CN108028188B

CN108028188B - P-type impurity diffusion composition, method for manufacturing semiconductor element using same, and method for manufacturing solar cell

Info

Publication number: CN108028188B
Application number: CN201680055017.4A
Authority: CN
Inventors: 北田刚; 稻叶智雄; 池上由洋
Original assignee: Toray Industries Inc
Current assignee: Toray Industries Inc
Priority date: 2015-09-29
Filing date: 2016-09-26
Publication date: 2022-03-22
Anticipated expiration: 2036-09-26
Also published as: JP6772836B2; TWI699006B; KR20180063056A; WO2017057238A1; CN108028188A; JPWO2017057238A1; TW201712882A

Abstract

The purpose of the present invention is to provide a p-type impurity diffusion composition having excellent diffusion into a semiconductor substrate and sufficient barrier properties against n-type impurities. In order to achieve the above object, the present invention has the following configurations. Namely, a p-type impurity diffusion composition comprising (A) a polysiloxane and (B) a p-type impurity diffusion component having an Si-O-B bond.

Description

P-type impurity diffusion composition, method for manufacturing semiconductor element using same, and method for manufacturing solar cell

Technical Field

The present invention relates to a p-type impurity diffusion composition for diffusing an impurity in a semiconductor substrate, a method for manufacturing a semiconductor element using the same, and a method for manufacturing a solar cell.

Background

Conventionally, as a method for forming a p-type or n-type impurity diffusion layer in a semiconductor substrate, the following methods are known: using boron tribromide (BBr)₃) Phosphorus oxychloride (POCl) was used as the p-type impurity diffusion component₃) The n-type impurity diffusion components are independently gas-diffused. However, in recent years, in the manufacture of solar cells, in order to improve production efficiency and the like, it has been required to form p-type and n-type impurity diffusions by simultaneously diffusing a p-type impurity diffusion component and an n-type impurity diffusion component into a semiconductor substrateLayer techniques. Such a technique cannot be applied to the gas diffusion method described above.

In view of this, application of a solid phase diffusion method has been studied in which a pattern of an impurity diffusion source is formed on a semiconductor substrate by a printing method or the like, and an impurity is diffused from the impurity diffusion source into the semiconductor substrate by thermal diffusion. For example, patent document 1 discloses the following method: a1 st impurity diffusion layer is formed on a surface of a semiconductor substrate and fired, then a 2 nd impurity diffusion layer is formed, and the semiconductor substrate is heated at a temperature higher than a firing temperature to simultaneously diffuse a 1 st impurity component and a 2 nd impurity component into the semiconductor substrate.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2014-42001

Disclosure of Invention

Problems to be solved by the invention

However, in the case of a conventional impurity diffusion composition in which a pattern of p-type and n-type impurity diffusion sources is formed on a semiconductor substrate and then simultaneously thermally diffused, an n-type impurity (for example, phosphorus element) may be mixed into a p-type impurity diffusion region. Further, this may cause a reduction in power generation efficiency, and therefore, it is required to prevent such mixing.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a p-type impurity diffusion composition having excellent diffusibility into a semiconductor substrate and sufficient barrier properties against n-type impurities.

Means for solving the problems

In order to solve the above problem, the p-type impurity diffusion composition of the present invention has the following configuration. Namely, a p-type impurity diffusion composition comprising (A) a polysiloxane and (B) a p-type impurity diffusion component having an Si-O-B bond.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a p-type impurity diffusion composition excellent in the diffusivity of a p-type impurity into a semiconductor substrate and the barrier property against an n-type impurity can be provided.

Drawings

FIG. 1 is a cross-sectional view showing a first example of a method for forming an impurity diffusion layer using a p-type impurity diffusion composition of the present invention.

FIG. 2 is a sectional view showing a process of a second example of a method for forming an impurity diffusion layer using a p-type impurity diffusion composition of the present invention.

FIG. 3 is a cross-sectional view showing an example of a process for producing a back contact solar cell using the p-type impurity diffusion composition of the present invention.

FIG. 4 is a cross-sectional view showing a third example of a method for forming an impurity diffusion layer using the p-type impurity diffusion composition of the present invention.

FIG. 5 is a cross-sectional view showing a fourth example of a method for forming an impurity diffusion layer using the p-type impurity diffusion composition of the present invention.

FIG. 6 is a cross-sectional view showing a process for forming an impurity diffusion layer in a sample for barrier property measurement.

Detailed Description

The p-type impurity diffusion composition of the present invention contains (A) polysiloxane and (B) a p-type impurity diffusion component having an Si-O-B bond.

The p-type impurity diffusion composition of the present invention is used as a p-type impurity diffusion source for forming a p-type impurity region in a semiconductor substrate. In this case, even if an n-type impurity diffusion source is separately provided on the same semiconductor substrate and a p-type impurity and an n-type impurity are simultaneously diffused (hereinafter, simply referred to as "simultaneous diffusion", this means that the p-type impurity and the n-type impurity are simultaneously diffused into the semiconductor substrate. This is because the p-type impurity diffusion composition of the present invention contains polysiloxane, and the reason is considered as follows.

One of the main causes of the n-type impurity mixed into the p-type impurity region is considered to be: the n-type impurity released into the atmosphere from the n-type impurity diffusion source is mixed into the p-type impurity diffusion source, and diffused to the p-type impurity region directly below the p-type impurity diffusion source by solid-phase diffusion. Since the polysiloxane contained in the p-type impurity diffusion composition of the present invention has high barrier properties against n-type impurities, it is considered that the n-type impurities can be prevented from being mixed into the p-type impurity diffusion source.

As described above, the p-type impurity diffusion composition of the present invention can be suitably used also in the case of simultaneous diffusion, but is not limited to this case and can be applied to the case of diffusing a p-type impurity in general.

In addition, the p-type impurity diffusion composition of the present invention can form a uniform film by containing polysiloxane, and can achieve uniform diffusion.

(A) Polysiloxanes

The polysiloxane used in the present invention is not particularly limited, and a polysiloxane obtained by condensation polymerization of an organosilane is preferably used.

The polysiloxane has an end group selected from hydrogen, hydroxyl, alkyl having 1-6 carbon atoms, alkoxy having 1-6 carbon atoms, acyloxy having 1-6 carbon atoms, and alkenyl having 2-10 carbon atoms.

The number of carbon atoms in the present invention indicates the total number of carbon atoms including a group further substituted on the group. For example, a methoxy-substituted butyl group has 5 carbon atoms.

For the p-type impurity diffusion composition of the present invention, it is particularly preferable that (a) the polysiloxane is represented by the following general formula (1).

[ chemical formula 1]

In the formula, R¹A plurality of R represents an aryl group having 6 to 15 carbon atoms¹Each may be the same or different.

R²A plurality of R's each representing one of a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms and an aryl group having 6 to 15 carbon atoms²Each may be the same or different.

R³And R⁴A plurality of R's each representing one of a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms and an alkenyl group having 2 to 10 carbon atoms³And R⁴Each may be the same or different.

Wherein R is²～R⁴The hydroxyl group, alkoxy group having 1 to 6 carbon atoms, acyloxy group having 1 to 6 carbon atoms and other R in the above formula²～R⁴Wherein any one of a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms and an acyloxy group having 1 to 6 carbon atoms is condensed to form a crosslinked structure.

X represents any one of a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and an aryl group having 6 to 15 carbon atoms, and Y represents any one of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and an acyl group having 1 to 6 carbon atoms.

n: m is 95: 5-25: 75. n and m represent the composition ratio (%) of the parenthesized components in the general formula (1), and n + m is 100.

The polysiloxane represented by the general formula (1) may be a block copolymer or a random copolymer.

When n is 25 or more, that is, when a unit containing an aryl group having 6 to 15 carbon atoms is contained in the polysiloxane in an amount of 25 mol% or more in terms of Si atom, the crosslink density of the polysiloxane skeleton does not become too high, and even when the thickness is thick, cracking can be further suppressed. Therefore, cracks are not easily generated in the firing and thermal diffusion steps, and therefore, not only can barrier properties against other impurities be improved, but also the stability of impurity diffusion can be improved in the simultaneous diffusion.

On the other hand, when n is 95% or less, that is, when the unit containing an aryl group having 6 to 15 carbon atoms in the polysiloxane is 95 mol% or less in terms of Si atom, the peeling residue after diffusion can be eliminated. The residue is considered to be carbide remaining without completely decomposing and volatilizing the organic matter, and this not only hinders diffusion but also causes an increase in contact resistance with an electrode formed later, thereby reducing efficiency of the solar cell. If the number of units containing an aryl group having 6 to 15 carbon atoms is more than 95 mol%, the composition film is likely to be too dense and to generate a residue before the organic component is completely decomposed and volatilized.

When the structural unit of the polysiloxane represented by the general formula (1) has a structure obtained by condensation polymerization of a 4-functional or 3-functional organosilane, R is²～R⁴The hydroxyl group, alkoxy group having 1 to 6 carbon atoms, acyloxy group having 1 to 6 carbon atoms in the group may be bonded to another R²～R⁴Wherein any one of the hydroxyl group, the alkoxy group having 1 to 6 carbon atoms and the acyloxy group having 1 to 6 carbon atoms forms a crosslinked structure.

