TW201339248A - Composition for forming mask, method of producing substrate for photovoltaic cell and method of producing photovoltaic cell element - Google Patents

Abstract

A composition for forming a mask, including: a silicon compound; a metal compound containing an alkali earth metal or an alkali metal; and a dispersion medium.

Description

Mask forming composition, solar cell substrate manufacturing method, and solar cell element manufacturing method

The present invention relates to a composition for forming a mask, a method for producing a substrate for a solar cell, and a method for producing a solar cell element.

The manufacturing steps of the conventional tantalum solar cell element will be described.

First, in order to promote high efficiency in order to promote the light trapping effect, a p-type germanium substrate having a textured structure is prepared, and then in a mixed gas of phosphorus, chlorine (POCl ₃ ), nitrogen, and oxygen, The n-type diffusion layer was uniformly formed by performing treatment for several tens of minutes at 800 ° C to 900 ° C. Next, an electrode paste such as silver (Ag) is applied to the light-receiving surface, and an electrode paste such as aluminum is applied to the back surface side, followed by baking, thereby obtaining a solar cell element.

However, sunlight is not incident directly under the electrode on the light-receiving side, and thus the portion does not generate electricity. Therefore, a back electrode type solar cell has been developed which has no electrode on the light receiving surface, and includes an n-type diffusion layer and a p ⁺ -type diffusion layer on the back surface, and includes an n-electrode and a p-electrode on each diffusion layer (for example, refer to Japanese Patent Laid-Open) Bulletin 2011-507246).

A method of forming such a back electrode type solar cell will be described. A mask is formed on the entire surface of the light receiving surface and the back surface of the n-type germanium substrate. Here, the mask has a function of hindering diffusion of the dopant into the germanium substrate. Next, a part of the mask on the back surface of the substrate is removed to form an opening. Further, when the p-type dopant is diffused from the opening of the mask to the back surface of the ruthenium substrate, the p ⁺ -type diffusion layer is formed only in the region corresponding to the opening. Next, after the mask on the back surface of the substrate is completely removed, a mask is formed on the entire surface of the back surface of the substrate. Then, a portion of the mask in a region different from the region where the p ⁺ -type diffusion layer is formed is removed to form an opening, and the n-type dopant is diffused from the opening toward the back surface of the germanium substrate to form an n ⁺ -type diffusion. Floor. Then, the mask on the back surface of the ruthenium substrate is completely removed, whereby a p ⁺ -type diffusion layer and an n ⁺ -type diffusion layer are formed on the back surface. Further, the back electrode type solar cell is completed by forming a texture structure, an antireflection film, a passivation film, an electrode, or the like.

As the mask, a method of forming an oxide film on the surface of a substrate by a thermal oxidation method has been proposed (for example, see JP-A-2002-329880). On the other hand, a mask forming method using a masking paste containing a SiO ₂ precursor has also been proposed (for example, refer to Japanese Laid-Open Patent Publication No. 2007-49079).

However, in the aforementioned Japanese Patent Laid-Open Publication No. 2002-329880 The method of producing an oxide film on the surface of a substrate by the thermal oxidation method described above has a problem in that the throughput is long and the manufacturing cost is high.

Further, in the method of using a masking paste containing a SiO ₂ precursor described in Japanese Laid-Open Patent Publication No. 2007-49079, the diffusion of a donor element or an acceptor element is physically prevented, and a mask containing SiO ₂ is additionally contained. It is difficult to form a dense film, and thus pinholes are easily formed, so that it is difficult to sufficiently prevent diffusion of dopants to the substrate.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and it is an object of the present invention to provide a composition for forming a mask which can sufficiently prevent a donor element or an acceptor element from diffusing into a semiconductor substrate, and a composition for forming the mask. A method for producing a substrate for a solar cell and a method for producing a solar cell element.

The specific means for solving the problem are as follows.

<1> A composition for forming a mask, comprising: a cerium compound, a metal compound containing an alkaline earth metal or an alkali metal, and a dispersion medium.

The composition for forming a mask according to the above aspect, wherein the total mass ratio of the alkaline earth metal or alkali metal-containing metal compound in the nonvolatile component is 5% by mass or more and less than 100% by mass. .

The composition for forming a mask according to the above-mentioned <1>, wherein the alkaline earth metal or alkali metal-containing metal compound is selected from the group consisting of magnesium, calcium, sodium, potassium, lithium, cesium, One or more of the group consisting of 铯, 铍, 锶, 钡, and radium are used as the metal element.

<4> The mask formation according to any one of <1> to <3> above a composition comprising the alkaline earth metal or alkali metal-containing metal compound selected from the group consisting of magnesium oxide, calcium oxide, magnesium carbonate, calcium carbonate, magnesium sulfate, calcium sulfate, calcium nitrate, magnesium hydroxide, and calcium hydroxide. One or more of the groups.

The composition for forming a mask according to any one of the above-mentioned items, wherein the metal compound containing an alkaline earth metal or an alkali metal is a solid particle at a normal temperature, and the particles are The volume average particle diameter is 30 μm or less.

The composition for forming a mask according to any one of the above aspects, wherein the bismuth compound contains a decane resin.

The composition for forming a mask according to any one of the above aspects, wherein the oxime compound is a siloxane compound obtained by hydrolysis-condensation of an alkoxy decane.

The composition for forming a mask according to any one of the above aspects, wherein the bismuth compound is selected from the group consisting of tetramethoxy decane, tetraethoxy decane, and tetrapropoxy hydride. A decyl alkane resin obtained by subjecting one or more compounds of the group consisting of decane and tetrabutoxy decane to hydrolysis and condensation.

The composition for forming a mask according to any one of the above aspects, wherein the dispersion medium is selected from the group consisting of water, an alcohol solvent, a glycol monoether solvent, and hydrazine ( Terpene) is one or more selected from the group consisting of solvents.

The composition for forming a mask according to any one of the above aspects, which further comprises an organic binder.

The composition for forming a mask according to the above <10>, wherein the organic binder comprises a component selected from the group consisting of an acrylic resin and a cellulose resin. One or more of the groups.

The composition for mask formation of any one of the above-mentioned <1> which further contains a thixotropic agent.

(13) A method for producing a substrate for a solar cell, comprising: applying the composition for mask formation according to any one of the above-mentioned items <1> to <12> to a semiconductor substrate in a pattern form, a step of forming a mask; and a step of partially forming a diffusion layer on the semiconductor substrate by doping the portion of the semiconductor substrate that is not doped with the donor element or the acceptor element.

The method for producing a substrate for a solar cell according to the above <13>, wherein the method of applying the composition for mask formation is a printing method or an inkjet method.

<15> A method of producing a solar cell element, comprising the step of forming an electrode on a diffusion layer of a substrate for a solar cell obtained by the production method according to the above <13> or <14>.

According to the present invention, a composition for forming a mask which can sufficiently prevent diffusion of a donor element or an acceptor element onto a semiconductor substrate, a method for producing a substrate for a solar cell using the composition for forming a mask, and a solar cell element can be provided. Production method.

10‧‧‧Substrate

11‧‧‧Material forming composition

12, 13‧‧‧Developing diffusion materials

12', 13'‧‧‧Roasting materials for coating diffusion materials

14‧‧‧n ⁺ type diffusion layer

15‧‧‧p ⁺ diffusion layer

16‧‧‧Anti-reflective film

17‧‧‧ Passivation film

18, 19‧‧‧ electrodes

FIG. 1 is a cross-sectional view conceptually showing an example of a manufacturing procedure of a solar cell substrate and a solar cell element of the present invention.

