickel-containing copper alloy particles 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 A case where two or more different types of phosphorus-tin-nickel-containing copper alloy particles are used in combination is exemplified.

  There is no restriction | limiting in particular as a particle diameter of a phosphorus- tin- nickel containing copper alloy particle. In the particle size distribution, the particle diameter (hereinafter sometimes abbreviated as “D50%”) when the volume integrated from the small diameter side is 50% is, for example, preferably 0.4 μm to 10 μm, and 1 μm to 7 μm. More preferably. By setting D50% of the phosphorus-tin-nickel-containing copper alloy particles to 0.4 μm or more, the oxidation resistance tends to be effectively improved. By making D50% of the phosphorus-tin-nickel-containing copper alloy particles 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 effectively reduced. Tend.

  The particle diameter of the phosphorus-tin-nickel-containing copper alloy particles is measured by a laser diffraction particle size distribution meter (for example, Beckman Coulter, Inc., LS 13 320 type laser scattering diffraction particle size distribution analyzer). Specifically, phosphorus-tin-nickel-containing copper alloy particles are added to 125 g of a solvent (terpineol) within a range of 0.01% by mass to 0.3% by mass 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 with the refractive index of the solvent being 1.48.

  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 electrode resistivity, the shape of the phosphorus-tin-nickel-containing copper alloy particles is preferably substantially spherical, flat or plate-like.

In addition, when the composition for forming a specific electrode includes phosphorus-tin-nickel-containing copper alloy particles in addition to phosphorus-tin-nickel-containing copper alloy particles, etc., the phosphorus content when the metal particle content is 100.0% by mass -The content rate of a tin- nickel containing copper alloy particle is preferably 10.0 mass%-98.0 mass%, for example, It is more preferable that it is 15.0 mass%-96.0 mass%, It is more preferable that it is 20.0 mass%-95.0 mass%, and it is especially preferable that it is 25.0 mass%-92.0 mass%.
By setting the content of the phosphorus-tin-nickel-containing copper alloy particles to 10.0% by mass or more, voids in the electrode tend to be effectively reduced and the electrode can be densified. In addition, by setting the content of the phosphorus-tin-nickel-containing copper alloy particles to 98.0% by mass or less, the resistivity of the electrode due to the inclusion of other metal particles is reduced, and the adhesion of the electrode to the silicon substrate is reduced. There exists a tendency which can express effects, such as improvement.

The phosphorus-tin-nickel-containing copper alloy can be produced by a commonly used method. The phosphorus-tin-nickel-containing copper alloy particles are obtained by using a phosphorus-tin-nickel-containing copper alloy prepared so as to have a desired copper content, phosphorus content, tin content, and nickel content. It can be prepared using conventional methods for preparing powders. For example, phosphorus-tin-nickel-containing copper alloy particles can be produced 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-nickel-containing copper alloy particle is obtained by melting a phosphorus-tin-nickel-containing copper alloy, pulverizing this by nozzle spraying, and drying and classifying the obtained powder. Can be manufactured. Moreover, the phosphorus-tin-nickel containing copper alloy particle | grains which have a desired particle diameter can be manufactured by selecting classification conditions suitably.

-Phosphorus-containing copper alloy particles-
The composition for specific electrode formation may further include at least one of phosphorus-containing copper alloy particles as metal particles. By including phosphorus-containing copper alloy particles, the resistivity of the formed electrode is lowered, and the adhesion of the electrode to the semiconductor substrate tends to be further improved. For example, this can be considered as follows. That is, depending on the combination of the composition of the phosphorus-tin-nickel-containing copper alloy particles and the composition of the phosphorus-containing copper alloy particles, the phosphorus-containing copper alloy particles are at a lower temperature during the heat treatment (firing) in the electrode forming step, and The reaction may begin with a large exotherm. Accordingly, the specific electrode forming composition during the heat treatment (firing) in the electrode forming step generates heat from a relatively low temperature, thereby causing a reaction (Cu-Sn-Ni) of the phosphorus-tin-nickel-containing copper alloy particles. Formation of alloy phase and formation of Sn—P—O glass phase) can be promoted.

  Furthermore, the phosphorus-containing copper alloy particles themselves may produce copper by reduction with phosphorus in the heat treatment (firing) in the electrode forming step, and it is considered that the resistivity of the entire electrode can be lowered. Further, the phosphorus-containing copper alloy particles participate in a network composed of a Cu-Sn-Ni alloy phase and a Sn-PO glass phase derived from phosphorus-tin-nickel-containing copper alloy particles by heat treatment (firing), so that the entire electrode It is considered that the resistivity of the electrode is reduced and the structure of the electrode is densified, and as a result, the strength in the electrode and the adhesion to the semiconductor substrate are improved.

  The phosphorus content contained in the phosphorus-containing copper alloy particles when the phosphorus-containing copper alloy particles are contained in the composition for forming a specific electrode is, for example, 0 from the viewpoint of oxidation resistance and heat generation effect during heat treatment (firing). It is preferably 0.1% by mass to 8.0% by mass, more preferably 0.2% by mass to 8.0% by mass, and further preferably 0.5% by mass to 7.7% by mass. preferable.

The phosphorus-containing copper alloy particles are an alloy containing copper and phosphorus, 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, Sn, and Al. , Zr, W, Mo, Ti, Co, Ni, and Au.
Moreover, the content rate of the other atoms inevitably mixed in the phosphorus-containing copper alloy particles can be, for example, 3% by mass or less in the phosphorus-containing copper alloy particles, and the oxidation resistance and the resistivity of the electrode. In view of the above, the content is preferably 1% by mass or less.

  In the present invention, the phosphorus-containing copper alloy particles may be used singly or in combination of two or more. In the present invention, “use in combination of two or more types of phosphorus-containing copper alloy particles” means that two or more types of phosphorus-containing copper alloy particles having the same particle shape such as particle diameter and particle size distribution described later, although the component ratios are different. Are used in combination, but when two or more types of phosphorus-containing copper alloy particles having the same component ratio but different particle shapes are used in combination, two or more types of phosphorus-containing copper alloy particles having different component ratios and particle shapes are used. The case where it uses in combination is mentioned.

The particle diameter of the phosphorus-containing copper alloy particles is not particularly limited, and D50% is, for example, preferably 0.4 μm to 10 μm, and more preferably 1 μm to 7 μm. By setting D50% of the phosphorus-containing copper alloy particles to 0.4 μm or more, the oxidation resistance tends to be effectively improved. Further, by setting D50% of the phosphorus-containing copper alloy particles to 10 μm or less, the phosphorus-containing copper alloy particles in the electrode, the phosphorus-tin-nickel-containing copper alloy particles, and tin added as necessary as described later The contact area with the contained particles, nickel-containing particles and silver particles increases, and the resistivity of the electrode tends to be effectively reduced.
In addition, the measuring method of the particle diameter (D50%) of phosphorus containing copper alloy particle is the same as the measuring method of the particle diameter of phosphorus- tin- nickel containing copper alloy particle.
The shape of the phosphorus-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 low resistivity of the electrode, the shape of the phosphorus-containing copper alloy particles is preferably substantially spherical, flat or plate-like.