In the p-type impurity diffusion composition of the present invention, R is preferably used for forming a film having a higher barrier property²And R⁴R represents any one of a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms or an acyloxy group having 1 to 6 carbon atoms³Represents an alkyl group having 1 to 4 carbon atoms or an alkenyl group having 2 to 4 carbon atoms. That is, the structural units of the polysiloxane are preferably each formed of a structure obtained by condensation polymerization of a 3-functional organosilane.

From the viewpoint of further improving barrier properties against other impurities and diffusion stability of p-type impurities during simultaneous diffusion, the unit containing an aryl group having 6 to 15 carbon atoms in the polysiloxane contained in the p-type impurity diffusion composition is more preferably 35 mol% or more, and still more preferably 40 mol% or more. In addition, in order not to generate residues (without being influenced by atmosphere and film thickness), the unit containing an aryl group having 6 to 15 carbon atoms is preferably 80 mol% or less. That is, n: m is particularly preferably 80: 20 to 40: 60 for the p-type impurity diffusion composition of the present invention.

R of the general formula (1)¹And R²The aryl group having 6 to 15 carbon atoms in (A) may be either unsubstituted or substituted, and may be selected according to the characteristics of the composition. Specific examples of the aryl group having 6 to 15 carbon atoms include phenyl group, p-tolyl group, m-tolyl group, o-tolyl group, p-hydroxyphenyl group, p-styryl group, p-methoxyphenyl group, naphthyl group,particularly preferred are phenyl, p-tolyl and m-tolyl.

R of the general formula (1)²～R⁴The C1-6 alkyl, C1-6 alkoxy, C1-6 acyloxy and C2-10 alkenyl in the composition can be any of unsubstituted or substituted ones, and can be selected according to the characteristics of the composition.

Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a tert-butyl group, a n-hexyl group, a trifluoromethyl group, a 3, 3, 3-trifluoropropyl group, a 3-methoxy-n-propyl group, a glycidyl group, a 3-glycidoxypropyl group, a 3-aminopropyl group, a 3-mercaptopropyl group, and a 3-isocyanatopropyl group, and in terms of the residue, a methyl group having 4 or less carbon atoms, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, and a tert-butyl group are preferable.

Specific examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, and a tert-butoxy group.

Specific examples of the acyloxy group having 1 to 6 carbon atoms include an acetoxy group, a propionyloxy group, an acryloyloxy group, and a benzoyloxy group.

Specific examples of the alkenyl group having 2 to 10 carbon atoms include a vinyl group, a 1-propenyl group, a 1-butenyl group, a 2-methyl-1-propenyl group, a 1, 3-butadienyl group, a 3-methoxy-1-propenyl group, a 3-acryloxypropyl group, and a 3-methacryloxypropyl group, and particularly, from the viewpoint of the residue, a vinyl group having 4 or less carbon atoms, a 1-propenyl group, a 1-butenyl group, a 2-methyl-1-propenyl group, a 1, 3-butadienyl group, and a 3-methoxy-1-propenyl group are preferable.

As having R as used in the general formula (1)¹And R²Preferred specific examples of the organosilane as the raw material of the unit(s) include phenyltrimethoxysilane, phenyltriethoxysilane, p-hydroxyphenyltrimethoxysilane, p-tolyltrimethoxysilane, p-styryltrimethoxysilane, p-methoxyphenyltrimethoxysilane, 1-naphthyltrimethoxysilane, 2-naphthyltrimethoxysilane, 1-naphthyltriethoxysilane, 2-naphthyltriethoxysilaneA triethoxy silane. Among them, phenyltrimethoxysilane, p-tolyltrimethoxysilane and p-methoxyphenyl trimethoxysilane are particularly preferable.

As having R as used in the general formula (1)³And R⁴Specific examples of the organic silane as a raw material of the unit (b) include 4-functional organic silanes such as tetramethoxysilane, tetraethoxysilane, tetraacetoxysilane, etc.; 3-functional organosilanes such as methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltri-n-butoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, ethyltri-n-butoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, glycidyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, trifluoromethyltrimethoxysilane, trifluoromethyltriethoxysilane, 3, 3, 3-trifluoropropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-mercaptopropyltrimethoxysilane; 2-functional organosilanes such as dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldiacetoxysilane, di (n-butyl) dimethoxysilane, and the like. These organosilanes may be used alone, or two or more kinds thereof may be used in combination. Among these organosilanes, 3-functional organosilanes are preferably used in view of the compactness of the film, the crack resistance, the residue and the curing rate.

The polysiloxane represented by the general formula (1) can be obtained by: after hydrolyzing the organosilane, the hydrolyzate is subjected to polycondensation in the presence of a solvent or in the absence of a solvent. The conditions (e.g., acid concentration, reaction temperature, reaction time, etc.) of the hydrolysis reaction may be appropriately set in consideration of the scale of the reaction, the size and shape of the reaction vessel, etc., and for example, it is preferable to add the acid catalyst and water to the organosilane in a solvent for 1 to 180 minutes and then react at room temperature to 110 ℃ for 1 to 180 minutes. By performing the hydrolysis reaction under such conditions, a vigorous reaction can be suppressed.

The hydrolysis reaction is preferably carried out in the presence of an acid catalyst. Examples of the acid catalyst include hydrogen halide-based inorganic acids such as hydrochloric acid, hydrobromic acid and hydroiodic acid; other inorganic acids such as sulfuric acid, nitric acid, phosphoric acid, hexafluorophosphoric acid, hexafluoroantimonic acid, boric acid, tetrafluoroboric acid, chromic acid, etc.; sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid; and carboxylic acids such as acetic acid, citric acid, formic acid, gluconic acid, lactic acid, oxalic acid, tartaric acid, pyruvic acid, citric acid, succinic acid, fumaric acid, and malic acid. In the present invention, the acid catalyst that can be used for preparing the polysiloxane (a) is preferably free of atoms other than silicon, hydrogen, carbon, oxygen, and nitrogen as much as possible, and formic acid, acetic acid, and carboxylic acid-based acid catalysts are preferably used from the viewpoint of doping properties. Among them, formic acid is preferable.

The preferable content of the acid catalyst is 0.1 to 5 parts by weight based on 100 parts by weight of the total organosilane used in the hydrolysis reaction. By setting the amount of the acid catalyst in the above range, it is possible to easily control so that the hydrolysis reaction proceeds necessarily and sufficiently.

It is preferable that after silanol is obtained by hydrolysis of organosilane, the reaction solution is heated at a temperature of 50 ℃ or higher and the boiling point of the solvent or lower for 1 to 100 hours as it is to perform polycondensation reaction. Further, reheating may be performed in order to increase the polymerization degree of the polysiloxane.

The solvent used for the hydrolysis reaction of the organosilane and the condensation reaction of the hydrolysate is not particularly limited, and may be appropriately selected in consideration of the stability, coatability, volatility, and the like of the resin composition. In addition, two or more solvents may be combined, or the reaction may be carried out without a solvent. Specific examples of the solvent include alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tert-butanol, 1-methoxy-2-propanol, pentanol, 4-methyl-2-pentanol, 3-methyl-2-butanol, 3-methyl-3-methoxy-1-butanol, 1-tert-butoxy-2-propanol, diacetone alcohol, terpineol, and TEXANOL; glycols such as ethylene glycol and propylene glycol; ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol tert-butyl ether, propylene glycol n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethyl ether, diethylene glycol methyl ethyl ether, dipropylene glycol n-butyl ether, dipropylene glycol monomethyl ether, diisopropyl ether, di-n-butyl ether, diphenyl ether, diethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, and ethylene glycol monobutyl ether; ketones such as methyl ethyl ketone, acetylacetone, methyl propyl ketone, methyl butyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, 2-heptanone, diisobutyl ketone, cyclohexanone, and cycloheptanone; amides such as dimethylformamide and dimethylacetamide; acetic acid esters such as isopropyl acetate, ethyl acetate, propyl acetate, butyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, butyl diglycol acetate, 1, 3-butanediol diacetate, ethyl diglycol acetate, dipropylene glycol methyl ether acetate, methyl lactate, ethyl lactate, butyl lactate, and triacetin; aromatic or aliphatic hydrocarbons such as toluene, xylene, hexane, cyclohexane, ethyl benzoate, naphthalene, 1, 2, 3, 4-tetrahydronaphthalene, and the like, γ -butyrolactone, N-methyl-2-pyrrolidone, N-dimethylimidazolidinone, dimethyl sulfoxide, propylene carbonate, and the like.

When a solvent is generated by the hydrolysis reaction, the hydrolysis may be carried out in the absence of a solvent. It is also preferable to adjust the concentration to an appropriate level in the form of the resin composition by further adding a solvent after the reaction is completed. In addition, depending on the purpose, the alcohol or the like produced after hydrolysis may be distilled off under heating and/or reduced pressure to remove an appropriate amount, and then an appropriate solvent may be added.