First, the composition for forming a mask of the present invention will be described. Next, a method for producing a substrate for a solar cell using a composition for forming a mask and a method for producing a solar cell element will be described.

In addition, in the present specification, the term "step" is not only an independent step, but even if it is impossible to clearly distinguish it from other steps, if the desired effect of the step is achieved, it is included in the term. Further, in the present specification, "~" means a range including the numerical values described before and after the minimum value and the maximum value. In addition, in the present specification, when a plurality of substances corresponding to the respective components are present in the composition as the amount of each component in the composition, if it is not particularly limited, it means that the composition is present in the composition. The total amount of each substance.

Moreover, the donor element or the acceptor element is sometimes referred to as a dopant.

<Material for mask formation>

The composition for mask formation of the present invention contains a ruthenium compound, a metal compound containing an alkaline earth metal or an alkali metal (hereinafter also referred to as "specific compound"), and a dispersion medium. The mask forming composition of the present invention inhibits diffusion of a donor element or an acceptor element as a dopant to a semiconductor substrate. Therefore, by using the mask forming composition of the present invention to form a mask in a region of the semiconductor substrate that does not require diffusion of a donor element or an acceptor element, the donor element and the acceptor element in the region can be sufficiently prevented. Expansion Scattered. Therefore, a doped region can be selectively formed in the semiconductor substrate. The reason for this can be considered as follows.

When the composition for mask formation contains a specific compound, after applying the composition for mask formation onto a semiconductor substrate, when a dopant compound is applied, a reaction occurs between the specific compound and the dopant compound. This reaction inhibits the diffusion of the donor element or the acceptor element to the semiconductor substrate because the reactivity is higher than the reaction between the dopant compound and the semiconductor substrate.

Further, in general, a doping compound containing a donor element or an acceptor element uses phosphorus oxide, boron oxide, phosphonium chloride or the like, and these are all acidic compounds (or compounds which react with water to exhibit acidity). Therefore, a particular compound is particularly preferred as a basic compound. The specific compound of the basic compound undergoes an acid-base reaction between the doped compounds, and the reactivity of the acid-base reaction is high, so that the diffusion of the donor element or the acceptor element to the semiconductor substrate is more effectively inhibited.

Further, since the metal compound containing an alkaline earth metal or an alkali metal is stable even at a high temperature (for example, 500 ° C or higher), the effect of the present invention can be sufficiently exhibited when the donor element or the acceptor element is thermally diffused to the semiconductor substrate.

In addition, when the metal compound containing an alkaline earth metal or an alkali metal is melted in the semiconductor substrate, it does not function as a recombination center of the carrier in the semiconductor substrate. Therefore, it is possible to suppress the deterioration of the conversion efficiency of the substrate for a solar cell. phenomenon.

(metal compound containing alkaline earth metal or alkali metal)

The composition for mask formation of the present invention includes an alkaline earth metal or an alkali gold a metal compound of the genus. By using a composition for mask formation including a metal compound containing an alkaline earth metal or an alkali metal, diffusion of the donor element or the acceptor element into the semiconductor substrate can be inhibited.

The metal compound containing an alkaline earth metal or an alkali metal may be a liquid or a solid at normal temperature (about 20 ° C). In order to maintain sufficient masking performance even at a high temperature, it is necessary to be chemically stable even at a high temperature. From this viewpoint, it is preferably a solid at a high temperature (for example, 500 ° C or higher) at which heat is diffused. Here, examples of the metal compound containing an alkaline earth metal or an alkali metal include a metal oxide containing an alkaline earth metal or an alkali metal, and a metal salt containing an alkaline earth metal or an alkali metal.

The metal compound containing an alkaline earth metal or an alkali metal is not particularly limited, and is preferably a material which changes to a basic compound at a high temperature of 700 ° C or higher at which the donor element or the acceptor element is thermally diffused. Further, from the viewpoint of exhibiting strong alkalinity, the metal compound preferably contains one or more selected from the group consisting of magnesium, calcium, sodium, potassium, lithium, rubidium, cesium, lanthanum, cerium, lanthanum, and radium. More preferably, the metal element contains one or more selected from the group consisting of magnesium, calcium, barium, potassium, and sodium, and more preferably contains one selected from the group consisting of magnesium, calcium, and potassium. In view of the above, it is more preferable to contain one or more selected from the group consisting of magnesium and calcium, from the viewpoint of low toxicity and ease of availability.

Furthermore, from the viewpoint of chemical stability, one or more selected from the group consisting of the following compounds: one or more kinds of metal oxides and metals selected from the group consisting of the metal elements are preferable. Carbonate, metal nitrate, metal sulfate and metal hydroxide; more preferably selected from metal oxides, metals One or more groups of carbonates and metal hydroxides.

Particularly preferred are metal oxides such as sodium oxide, potassium oxide, lithium oxide, calcium oxide, magnesium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, oxidized radium oxide, and composite oxides of these compounds; a metal hydroxide such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, magnesium hydroxide, barium hydroxide, barium hydroxide, barium hydroxide, barium hydroxide, barium hydroxide or radium hydroxide; Metal carbonates such as sodium, potassium carbonate, lithium carbonate, calcium carbonate, magnesium carbonate, barium carbonate, barium carbonate, barium carbonate, barium carbonate, barium carbonate, and radium carbonate; sodium nitrate, potassium nitrate, lithium nitrate, calcium nitrate, magnesium nitrate , metal nitrates such as cerium nitrate, cerium nitrate, cerium nitrate, cerium nitrate, cerium nitrate, radium nitrate; sodium sulfate, potassium sulfate, lithium sulfate, calcium sulfate, magnesium sulfate, barium sulfate, barium sulfate, barium sulfate, barium sulfate, Metal sulfates such as barium sulfate and radium sulfate.

More preferably, one or more selected from the group consisting of the metal oxide, the composite oxide, the metal hydroxide, and the metal carbonate are used.

Among these compounds, from the viewpoint of low toxicity and ease of availability, it is preferred to use sodium carbonate, sodium oxide, potassium carbonate, potassium oxide, calcium carbonate, calcium hydroxide, calcium oxide, magnesium carbonate, or hydroxide. More than one of magnesium, magnesium sulfate, calcium sulfate, calcium nitrate and magnesium oxide, more preferably selected from the group consisting of magnesium oxide, calcium oxide, magnesium carbonate, calcium carbonate, magnesium sulfate, calcium sulfate, calcium nitrate, magnesium hydroxide and One or more types of the group consisting of calcium hydroxide, and more preferably one or more selected from the group consisting of calcium carbonate, calcium oxide, magnesium carbonate, calcium sulfate, and magnesium oxide, and more preferably calcium carbonate.

When the metal compound containing an alkaline earth metal or an alkali metal is solid at normal temperature and has a particle shape, the particle diameter of the particle is preferably 30 μm or less, more preferably 0.01 μm to 30 μm, furthermore. Preferably, it is 0.02 μm to 10 μm, and even more preferably 0.03 μm to 5 μm.

When the particle diameter is 30 μm or less, the donor element or the acceptor element can be uniformly diffused (doped) in a desired region of the semiconductor substrate. In addition, when it is 0.01 μm or more, the metal compound containing an alkaline earth metal or an alkali metal is easily uniformly dispersed in the composition for forming a mask. Further, the metal compound containing an alkaline earth metal or an alkali metal may also be dissolved in the dispersion medium.