  Moreover, when the composition for specific electrode formation contains phosphorus-containing copper alloy particles as metal particles, the content of phosphorus-containing copper alloy particles is a phosphorus-containing copper alloy when the metal particle content is 100.0% by mass. The particle content is, for example, preferably 0.1% by mass to 50.0% by mass, and more preferably 0.5% by mass to 45.0% by mass.

  The phosphorus and copper contents in the phosphorus-containing copper alloy particles are also inductively coupled plasma mass spectrometry (ICP-MS) or energy dispersive X-ray, as with the phosphorus-tin-nickel-containing copper alloy particles. It can be measured by spectroscopic (EDX) quantitative analysis.

  From the viewpoint of oxidation resistance and the ability to form a Sn—PO glass phase, the copper content when the content of the metal particles is 100.0% by mass is, for example, 50.0% by mass to 92.0%. The mass is preferably 5% by mass, more preferably 55.0% by mass to 88.0% by mass, and still more preferably 60.0% by mass to 85.0% by mass.

(Solvent and resin)
The composition for specific electrode formation contains at least 1 type of resin. Moreover, the composition for specific electrode formation contains at least 1 type of a solvent. Thereby, the liquid physical properties (viscosity, surface tension, etc.) of the composition for forming a specific electrode can be adjusted within a range suitable for an application method when applying to a semiconductor substrate or the like.

  There is no restriction | limiting in particular as a solvent. Solvents include hydrocarbon solvents such as hexane, cyclohexane and toluene, halogenated hydrocarbon solvents such as dichloroethylene, dichloroethane and dichlorobenzene, and cyclics such as tetrahydrofuran, furan, tetrahydropyran, pyran, dioxane, 1,3-dioxolane and trioxane. Ether solvents, amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, sulfoxide solvents such as dimethyl sulfoxide, diethyl sulfoxide, ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, cyclohexanone, ethanol, 2-propanol, Alcohol solvents such as 1-butanol and diacetone alcohol, 2,2,4-trimethyl-1,3-pentanediol monoacetate, 2,2,4-trimethyl-1,3- Nantanediol monopropionate, 2,2,4-trimethyl-1,3-pentanediol monobutyrate, ester solvents of polyhydric alcohols such as ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, butyl cellosolve, diethylene glycol mono Examples include ether solvents of polyhydric alcohols such as butyl ether and diethylene glycol diethyl ether, and terpene solvents such as terpinene, terpineol, myrcene, alloocimene, limonene, dipentene, pinene, carvone, osmene, and ferrandrene. A solvent may be used individually by 1 type or may combine 2 or more types.

  As the solvent, from the viewpoint of impartability (coatability and printability) when forming the electrode-forming composition on the semiconductor substrate, from the group consisting of polyhydric alcohol ester solvent, terpene solvent and polyhydric alcohol ether solvent. It is preferably at least one selected, and more preferably at least one selected from the group consisting of polyhydric alcohol ester solvents and terpene solvents.

  As the resin, any resin that is usually used in the technical field can be used without particular limitation as long as it is a resin that can be thermally decomposed in the degreasing step, whether it is a natural polymer compound or a synthetic polymer compound. Good. Specifically, examples of the resin include cellulose resins such as methylcellulose, ethylcellulose, carboxymethylcellulose, and nitrocellulose; acrylic resins such as polyvinyl alcohol compounds, polyvinylpyrrolidone compounds, and polyethyl acrylate; vinyl acetate-acrylate copolymers; Examples include butyral resins such as polyvinyl butyral, phenol-modified alkyd resins, alkyd resins such as castor oil fatty acid-modified alkyd resins, epoxy resins, phenol resins, and rosin ester resins. Resin may be used individually by 1 type or may combine 2 or more types.

  The resin is preferably at least one selected from the group consisting of a cellulose resin and an acrylic resin from the viewpoint of suppressing resin residues in the heat treatment (firing) in the electrode forming step.

  The weight average molecular weight (Mw) of the resin is not particularly limited. Among these, the weight average molecular weight of the resin is preferably, for example, 5,000 to 500,000, and more preferably 10,000 to 300,000. When the weight average molecular weight of the resin is 5000 or more, an increase in the viscosity of the specific electrode forming composition tends to be suppressed. This can be considered to be because, for example, a sufficient steric repulsion effect is obtained when the resin is adsorbed on the metal particles, and aggregation of the resins is suppressed. On the other hand, when the weight average molecular weight of the resin is 500,000 or less, aggregation of the resins in the composition for forming a specific electrode is suppressed, and an increase in the viscosity of the composition for forming a specific electrode tends to be suppressed. Further, when the weight average molecular weight of the resin is 500,000 or less, the thermal decomposition temperature of the resin is suppressed from being increased, and the resin is suppressed from remaining as a residue when the specific electrode forming composition is heat-treated (fired). There is a tendency that a low resistivity electrode can be formed.

The weight average molecular weight of the resin is obtained by conversion using a standard polystyrene calibration curve from a molecular weight distribution measured using GPC (gel permeation chromatography). The calibration curve is approximated in three dimensions using five standard polystyrene sample sets (PStQuick MP-H, PStQuick B, Tosoh Corporation). The measurement conditions of GPC are as follows.
Apparatus: (Pump: L-2130 type [Hitachi High-Technologies Corporation]), (Detector: L-2490 type RI [Hitachi High-Technologies Corporation]), (Column oven: L-2350 [Corporation] Hitachi High-Technologies])
Column: Gelpack GL-R440 + Gelpack GL-R450 + Gelpack GL-R400M (3 in total) (Hitachi Chemical Co., Ltd.)
-Column size: 10.7 mm x 300 mm (inner diameter)
・ Eluent: Tetrahydrofuran ・ Sample concentration: 10 mg / 2 mL
・ Injection volume: 200 μL
・ Flow rate: 2.05 mL / min ・ Measurement temperature: 25 ° C.

The content of the solvent and resin in the composition for forming a specific electrode used in the present invention should be appropriately selected according to the type of solvent and resin to be used so that the composition for forming a specific electrode has desired liquid properties. Can do. For example, it is preferable that the total content rate of a solvent and resin is 3.0 mass%-50.0 mass% in the total mass of the composition for specific electrode formation, and is 5.0 mass%-45 mass%. It is more preferable that the content is 7% by mass to 40% by mass.
When the total content of the solvent and the resin is within the above range, the application suitability when applying the specific electrode forming composition to the semiconductor substrate is improved, and an electrode having a desired width and height is more easily obtained. There is a tendency to form.
The content ratio of the solvent and the resin in the composition for forming a specific electrode can be appropriately selected according to the type of solvent and resin to be used so that the composition for forming a specific electrode has desired liquid properties.

(Glass particles)
The composition for forming a specific electrode may further include glass particles. When the composition for forming a specific electrode contains glass particles, the adhesion between the formed electrode and the semiconductor substrate is improved in the heat treatment from the degreasing step to the electrode forming step. In particular, in the formation of the electrode on the light-receiving surface side of the solar cell, the silicon nitride constituting the antireflection layer is removed by so-called fire-through during the heat treatment from the degreasing process to the electrode forming process, and an ohmic contact between the electrode and the semiconductor substrate is formed. The

The glass particles preferably have a softening point of 650 ° C. or lower and a crystallization start temperature of higher than 650 ° C. from the viewpoint of lowering the resistivity of the electrode to be formed and the adhesion between the electrode and the semiconductor substrate. From the viewpoints of reactivity between other metal particles such as phosphorus-tin-nickel-containing copper alloy particles and phosphorus-containing copper alloy particles contained if necessary, the softening point of the glass particles is 600 ° C. or less. It is more preferable that
The softening point and the crystallization start temperature are measured by a usual method using a differential thermal-thermogravimetric analyzer (TG-DTA).