The amount of the solvent used in the hydrolysis reaction is preferably 80 parts by weight or more and 500 parts by weight or less with respect to 100 parts by weight of the total organosilane. By making the amount of the solvent in the above range, it is possible to easily control so that the hydrolysis reaction proceeds necessarily and sufficiently. The water used in the hydrolysis reaction is preferably ion-exchanged water. The amount of water is arbitrarily selected, and is preferably in the range of 1.0 to 4.0 mol per 1mol of Si atoms.

The polysiloxane represented by the general formula (1) is preferably prepared by reacting R¹R²Si(OR⁸)₂Organosilanes of formula (I) and R³R⁴Si(OR⁹)₂The organosilane shown below is hydrolyzed and polycondensed to obtain a reaction product. Wherein R is⁸And R⁹Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an acyl group having 1 to 6 carbon atoms.

Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a tert-butyl group, and a n-hexyl group. Specific examples of the acyl group having 1 to 6 carbon atoms include acetyl group, propionyl group, benzoyl group and the like.

The molar ratio of each unit of the polysiloxane represented by the general formula (1) can be adjusted by the kind and amount of the organosilane to be added at the time of hydrolysis and condensation reaction.

The content of the polysiloxane represented by the general formula (1) in the diffusion composition of the present invention is preferably 60% by weight or more, more preferably 80% by weight or more, and particularly preferably 90% by weight or more, of the total polysiloxane component, from the viewpoint of improving barrier properties against other impurities and diffusion stability of p-type impurities at the time of simultaneous diffusion.

The weight average molecular weight (Mw) of the polysiloxane used in the present invention is preferably 1000 or more, more preferably 2000 or more, in terms of a molecular weight in terms of polystyrene as measured by Gel Permeation Chromatography (GPC). This can suppress shrinkage of the film during firing, and a denser film can be obtained. In addition, the upper limit of Mw is preferably less than 50000, more preferably less than 20000, from the viewpoint of peelability. In the present invention, the weight average molecular weight of the polysiloxane is a value determined by a method described later.

The 20% thermal decomposition temperature of the polysiloxane is preferably 550 ℃ or higher. Thus, when the composition contains an organic component such as a thickener, the silicone flows after the organic component other than the polysiloxane is completely removed by thermal decomposition, and therefore a more dense film with less residue can be obtained. Here, the 20% thermal decomposition temperature is a temperature at which the weight of polysiloxane is reduced by 20% by thermal decomposition. The thermal decomposition temperature can be measured using a thermogravimetric apparatus (TGA) or the like.

(B) P-type impurity diffusion component having Si-O-B bond

The p-type impurity diffusion component having an Si — O — B bond in the present invention is a component for uniformly mixing with polysiloxane and diffusing boron into a semiconductor substrate at the time of thermal diffusion. Having an Si — O — B bond can fix the boron atom to the impurity diffusion source up to the diffusion temperature, and thus stable diffusion can be achieved.

Whether or not a component containing an Si-O-B bond is contained can be analyzed using X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), nuclear magnetic resonance (B-NMR, Si-NMR), or the like.

The p-type impurity diffusion component having an Si — O — B bond is not particularly limited, and a reaction product of organosilane and boron compound is preferably used.

In the p-type impurity diffusion composition of the present invention, it is particularly preferable that the (B) p-type impurity diffusion component having an Si — O — B bond contains a partial structure represented by the following general formula (2).

[ chemical formula 2]

In the formula, R⁵And R⁶A plurality of R's each representing one of a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms and an aryl group having 6 to 15 carbon atoms⁵And R⁶Each may be the same or different.

R of the general formula (2)⁵And R⁶The alkoxy group having 1 to 6 carbon atoms and the acyloxy group having 1 to 6 carbon atoms in the compound may be any of unsubstituted or substituted ones, and may be selected according to the characteristics of the composition.

The aryl group having 6 to 15 carbon atoms may be either unsubstituted or substituted, and may be selected according to the characteristics of the composition. Specific examples of the aryl group having 6 to 15 carbon atoms include a phenyl group, a p-tolyl group, an m-tolyl group, an o-tolyl group, a p-hydroxyphenyl group, a p-styryl group, a p-methoxyphenyl group, and a naphthyl group, and particularly a phenyl group, a p-tolyl group, and an m-tolyl group are preferable.

The compound containing a partial structure represented by the general formula (2) is preferably a compound obtained by polycondensation of an organosilane with a boron compound in the presence or absence of a solvent.

Having R as a compound containing a partial structure represented by the general formula (2)⁵And R⁶Specific examples of the organic silane as the raw material of the unit (b) include 4-functional organic silanes such as tetramethoxysilane and tetraethoxysilaneTetrapropoxysilane, tetrabutoxysilane, and the like.

Examples of the 3-functional organosilane include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltri-n-butoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, ethyltri-n-butoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, glycidyl trimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, trifluoromethyltrimethoxysilane, trifluoromethyltriethoxysilane, 3, 3, 3-trifluoropropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, phenyltrimethoxysilane, the like, Phenyltriethoxysilane, p-hydroxyphenyltrimethoxysilane, p-tolyltrimethoxysilane, p-styryltrimethoxysilane, p-methoxyphenyl trimethoxysilane, 1-naphthyltrimethoxysilane, 2-naphthyltrimethoxysilane, 1-naphthyltriethoxysilane, 2-naphthyltriethoxysilane.

Examples of the 2-functional organosilane include dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, dipropyldiethoxysilane, dibutyldimethoxysilane, dibutyldiethoxysilane, dibutyldipropoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldipropoxysilane, and phenylmethyldimethoxysilane.

Among them, methyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, diphenyldimethoxysilane can be preferably used. These organosilanes may be used alone, or two or more kinds thereof may be used in combination.

In the p-type impurity diffusion composition of the present invention, in order to form a film having a higher barrier property against n-type impurities, it is preferableIs that R⁵R represents any one of an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 15 carbon atoms⁶Represents any one of a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or an acyloxy group having 1 to 6 carbon atoms. That is, the organosilane is preferably a 3-functional organosilane.

In the p-type impurity diffusion composition of the present invention, R is preferably R in order to further improve the storage stability of the diffusing agent composition, the barrier property against other impurities in the simultaneous diffusion, and the diffusion stability of the p-type impurity⁵Wherein the molar ratio of the alkyl group with 1-6 carbon atoms to the aryl group with 6-15 carbon atoms is 95: 5-5: 95. The molar ratio is more preferably 80: 20 to 20: 80 between an alkyl group having 1 to 6 carbon atoms and an aryl group having 6 to 15 carbon atoms.

R⁵When the molar ratio of aryl groups having 6 to 15 carbon atoms in (B) is 5% or more (more preferably 20% or more), the reflow (reflow) effect of the polysiloxane can be improved when the p-type impurity diffusion composition of the present invention is fired. Thus, it is considered that the film obtained from the p-type impurity diffusion composition of the present invention is more dense, the crack resistance is improved, and the barrier property against n-type impurities is further improved. The reflow effect of the polysiloxane herein means the following effect: when organic substances such as binders decompose during firing and voids are formed in the film, the polysiloxane flows to fill the voids, thereby forming a dense film.

In addition, R⁵When the molar ratio of aryl groups having 6 to 15 carbon atoms in (b) is 95% or less (more preferably 80% or less), the peeling residue after diffusion can be eliminated. The residue is considered to be carbide remaining without completely decomposing and volatilizing the organic matter, and this not only hinders diffusion but also causes an increase in contact resistance with an electrode formed later, thereby reducing efficiency of the solar cell. It is considered that when the ratio of the aryl group having 6 to 15 carbon atoms is more than 95% (more preferably more than 80%), the composition film becomes too dense and residues are likely to be generated before the organic component is completely decomposed/volatilized.

R in the general formula (2)⁵In (1)The molar ratio of the alkyl group having 1 to 6 carbon atoms to the aryl group having 6 to 15 carbon atoms can be adjusted depending on the kind and amount of the organic silane to be added during the polycondensation reaction.

Examples of the boron compound used as a raw material for the p-type impurity diffusion component having an Si — O — B bond and including the partial structure represented by the general formula (2) include compounds that generate boric acid by hydrolysis and the like, such as boric acid, diboron trioxide, trimethyl borate, triethyl borate, tripropyl borate, and tributyl borate. Among them, boric acid can be preferably used.

Preferably, 1 mole or more of organosilane is used per 1 mole of boron compound. This can provide sufficient solubility in a solution containing a polysiloxane, and can fix boron atoms in the impurity diffusion composition film up to the diffusion temperature, thereby enabling stable diffusion.

The p-type impurity diffusion component having an Si — O — B bond, which contains a partial structure represented by general formula (2), is preferably a substance represented by general formula (3) below.

[ chemical formula 3]

R in the general formula (3)⁵、R⁶Is as defined above. l represents an integer of 2 or more, preferably 2 to 10. This enables the boron atoms to be further fixed in the impurity diffusion composition film up to the diffusion temperature, and thus enables stable diffusion.

When the p-type impurity diffusion component having an Si-O-B bond represented by the general formula (3) has a terminal group, the terminal group is not particularly limited, but is preferably a group selected from the group consisting of a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms, and an alkenyl group having 2 to 10 carbon atoms.

In the p-type impurity diffusion component having an Si-O-B bond represented by the general formula (3), the constitutional units in parentheses in the general formula (3) may be bonded by a head-to-tail bond or a head-to-head bond, respectively.