Further, the particle diameter indicates a volume average particle diameter, which can be measured by a laser scattering diffraction particle size distribution measuring apparatus or the like. The volume average particle diameter can detect the relationship between the intensity of scattered light of the laser light irradiated by the particles and the angle, and is calculated based on the Mie scattering theory. The dispersion medium at the time of measurement is not particularly limited, and it is preferred to use a dispersion medium which does not dissolve the particles to be measured.

The method of obtaining particles of a specific compound having a particle diameter of 30 μm or less is not particularly limited, and for example, it can be obtained by pulverization treatment. The pulverization method may be a dry pulverization method or a wet pulverization method. The dry pulverization method may be a jet mill, a vibrating mill, a ball mill or the like. As the wet pulverization method, a bead mill, a ball mill or the like can be used.

When the impurities caused by the pulverizing device are mixed into the composition for forming a mask during the pulverization treatment, the life of the carrier in the semiconductor substrate is lowered, so that the pulverization container, the beads, and the beads are preferable. Materials such as materials have a small influence on the semiconductor substrate. The material of the container or the like which is suitably used at the time of pulverization can be Alumina, partially stabilized zirconia, and the like are listed. Further, as a method of obtaining particles of a specific compound having a particle diameter of 30 μm or less, a gas phase oxidation method, a hydrolysis method, or the like can be used in addition to the pulverization method.

Further, the particles of the specific compound may be a carrier (for example, cerium oxide particles) containing a compound other than the metal compound containing an alkaline earth metal or an alkali metal, and the surface of the carrier may be coated or dispersed to carry an alkaline earth metal or a base. A material of a metal metal compound. In this form, the effective surface area of the metal compound containing an alkaline earth metal or an alkali metal can be increased, and the property of suppressing the diffusion of the donor element or the acceptor element into the semiconductor substrate can be improved.

The carrier is preferably a material exhibiting a BET specific surface area of 10 m ² /g or more, and examples thereof include particles of an inorganic material such as SiO ₂ , activated carbon, carbon fibers, or zinc oxide.

The shape of the particles is not particularly limited, and may be any of a substantially spherical shape, a flat shape, a scale shape, a block shape, a spheroidal shape, a plate shape, and a rod shape. The shape of the particles can be confirmed by an electron microscope or the like.

The content ratio of the alkaline earth metal or alkali metal-containing metal compound in the composition for forming a mask can be determined in consideration of coatability, diffusibility of a donor element or an acceptor element, and the like. In general, the content ratio of the metal compound containing an alkaline earth metal or an alkali metal in the composition for forming a mask is preferably 0.1% by mass or more and 95% by mass based on 100% by mass of the composition for mask formation. More preferably, it is 0.1% by mass or more and 80% by mass or less, more preferably 0.1% by mass or more and 50% by mass or less, still more preferably 2% by mass or more and 50% by mass or less, and particularly preferably 5% by mass or less. The mass% or more and 20% by mass or less.

When the content of the metal compound containing an alkaline earth metal or an alkali metal is 0.1% by mass or more, diffusion of the donor element or the acceptor element into the semiconductor substrate can be sufficiently inhibited. When it is 95% by mass or less, the dispersibility of the metal compound containing an alkaline earth metal or an alkali metal in the composition for forming a mask is improved, and the coatability to the substrate is improved.

Further, the total mass ratio of the alkaline earth metal and the alkali metal-containing metal compound among all the nonvolatile components of the mask forming composition is preferably 5% by mass or more and less than 100% by mass, and more preferably 20% by mass or more. 99% by mass or less. If it is in the above range, there is a tendency that a sufficient mask control effect is obtained.

Here, the non-volatile component means a component that does not volatilize when heat-treated at 600 ° C or higher. Further, the nonvolatile matter can be obtained by a thermogravimetric analyzer TG, and the total content of the alkaline earth metal and alkali metal-containing metal compound in the nonvolatile matter can be determined by ICP emission spectrometry/mass spectrometry (ICP-MS). Method), obtained by atomic absorption method.

(矽 compound)

The composition for mask formation of the present invention contains a ruthenium compound. By containing a ruthenium compound, it functions as an inorganic binder, and the metal compound containing an alkaline earth metal or an alkali metal is bonded to each other at a high temperature, and it is easy to bond the metal compound containing an alkaline earth metal or an alkali metal to a semiconductor substrate.

The antimony compound is preferably a naphthene resin from the viewpoint of dispersibility in the composition for forming a mask. More preferably, the siloxane oxide is a hydrolysis condensate comprising an alkoxy decane. Ease of alkoxydecane in reactivity control Excellent in terms of stability.

Here, the hydrolysis condensation means that the alkoxydecane compound is hydrolyzed and subjected to dehydration (H ₂ O) condensation to polymerize. Preferably, the rhodium oxide resin is R ₃ SiO-(R ₂ SiO) _n -OSiR ₃ (wherein R ₂ and R ₃ are alkoxy groups, which may be the same or different; n is 1 to 1) The compound represented by the integer).

The alkoxy group constituting the alkoxydecane compound is preferably a linear or branched alkoxy group, more preferably a linear or branched alkoxy group having 1 to 24 carbon atoms. Further, a linear or branched alkoxy group having a carbon number of 1 to 10 is more preferable, and a linear or branched alkoxy group having a carbon number of 1 to 4 is particularly preferable.

Specific examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an isopropoxy group, an isobutoxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, and a 2- Ethylhexyloxy, trioctyloxy, nonyloxy, dodecyloxy, tetradecyloxy, 2-hexyldecyloxy, hexadecyloxy, octadecyloxy, cyclohexyl Oxy, octylcyclohexyloxy and the like.

As the alkoxydecane compound, from the viewpoint of easiness of obtaining and chemical stability, it is preferred to contain a compound selected from the group consisting of tetramethoxy decane, tetraethoxy decane, tetrapropoxy decane, and tetrabutoxy One or more kinds of decanes.

The weight average molecular weight (Mw) of the siloxane resin is preferably from 150 to 100,000, more preferably from 1,000 to 50,000, from the viewpoint of dispersibility in the composition for forming a mask. Further, the weight average molecular weight is measured by a gel permeation chromatography (GPC) method, and is converted using a calibration curve of standard polystyrene.

The decane resin can be obtained by a known method. For example, it can be obtained by stirring water (H ₂ O) and the alkoxydecane compound in a dispersion medium to be described later. Moreover, in order to shorten the reaction time, a catalyst may also be added. The catalyst may, for example, be hydrochloric acid, phosphoric acid, nitric acid, boric acid, sulfuric acid, hydrofluoric acid or the like. Among them, nitric acid is preferably used.

In the present invention, when a decane resin is used as the ruthenium compound, the previously synthesized oxime resin may be mixed with a metal compound containing an alkaline earth metal or an alkali metal, a dispersion medium, and an organic binder to prepare a mask. The composition for formation may be prepared by mixing water with the alkoxydecane compound, a metal compound containing an alkaline earth metal or an alkali metal, and a dispersion medium to prepare a composition for forming a mask.

Further, a cerium oxide (SiO ₂ , SiO, or the like) may be contained as the cerium compound. The shape of the cerium oxide is not particularly limited. For example, when it is in the form of particles, a substantially spherical shape, a flat shape, a block shape, a plate shape, a scale shape, or the like can be exemplified. When the cerium oxide is in the form of particles, the volume average particle diameter is preferably 20 μm or less; more preferably 5 μm or less. When a niobium oxide having a volume average particle diameter of 20 μm or less is used, it is easily dispersed in the composition for forming a mask, and productivity is improved. Further, the lower limit of the volume average particle diameter is not particularly limited, but is preferably 0.01 μm or more.