  When the electrode-forming composition is used to form an electrode on the light-receiving surface side of a solar cell, the glass particles are softened or melted at the electrode-forming temperature and come into contact with an antireflection layer composed of silicon nitride to oxidize silicon nitride. Thus, silicon dioxide is produced, and by incorporating this silicon dioxide, the antireflection layer can be removed, and glass particles usually used in this technical field can be used without any particular limitation.

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

  When the composition for forming a specific electrode is used to form an electrode other than the electrode on the light-receiving surface side of the solar cell, for example, a back output electrode, a through-hole electrode and a back electrode in a back contact solar cell element, the glass particles are The softening point is preferably 650 ° C. or lower, and the crystallization start temperature is preferably higher than 650 ° C. If it is such a glass particle, the glass particle which does not contain the component required for fire through like lead can be used.

Examples of the glass component constituting the glass particles include silicon oxide (SiO or SiO ₂ ), phosphorus oxide (P ₂ O ₅ ), aluminum oxide (Al ₂ O ₃ ), boron oxide (B ₂ O ₃ ), and 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 O} 3), niobium oxide (N 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). Can be mentioned.

Among them, glass particles containing at least one selected from the group consisting of 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 are used. It is preferable to use glass particles containing at least one selected from the group consisting of SiO ₂ , PbO, B ₂ O ₃ , Bi ₂ O ₃ , and Al ₂ O ₃ . In the case of such glass particles, the softening point tends to be effectively reduced. Furthermore, since such glass particles have improved wettability with phosphorus-tin-nickel-containing copper alloy particles, sintering between the particles proceeds in the electrode forming step, and an electrode with low resistivity can be formed. It tends to be possible.

  As content rate of the boron content in a glass particle, it is preferable that it is 0.1 mass% or more in the total mass of glass, and it is more preferable that it is 0.1 mass%-50 mass%. The boron content in the glass particles can be measured using quantitative analysis of the inductively coupled plasma mass spectrometry (ICP-MS) method or the like.

On the other hand, from the viewpoint of reducing the contact resistivity of the electrode, for example, glass particles containing phosphorous pentoxide (phosphate glass, P ₂ O ₅ glass particles) are preferable. More preferably, the glass particles further contain divanadium oxide (P ₂ O ₅ —V ₂ O ₅ glass particles). By further containing divanadium pentoxide, the oxidation resistance is improved and the resistivity of the electrode tends to decrease. This can be attributed to, for example, that the softening point of the glass is lowered by further containing divanadium pentoxide. When using diphosphorus pentoxide-divanadium pentoxide glass particles (P ₂ O ₅ —V ₂ O ₅ glass particles), the content of divanadium pentoxide is, for example, 1% by mass or more in the total mass of the glass. It is preferable that it is 1 mass%-70 mass%.

There is no restriction | limiting in particular as a particle diameter of a glass particle. The D50% of the glass particles is preferably 0.5 μm to 10 μm, for example, and more preferably 0.8 μm to 8 μm. When the D50% of the glass particles is 0.5 μm or more, the workability in the preparation of the electrode forming composition tends to be improved. By setting the D50% of the glass particles to 10 μm or less, the glass particles can be uniformly dispersed in the electrode forming composition, and fire-through can be efficiently generated in the electrode forming step. There is also a tendency to improve the adhesion to the substrate.
In addition, the measuring method of D50% of a glass particle is the same as the measuring method of the particle diameter of a phosphorus- tin- nickel containing copper alloy particle.

  The shape of the glass 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 a reduction in the resistivity of the electrode, the shape of the glass particles is preferably substantially spherical, flat or plate-like.

  When the composition for specific electrode formation contains glass particles, the content of the glass particles is preferably 0.1% by mass to 15.0% by mass, for example, in the total mass of the composition for specific electrode formation. It is more preferable that it is 0.5 mass%-12.0 mass%, and it is still more preferable that it is 1.0 mass%-10.0 mass%. By including glass particles with a content in such a range, oxidation resistance, lower electrode resistivity, and lower contact resistivity tend to be achieved effectively. Furthermore, it exists in the tendency which can promote the contact between phosphorus- tin- nickel containing copper alloy particles, and reaction.

  In the composition for forming a specific electrode, the mass ratio of glass particles to the mass of all metal particles (glass particles / all metal particles) is preferably 0.01 to 0.20, for example, 0.03 to 0 .15 is more preferable. By including glass particles with a content in such a range, oxidation resistance, lower electrode resistivity, and lower contact resistivity tend to be achieved effectively. Furthermore, it exists in the tendency which can promote the contact between metal particles and reaction.

  Further, the ratio of the particle size (D50%) of the glass particles to the particle size (D50%) of all metal particles (glass particles / total metal particles) is preferably 0.05 to 100, for example, 0.1 It is preferably ~ 20. By setting such a particle size ratio, there is a tendency to effectively achieve oxidation resistance, lower electrode resistivity, and lower contact resistivity. Furthermore, it exists in the tendency which can promote the contact between metal particles and reaction.

(flux)
The composition for forming a specific electrode may further contain at least one flux. By including the flux, when an oxide film is formed on the surface of the metal particles, the oxide film is removed, and the reaction of the phosphorus-tin-nickel-containing copper alloy particles during the heat treatment (firing) in the electrode forming process is promoted. Tend to be able to. Moreover, the effect that the adhesiveness of an electrode and a semiconductor substrate improves is also acquired by containing a flux.

  The flux is not particularly limited as long as the oxide film formed on the surface of the metal particles can be removed. Specifically, for example, fatty acids, boric acid compounds, fluorinated compounds, and borofluorinated compounds can be mentioned as preferred fluxes. A flux may be used individually by 1 type or may be used in combination of 2 or more type.

  More specifically, the flux includes 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 fluoride, 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 more preferable from the viewpoint of complementing the heat resistance during heat treatment from the degreasing process to the electrode forming process (the property that the flux does not volatilize at low temperatures during heat treatment (firing)) and the oxidation resistance of the metal particles. It is mentioned as a preferable flux.

  When the composition for forming a specific electrode contains a flux, the flux content is formed by effectively removing the oxidation resistance of the metal particles and by removing the flux upon completion of the heat treatment (firing). From the viewpoint of reducing the porosity, it is preferably 0.1% by mass to 5% by mass and more preferably 0.3% by mass to 4% by mass in the total mass of the specific electrode forming composition. Preferably, it is more preferably 0.5% to 3.5% by mass, particularly preferably 0.7% to 3% by mass, and extremely preferably 1% to 2.5% by mass. preferable.

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

<Method for producing electrode forming composition>
There is no restriction | limiting in particular as a manufacturing method of the composition for electrode formation. Other components such as metal particles, solvents, resins, glass particles and the like can be produced by dispersing and mixing them using a commonly used dispersion method and mixing method.
The dispersion method and the mixing method are not particularly limited, and can be appropriately selected and applied from commonly used dispersion methods and mixing methods.