The p-type impurity diffusion component having an Si — O — B bond may have a partial structure represented by the following general formula (4).

[ chemical formula 4]

R in the general formula (4)⁵、R⁶Is as defined above. R⁷Represents any one of a hydrogen atom and an alkyl group having 1 to 6 carbon atoms. Plural R⁷Each may be the same or different. k represents an integer of 1 or more, preferably 2 to 10. This enables the boron atoms to be further fixed in the impurity diffusion composition film up to the diffusion temperature, and thus enables stable diffusion.

In the partial structure represented by the general formula (4), the structural units in parentheses in the general formula (4) may be bonded by a head-to-tail bond or a head-to-head bond.

Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a tert-butyl group, a n-hexyl group, a trifluoromethyl group, a 3, 3, 3-trifluoropropyl group, a 3-methoxy-n-propyl group, a glycidyl group, a 3-glycidoxypropyl group, a 3-aminopropyl group, a 3-mercaptopropyl group, and a 3-isocyanatopropyl group.

The conditions (e.g., reaction temperature, reaction time, etc.) of the polycondensation reaction of the organosilane and the boron compound may be appropriately set in consideration of the scale of the reaction, the size and shape of the reaction vessel, etc., and it is preferable that, for example, the organosilane and the boron compound are mixed and then reacted at room temperature to 110 ℃ for 1 to 180 minutes. From the viewpoint of diffusion uniformity, the compound containing the partial structure represented by the general formula (2) is preferably taken out in a liquid state, and it is also preferable to adjust the concentration to an appropriate level as a composition by further adding a solvent after the reaction is completed.

The solvent used in the polycondensation reaction of the organosilane and the boron compound is not particularly limited, and may be appropriately selected in consideration of the stability, coatability, volatility, and the like of the resin composition. In addition, 2 or more solvents may be combined, or the reaction may be carried out without a solvent.

Specific examples of the solvent include:

alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tert-butanol, 1-methoxy-2-propanol, pentanol, 4-methyl-2-pentanol, 3-methyl-2-butanol, 3-methyl-3-methoxy-1-butanol, 1-tert-butoxy-2-propanol, diacetone alcohol, terpineol, and TEXANOL; glycols such as ethylene glycol and propylene glycol;

ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol tert-butyl ether, propylene glycol n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethyl ether, diethylene glycol methyl ethyl ether, dipropylene glycol n-butyl ether, dipropylene glycol monomethyl ether, diisopropyl ether, di-n-butyl ether, diphenyl ether, diethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, and ethylene glycol monobutyl ether;

ketones such as methyl ethyl ketone, acetylacetone, methyl propyl ketone, methyl butyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, 2-heptanone, diisobutyl ketone, cyclohexanone, and cycloheptanone;

amides such as dimethylformamide and dimethylacetamide;

acetic acid esters such as isopropyl acetate, ethyl acetate, propyl acetate, butyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, butyl diglycol acetate, 1, 3-butanediol diacetate, ethyl diglycol acetate, dipropylene glycol methyl ether acetate, methyl lactate, ethyl lactate, butyl lactate, and triacetin;

aromatic or aliphatic hydrocarbons such as toluene, xylene, hexane, cyclohexane, ethyl benzoate, naphthalene, and 1, 2, 3, 4-tetrahydronaphthalene;

gamma-butyrolactone, N-methyl-2-pyrrolidone, N-dimethylimidazolidinone, dimethyl sulfoxide, propylene carbonate; and so on.

SiO of Si component contained in p-type impurity diffusion composition₂The mass ratio of the converted mass to the mass of the impurity atom contained in the p-type impurity diffusion composition is preferably SiO₂The ratio of impurity atoms is 99: 1-30: 70. By setting the mass ratio to the above range, excellent doping performance can be obtained. The mass ratio is more preferably in the range of 95: 5 to 40: 60, and most preferably in the range of 90: 10 to 50: 50. Here, SiO is the Si component₂The content of Si component in the composition is converted into SiO in terms of mass₂The mass of (c). The mass ratio can be calculated by inorganic analysis such as ICP emission analysis and fluorescent X-ray analysis.

(solvent)

The p-type impurity diffusion composition of the present invention preferably contains a solvent. The solvent may be used without particular limitation, and a solvent having a boiling point of 100 ℃ or higher is preferable from the viewpoint of further improving printability in the case of using a screen printing method, a spin coating printing method, or the like. When the boiling point is 100 ℃ or higher, for example, when the p-type impurity diffusion composition is printed on a printing plate used in a screen printing method, drying and sticking of the p-type impurity diffusion composition on the printing plate can be suppressed.

The content of the solvent having a boiling point of 100 ℃ or higher is preferably 20% by weight or higher with respect to the total amount of the solvent. Examples of the solvent having a boiling point of 100 ℃ or higher include diethylene glycol methyl ethyl ether (boiling point 176 ℃) ethylene glycol monoethyl ether acetate (boiling point 156.4 ℃), ethylene glycol monomethyl ether acetate (boiling point 145 ℃), methyl lactate (boiling point 145 ℃), ethyl lactate (boiling point 155 ℃), diacetone alcohol (boiling point 169 ℃), propylene glycol monomethyl ether acetate (boiling point 145 ℃), 3-methoxy-3-methyl-1-butanol (boiling point 174 ℃), dipropylene glycol monomethyl ether (boiling point 188 ℃), dipropylene glycol N-butyl ether (boiling point 229 ℃), γ -butyrolactone (boiling point 204 ℃), diethylene glycol monoethyl ether acetate (boiling point 217 ℃), butyl diethylene glycol acetate (boiling point 246 ℃), ethyl acetoacetate (boiling point 181 ℃), and N-methyl-2-pyrrolidone (boiling point 204 ℃), n, N-dimethyl imidazolidinone (boiling point: 226 ℃ C.), dipropylene glycol methyl ether acetate (boiling point: 213 ℃ C.), 1, 3-butanediol diacetate (boiling point: 232 ℃ C.), diisobutyl ketone (boiling point: 168 ℃ C.), propylene glycol tert-butyl ether (boiling point: 151 ℃ C.), propylene glycol N-butyl ether (boiling point: 170 ℃ C.), acetylacetone (boiling point: 140 ℃ C.), diethylene glycol monobutyl ether (boiling point: 171 ℃ C.), and diethylene glycol monobutyl ether acetate (boiling point: 245 ℃ C.).

Specific examples of the solvent having a boiling point of less than 100 ℃ include alcohols such as methanol, ethanol, propanol, isopropanol, and tert-butanol; ethers such as diethyl ether and diisopropyl ether; ketones such as methyl ethyl ketone; acetates such as isopropyl acetate, ethyl acetate, propyl acetate, n-propyl acetate, and 3-methyl-3-methoxybutyl acetate; and aliphatic hydrocarbons such as hexane and cyclohexane.

(surfactant)

The p-type impurity diffusion composition of the present invention may contain a surfactant. By containing the surfactant, coating unevenness is improved, and a uniform coating film can be obtained. As the surfactant, a fluorine-based surfactant or a silicone-based surfactant is preferably used.

Specific examples of the fluorine-based surfactant include a fluorine-based surfactant containing 1, 1, 2, 2-tetrafluorooctyl (1, 1, 2, 2-tetrafluoropropyl) ether, 1, 2, 2-tetrafluorooctylhexyl ether, octaethyleneglycol bis (1, 1, 2, 2-tetrafluorobutyl) ether, hexaethyleneglycol (1, 1, 2, 2, 3, 3-hexafluoropentyl) ether, octapropyleneglycol bis (1, 1, 2, 2-tetrafluorobutyl) ether, hexapropyleneglycol bis (1, 1, 2, 2, 3, 3-hexafluoropentyl) ether, sodium perfluorododecylsulfonate, 1, 2, 2, 8, 8, 9, 9, 10, 10-decafluorododecane, 1, 2, 2, 3, 3-hexafluorodecane, N- [3- (perfluorooctanesulfonamide) propyl ] -N, examples of the compound having a fluoroalkyl group or a fluoroalkylene group at least any one of the terminal, main chain and side chain include N' -dimethyl-N-carboxymethyleneammonium betaine, perfluoroalkyl sulfonamide propyltrimethylammonium salt, perfluoroalkyl-N-ethylsulfonyl glycinate, bis (N-perfluorooctylsulfonyl-N-ethylaminoethyl) phosphate, and monoperfluoroalkylethyl phosphate. Commercially available products include fluorine-based surfactants such as MEGAFACE F142D, MEGAFACE F172, MEGAFACE F173, MEGAFACE F183, MEGAFACE F444, MEGAFACE F475, MEGAFACE F477 (manufactured by Dainippon ink chemical industry Co., Ltd.), Eftop EF301, Eftop 303, Eftop 352 (manufactured by New autumn chemical Co., Ltd.), Fluorad FC-430, Fluorad FC-431 (manufactured by Sumitomo 3M Co., Ltd.), Asahi Guard AG710, Surflon S-382, Surflon SC-101, Surflon SC-102, Surflon SC-103, Surflon SC-104, Surflon SC-105, Surflon SC-106 (manufactured by Asahi Nitron Co., Ltd.), BM-1000, BM-1100 (manufactured by Yusho Co., Ltd.), NBX-15, FTX-218, and DFX-218 (manufactured by Neos).