In the composition for forming a mask of the present invention, the content of the cerium compound is preferably more than 0% by mass and not more than 99.9% by mass, more preferably 0.5% by mass to 90% by mass, still more preferably 10% by mass or more and 80% by mass or less. When the content of the ruthenium compound is 99.9% by mass or less, it can be fully utilized due to inclusion. The shielding effect of the composition for mask formation by the metal compound containing an alkaline earth metal or an alkali metal.

Further, the mass ratio of the total content of the metal compound containing an alkaline earth metal and an alkali metal to the total content of the cerium compound ((metal compound containing an alkaline earth metal and an alkali metal) / (矽 compound)) is preferably 99.9/0.1 to 0.1. /99.9, more preferably 99/1~20/80.

(dispersion medium)

The composition for mask formation of the present invention contains a dispersion medium. The dispersion medium is a medium in which the above-described alkaline earth metal or alkali metal-containing metal compound is dispersed or dissolved in the composition. Further, examples of the dispersion medium include a solvent, water, and an organic binder.

Examples of the solvent include acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, and A. Base hexyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, trimethyl fluorenone, cyclohexanone, cyclopentanone, methyl cyclohexanone, 2,4-pentanedione, acetone a ketone solvent such as acetone; diethyl ether, methyl ethyl ether, methyl n-propyl ether, diisopropyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyl dioxane, Diol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol dibutyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, Diethylene glycol methyl-ethyl ether, diethylene glycol methyl-n-propyl ether, diethylene glycol methyl-n-butyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl Dibutyl ether, diethylene glycol methyl-n-hexyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl-ethyl ether, triethylene glycol methyl-n-butyl Ether, triethylene glycol di-n-butyl ether, triethylene Alcohol methyl-n-hexyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol methyl-ethyl ether, tetraethylene glycol methyl-n-butyl ether, diethylene glycol Di-n-butyl ether, tetraethylene glycol methyl-n-hexyl ether, tetraethylene glycol di-n-butyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol dibutyl ether, dipropylene glycol dimethyl ether , dipropylene glycol diethyl ether, dipropylene glycol methyl-ethyl ether, dipropylene glycol methyl-n-butyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl-n-hexyl ether, tripropylene glycol Dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol methyl-ethyl ether, tripropylene glycol methyl-n-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl-n-hexyl ether, tetrapropylene glycol dimethyl ether, An ether solvent such as tetrapropylene glycol diethyl ether, tetrapropylene glycol methyl-ethyl ether, tetrapropylene glycol methyl-n-butyl ether, tetrapropylene glycol di-n-butyl ether, tetrapropylene glycol methyl-n-hexyl ether or tetrapropylene glycol di-n-butyl ether Methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate Ester, second butyl acetate, n-amyl acetate, second amyl acetate, 3-methoxybutyl acetate, methyl amyl acetate, 2-ethylbutyl acetate, 2-ethyl acetate Hexyl ester, 2-(2-butoxyethoxy)ethyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, decyl acetate, methyl acetate, ethyl acetate Ester, diethylene glycol methyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, dipropylene glycol diethyl ether acetate, glycol diacetate, methoxy triethylene acetate Alcohol ester, ethyl propionate, n-butyl propionate, isoamyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, B Glycol methyl ether propionate, ethylene glycol ethyl ether propionate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol diethyl ether acetate, propylene glycol ethyl ether Ester, γ-butyrolactone, γ-valerolactone and other esters Solvent; acetonitrile, N-methylpyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone, N-butylpyrrolidone, N-hexylpyrrolidone, N-cyclohexylpyrrolidine Aprotic polar solvents such as ketone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylhydrazine; methanol, ethanol, n-propanol, isopropanol, n-butyl Alcohol, isobutanol, second butanol, third butanol, n-pentanol, isoamyl alcohol, 2-methylbutanol, second pentanol, third pentanol, 3-methoxybutanol, positive Alcohol, 2-methylpentanol, second hexanol, 2-ethylbutanol, second heptanol, n-octanol, 2-ethylhexanol, second octanol, n-nonanol, n-nonanol, Sec-undecyl alcohol, trimethyl sterol, second-tetradecanol, second heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene Alcohol, 1,2-propanediol, 1,3-butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol and other alcoholic solvents; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether (race Bismuth), ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether , diethylene glycol mono-n-hexyl ether, ethoxy triethylene glycol, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether and other glycol Monoether solvent; α-terpinene, α-rosinol, myrcene, allo-ocimene, limonene, dipentene, α-pinene, β-pinene, terpineol, fragrant ketone, basilene An anthraquinone solvent such as cressine. These solvents may be used alone or in combination of two or more.

Among these solvents, from the viewpoint of coatability on a semiconductor substrate, the dispersion medium is preferably water, an alcohol solvent, a glycol monoether solvent, or an oxime solvent, more preferably water or alcohol. Celluloid, alpha-rosin, diethylene glycol mono-n-butyl ether, or diethylene glycol mono-n-butyl ether acetate, further preferably water, alcohol, alpha-rosin or race 珞苏.

The content of the dispersion medium in the composition for forming a mask can be determined in consideration of the coating property and the dopant concentration. For example, the composition for forming a mask is preferably 5% by mass or more and 99% by mass or less. More preferably, it is 20 mass% or more and 95 mass% or less, and further more preferably 40 mass% or more and 90 mass% or less.

The composition for mask formation of the present invention may also contain an organic binder. The organic binder can be suitably selected: polyvinyl alcohol; polypropylene decylamine resin; polyvinyl decylamine resin; polyvinylpyrrolidone resin; polyethylene oxide resin; polyfluorene resin; acrylamide alkyl hydrazine resin; Cellulose derivatives such as ether ether, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose; gelatin, gelatin derivatives; starch, starch derivatives; sodium alginate; xanthan; Guar gum, guar gum derivative; scleroglucan, scleroglucan derivative; tragacanth, xanthine derivative; dextrin, dextrin derivative; (meth)acrylic resin (meth) acrylate resin, (meth) acrylate resin such as dimethylaminoethyl methacrylate resin; butadiene resin; styrene resin; and copolymerization of the organic binder Things.

Among these organic binders, from the viewpoints of self-decomposability and prevention of dripping at the time of screen printing, it is preferred to contain an acrylic resin or a cellulose derivative. These organic binders may be used alone or in combination of two or more.

The molecular weight of the organic binder is not particularly limited, and is preferably adjusted in view of the desired viscosity as a composition. In addition, the content of the organic binder is preferably 0.5% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 25% by mass or less, more preferably in the mask forming composition. More preferably, it is 3% by mass or more and 20% by mass or less.

As the dispersion medium, a dispersion medium in which the above organic binder is dissolved may also be used.

(other ingredients)

The composition for mask formation may contain various additives such as a tackifier, a wetting agent, a surfactant, an inorganic powder, and a thixotropic agent, in addition to a ruthenium compound, a metal compound containing an alkaline earth metal or an alkali metal, and a dispersion medium. ingredient.

Examples of the surfactant include a nonionic surfactant, a cationic surfactant, an anionic surfactant, and the like. Among them, a nonionic surfactant or a cationic surfactant is preferred because it has less impurities such as heavy metals introduced into the semiconductor element. Further, a ruthenium-based surfactant, a fluorine-based surfactant, and a hydrocarbon-based surfactant are exemplified as the nonionic surfactant, and a hydrocarbon-based interface is preferred from the viewpoint of rapid calcination during heating such as diffusion. Active agent.