<Solar cell element>
The solar cell element of the present invention is a solar cell element produced by the production method of the solar cell element of the present invention. Specifically, the solar cell element of the present invention is for forming an electrode containing a semiconductor substrate, metal particles containing phosphorus-tin-nickel-containing copper alloy particles, a solvent, and a resin on at least one surface of the semiconductor substrate. An application step of applying the composition to form an electrode-forming composition layer; a drying step of heat-treating the electrode-forming composition layer at a temperature of less than 300 ° C. for 1 second to 15 minutes to evaporate the solvent; and electrode formation The composition layer for heat treatment is heat treated at a temperature of 300 ° C. or higher and lower than 600 ° C. for 5 seconds to 2 minutes to thermally decompose the resin, and the electrode forming composition layer is heated at a temperature of 600 ° C. to 1000 ° C. An electrode forming step of heat-treating (firing) for 1 minute, and a copper-containing electrode formed by at least.
In this specification, the solar cell element means a device having a semiconductor substrate on which a pn junction is formed and an electrode formed on the semiconductor substrate.

  Hereinafter, although the specific example of the solar cell element of this invention is demonstrated, referring drawings, this invention is not limited to this. As an example of a typical solar cell element, FIG. 1, FIG. 2 and FIG. 3 show a schematic sectional view, a schematic plan view of a light receiving surface, and a schematic plan view of a back surface, respectively.

As shown in the schematic cross-sectional view of FIG. 1, an n ⁺ -type diffusion layer 2 is formed near the surface of one surface of the semiconductor substrate 1, and the output extraction electrode 4 and the antireflection layer are formed on the n ⁺ -type diffusion layer 2. 3 is formed. Further, 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, a single crystal or polycrystalline silicon substrate 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. In order to suppress the reflection of sunlight, the light receiving surface side is formed with unevenness (also referred to as texture, not shown) using an etching solution containing NaOH and IPA (isopropyl alcohol). Phosphorus or the like is doped on the light receiving surface side, the n ⁺ -type diffusion layer 2 is formed with a thickness of the order of submicron, 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 PECVD (plasma enhanced chemical vapor deposition) or the like.

Next, a method of forming the light receiving surface electrode 4 provided on the light receiving surface side schematically shown in FIG. 2, and the back surface collecting electrode 5 and the back surface output extraction electrode 6 formed on the back surface schematically shown in FIG. To do.
The light-receiving surface electrode 4 and the back surface output extraction electrode 6 are formed from a specific electrode forming composition. Moreover, the electrode 5 for back surface current collection is formed from the composition for aluminum electrode formation containing a glass particle. As a first method for forming the light-receiving surface electrode 4, the back surface collecting electrode 5 and the back surface output extraction electrode 6, the specific electrode forming composition and the aluminum electrode forming composition are applied in a desired pattern by screen printing or the like. Then, the light-receiving surface electrode 4, the back surface output extraction electrode 6, and the back surface collecting electrode 5 are collectively formed by sequentially performing the above-described drying step, degreasing step, and electrode forming step.

During the heat treatment (firing) in the electrode forming step, the glass particles contained in the specific electrode forming composition for forming the light receiving surface electrode 4 react with the antireflection layer 3 on the light receiving surface side (fire through). The light-receiving surface electrode 4 and the n ⁺ -type diffusion layer 2 are electrically connected (ohmic contact).

  In the present invention, the light-receiving surface electrode 4 is formed using the composition for forming a specific electrode, so that copper is suppressed as a conductive metal, and copper oxidation is suppressed. , Formed with good productivity.

  Furthermore, in the present invention, the formed electrode comprises a Cu—Sn—Ni alloy phase (alloy phase containing copper, tin and nickel, not shown) and a Sn—PO glass phase (tin, phosphorus and oxygen). The Sn—PO glass phase is preferably disposed between the light receiving surface electrode 4 or the back surface output extraction electrode 6 and the semiconductor substrate 1. Is more preferable. Thereby, the reaction between copper and the semiconductor substrate is suppressed, and an electrode having a low resistivity and excellent adhesion can be formed.

On the back surface side, during the heat treatment (firing) in the electrode forming step, aluminum in the aluminum electrode forming composition for forming the back surface collecting electrode 5 diffuses into the back surface of the semiconductor substrate 1 and becomes p ⁺ type. By forming the diffusion layer 7, an ohmic contact can be obtained between the semiconductor substrate 1 and the back surface collecting electrode 5.

  As a second method for forming the light-receiving surface electrode 4, the back surface collecting electrode 5 and the back surface output extraction electrode 6, the aluminum electrode forming composition for forming the back surface collecting electrode 5 is first applied and dried. After degreasing and heat treatment (firing) to form the back surface collecting electrode 5, the specific electrode forming composition is applied to the light receiving surface side and the back surface side, dried and degreased, and then heat treated (firing) under the above conditions. And a method of forming the light receiving surface electrode 4 and the back surface output extraction electrode 6.

  FIG. 4 is a schematic plan view of a back-side electrode structure common to so-called back contact solar cell elements that are another embodiment, and FIG. 4 shows a schematic structure of a solar cell element that is a back contact solar cell element according to another embodiment. The perspective views are shown in FIGS. 5, 6 and 7, respectively. FIG. 5 is a perspective view of the AA cross section in FIG.

In the semiconductor substrate 1 of the solar cell element having the structure shown in the perspective view of FIG. 5, through holes that penetrate both the light receiving surface side and the back surface side are formed by laser drilling, etching, or the like. Further, a texture (not shown) for improving the light incident efficiency is formed on the light receiving surface side. Further, an n ⁺ -type diffusion layer 2 by n-type diffusion treatment is formed on the light-receiving surface side, and an antireflection layer (not shown) is formed on the n ⁺ -type diffusion layer 2. These are manufactured by the same process as the conventional silicon solar cell element. The n ⁺ type diffusion layer 2 is also formed around the surface of the through hole and the opening on the back surface side of the through hole.

Next, the specific electrode forming composition is filled in the previously formed through hole by a printing method, an ink jet method, or the like, and the specific electrode forming composition is applied to the light-receiving surface side in a grid shape. A composition layer for forming the hall electrode 9 and the light receiving surface collecting electrode 8 is formed.
Here, the electrode forming composition used for filling and application is preferably one having an optimum composition for each process such as physical properties such as viscosity, but the electrode forming composition having the same composition is used. The filling and application may be performed in a lump.

On the other hand, an n ⁺ -type diffusion layer 2 and a p ⁺ -type diffusion layer 7 for preventing carrier recombination are formed on the back surface side. Here, boron (B), aluminum (Al), or the like is used as an impurity element for forming the p ⁺ -type diffusion layer 7. The p ⁺ -type diffusion layer 7 may be formed, for example, by performing a thermal diffusion process using B as a diffusion source in a step before the formation of the antireflection layer, and when using Al as an impurity element May be formed by applying a composition for forming an aluminum electrode on the opposite surface side in the application step of the composition for forming a specific electrode, and performing heat treatment (firing).