Commercially available silicone surfactants include SH28PA, SH7PA, SH21PA, SH30PA, and ST94PA (manufactured by Toray Dow Corning Co., Ltd.), BYK067A, BYK310, BYK322, BYK331, BYK333, and BYK355 (manufactured by BYK-Chemie Japan Co., Ltd.).

When the surfactant is contained, the content of the surfactant in the p-type impurity diffusion composition is preferably 0.0001 to 1% by weight.

(thickening agent)

The p-type impurity diffusion composition of the present invention preferably contains a thickener for adjusting viscosity. This enables coating with a more precise pattern by a printing method such as screen printing. Examples of the organic thickener include cellulose, cellulose derivatives, starch derivatives, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyurethane resin, polyurea resin, polyimide resin, polyamide resin, epoxy resin, polystyrene resin, polyester resin, synthetic rubber, natural rubber, polyacrylic acid, various acrylic resins, polyethylene glycol, polyethylene oxide, polypropylene glycol, polypropylene oxide, silicone oil, sodium alginate, xanthan gum polysaccharide, gellan gum polysaccharide, guar gum polysaccharide, carrageenan polysaccharide, locust bean gum polysaccharide, carboxyvinyl polymer, hydrogenated castor oil and fatty acid amide wax, special fatty acid, oxidized polyethylene, a mixture of oxidized polyethylene and amide, and the like, Fatty acid-based polycarboxylic acids, phosphate ester-based surfactants, salts of long-chain polyaminoamides with phosphoric acid, special modified polyamide-based surfactants, and the like.

Among the inorganic systems, bentonite, montmorillonite, magnesium montmorillonite, ferrimontmorillonite, ferrimontmorillonites, beidellite, aluminum beidellite (aluminum beidellite), saponite, aluminum saponite, laponite, aluminum silicate, aluminum magnesium silicate, organohectorite, finely particulate silica, colloidal alumina, calcium carbonate, and the like may be mentioned. They may be used in combination of a plurality.

Further, commercially available products include 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, 2200, 2260, 2280, and 2450 (the same applies to Daicel Finechem, Inc.) as cellulose-based thickeners.

Polysaccharide thickeners include Viscarin PC209, Viscarin PC389, SeaKem XP8012 (manufactured by FMC Chemicals, Inc., supra), CAM-H, GJ-182, SV-300, LS-20, LS-30, XGT, XGK-D, G-100, and LG-10 (all trade names of Mitsubishi corporation).

The acrylic thickener includes #2434T, KC-7000, KC-1700P (manufactured by Kyoeisha Co., Ltd.), AC-10LHPK, AC-10SHP, 845H, PW-120 (manufactured by Toyao corporation Co., Ltd.), and the like.

Examples of the hydrogenated castor oil thickener include Disparlon 308, NAMLONT-206 (manufactured by Nanguo Kabushiki Kaisha Co., Ltd.), T-20SF, and T-75F (manufactured by Ito Kabushiki Kaisha Co., Ltd.).

The polyethylene oxide-based thickener includes D-10A, D-120, D-120-10, D-1100, DS-525, DS-313 (manufactured by Ivy oil Co., Ltd., supra), Disparlon 4200-20, Disparlon PF-911, Disparlon PF-930, Disparlon 4401-25X, Disparlon NS-30, Disparlon NS-5010, Disparlon NS-5025, Disparlon NS-5810, Disparlon NS-5210, Disparlon NS-5310 (manufactured by Nanguo Kabushiki Kaisha, Flowon SA-300H (manufactured by Kyoeisha Co., Ltd., supra)), PEO-1, PEO-3 (manufactured by Sumitomo Kabushiki Kaisha, supra), and the like.

Examples of the amide-based thickener include T-250F, T-550F, T-850F, T-1700, T-1800, T-2000 (manufactured by Ivy oil Co., Ltd., above), Disparlon 6500, Disparlon 6300, Disparlon 6650, Disparlon 6700, Disparlon 3900EF (manufactured by Machina chemical Co., Ltd.), Talen 7200, Talen 7500, Talen 8200, Talen 8300, Talen 8700, Talen 8900, Talen KY-2000, KU-700, Talen M-1020, Talen VA-780, Talen VA-750B, Talen 2450 0, Flowon SD-700, Flowon SDR-80, and Flowon EC-121 (manufactured by Kyowa chemical Co., Ltd., above).

Examples of the bentonite-based thickener include Ben-gel (Japanese: べンゲル), Ben-gel HV, Ben-gel HVP, Ben-gel F, Ben-gel FW, Ben-gel Bright 11, Ben-gel A, Ben-gel W-100U, Ben-gel W-300U, Ben-gel SH, Muben, S-Ben (Japanese: Industrial スべン), S-Ben C, S-Ben E, S-Ben W, S-Ben P, S-Ben WX, Organite, and Organite D (manufactured by Hojun, Ltd.).

The fine-particle silica-based thickener includes AEROSILR 972, AEROSILR 974, AEROSILR NY50, AEROSILR RY200S, AEROSILR RY200, AEROSILR RX50, AEROSILR NAX50, AEROSILR RX200, AEROSILR RX300, AEROSILR NKC 130, AEROSILR 805, AEROSILR 104, AEROSILR R R711, AEROSILR OX50, AEROSILR 50, AEROSILR 90G, AEROSILR 130, AEROSILR 200, AEROSILR 300, AEROSILR 380 (manufactured by Nippon Aerosil corporation), WACKER HDK S13, WACKER HDK V15, WACKER HDK N20, WACKER HDK N20P, WACKER HDK T30, WACKER HDK T40, WACKER HDK H15, WACKER HDK H18, WACKER HDK H20, WACKER HDK H30 (manufactured by Asahi Kasei corporation), and the like.

The 90% thermal decomposition temperature of the thickener is preferably 400 ℃ or lower from the viewpoint of forming a dense film and reducing the residue. Specifically, polyethylene glycol, polyethylene oxide, polypropylene glycol, polypropylene oxide, and various acrylate resins are preferable, and among them, polyethylene oxide, polypropylene oxide, and acrylate resins are more preferable. In particular, an acrylate resin is preferable from the viewpoint of storage stability. Here, the 90% thermal decomposition temperature is a temperature at which the weight of the thickener is reduced by 90% by thermal decomposition. The thermal decomposition temperature can be measured using a thermogravimetric apparatus (TGA) or the like.

Examples of the acrylate-based resin include polyacrylates such as polymethyl methacrylate, polyethyl methacrylate, polypropyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polypropyl acrylate, polybutyl acrylate, polyhydroxyethyl methacrylate, polymethyl methacrylate, and polyglycidyl methacrylate, and copolymers thereof. In the case of a copolymer, the acrylic ester component may be 60 mol% or more in terms of polymerization ratio, and a component capable of vinyl polymerization such as polyacrylic acid and polystyrene may be copolymerized as another copolymerization component.

Further, the 2 kinds of copolymers are also preferable for polyethylene oxide and polypropylene oxide. The weight average molecular weight of the acrylic resin, polyethylene oxide, and polypropylene oxide is preferably 10 ten thousand or more, since the thickening effect is good.

The content of these thickeners in the p-type impurity diffusion composition is preferably 3 wt% or more and 20 wt% or less. By setting the range, a sufficient viscosity adjusting effect can be obtained, and a dense film can be formed.

The viscosity of the p-type impurity diffusion composition of the present invention is not limited, and can be appropriately changed depending on the printing method and the film thickness.

The p-type impurity diffusion composition of the present invention is not particularly limited in solid concentration, and the concentration is preferably in the range of 1 wt% to 90 wt%. If the concentration is less than this range, the coating film thickness becomes too thin, and it becomes difficult to obtain desired doping properties, and if the concentration is more than this range, the storage stability is lowered.

(method for manufacturing semiconductor device)

A method for forming an impurity diffusion layer using the p-type impurity diffusion composition of the present invention and a method for manufacturing a semiconductor device using the same will be described.

A first aspect of a method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device including the steps of: a step of applying the p-type impurity diffusion composition of the present invention to a semiconductor substrate to form a p-type impurity diffusion composition film; and a step of forming a p-type impurity diffusion layer by diffusing a p-type impurity from the p-type impurity diffusion composition film.

In addition, a second aspect of the method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device including the steps of: a step of coating the n-type impurity diffusion composition on a semiconductor substrate to form an n-type impurity diffusion composition film; a step of applying the p-type impurity diffusion composition of the present invention after the above step to form a p-type impurity diffusion composition film; and a step of simultaneously forming an n-type impurity diffusion layer and a p-type impurity diffusion layer by heating the semiconductor substrate.

A third aspect of the method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device including the steps of: a step of applying the p-type impurity diffusion composition of the present invention to one surface of a semiconductor substrate to form a p-type impurity diffusion composition film; coating the other surface of the semiconductor substrate with an n-type impurity diffusion composition to form an n-type impurity diffusion composition film; and a step of simultaneously forming a p-type impurity diffusion layer and an n-type impurity diffusion layer by heating the semiconductor substrate.