The hydrocarbon-based surfactant may, for example, be an ethylene oxide-propylene oxide block copolymer or an acetylene glycol compound, and is more preferably an acetylene glycol compound from the viewpoint of further reducing the unevenness of the resistance value of the semiconductor element.

The inorganic powder may, for example, be a powder of cerium oxide, cerium nitride, cerium carbide or the like.

The composition for mask formation may also include a thixotropic agent containing a solid. Thereby, thixotropy can be easily controlled, and a composition for forming a mask for screen printing having a viscosity suitable for screen printing, and a composition for forming a mask for inkjet having a viscosity suitable for inkjet printing can be formed. . Further, it is further possible to suppress the mask forming composition at the time of printing from oozing or dripping from the printed pattern by controlling thixotropy. The aforementioned organic binder It may also function as a thixotropic agent, and such a material may be exemplified by ethyl cellulose.

The composition for forming a mask of the present invention preferably has a content ratio of iron, tungsten, gold, nickel, chromium, manganese, or the like from the viewpoint of not contaminating the semiconductor substrate, that is, suppressing recombination of carriers in the semiconductor substrate. The composition for mask formation is 10% by mass or less, more preferably 5% by mass or less, and still more preferably 1% by mass or less.

The viscosity of the composition for mask formation is not particularly limited. Specifically, it is preferably 1 mPa at 25 ° C. s~400 Pa. s, more preferably 10 mPa. s~100 Pa. s. If the composition for mask formation has a viscosity of 1 mPa. Above s, it is difficult to produce dripping when applied to a semiconductor substrate; and if it is 400 Pa. Below s, it becomes possible to form a fine coating pattern.

Further, the viscosity of the composition for mask formation can be determined by a rotation method, a stress control method, or a strain control method using a B-type viscometer, an E-type viscometer, a viscoelasticity measuring device, or the like.

The composition for mask formation of the present invention may be a metal compound containing an alkaline earth metal or an alkali metal, a dispersion medium, a ruthenium compound, and optionally added components by using a blender, a mixer, a mortar, or a rotor. Obtained by mixing. Moreover, when mixing is performed, heating may be performed as needed. The heating temperature at this time can be, for example, 30 ° C to 100 ° C.

<Method for Manufacturing Solar Cell Substrate and Solar Cell Element>

The method for producing a substrate for a solar cell according to the present invention includes the step of applying the composition for mask formation to a semiconductor substrate in a pattern, thereby forming a step of forming a mask; a portion of the semiconductor substrate on which the mask is not formed is doped with a donor element or an acceptor element, thereby partially forming a diffusion layer in the semiconductor substrate.

Further, the method for producing a solar cell element of the present invention comprises the step of forming an electrode on a diffusion layer of a substrate for a solar cell obtained by the above-described production method.

Here, a solar cell substrate and a method for producing a solar cell element using the composition for mask formation of the present invention will be described with reference to FIG. 1 . FIG. 1 is a schematic cross-sectional view conceptually showing an example of a manufacturing procedure of a solar cell substrate and a solar cell element of the present invention.

In addition, although the back electrode type solar cell substrate and the solar cell element are described in FIG. 1, the mask forming composition of the present invention can be applied to any type of solar cell substrate and solar cell element.

As another form other than the back electrode type, a selective emitter type and a double-sided light receiving type can be exemplified. In the substrate for a selective emitter type solar cell, a diffusion layer having a higher dopant concentration than other regions is formed directly under the electrode on the light-receiving surface side. In order to form the region of the high concentration diffusion layer, the composition for mask formation of the present invention can be used. Further, in the double-sided light-receiving solar cell element, a finger bar and a bus bar are formed as electrodes on both surfaces, and an n ⁺ -type diffusion layer is formed on one side of the semiconductor substrate, and the other side is formed on the other side. A p ⁺ -type diffusion layer is formed. In order to selectively form the n ⁺ -type diffusion layer and the p ⁺ -type diffusion layer in a positional manner, the composition for mask formation of the present invention can be used.

In (1) of FIG. 1, an alkali solution is applied to a substrate as the n-type semiconductor substrate 10 to remove the damaged layer, and a texture structure is obtained by etching.

Specifically, the damage layer on the surface of the crucible substrate generated when the ingot was sliced was removed by 20% by mass of caustic soda. Then, etching is performed on a mixture of 1% by mass of caustic soda and 10% by mass of isopropyl alcohol to form a texture structure on the n-type semiconductor substrate 10 (the description of the texture structure is omitted in the drawing). The solar cell element promotes optical confinement effects by forming a texture structure on the light-receiving surface (surface) side of the ruthenium substrate, thereby achieving high efficiency.

In (2) of FIG. 1, the mask forming composition 11 of the present invention is applied to the surface (i.e., the light receiving surface) of the n-type semiconductor substrate 10 and the back surface opposite to the light receiving surface. In the present invention, the application method is not limited, and there are a printing method, a spinning method, a brushing method, a spray method, a doctor blade method, a roll coating method, an inkjet method, etc., and a printing method or an inkjet method is preferably used.

The application amount of the above-mentioned composition for mask formation is not particularly limited, and is, for example, preferably 0.01 g/m ² to 100 g/m ² , more preferably 0.1 g/m ² to 20 g/m ² . The coating thickness of the above-mentioned composition for mask formation is not particularly limited, but is preferably 0.1 μm to 50 μm, more preferably 1 μm to 30 μm.

Further, depending on the composition of the composition for mask formation, there is a case where a drying step for volatilizing the dispersion medium contained in the composition must be performed after application. In this case, it is dried at a temperature of about 80 ° C to 300 ° C, and dried for 1 minute to 10 minutes when using a hot plate, and 10 minutes to 30 minutes when using a dryer or the like. Dry. The drying conditions depend on the formation of the mask The content ratio of the dispersion medium of the composition is not particularly limited to the above conditions in the present invention.

Further, in the case of a printing method, an inkjet method, or the like, a mask having a pattern can be obtained by applying the mask forming composition 11 in a pattern. On the other hand, in the case of a spin method, a brushing method, a spray method, a doctor blade method, a roll coating method, or the like, the mask forming composition 11 can be applied to the entire surface, and then partially removed by etching or the like. Thus, a patterned mask is obtained.

Next, in (3) of FIG. 1, a coating diffusion material 12 for forming an n ⁺ -type diffusion layer and a p ⁺ -type diffusion layer, and a diffusion material for coating 13 are applied. Next, in (4) of FIG. 1, thermal diffusion is performed to form the n ⁺ -type diffusion layer 14 and the p ⁺ -type diffusion layer 15 in the n-type semiconductor substrate 10. The coating diffusion material 12 and the coating diffusion material 13 serve as the calcined material 12' for the coating diffusion material and the calcined material 13' of the coating diffusion material, and are generally formed by the heat treatment for performing thermal diffusion. Glass layer. The heat treatment temperature for performing thermal diffusion is not particularly limited, and it is preferred to carry out heat treatment at a temperature of 750 ° C to 1050 ° C for 1 minute to 300 minutes.

Here, although the method of simultaneously forming the n ⁺ -type diffusion layer 14 and the p ⁺ -type diffusion layer 15 is shown, it is also possible to diffuse individually. In other words, the coating diffusion material 13 for forming the p ⁺ -type diffusion layer 15 may be first coated and thermally diffused, and the calcined product 13' of the coating diffusion material may be removed and then coated to form n. The coating of the ⁺ -type diffusion layer 14 is thermally diffused by the diffusion material 12, and the baked product 12' of the diffusion material for coating is removed.