On the back side, as shown in the plan view of FIG. 4, the composition for forming a specific electrode is applied in stripes on the n ⁺ type diffusion layer 2 and the p ⁺ type diffusion layer 7, respectively. A back electrode 11 is formed. Here, when the p ⁺ type diffusion layer 7 is formed using the aluminum electrode forming composition, the back electrode may be formed using the specific electrode forming composition only on the n ⁺ type diffusion layer 2.

  Moreover, the solar cell element having the structure shown in the perspective view of FIG. 6 is manufactured in the same manner as the solar cell element having the structure shown in the perspective view of FIG. 5 except that the light receiving surface collecting electrode is not formed. Can do. That is, in the solar cell element having the structure shown in the perspective view of FIG. 6, the specific electrode forming composition can be used for forming the through-hole electrode 9, the back electrode 10, and the back electrode 11.

  The solar cell element having the structure shown in the perspective view of FIG. 7 has the structure shown in the perspective view of FIG. 5 except that the n-type silicon substrate 12 is used as the semiconductor substrate and no through hole is formed. It can be manufactured in the same manner as the solar cell element. That is, in the solar cell element having the structure shown in the perspective view of FIG. 7, the specific electrode forming composition can be used for forming the back electrode 10 and the back electrode 11.

  In addition, the heat processing temperature in a drying process, a degreasing process, and an electrode formation process can attach a thermocouple to a part of semiconductor substrate, and can measure it using normal temperature measurement software. At this time, by connecting a thermocouple to the semiconductor substrate with a high-temperature adhesive or the like, it can be considered that the measured temperature becomes equal to the temperature of the substrate, that is, the temperature in the actual process. .

  When performing a drying process using an air dryer or a hot plate, the time after the temperature of the semiconductor substrate to which the thermocouple is attached reaches the set temperature can be set as the drying time.

In addition, a method for measuring the temperature of the degreasing process and the electrode forming process using a tunnel furnace will be described with reference to FIG. FIG. 8 is a graph plotting temperature versus time when a semiconductor substrate is transported and moved into a tunnel furnace where a thermocouple is attached to the semiconductor substrate and heated to a predetermined temperature. Temperatures T ₁ is the temperature at which turning on the semiconductor substrate in a tunnel furnace. Temperature T _2, the temperature at which the degreasing switched to electrode forming step - a (hereinafter, referred to as "degreasing process electrode forming step switching temperature"). Temperature T ₃ is the highest temperature in the electrode forming step. Time t ₁ is the time at which heating starts from room temperature by the heater of the tunnel furnace. Time t ₂ is the time when switching the electrode forming step degreasing (hereinafter - also referred to as "degreasing process electrode forming step switching time") is. Time t ₃ is the time when cooled to temperature T ₂ in the electrode forming step. Time t ₄ is the time when the electrode is cooled to the temperature T ₁ after the electrode forming step. In the manufacturing method of the solar cell element of the present invention, temperature _{T 2} is less than 300 ° C. or higher 600 ° C., the temperature _{T 3} is 600 ° C. or higher 1000 ° C. or less.

The time _(t 2 -t ₁₎ degreasing zone, firing zone time _(t 3 -t _2), when the time _(t 4 -t ₃₎ a cooling zone, the method for manufacturing the solar cell device of the present invention In the degreasing zone, the time during which the semiconductor substrate is heat-treated at a temperature of 300 ° C. or higher and lower than 600 ° C. is 5 seconds to 2 minutes, and in the firing zone, the semiconductor substrate is heated to a temperature of 600 ° C. or higher and 1000 ° C. or lower for 5 seconds to 1 minute. It is preferable to heat-treat.

No particular limitation is imposed on the cooling zone of the time (t 4 _{-t 3),} productivity, and in terms of equipment structure, for example, be a 2 seconds to 5 minutes, and 5 seconds to 4 minutes Of these, 10 seconds to 3 minutes is more preferable.

There is no particular restriction on the maximum temperature T ₃ in the electrode forming step. From the viewpoint of the productivity of the solar cell element, the composition for forming the specific electrode, and the characteristics of the electrode formed from the composition for forming the aluminum electrode and the composition for forming the silver electrode used as necessary, the maximum temperature T ₃ is preferably 600 ° C. or higher and 1000 ° C. or lower, more preferably 625 ° C. or higher and 975 ° C. or lower, and further preferably 650 ° C. or higher and 950 ° C. or lower.

In addition the electrode forming step, there is no particular limitation on the heating rate when heating from temperature T ₂ to the temperature T _3. From the viewpoint of the productivity of the solar cell element, the specific electrode forming composition, and the characteristics of the electrode formed from the aluminum electrode forming composition and the silver electrode forming composition used as necessary, 20 ° C / s to 150 ° C / s, more preferably 30 ° C / s to 140 ° C / s, and still more preferably 40 ° C / s to 130 ° C / s.

The composition for forming a specific electrode is not limited to the use of the above-mentioned solar cell electrode, but is an electrode wiring for a plasma display, a shield wiring, a ceramic capacitor, an antenna circuit, various sensor circuits, and a heat dissipation material for a semiconductor device. It can use suitably also for uses, such as.
Among these, it can be suitably used particularly when an electrode is formed on a substrate containing silicon.

<Solar cell>
In this specification, the solar cell is configured by providing a wiring material such as a tab wire on the electrode of the solar cell element, and connecting a plurality of solar cell elements via the wiring material as necessary, and sealing resin It means a state sealed with, for example.
The solar cell of this invention has the solar cell element of this invention, and the wiring material arrange | positioned on the electrode of the said solar cell element. The solar cell of this invention should just be comprised by arrange | positioning the wiring material on the electrode of a solar cell element including at least 1 of the solar cell element of this invention. If necessary, the solar cell may be constituted by connecting a plurality of solar cell elements via a wiring material and further sealing with a sealing material.
The wiring material and the sealing material are not particularly limited, and can be appropriately selected from those usually used in the industry.

  As the wiring material, for example, a solder-coated copper wire (tab wire) for solar cells can be suitably used. The composition of the solder can include Sn-Pb, Sn-Pb-Ag, Sn-Ag-Cu, etc. In consideration of the influence on the environment, Sn-Ag-Cu based which does not substantially contain lead It is preferable to use solder.

There is no particular limitation on the thickness of the copper wire of the tab wire, from the viewpoint of the difference in thermal expansion coefficient or connection reliability with the solar cell element during the heating and pressing treatment and the resistivity of the tab wire itself, 0.05 mm to It can be 0.5 mm, and is preferably 0.1 mm to 0.5 mm.
Moreover, the cross-sectional shape of the tab line is not particularly limited, and any of a rectangular shape (flat tab) and an elliptical shape (round tab) can be applied, and a rectangular shape (flat tab) is preferably used.
The total thickness of the tab wire is not particularly limited, and is preferably 0.1 mm to 0.7 mm, and more preferably 0.15 mm to 0.5 mm.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” are based on mass.