Hereinafter, a method of forming an impurity diffusion layer, which is applicable to the above-described method of manufacturing a semiconductor device, will be described with reference to the drawings. The above are merely examples, and the methods applicable to the method for manufacturing a semiconductor device of the present invention are not limited to these.

Fig. 1 shows a method for forming an impurity diffusion layer in which a p-type impurity diffusion composition of the present invention is applied to a semiconductor substrate to diffuse a p-type impurity from a p-type impurity diffusion composition film to the semiconductor substrate.

First, as shown in fig. 1(a), a p-type impurity diffusion composition film 2 is formed on a semiconductor substrate 1.

As the semiconductor substrate 1, for example, an impurity concentration of 10¹⁵～10¹⁶Atom/cm³(atoms/cm³) An n-type single crystal silicon substrate, a polycrystalline silicon substrate, and a crystalline silicon substrate in which other elements such as germanium and carbon are mixed. P-type crystalline silicon, semiconductors other than silicon, may also be used. For the semiconductor substrate 1, it is preferable that the thickness is50 to 300 μm and has an outline of a substantially quadrangular shape with sides of 100 to 250 mm. In order to remove the cut surface damage and the natural oxide film, the surface is preferably etched in advance with a hydrofluoric acid solution, an alkaline solution, or the like.

A protective film may be formed on the light-receiving surface of the semiconductor substrate 1. As the protective film, a known protective film such as silicon oxide or silicon nitride formed by a CVD (chemical vapor deposition) method, a Spin On Glass (SOG) method, or the like can be used.

Examples of the method of applying the p-type impurity diffusion composition include spin coating, screen printing, inkjet printing, slit coating, spray coating, relief printing, and gravure printing.

After the coating film is formed by these methods, the p-type impurity diffusion composition film 2 is preferably dried at 50 to 200 ℃ for 30 seconds to 30 minutes using a hot plate, an oven, or the like. The film thickness of the p-type impurity diffusion composition film 2 after drying is preferably 100nm or more from the viewpoint of the diffusion of the p-type impurity, and is preferably 3 μm or less from the viewpoint of the residue after etching.

Next, as shown in fig. 1(b), a p-type impurity is diffused into the semiconductor substrate 1 to form a p-type impurity diffusion layer 3. The diffusion method of the p-type impurity can utilize a known thermal diffusion method, and for example, an electric heating, an infrared heating, a laser heating, a microwave heating, or the like can be used.

The time and temperature of the thermal diffusion can be set as appropriate so as to obtain desired diffusion characteristics such as impurity diffusion concentration and diffusion depth. For example, the surface impurity concentration can be made 10 by heating and diffusing at 800 ℃ to 1200 ℃ for 1 to 120 minutes¹⁹～10²¹Atom/cm³The p-type diffusion layer of (1).

The diffusion atmosphere is not particularly limited, and may be performed in the atmosphere, and the amount of oxygen in the atmosphere may be appropriately controlled by an inert gas such as nitrogen or argon. From the viewpoint of shortening the diffusion time, it is preferable to set the oxygen concentration in the atmosphere to 3% or less. If necessary, the sintering may be carried out at a temperature in the range of 200 to 850 ℃ before the diffusion.

Next, as shown in fig. 1(c), the p-type impurity diffusion composition film 2 formed on the surface of the semiconductor substrate 1 is removed by a known etching method. The material used for etching is not particularly limited, and for example, a material containing at least 1 of hydrogen fluoride, ammonium, phosphoric acid, sulfuric acid, and nitric acid as an etching component and containing water, an organic solvent, and the like as other components is preferable. Through the above steps, a p-type impurity diffusion layer can be formed in the semiconductor substrate.

Fig. 2 shows a method for forming an impurity diffusion layer, which is characterized by comprising the steps of: a step of applying the n-type impurity diffusion composition to a semiconductor substrate to diffuse n-type impurities from the n-type impurity diffusion composition to the semiconductor substrate; and a step of applying and diffusing a p-type impurity to the semiconductor substrate using the n-type impurity diffusion composition as a mask.

In fig. 3, a method for manufacturing a solar cell using the impurity diffusion layer is described by taking a method for manufacturing a back-bonded solar cell as an example.

First, as shown in fig. 2(a), an n-type impurity diffusion composition film 4 is formed on a semiconductor substrate 1.

Examples of the method for forming the n-type impurity diffusion composition film 4 include screen printing, ink jet printing, slit coating, spray coating, relief printing, and gravure printing. After the coating film is formed by the above method, the n-type impurity diffusion composition film 4 is preferably dried at 50 to 200 ℃ for 30 seconds to 30 minutes using a hot plate, an oven, or the like. The thickness of the n-type impurity diffusion composition film 4 after drying is preferably 200nm or more in view of the masking property with respect to the p-type impurity, and preferably 5 μm or less in view of the crack resistance.

Next, as shown in fig. 2(b), the n-type impurity in the n-type impurity diffusion composition film 4 is diffused into the semiconductor substrate 1, thereby forming an n-type impurity diffusion layer 5. The diffusion method of the n-type impurity can utilize a known thermal diffusion method, and for example, an electric heating, an infrared heating, a laser heating, a microwave heating, or the like can be used.

The time and temperature of the thermal diffusion can be used to obtain the impurity diffusionThe mode of desired diffusion characteristics such as the diffusion density and the diffusion depth is appropriately set. For example, the surface impurity concentration can be made 10 by heating and diffusing at 800 ℃ to 1200 ℃ for 1 to 120 minutes¹⁹～10²¹Atom/cm³The n-type diffusion layer of (1).

The diffusion atmosphere is not particularly limited, and may be performed in the atmosphere, or the amount of oxygen in the atmosphere may be appropriately controlled by an inert gas such as nitrogen or argon. From the viewpoint of shortening the diffusion time, it is preferable to set the oxygen concentration in the atmosphere to 3% or less. If necessary, the sintering may be carried out at a temperature in the range of 200 to 850 ℃ before the diffusion.

After the n-type impurity is diffused into the semiconductor substrate 1, the n-type impurity diffusion composition film 4 can be peeled off by peeling with a known etching solution such as hydrofluoric acid. After the above operation, the p-type impurity diffusion composition may be applied to the semiconductor substrate on which the n-type impurity diffusion layer is formed, and the p-type impurity may be diffused, but as described below, printing of the p-type impurity diffusion composition and diffusion of the p-type impurity may be performed without peeling off the n-type impurity diffusion composition film 4, which is preferable from the viewpoint of reducing the number of steps.

After the diffusion of the n-type impurity, the n-type impurity diffusion composition film 4 is fired as necessary, and then, as shown in fig. 2(c), the p-type impurity diffusion composition of the present invention is applied using the n-type impurity diffusion composition film 4 as a mask. In this case, as shown in fig. 2(c), the p-type impurity diffusion composition 2 may be formed over the entire surface, or the p-type impurity diffusion composition 2 may be formed only in a portion where the n-type impurity diffusion composition film 4 is not present. Further, the coating may be performed so that a part of the p-type impurity diffusion composition 2 overlaps the n-type impurity diffusion composition film 4.

After the coating film is formed by the above method, the p-type impurity diffusion composition film 2 is preferably dried at 50 to 200 ℃ for 30 seconds to 30 minutes using a hot plate, an oven, or the like. The film thickness of the p-type impurity diffusion composition 2 after drying is preferably 100nm or more from the viewpoint of the diffusivity of the p-type impurity, and preferably 3 μm or less from the viewpoint of the residue after etching.

Next, as shown in fig. 2(d), the p-type impurity diffusion layer 3 is formed by diffusing the p-type impurity diffusion composition 2 into the semiconductor substrate 1 using the fired n-type impurity diffusion composition film 4 as a mask layer. The diffusion method of the p-type impurity can utilize a known thermal diffusion method, and for example, electrical heating, infrared heating, laser heating, microwave heating, or the like can be utilized.

The time and temperature of the thermal diffusion can be set as appropriate so as to obtain desired diffusion characteristics such as impurity diffusion concentration and diffusion depth. For example, the surface impurity concentration can be 10 by heating and diffusing at 800 ℃ to 1200 ℃ for 1 to 120 minutes¹⁹～10²¹Atom/cm³The p-type diffusion layer of (1).

Next, as shown in fig. 2(e), the n-type impurity diffusion composition film 4 and the p-type impurity diffusion composition film 2 formed on the surface of the semiconductor substrate 1 are removed by a known etching method. The material used for etching is not particularly limited, and for example, a material containing at least 1 of hydrogen fluoride, ammonium, phosphoric acid, sulfuric acid, and nitric acid as an etching component and containing water, an organic solvent, and the like as other components is preferable. Through the above steps, n-type and p-type impurity diffusion layers can be formed in the semiconductor substrate. By setting such a step, the steps can be simplified as compared with conventional methods.

Here, an example in which the application/diffusion of the p-type impurity diffusion composition is performed after the application/diffusion of the n-type impurity diffusion composition is shown, but the application/diffusion of the n-type impurity diffusion composition may be performed after the application/diffusion of the p-type impurity diffusion composition. That is, instead of the application/diffusion of the n-type impurity diffusion composition, the application/diffusion of the p-type impurity diffusion composition may be performed in fig. 2(a) to (b), and instead of the application/diffusion of the p-type impurity diffusion composition, the application/diffusion of the n-type impurity diffusion composition may be performed in fig. 2(c) to (d). This is because the p-type impurity diffusion composition of the present invention has barrier properties against n-type impurities.