Here, the case where the coating diffusion material 12 and the coating diffusion material 13 are used has been described, and the same can be applied to a method using POCl ₃ gas or BBr ₃ gas. In this case, a predetermined region of the p ⁺ -type diffusion layer 15 is formed as an opening in the n-type semiconductor substrate 10, and a mask is formed outside the region of the opening by the mask forming composition. Next, a p ⁺ -type diffusion layer 15 is formed on the n-type semiconductor substrate 10 corresponding to the opening, and then the mask is removed. Next, a predetermined region in which the n ⁺ -type diffusion layer 14 is formed is used as an opening portion, and a mask is formed outside the region of the opening portion by the mask forming composition. Next, an n ⁺ -type diffusion layer 14 is formed on the n-type semiconductor substrate 10 corresponding to the opening.

Next, in (5) of FIG. 1, the mask forming composition 11 and the calcining material 12' for coating diffusion material and the calcined material 13' of the coating diffusing material are removed to obtain a solar cell substrate. . The removal method may be a method of immersing in an aqueous solution containing an acid, preferably a coating for forming the mask 11, and a diffusion for coating for forming the n ⁺ -type diffusion layer 14 and the p ⁺ -type diffusion layer 15 . The composition of the calcined material 12' of the material and the calcined product 13' of the diffusion material for coating is determined. Specifically, it is preferred to include a step of etching a glass layer formed on the semiconductor substrate by thermal diffusion treatment by an aqueous solution containing hydrofluoric acid. More specifically, a method in which a metal compound containing an alkaline earth metal or an alkali metal is removed by hydrochloric acid (for example, 10% by mass aqueous HCl solution), followed by washing with water, further by an aqueous solution of hydrofluoric acid (for example, 2.5% by mass) The HF aqueous solution) is a method in which the calcined product 12' of the diffusion material for coating and the calcined product 13' of the diffusion material for coating are etched and then washed with water.

Next, in (6) of Fig. 1, application to the surface as a light receiving surface The anti-reflection film 16 is applied with a passivation film 17 on the back side. The composition of the anti-reflection film 16 and the passivation film 17 may be the same or different. The anti-reflection film 16 is, for example, a tantalum nitride film, and the passivation film 17 is, for example, a hafnium oxide film. The film thickness of the antireflection film and the passivation film is not particularly limited, but is preferably 10 nm to 300 nm, and more preferably 30 nm to 150 nm.

Next, in (7) of Fig. 1, the portion where the electrode is formed is opened on the passivation film 17. The method of the opening is not particularly limited. For example, an etching liquid (for example, a solution containing hydrofluoric acid, ammonium fluoride or phosphoric acid) may be applied to a place to be opened by an inkjet method or the like, and heat-treated to be opened.

Next, in (8) of FIG. 1, the n-electrode 18 and the p-electrode 19 are formed on the n ⁺ -type diffusion layer 14 and the p ⁺ -type diffusion layer 15, respectively. In the present invention, the material or formation method of the electrode 18 and the electrode 19 is not particularly limited. For example, an electrode forming paste containing a metal of aluminum, silver, or copper can be applied and dried to form the electrode 18 and the electrode 19. Next, the electrode 18 and the electrode 19 are fired to complete the solar cell element.

Further, when the paste for electrode formation containing glass frit is used as the paste for electrode formation, the step of opening shown in (7) of Fig. 1 can be omitted. When the paste for forming an electrode containing glass frit is applied onto the passivation film 17 and baked in the range of 600 ° C to 900 ° C for several seconds to several minutes, the passivation film 17 on the back side of the glass frit is melted, and the metal in the paste The particles (for example, silver particles) form a contact portion with the tantalum substrate 10 to be solidified. Thereby, the formed surface electrode 18 and surface electrode 19 are electrically connected to the ruthenium substrate 10. It is called fire through.

<solar battery>

A solar cell contains one or more of the above solar cell components in a solar cell A wiring material is disposed on the electrode of the element. The solar cell may be further connected to a plurality of solar cell elements via a wiring material as needed, and further sealed by a sealing material.

The wiring material and the sealing material are not particularly limited, and may be appropriately selected from wiring materials and sealing materials generally used in the art.

In addition, the entire disclosure of the Japanese Patent Application No. 2012-002633 is hereby incorporated by reference.

All of the documents, patent applications, and technical specifications described in the specification are incorporated by reference to the same extent as individually and individually incorporated by reference. To this manual.

[Examples]

Hereinafter, the embodiments of the present invention will be further specifically described, but the present invention is not limited to the embodiments. In addition, unless otherwise stated, all reagents are used as reagents. Moreover, "%" means "% by mass" unless otherwise specified.

Further, the volume average particle diameter of the alkaline earth metal or alkali metal-containing metal compound in the examples is manufactured by a laser diffraction scattering particle size distribution measuring apparatus (Beckman Coulter, Inc.). LS 13 320), the particle size was measured in a dispersed state.

<Example 1> (Modulation of composition 1 for mask formation)

10 g of tetraethoxy decane (manufactured by Tama Chemical Co., Ltd., n-decanoic acid ethyl ester), 4 g of water, 0.1 g of nitric acid, and ethanol were mixed and stirred. Second, will oxidize Magnesium (manufactured by Wako Pure Chemical Industries, Ltd., volume average particle diameter of 0.2 μm, amorphous particles) 10 g was mixed in a mortar to prepare a composition 1 for mask formation. The composition for mask formation 1 has a viscosity of 0.2 Pa at 25 ° C and 5 rpm. s. In addition, the viscosity was measured by setting the amount of the mask forming composition to 0.5 ml by an E-type viscometer (manufactured by Tokyo Keiki Co., Ltd.).

(modulation of phosphorus diffusion liquid)

A 20% by mass aqueous solution of ammonium dihydrogen phosphate (manufactured by Wako Pure Chemical Industries, Ltd.) was prepared, and a saturated aqueous solution of ammonium dihydrogen phosphate of a supernatant liquid was used as a phosphorus diffusion liquid.

(thermal diffusion and etching steps)

On the surface of the n-type ruthenium substrate (hereinafter also referred to as "n-type ruthenium substrate") after slicing, the composition for mask formation 1 was spin-coated by a spin coater (MS-A100, manufactured by Mikasa Co., Ltd.). (Speed: 1000 rpm) was dried on a hot plate at 200 ° C for 5 minutes on the entire surface of one side. Next, another crucible substrate was prepared, and the phosphorus diffusion liquid was spin-coated at 500 rpm and dried at 200 °C.

The two tantalum substrates were heated at 950 ° C for 10 minutes while being opposed to each other at a distance of 1 mm to diffuse phosphorus onto the tantalum substrate coated with the mask forming composition 1 . Then, the ruthenium substrate coated with the composition for mask formation 1 was immersed in a 10 mass% HCl aqueous solution for 5 minutes, washed with water, and further immersed in a 2.5% by mass aqueous HF solution for 5 minutes. After washing with water and drying, the portion to which the composition for mask formation 1 was applied was subjected to the following evaluation.

(Measurement of sheet resistance)

The sheet resistance of the portion coated with the mask forming composition 1 was measured by a four-probe method using a Loresta-EP MCP-T360 type low resistivity meter manufactured by Mitsubishi Chemical Corporation. The sheet resistance of the portion to which the composition for mask formation 1 was applied was 190 Ω/□.