<Example 1>
(A) Preparation of electrode-forming composition 1 Phosphorus containing 75.0% by mass of copper, 6.0% by mass of phosphorus, 9.0% by mass of tin, and 10.0% by mass of nickel A tin-nickel-containing copper alloy was prepared by a conventional method, dissolved, powdered by a water atomization method, dried, and classified. For classification, a Nisshin Engineering Co., Ltd., forced vortex classifier (turbo classifier; TC-15) was used. The classified powder is blended with an inert gas and subjected to deoxidation and dehydration treatment. 75.0% by mass of copper, 6.0% by mass of phosphorus, 9.0% by mass of tin, 10.0% Phosphorus-tin-nickel-containing copper alloy particles containing mass% nickel were prepared. In addition, the particle diameter (D50%) of the phosphorus-tin-nickel-containing copper alloy particles was 5.0 μm, and the shape thereof was substantially spherical.

Silicon dioxide (SiO ₂ ) 3.0 mass%, lead oxide (PbO) 60.0 mass%, boron oxide (B ₂ O ₃ ) 18.0 mass%, bismuth oxide (Bi ₂ O ₃ ) 5.0 mass% A glass composed of 5.0% by mass of aluminum oxide (Al ₂ O ₃ ) and 9.0% by mass of zinc oxide (ZnO) (hereinafter sometimes abbreviated as “G01”) was prepared. The obtained glass G01 had a softening point 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-nickel-containing copper alloy particles and glass particles were determined by observing using Hitachi High-Technologies Corporation, TM-1000 scanning electron microscope. The particle diameter (D50%) of the phosphorus-tin-nickel-containing copper alloy particles and glass particles was calculated using a Beckman Coulter Co., Ltd., LS 13 320 type laser scattering diffraction particle size distribution analyzer (measurement wavelength: 632 nm). . The softening point and the crystallization start temperature of the glass particles were obtained from a differential heat (DTA) curve using a Shimadzu Corporation, DTG-60H type differential thermal / thermogravimetric measuring device. 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.

  70.8 parts of the phosphorus-tin-nickel-containing copper alloy particles obtained above, 4.2 parts of glass G01 particles, 20.0 parts of diethylene glycol monobutyl ether (BC), and ethyl polyacrylate (EPA, Fujikura) 5 parts of Kasei Chemical Co., Ltd., weight average molecular weight: 155000) were mixed and mixed using an automatic mortar kneader to form a paste, thereby preparing electrode-forming composition 1.

(B) Fabrication of solar cell element A p-type semiconductor substrate having a thickness of 190 μm having an n ⁺ -type diffusion layer, a texture, and an antireflection layer (silicon nitride layer) formed on the light receiving surface is prepared, and the size is 125 mm × 125 mm. Cut out. On the light receiving surface, the electrode-forming composition 1 obtained above was printed using a screen printing method so as to form an electrode pattern as shown in FIG. The electrode pattern is composed of 150 μm wide finger lines and 1.5 mm wide bus bars, and the printing conditions (screen plate mesh, printing speed and printing pressure) are appropriately set so that the thickness after heat treatment (firing) is 20 μm. It was adjusted.

The printed semiconductor substrate was heat-treated at a set temperature of 150 ° C. for 15 minutes using a blower dryer (CLEAN OVEN PVHC-211; ESPEC Corporation), and the solvent was evaporated away to remove the composition 1 for electrode formation. Dried.
Separately, the tip of a K-type thermocouple (sheath length 5000 mm, diameter 0.5 mm) is attached to a part of another p-type semiconductor substrate different from the above-mentioned semiconductor substrate with a high-temperature adhesive, and the above set conditions are dried. Heat treated with a machine. At this time, the temperature measured using a multi-input data collection system (NR-TH08; manufactured by Keyence Corporation) was 150 ° C. This measured temperature was used as the heating temperature in the drying step.

  Subsequently, the electrode-forming composition 1 and the aluminum electrode-forming composition (PVG Solutions, PVG-AD-02) are placed on the surface opposite to the light-receiving surface (hereinafter also referred to as “back surface”). Similarly to the above, screen printing was performed so that an electrode pattern as shown in FIG. 3 was obtained.

The pattern of the back surface output extraction electrode 6 formed using the electrode forming composition 1 was composed of two lines, and was printed so that the size of one line was 123 mm × 5 mm. The printing conditions (screen plate mesh, printing speed and printing pressure) were appropriately adjusted so that the thickness of the back surface output extraction electrode 6 after heat treatment (firing) was 15 μm. Further, the aluminum electrode forming composition was printed on the entire surface other than the back surface output extraction electrode 6 to form a pattern of the back surface collecting electrode 5. Moreover, the printing conditions of the composition for forming an aluminum electrode were appropriately adjusted so that the thickness of the back surface collecting electrode 5 after heat treatment (firing) was 30 μm.
Thereafter, the solvent is removed by evaporation using a blow dryer under the same conditions as when the electrode-forming composition 1 applied to the light-receiving surface is dried, and the electrode-forming composition 1 and the aluminum electrode-forming composition are removed. Dried.

Subsequently, degreasing and heat treatment (firing) was performed in an air atmosphere using a tunnel furnace (Noritake Co., Ltd., single-row transport W / B tunnel furnace) to produce a solar cell element 1 on which a desired electrode was formed. .
In addition, when performing degreasing and heat treatment (firing), conditions such as a set temperature of the heater of the tunnel furnace, a gas flow rate, and a conveyance speed were appropriately set. Similar to the drying process, when the temperature was measured using a multi-input data collection system, the heat treatment time at 300 ° C. or more and less than 600 ° C. in the degreasing process was 20 seconds, and the degreasing process-electrode forming process switching temperature (T _2). The temperature was 400 ° C., the heat treatment time at 600 ° C. to 1000 ° C. in the electrode formation step was 8 seconds, and the highest heat treatment (firing) ultimate temperature (T ₃ temperature) was 800 ° C. The rate of temperature increase when the temperature was increased from the T ₂ temperature to the T ₃ temperature was 90 ° C./s.

<Example 2>
Example 1 is the same as Example 1 except that the drying conditions for the electrode-forming composition 1 and the aluminum electrode-forming composition applied to the light-receiving surface and the back surface were changed to a setting temperature of 170 ° C. for 8 minutes. Thus, a solar cell element 2 was produced. As in Example 1, the temperature of the semiconductor substrate was measured separately under the above drying conditions using a K-type thermocouple and found to be 170 ° C. This measured temperature was taken as the heating temperature in the drying step of Example 2.

<Example 3>
In Example 1, except that the conditions such as the set temperature of the heater of the tunnel furnace, the gas flow rate, and the conveying speed were appropriately set so that the heat treatment time at 300 ° C. or more and less than 600 ° C. in the degreasing process was 10 seconds. In the same manner as in Example 1, a solar cell element 3 was produced.

<Example 4>
In Example 1, conditions such as the set temperature of the heater of the tunnel furnace, the gas flow rate, and the conveyance speed are appropriately set so that the heat treatment time at 600 ° C. to 1000 ° C. in the heat treatment (firing) for electrode formation is 12 seconds. A solar cell element 4 was produced in the same manner as in Example 1 except that the setting was made. Note that the rate of temperature increase when the temperature was increased from the T ₂ temperature to the T ₃ temperature was 76 ° C./s.