Next, a method for manufacturing a solar cell according to the present invention will be described with reference to fig. 3, taking a back-contact solar cell as an example. First, as shown in fig. 3(f), the protective film 6 is formed on the entire back surface of the semiconductor substrate 1 on which the n-type impurity diffusion layer 5 and the p-type impurity diffusion layer 3 are formed on the back surface. Next, as shown in fig. 3(g), the protective film 6 is patterned by etching or the like to form a protective film opening 6 a. Further, as shown in fig. 3(h), an electrode paste is applied in a pattern in a region including the protective film opening 6a by a stripe coating method, a screen printing method, or the like, and fired, thereby forming the n-type contact electrode 8 and the p-type contact electrode 7. By the above method, the back contact solar cell 9 can be obtained.

A method for forming another impurity diffusion layer using the p-type impurity diffusion composition of the present invention will be described with reference to fig. 4. Fig. 4 shows a method for forming an impurity diffusion layer, which includes the following steps: a step of forming a pattern by using the n-type impurity diffusion composition; a step of coating a p-type impurity diffusion composition using the n-type impurity diffusion composition as a mask; and diffusing n-type and p-type impurities from the n-type impurity diffusion composition and the p-type impurity diffusion composition into the semiconductor substrate.

First, as shown in fig. 4(a), an n-type impurity diffusion composition film 4 is formed in a pattern on a semiconductor substrate 1. Next, after the n-type impurity diffusion composition 4 is fired as necessary, as shown in fig. 4(b), the p-type impurity diffusion composition film 2 is formed using the n-type impurity diffusion composition film 4 as a mask. Next, as shown in fig. 4(c), the n-type impurity diffusion component in the n-type impurity diffusion composition film 4 and the p-type impurity diffusion component in the p-type impurity diffusion composition film 2 are simultaneously diffused into the semiconductor substrate 1, thereby forming the n-type impurity diffusion layer 5 and the p-type impurity diffusion layer 3. The methods of applying, firing and diffusing the impurity diffusion composition include the same methods as described above.

Next, as shown in fig. 4(d), the n-type impurity diffusion composition film 4 and the p-type impurity diffusion composition film 2 formed on the surface of the semiconductor substrate 1 are removed by a known etching method. Through the above steps, n-type and p-type impurity diffusion layers can be formed in the semiconductor substrate. By setting such a step, the steps can be simplified as compared with conventional methods.

Here, an example in which the application of the p-type impurity diffusion composition is performed after the application of the n-type impurity diffusion composition is shown, but the application of the n-type impurity diffusion composition may be performed after the application of the p-type impurity diffusion composition. That is, instead of the application of the n-type impurity diffusion composition, the application of the p-type impurity diffusion composition may be performed in fig. 4(a), and instead of the application/diffusion of the p-type impurity diffusion composition, the application of the n-type impurity diffusion composition may be performed in fig. 4 (b).

Further, a method for forming another impurity diffusion layer using the p-type impurity diffusion composition of the present invention will be described with reference to fig. 5.

As shown in fig. 5(a), a p-type impurity diffusion composition film 2 of the present invention is formed on a semiconductor substrate 1. After the p-type impurity diffusion composition film 2 is fired as necessary, as shown in fig. 5(b), an n-type impurity diffusion composition film 4 is formed on the surface of the semiconductor substrate 1 opposite to the surface on which the p-type impurity diffusion composition film 2 is formed.

Next, as shown in fig. 5(c), the semiconductor substrate is heated, whereby the p-type impurity diffusion composition film 2 and the n-type impurity diffusion composition film 4 are diffused into the semiconductor substrate 1 at the same time, and the p-type impurity diffusion layer 3 and the n-type impurity diffusion layer 5 are formed. The methods of applying, firing and diffusing the impurity diffusion composition include the same methods as described above.

Next, as shown in fig. 5(d), the p-type impurity diffusion composition film 2 and the n-type impurity diffusion composition film 4 formed on the surface of the semiconductor substrate 1 are removed by a known etching method. Through the above steps, n-type and p-type impurity diffusion layers can be formed in the semiconductor substrate. By setting such a step, the steps can be simplified as compared with conventional methods.

Here, an example in which the application of the n-type impurity diffusion composition is performed after the application of the p-type impurity diffusion composition is described, but the application of the p-type impurity diffusion composition may be performed after the application of the n-type impurity diffusion composition.

The method for manufacturing a solar cell of the present invention includes a step of manufacturing a semiconductor element by the method for manufacturing a semiconductor element of the present invention. By including the method for manufacturing a semiconductor element of the present invention in the method for manufacturing a solar cell of the present invention, the process can be simplified as compared with the conventional method as described above. As a method for manufacturing the solar cell of the present invention from the semiconductor element obtained by the method for manufacturing a semiconductor element of the present invention, a known method can be used. Specific examples thereof include the method described above with reference to fig. 3. In the solar cell obtained by the method for manufacturing a solar cell according to the present invention, since the n-type impurity can be prevented from being mixed into the p-type impurity diffusion region, it is possible to suppress the occurrence of a problem of "a decrease in power generation efficiency due to the n-type impurity being mixed into the p-type impurity diffusion region".

The present invention is not limited to the above-described embodiments, and various modifications such as design changes may be made based on the knowledge of those skilled in the art, and such modified embodiments are also included in the scope of the present invention.

The p-type impurity diffusion composition of the present invention can also be extended to photovoltaic elements such as solar cells, semiconductor devices in which impurity diffusion regions are formed in a pattern on the surface of a semiconductor, such as transistor arrays, diode arrays, photodiode arrays, converters, and the like.

Examples

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Among the compounds used, the compounds abbreviated as those shown below are used.

gamma-BL: gamma-butyrolactone

MeTMS: methyltrimethoxysilane

PhTMS: phenyltrimethoxysilane

DMeDMS: dimethoxydimethylsilane.

(1) Solution viscosity and storage stability

The viscosity was measured using a rotational viscometer TVE-25L (model E digital viscometer) manufactured by Toyobo industries, Ltd., at a liquid temperature of 25 ℃ and a rotation speed of 20 rpm.

(2) Evaluation of peelability

An n-type Silicon wafer (made by Ferrotec Silicon, Inc., having a surface resistivity of 410. omega./□) cut into 3 cm. times.3 cm was immersed in a 1% hydrofluoric acid aqueous solution for 1 minute, washed with water, blown, and treated with a hot plate at 140 ℃ for 5 minutes.

The impurity diffusion composition to be measured was applied to the silicon wafer by a known spin coating method so that the pre-baking film thickness became about 500 nm. After coating, the silicon wafer was prebaked at 140 ℃ for 5 minutes.

Next, each silicon wafer was placed in an electric furnace, and was maintained at 900 ℃ for 30 minutes in an atmosphere of 99: 1 (volume ratio) of nitrogen to oxygen, thereby thermally diffusing the impurities.

Each silicon wafer after thermal diffusion was immersed in a 5 wt% hydrofluoric acid aqueous solution at 23 ℃ for 1 minute, and the diffusing agent and the mask were peeled off. After the peeling, the silicon wafer was immersed in pure water and washed, and the presence or absence of residue on the surface was visually observed. A case where the surface deposit was visually recognized after 1 minute of immersion and could not be removed even by wiping with a wiper was evaluated as poor (worse); the case where the surface deposit was visually recognized after 1 minute of immersion, but could be removed by wiping with a wiper was evaluated as bad (bad); the surface of the substrate was evaluated as good (good) when the substrate was immersed for more than 30 seconds and within 1 minute, and the surface deposits could not be visually observed; it was evaluated that the surface deposits could not be visually confirmed within 30 seconds of immersion (excellent). From the viewpoint of production cycle, good (good) can be used, and excellent (excelent) is preferable.

(3) Diffusivity

The diffused silicon wafer used for the evaluation of the peeling property was subjected to p/n determination using a p/n determination machine, and the surface resistance was measured using a four-probe surface resistance measuring apparatus RT-70V (manufactured by NAPSON corporation) and used as the sheet resistance value. The sheet resistance value is an index of diffusion of an impurity, and a smaller resistance value indicates a larger amount of diffusion of an impurity. Evaluating the sheet resistance value of 40-70 (omega/□) as excellent (excellent); the sheet resistance value was 71100(Ω/□) and evaluated as good (good); the sheet resistance value of 101(Ω/□) or more was evaluated as bad (bad).

(4) Uniformity of diffusion

The surface concentration distribution of the impurity was measured with respect to the diffused silicon wafer used for the sheet resistance value measurement using a secondary ion mass spectrometer IMS7f (manufactured by Camera). Reading surface concentrations at 10 points at intervals of 100 μm from the obtained surface concentration distribution, calculating a "standard deviation/average value" which is a ratio of the average value to the standard deviation, and determining that the "standard deviation/average value" is 0.3 or less as excellent (excellent); judging that the "standard deviation/average value" is more than 0.3 and 0.6 or less as good (good); determining that the "standard deviation/average value" is more than 0.6 and 1.0 or less as bad (bad); the case where the "standard deviation/average" exceeds 1.0 is determined as the difference (worst). The surface concentration unevenness of the impurities has a large influence on the power generation efficiency, and is most preferably (excellent).