Further, as a reference sample, the n-type ruthenium substrate after the dicing was immersed in a 2.5% by mass aqueous HF solution for 5 minutes, and the sheet resistance after washing with water was measured and found to be 240 Ω/□.

<Example 2>

In the same manner as in Example 1, except that 10 g of calcium oxide (manufactured by Wako Pure Chemical Industries, Ltd., volume average particle diameter: 2.5 μm, amorphous particles) was used instead of magnesium oxide, the mask formation was carried out in the same manner as in Example 1. Composition 2. The composition for forming the mask 2 has a viscosity of 0.15 Pa at 25 ° C. s.

In the first embodiment, the composition 2 for mask formation was used in the same manner as in Example 1 except that the composition for mask formation 2 was used. The sheet resistance of the portion coated with the mask forming composition 2 was 150 Ω/□.

<Example 3>

10 g of tetraethoxy decane (manufactured by Tama Chemical Co., Ltd., n-decanoic acid ethyl ester), 4 g of water, and 0.1 g of nitric acid were mixed and stirred. Next, 10 g of calcium carbonate (manufactured by high-purity chemical, volume average particle diameter of 2.0 μm, amorphous particles), and 15% by mass of ethyl cellulose (manufactured by Dow Chemical, STD200) were dissolved. 20 g of rosin (manufactured by Nippon Chemical Co., Ltd.) and 5 g of α-rosinol were mixed in a mortar and stirred sufficiently to prepare a composition 3 for mask formation. The mask is formed by using The viscosity of the material 3 at 25 ° C is 0.2 Pa. s.

The mask forming composition 3 was spin-coated on an n-type ruthenium substrate, and dried at 150 °C. The subsequent steps were carried out in the same manner as in Example 1 and evaluated. The sheet resistance of the portion coated with the mask forming composition 3 was 180 Ω/□.

<Example 4>

10 g of tetraethoxy decane (manufactured by Tama Chemical Co., Ltd., n-decanoic acid ethyl ester), 4 g of water, and 0.1 g of nitric acid were mixed and stirred. Next, calcium sulfate (manufactured by Wako Pure Chemical Industries, Ltd., volume average particle diameter of 1.5 μm, amorphous particles) 10 g, and 15% by mass of ethyl cellulose (manufactured by Dow Chemical, STD200) α-rosin (manufactured by Seiko Chemical Co., Ltd.) 20 g of α-rosinol 5 g was mixed in a mortar, and the composition 4 for mask formation was prepared by stirring well. The composition for forming the mask 4 has a viscosity of 0.2 Pa at 25 ° C. s.

The mask forming composition 4 was spin-coated on an n-type ruthenium substrate, and dried at 150 °C. The subsequent steps were carried out in the same manner as in Example 1 and evaluated. The sheet resistance of the portion coated with the mask forming composition 4 was 220 Ω/□.

<Example 5>

10 g of tetraethoxy decane (manufactured by Tama Chemical Co., Ltd., n-decanoic acid ethyl ester), 4 g of water, and 0.1 g of nitric acid were mixed and stirred. Next, 10 g of magnesium oxide (manufactured by Wako Pure Chemical Industries, volume average particle diameter: 0.2 μm, amorphous particles), and α-rosin alcohol (15% by mass of ethyl cellulose (manufactured by Dow Chemical, STD200) were dissolved ( 20 g of α-rosinol and 5 g of α-rosinol were mixed in a mortar and stirred well to prepare a composition 5 for mask formation. The mask forming composition 5 is viscous at 25 ° C The degree is 0.2 Pa. s.

The mask forming composition 5 was spin-coated on an n-type ruthenium substrate, and dried at 150 °C. The subsequent steps were carried out in the same manner as in Example 1 and evaluated. The sheet resistance of the portion coated with the mask forming composition 5 was 200 Ω/□.

<Example 6>

60 g of calcium oxide (manufactured by Wako Pure Chemical Industries, volume average particle diameter of 2.5 μm, amorphous particles), butyl carbitol (manufactured by Wako Pure Chemical Industries, diethylene glycol monobutyl ether), 60 g, The dispersion 1 was prepared by pulverizing and dispersing at 600 rpm by using a planetary ball mill by stabilizing zirconia particles of 3 mm.

Next, 10 g of tetraethoxy decane (manufactured by Tama Chemical Co., Ltd., ethyl decanoate), 4 g of water, and 0.1 g of nitric acid were mixed and stirred to prepare a decane solution 1. 5 g of the dispersion 1 and 5 g of the decane solution 1 were mixed to prepare a composition for mask formation 6. The viscosity at 25 ° C was 0.1 Pa. s.

The mask forming composition 6 was spin-coated on an n-type ruthenium substrate, and dried at 150 °C. The subsequent steps were carried out in the same manner as in Example 1 and evaluated. The sheet resistance of the portion coated with the mask forming composition 6 was 240 Ω/□.

<Example 7>

1 g of the dispersion prepared in Example 6 and 1, 9 g of decane solution 1 were mixed to prepare a composition 7 for mask formation. The mask forming composition 7 has a viscosity of 80 mPa at 25 ° C. s.

The mask forming composition 7 was spin-coated on an n-type ruthenium substrate, and dried at 150 °C. The subsequent steps were carried out in the same manner as in Example 1 and evaluated. The sheet resistance of the portion coated with the mask forming composition 7 was 140 Ω/□.

<Example 8>

0.1 g of the dispersion liquid prepared in Example 6 and 9.9 g of decane solution 1 were mixed to prepare a composition for mask formation 8. The composition for forming the mask 8 has a viscosity of 55 mPa at 25 ° C. s.

The mask forming composition 8 was spin-coated on an n-type ruthenium substrate, and dried at 150 °C. The subsequent steps were carried out in the same manner as in Example 1 and evaluated. The sheet resistance of the portion coated with the mask forming composition 8 was 90 Ω/□.

<Example 9>

2 g of butyl carbitol dissolved in 20% by mass of ethyl cellulose (manufactured by Dow Chemical, STD200), 5 g of the dispersion prepared in Example 6, and 1 g of decane solution 1 were mixed. The composition for forming the mask is prepared 9. The viscosity at 25 ° C is 8 Pa. s.

The mask forming composition 9 was spin-coated on an n-type ruthenium substrate, and dried at 150 °C. The subsequent steps were carried out in the same manner as in Example 1 and evaluated. The sheet resistance of the portion coated with the mask forming composition 9 was 190 Ω/□.

<Example 10>

1 g of butyl carbitol dissolved in 20% by mass of ethyl cellulose (manufactured by Dow Chemical, STD200), 8 g of the dispersion prepared in Example 6, and 1 g of decane solution 1 were mixed. The composition for forming the mask 10 is prepared. The viscosity at 25 ° C is 10 Pa. s.

By screen printing machine (MT-320T, made by Microtek) The mask-forming composition 10 was applied to one of the surfaces of the n-type ruthenium substrate, dried on a hot plate at 150 ° C for 5 minutes, and then dried on a hot plate at 500 ° C for 1 minute. The subsequent steps were carried out in the same manner as in Example 1 and evaluated. The sheet resistance of the portion coated with the mask forming composition 10 was 230 Ω/□.

<Example 11>

An n-type germanium substrate coated with the mask forming composition 10 was prepared in the same manner as in the tenth embodiment.