<Example 5>
In Example 1, the copper content of the phosphorus-tin-nickel-containing copper alloy particles was changed from 75.0 mass% to 68.0 mass%, and the phosphorus content was changed from 6.0 mass% to 5.5 mass%. In the same manner as in Example 1 except that the tin content was changed from 9.0% by mass to 12.5% by mass and the nickel content was changed from 10.0% by mass to 14.0% by mass. Thus, an electrode forming composition 5 was prepared, and a solar cell element 5 was produced.

<Example 6>
In Example 1, the content of the phosphorus-tin-nickel-containing copper alloy particles was changed from 70.8 parts to 72.7 parts, and the content of the glass G01 particles was changed from 4.2 parts to 7.3 parts. The content of diethylene glycol monobutyl ether (BC) was changed from 20.0 parts to 16.0 parts, and the content of polyethyl acrylate (EPA) was changed from 5.0 parts to 4.0 parts. In the same manner as in Example 1, a composition 6 for forming an electrode was prepared, and a solar cell element 6 was produced.

<Example 7>
In Example 1, except that the particle diameter (D50%) of the phosphorus-tin-nickel-containing copper alloy particles was changed from 5.0 μm to 2.5 μm, the electrode forming composition 7 was prepared in the same manner as in Example 1. The solar cell element 7 was prepared.

<Example 8>
In Example 1, the content of phosphorus-tin-nickel-containing copper alloy particles was changed from 70.8 parts to 49.6 parts, and 21.2 parts of phosphorus-containing copper alloy particles containing 7.0% by mass of phosphorus. Except for the addition, an electrode-forming composition 8 was prepared in the same manner as in Example 1, and a solar cell element 8 was produced.
The phosphorus-containing copper alloy particles used in Example 8 were prepared after water atomization, deoxygenation and dehydration, in the same manner as the phosphorus-tin-nickel-containing copper alloy particles of Example 1. The phosphorus-containing copper alloy particles had a particle size (D50%) of 5.0 μm and a substantially spherical shape.

<Examples 9 to 13>
In Example 1, the copper content of phosphorus-tin-nickel containing copper alloy particles, phosphorus content, tin content and nickel content, particle diameter (D50%) and content, phosphorus content of phosphorus containing copper alloy particles , Particle diameter (D50%) and content, type and content of glass particles, type and content of solvent, type and content of resin, heat treatment temperature and heat treatment time in the drying step, 300 ° C. to 600 ° C. in the degreasing step Heat treatment time below, degreasing step-electrode formation step switching temperature (T ₂ temperature), heat treatment time at electrode forming step from 600 ° C. to 1000 ° C., rise from T ₂ temperature to maximum attained temperature (T ₃ temperature) rise rate, and the highest temperature of (T ₃ temperature), except that was changed as shown in Table 1 and Table 2, example and 1 Similarly electrode forming composition 9-13 and were respectively prepared, Solar cell elements 9 to 13 were produced.

Glass G02 particles were obtained by the following method. First, vanadium oxide (V ₂ O ₅ ) 45.0 mass%, phosphorus oxide (P ₂ O ₅ ) 24.2 mass%, barium oxide (BaO) 20.8 mass%, antimony oxide (Sb ₂ O ₃ ) 5 A glass (hereinafter sometimes abbreviated as “G02”) composed of 0.0 mass% and tungsten oxide (WO ₃ ) 5.0 mass% was prepared. The obtained glass G02 was pulverized to obtain glass G02 particles having a particle size (D50%) of 2.5 μm. The softening point of the glass G02 was 492 ° C., and the crystallization start temperature exceeded 650 ° C. Furthermore, the shape of the glass G02 particles was substantially spherical.

  The solvent “Ter” shown in Table 1 means terpineol, and the resin “EC” means ethyl cellulose (Dow Chemical Japan, Inc., weight average molecular weight: 190000).

<Comparative Example 1>
In Example 1, the composition C1 for electrode formation was the same as that of Example 1, except that each component was changed to the composition shown in Table 1 without using the phosphorus-tin-nickel-containing copper alloy particles. Was prepared. Further, a solar cell element C1 was produced in the same manner as in Example 1 except that the electrode forming composition C1 not containing phosphorus-tin-nickel-containing copper alloy particles was used.

<Comparative example 2>
In Example 1, an electrode having the composition shown in Table 1 was used in the same manner as in Example 1 except that copper particles (purity 99.5% by mass) were used instead of the phosphorus-tin-nickel-containing copper alloy particles. A forming composition C2 was prepared. Further, a solar cell element C2 was produced in the same manner as in Comparative Example 1 except that the electrode forming composition C2 was used.

<Comparative Example 3>
In Example 1, without using phosphorus-tin-nickel-containing copper alloy particles, except that only phosphorus-containing copper alloy particles containing 7.0% by mass of phosphorus were used as metal particles, the same as in Example 1, An electrode forming composition C3 having the composition shown in Table 1 was prepared. Furthermore, a solar cell element C3 was produced in the same manner as in Comparative Example 1 except that the electrode forming composition C3 was used.

<Comparative example 4>
In Example 1, the conditions such as the set temperature of the heater of the tunnel furnace, the gas flow rate, the conveyance speed, etc. are appropriately set, and the heat treatment time at 300 ° C. or more and less than 600 ° C. in the degreasing process is set to 1 second. In the same manner as in Example 1, a solar cell element C4 was produced.

<Comparative Example 5>
In Example 1, the conditions such as the set temperature of the heater of the tunnel furnace, the gas flow rate, the conveyance speed were appropriately set, and the heat treatment time at 600 ° C. or more and 1000 ° C. or less in the electrode formation step was set to 100 seconds. In the same manner as in Example 1, a solar cell element C5 was produced.

<Evaluation>
Evaluation of the produced solar cell element is as follows: Wacom Denso Corporation, WXS-155S-10 as pseudo-sunlight, and IV CURVE TRACER MP-160 (EKO INSTRUMENT) as current-voltage (IV) evaluation measuring instrument. In combination with a measuring device. Jsc (short circuit current), Voc (open voltage), F. F. (Fill factor, shape factor) and η (conversion efficiency) are obtained by measuring in accordance with JIS-C-8912: 2011, JIS-C-8913: 2005 and JIS-C-8914: 2005, respectively. It is a thing.

  In the solar cell element having a double-sided electrode structure, the obtained measured values are converted into relative values with the measured value of Comparative Example 1 (solar cell element C1) as 100.0, and are shown in Table 3. In Comparative Example 2, the resistivity of the formed electrode was large and could not be evaluated. The reason is considered to be due to oxidation of copper particles.

Next, among the electrodes formed using the prepared electrode forming composition, the cross section of the light-receiving surface electrode was observed at an acceleration voltage of 15 kV using a scanning electron microscope Miniscope TM-1000 (Hitachi Ltd.). The presence or absence of a Cu—Sn—Ni alloy phase in the electrode and the presence or absence of a Sn—PO glass phase were investigated. The results are shown in Table 3.
In Comparative Example 1, since the electrode-forming composition C1 used contained only silver particles as metal particles, the Cu—Sn—Ni alloy phase and Sn—P—O in the back surface output extraction electrode were used. The presence or absence of a glass phase was not investigated.

  Furthermore, the adhesive force with respect to a silicon substrate was measured about the back surface output extraction electrode among the electrodes formed using the prepared composition for electrode formation. Specifically, a stud pin (pin diameter: φ4.1 mm) was joined onto the back surface output extraction electrode using an adhesive, and this was heat-treated in an oven at 180 ° C. for 1 hour in the air and cooled to room temperature. Thereafter, a tensile load was applied to the stud pin using a thin film adhesion strength measuring device (Romulus, QUAD GROUP), and the load at break was evaluated. Further, at this time, the location of the fracture was also observed. In addition, evaluation evaluated 6 points about each electrode and made the average value the adhesive force. The results are shown in Table 3.

  From Table 3, it can be seen that in Comparative Example 3, the power generation performance was degraded as compared with Comparative Example 1. This is considered as follows, for example. That is, since the electrode-forming composition C3 used in Comparative Example 3 contained phosphorus-containing copper alloy particles as metal particles and did not contain phosphorus-tin-nickel-containing copper alloy particles, a Sn—PO glass phase was formed. In the degreasing process and the electrode forming process, it is considered that the mutual diffusion of copper and silicon occurs in the silicon substrate, and the pn junction characteristics in the substrate are deteriorated.

  The power generation performance of the solar cell elements produced in Examples 1 to 13 was almost the same as the measured value of the solar cell element of Comparative Example 1. As a result of observation of the cross-sectional structure of the light-receiving surface electrode, a Cu—Sn—Ni alloy phase and a Sn—PO glass phase were present in the light-receiving surface electrode.

In addition, from the results of Table 3, the adhesion of the back surface output extraction electrodes of the solar cells produced in Examples 1 to 13 to the silicon substrate was almost the same as that of Comparative Example 1. In particular, it can be understood that the formed electrode is in close contact with the silicon substrate with high strength because the broken portion was in the silicon substrate. In Comparative Example 2, it is considered that the inside of the electrode is occupied by a melt of copper oxide and glass frit and is in close contact with the silicon substrate with a certain degree of strength. As for the comparative example 3, as described above, mutual diffusion of copper and silicon occurs between the electrode after the degreasing step and the electrode forming step and the silicon substrate, and a reactant phase (Cu ₃ Si) is formed. It is considered that the adhesion force of the electrode is reduced by lifting a part from the substrate.

  About the solar cell element C4 produced in Comparative Example 4, the power generation performance and the adhesion to the silicon substrate were slightly decreased as compared with those of Comparative Example 1. This can be considered, for example, as follows. That is, since the heat treatment time at 300 ° C. or more and less than 600 ° C. in the degreasing step in producing the solar cell element C4 was short, the resin was not sufficiently decomposed and the resin remained as a carbon component in the electrode. It is considered that the electrode forming step has been performed. The remaining carbon component inhibits the sintering reaction of the electrode and the formation of the Sn—PO glass phase in the electrode forming step, and voids are generated in the electrode, so that the power generation performance is improved due to the increase in the resistivity of the electrode. It is considered that the formation of the Sn—PO glass phase was incomplete, and the adhesion to the substrate was reduced due to the formation of voids in the electrodes.

  About the solar cell element C5 produced in the comparative example 5, the adhesive force with respect to a silicon substrate fell a little compared with the thing of the comparative example 1, and the electric power generation performance of the solar cell element fell. This can be considered, for example, as follows. That is, since the heat treatment time at 600 ° C. or more and 1000 ° C. or less in the electrode forming step when producing the solar cell element C5 was long, the amount of aluminum diffused from the aluminum electrode formed on the back surface to the semiconductor substrate was too large, It is considered that carrier recombination on the back surface is likely to occur. In addition, the glass frit also erodes the semiconductor substrate portion under the antireflection layer (silicon nitride layer) for the light receiving surface electrode, and the characteristics (semiconductor characteristics) of the pn junction formed in advance are reduced. It is considered that the power generation performance of the battery element was lowered. Moreover, about the slight fall of adhesive force, it is thought that the Sn-PO glass phase formed in the degreasing process of an electrode formation composition and an electrode formation process becomes thick easily. As a result, in the cooling step after the electrode formation step, a void (crack) is generated at the interface between the Cu—Sn—Ni alloy phase and the Sn—PO glass phase, and this void is measured when the adhesion is measured. It is considered that the base point breakage (that is, the breakage within the electrode) occurred and the measured value was lowered.

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 n ⁺ type diffused layer 3 Antireflection layer 4 Light reception surface electrode and output extraction electrode 5 Back surface collection electrode 6 Back surface output extraction electrode 7 p ⁺ type diffusion layer 8 Light reception surface collection electrode 9 Through-hole electrode 10 Back electrode 11 Back electrode 12 n-type silicon substrate

Claims (11)

Application for forming an electrode-forming composition layer by applying an electrode-forming composition containing metal particles containing phosphorus-tin-nickel-containing copper alloy particles, a solvent, and a resin on at least one surface of a semiconductor substrate Process,
A drying step of heat-treating the electrode-forming composition layer at a temperature of less than 300 ° C. for 1 second to 15 minutes to evaporate the solvent;
A degreasing step in which the electrode forming composition layer is heat-treated at a temperature of 300 ° C. or higher and lower than 600 ° C. for 5 seconds to 2 minutes, and the resin is thermally decomposed;
An electrode forming step of heat-treating the electrode-forming composition layer at a temperature of 600 ° C. or higher and 1000 ° C. or lower for 5 seconds to 1 minute to form a copper-containing electrode that is a heat-treated product of the electrode-forming composition;
The manufacturing method of the solar cell element which contains these in this order.   The method for manufacturing a solar cell element according to claim 1, wherein the degreasing step and the electrode forming step are performed continuously.   The method for producing a solar cell element according to claim 1 or 2, wherein the phosphorus-tin-nickel-containing copper alloy particles have a phosphorus content of 2.0 mass% to 15.0 mass%.   The method for producing a solar cell element according to any one of claims 1 to 3, wherein the phosphorus-tin-nickel-containing copper alloy particles have a tin content of 3.0 mass% to 30.0 mass%. .   The method for producing a solar cell element according to any one of claims 1 to 4, wherein the phosphorus-tin-nickel-containing copper alloy particles have a nickel content of 3.0% by mass to 30.0% by mass. .   The method for manufacturing a solar cell element according to any one of claims 1 to 5, wherein the electrode-forming composition further comprises glass particles.   Before the electrode formation step, the method further includes a step of applying an aluminum electrode formation composition to a portion of the semiconductor substrate where the electrode formation composition is not applied, and in the electrode formation step, the copper-containing electrode and The manufacturing method of the solar cell element of any one of Claims 1-6 which forms an aluminum electrode collectively.   Before the electrode formation step, the method further includes the step of applying a silver electrode formation composition to a portion of the semiconductor substrate to which the electrode formation composition and the aluminum electrode formation composition are not applied. The method for manufacturing a solar cell element according to claim 7, wherein in the step, the copper-containing electrode, the aluminum electrode, and the silver electrode are collectively formed.   9. The solar cell element according to claim 1, wherein the copper-containing electrode includes an alloy phase containing copper, tin, and nickel and a glass phase containing tin, phosphorus, and oxygen. Production method.   The solar cell element manufactured by the manufacturing method of any one of Claims 1-9.   The solar cell which has the solar cell element of Claim 10, and the wiring material arrange | positioned on the electrode of the said solar cell element.