Further, another crucible substrate was prepared, and a saturated aqueous solution of B ₂ O ₃ was spin-coated thereon at 200 rpm, and dried at 200 °C.

The two ruthenium substrates were heated at 950 ° C for 30 minutes while flowing the nitrogen at a distance of 1 mm, and the boron was diffused to the ruthenium substrate on which the mask formation composition 10 was applied. Then, the ruthenium substrate coated with the mask-forming composition 10 was immersed in a 10 mass% HCl aqueous solution for 5 minutes, washed with water, and further immersed in a 2.5% by mass aqueous HF solution for 5 minutes. After washing with water and drying, the sheet resistance was measured for the portion coated with the mask forming composition 10 and the uncoated portion.

The sheet resistance of the portion to which the mask forming composition 10 was applied was 240 Ω/□, whereas the sheet resistance of the uncoated portion was 55 Ω/□.

<Example 12>

A polyvinyl alcohol (weight average molecular weight of 10,000, partially alkalized type, and Wako Pure Chemical Industries, Ltd.) was dissolved in water to prepare a 10% aqueous solution of polyvinyl alcohol. 8 g of this solution, calcium oxide (manufactured by Wako Pure Chemical Industries, volume average particle size of 2.5 μm, Amorphous particles) 1.5 g, fumed silica (Fumed Silica) (R200 from Aerosil, average secondary particle size of 5.0 μm), surfactant SH28PA (anthrone-based surfactant, Dow Corning East 0.2 g was produced by mixing in an automatic mortar mixing device to prepare a mask forming composition 11. It contains smoked cerium oxide as a cerium compound, but smoked cerium oxide also has the effect of being a tackifier and a thixotropic agent. The weight average molecular weight of the polyvinyl alcohol was measured by using GPC (UV-8220 manufactured by Tosoh Corporation) and the solvent was measured using N-methyl-2-pyrrolidone. The mask forming composition 11 has a viscosity of 17 mPa at 25 ° C. s.

The mask forming composition 11 was filtered with a membrane filter having a pore size of 30 μm to remove foreign matter, and this was supplied to a piezoelectric inkjet apparatus (manufactured by MICROJET Co., Ltd.) equipped with a nozzle having a pore diameter of 50 μm. The product name is nanometer printer 1000). Using the ink jet apparatus (manufactured by Epson Corporation), the mask forming composition 11 was applied onto the surface of the sliced n-type ruthenium substrate to have a linear pattern having a line width of 50 μm and a length of 40 mm. Then, it was dried on a hot plate at 150 ° C for 5 minutes, and then evaluated in the same manner as in Example 1. The sheet resistance of the portion coated with the mask forming composition 11 was 200 Ω/□.

<Comparative Example 1> (Comparison of Comparative Example Composition 1)

In Comparative Example 1, Comparative Example Composition 1 was prepared in the same manner as in Example 1 except that magnesium oxide was not added. Comparative Example Composition 1 had a viscosity of 6 Pa at 25 ° C. s.

In Comparative Example 1, Comparative Example Composition 1 was used instead of the mask forming composition. The evaluation was carried out in the same manner as in Example 1 except that the material 1 was used. The sheet resistance of the portion to which the comparative example composition 1 was applied was 25 Ω/□.

<Comparative Example 2>

In the first embodiment, evaluation was carried out in the same manner as in Example 1 except that the masking was not performed on the n-type ruthenium substrate. The sheet resistance of the n-type germanium substrate is 10 Ω/□.

<Comparative Example 3>

In Comparative Example 1, a comparative example composition 3 was prepared in the same manner as in Example 1 except that cerium oxide (manufactured by high-purity chemistry, volume average particle diameter: 1 μm) was used instead of magnesium oxide. Comparative Example 3 had a viscosity of 0.18 Pa at 25 ° C. s.

In the same manner as in Example 1, except that the composition of the comparative example 3 was used instead of the composition for forming the mask 1 in the first embodiment, the evaluation was carried out. The sheet resistance of the portion to which the comparative example composition 3 was applied was 30 Ω/□.

According to the above, it is understood that the diffusion of the donor element and the acceptor element can be sufficiently prevented by using a composition for mask formation comprising a ruthenium compound, a metal compound containing an alkaline earth metal or an alkali metal, or a dispersion medium.

10‧‧‧Substrate

11‧‧‧Material forming composition

12, 13‧‧‧Developing diffusion materials

12', 13'‧‧‧Roasting materials for coating diffusion materials

14‧‧‧n ⁺ type diffusion layer

15‧‧‧p ⁺ diffusion layer

16‧‧‧Anti-reflective film

17‧‧‧ Passivation film

18, 19‧‧‧ electrodes

Claims (15)

A composition for forming a mask, comprising: a cerium compound, a metal compound containing an alkaline earth metal or an alkali metal, and a dispersion medium. The composition for forming a mask according to the first aspect of the invention, wherein the total mass ratio of the alkaline earth metal or alkali metal-containing metal compound in the nonvolatile component is 5% by mass or more and less than 100% by mass. The composition for forming a mask according to claim 1 or 2, wherein the alkaline earth metal or alkali metal-containing metal compound is selected from the group consisting of magnesium, calcium, sodium, potassium, lithium, cesium, cesium, One or more of the group consisting of 铍, 锶, 钡, and radium are used as the metal element. The mask forming composition according to any one of claims 1 to 3, wherein the alkaline earth metal or alkali metal-containing metal compound is selected from the group consisting of magnesium oxide, calcium oxide, magnesium carbonate, and carbonic acid. One or more of the group consisting of calcium, magnesium sulfate, calcium sulfate, calcium nitrate, magnesium hydroxide, and calcium hydroxide. The mask forming composition according to any one of claims 1 to 4, wherein the alkaline earth metal or alkali metal-containing metal compound is solid particles at a normal temperature, and the volume of the particles The average particle size is 30 μm or less. The composition for mask formation according to any one of claims 1 to 5, wherein the bismuth compound comprises a decane resin. The composition for forming a mask according to any one of the preceding claims, wherein the oxime compound is a siloxane compound obtained by hydrolytic condensation of an alkoxy decane. The mask forming composition according to any one of claims 1 to 7, wherein the hydrazine compound is selected from the group consisting of tetramethoxy decane, tetraethoxy decane, and tetrapropoxy decane. And a decyl alkane resin obtained by hydrolyzing and condensing one or more compounds of the group consisting of tetrabutoxydecane. The composition for forming a mask according to any one of claims 1 to 8, wherein the dispersion medium is selected from the group consisting of water, an alcohol solvent, a glycol monoether solvent, and an oxime solvent. One or more types of groups are formed. The composition for mask formation according to any one of claims 1 to 9, which further comprises an organic binder. The composition for forming a mask according to claim 10, wherein the organic binder contains one or more selected from the group consisting of an acrylic resin and a cellulose resin. The composition for mask formation according to any one of claims 1 to 11, further comprising a thixotropic agent. A method for producing a substrate for a solar cell, comprising: applying a composition for mask formation according to any one of claims 1 to 12 to a semiconductor substrate in a pattern to form a mask a step of forming a diffusion layer in the semiconductor substrate, wherein a portion of the semiconductor substrate on which the mask is not formed is doped with a donor element or an acceptor element. The manufacturer of the solar cell substrate according to claim 13 of the patent application scope The method in which the composition for mask formation is applied is a printing method or an inkjet method. A method of producing a solar cell element, comprising the step of forming an electrode on a diffusion layer of a substrate for a solar cell obtained by the production method according to claim 13 or claim 14.