(5) Barrier property

As shown in fig. 6(a), a p-type impurity diffusion composition film 62 is formed by applying a p-type impurity diffusion composition onto an n-type silicon wafer 61 by a known spin coating method so that the pre-baking film thickness becomes about 500 nm. After formation, the n-type silicon wafer was prebaked at 140 ℃ for 5 minutes to prepare a p-type impurity diffusion composition-coated substrate.

Next, as shown in fig. 6(b), an n-type impurity diffusion composition film 64 was formed by applying an n-type impurity diffusion composition (OCD T-1, manufactured by tokyo chemical industries, inc.) onto the n-type silicon wafer 61 by a known spin coating method so that the pre-baking film thickness was about 500 nm. After formation, the n-type silicon wafer was prebaked at 140 ℃ for 5 minutes to prepare an n-type impurity diffusion composition-coated substrate.

Next, as shown in fig. 6(c), the p-type impurity diffusion composition-coated substrate and the n-type impurity diffusion composition-coated substrate were placed in an electric furnace so as to face each other at an interval of 5 mm. After the arrangement, the p-type impurity diffusion layer 63 and the n-type impurity diffusion layer 65 were formed by thermal diffusion of impurities while maintaining the temperature at 900 ℃ for 30 minutes in an atmosphere of 99: 1 (volume ratio) of nitrogen to oxygen (fig. 6 (d)).

After the thermal diffusion, each n-type silicon wafer was immersed in a 5 wt% hydrofluoric acid aqueous solution at 23 ℃ for 1 minute, and the cured diffusing agent was peeled off (fig. 6 (e)).

The surface concentration distribution of phosphorus element was measured using a secondary ion mass spectrometer IMS7f (manufactured by Camera) for a substrate obtained by thermally diffusing and peeling a p-type impurity diffusion composition-coated substrate. The lower the surface concentration of the phosphorus element, the higher the barrier property against the phosphorus element diffused from the n-type impurity diffusion composition on the opposite side. The surface concentration of the obtained phosphorus element is 10¹⁷Atom/cm³The following case was judged as excellent (excelent); the surface concentration of the phosphorus element exceeds 10¹⁷Atom/cm³And is 10¹⁸Atom/cm³The following cases were judged to be good (good); the surface concentration of the phosphorus element exceeds 10¹⁸Atom/cm³Is determined to be bad (bad).

(6) Determination of the weight average molecular weight of the polysiloxane

The weight average molecular weight of the polysiloxane was determined by filtering a sample through a membrane filter having a pore size of 0.45 μm and converting the filtered sample into polystyrene by GPC (HLC-8220 GPC, Tosoh corporation, Inc.) (tetrahydrofuran as a developing solvent, at a developing rate of 0.4 ml/min; column, TSKgel SuperHM-H, Tosoh Co., Ltd.).

Example 1

(1) Synthesis of polysiloxane solutions

164.93g (1.21mol) of KBM-13(MeTMS, manufactured by shin-Etsu chemical Co., Ltd.), 204.07g (1.21mol) of KBM-103 (PhTMS, manufactured by shin-Etsu chemical Co., Ltd.), and 363.03g of γ -BL were put into a 1000mL three-necked flask, and an aqueous formic acid solution prepared by dissolving 0.1.215g of formic acid in 130.76g of water was added thereto over 30 minutes while stirring at 40 ℃. After the completion of the dropwise addition, the mixture was stirred at 40 ℃ for 1 hour, then heated to 70 ℃ and stirred for 30 minutes. After that, the oil bath was warmed to 115 ℃.1 hour after the start of the temperature rise, the internal temperature of the solution reached 100 ℃ and from this time, the solution was stirred under heating for 1 hour (internal temperature 100110 ℃). The resulting solution was cooled in an ice bath to give polysiloxane solution a (PhTMS (50 mol%)/memts (50 mol%), i.e. a material of formula (1) in which n: m is 50: 50). The solid content concentration of the polysiloxane solution A was 39.8% by weight. The polysiloxane in the polysiloxane solution a had a weight average molecular weight (Mw) of 2900.

(2) Synthesis of p-type impurity diffusion component

Into a 1000mL three-necked flask were charged 366.75g (2.69mol) of KBM-13(MeTMS), 83.25g (1.35mol) of B (OH)₃(boric acid), heated to 40 ℃ and stirred for 1 hour. Then, 550.0g of γ -BL was added thereto, the temperature was raised to 90 ℃ and the mixture was stirred for 1 hour (inner temperature: 75 to 85 ℃). The resulting solution was cooled in an ice bath to obtain p-type impurity solution a. The p-type impurity solution A had a solid content concentration of 52.3 wt%.

(3) production of P-type impurity diffusion composition

20.05g of the polysiloxane solution A synthesized in the above (1), 15.26g of the p-type impurity solution A synthesized in the above (2), 44.65g of γ -BL, and 0.04g of a silicone surfactant BYK333(BYK-Chemie Japan, Inc.) were mixed and sufficiently stirred until uniform, to obtain a p-type impurity diffusion composition A (solid content concentration: 20%).

The viscosity of the p-type impurity diffusion composition a obtained in the above was the result shown in table 2. Further, using the obtained p-type impurity diffusion composition a, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and the results showed good results as shown in table 2.

Example 2

An impurity diffusion composition B was obtained in the same manner as in example 1 except that the raw material addition ratio was PhTMS (90 mol%)/memts (10 mol%) so that the composition of polysiloxane was changed to 90: 10, where n: m in the general formula (1). Using the obtained impurity diffusion composition B, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2. The polysiloxane in the polysiloxane solution used had a weight average molecular weight (Mw) of 2300.

Example 3

An impurity diffusion composition C was obtained in the same manner as in example 1 except that the raw material addition ratio was PhTMS (80 mol%)/memts (20 mol%) so that the composition of polysiloxane was 80: 20, where n: m was in the general formula (1). Using the obtained impurity diffusion composition C, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2. The polysiloxane in the polysiloxane solution used had a weight average molecular weight (Mw) of 2500.

Example 4

An impurity diffusion composition D was obtained in the same manner as in example 1 except that the raw material addition ratio was PhTMS (40 mol%)/memts (60 mol%) so that the composition of polysiloxane was 40: 60, where n: m was in the general formula (1). Using the obtained impurity diffusion composition D, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2. The weight average molecular weight (Mw) of the polysiloxane in the polysiloxane solution used was 3100.

Example 5

An impurity diffusion composition E was obtained in the same manner as in example 1 except that the raw material addition ratio was PhTMS (30 mol%)/memts (70 mol%) so that the composition of polysiloxane was 30: 70, where n: m was in the general formula (1). Using the obtained impurity diffusion composition E, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2. The polysiloxane solution used had a weight average molecular weight (Mw) of 3400.

In examples 1 to 5, when the aryl group ratio in the polysiloxane was 40 mol% or more, the diffusion uniformity was excellent, and when it was 80 mol% or less, the releasability showed particularly good results. Examples 1 to 5 all showed good results in terms of barrier properties.

Example 6

An impurity diffusion composition F was obtained in the same manner as in example 1, except that the material used for obtaining the p-type impurity diffusion component (B) was changed to mepms. Using the obtained impurity diffusion composition F, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2.

Example 7

An impurity diffusion composition G was obtained in the same manner as in example 1, except that the material for obtaining the p-type impurity diffusion component (B) was changed to dmems (manufactured by shin-Etsu chemical industries, Ltd.). Using the obtained impurity diffusion composition G, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2.

Example 8

An impurity diffusion composition K was obtained in the same manner as in example 1 except that (3) the polysiloxane solution synthesized in (1) was changed to 10.03g and the p-type impurity solution a synthesized in (2) was changed to 22.89g in the preparation of the p-type impurity diffusion composition. Using the obtained impurity diffusion composition K, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2.

Example 9

The p-type impurity diffusion component (B) is R in the general formula (2)⁵An impurity diffusion composition L was obtained in the same manner as in example 1, except that in the form of a diffusion component in which the molar ratio of methyl groups to phenyl groups in the composition was 5: 95, the raw material was changed to memts (5 mol%)/PhTMS (95 mol%). Using the obtained impurity diffusion composition L, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2.

Example 10

The p-type impurity diffusion component (B) is R in the general formula (2)⁵An impurity diffusion composition M was obtained in the same manner as in example 1, except that the molar ratio of methyl groups to phenyl groups in the diffusion composition was 20: 80, and the raw material was changed to memts (20 mol%)/PhTMS (80 mol%). Using the obtained impurity diffusion composition M, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2.

Example 11

The p-type impurity diffusion component (B) is R in the general formula (2)⁵An impurity diffusion composition N was obtained in the same manner as in example 1, except that the molar ratio of methyl groups to phenyl groups in the diffusion composition was changed to 50: 50 methyl groups/phenyl groups, and that the raw material was changed to 50 mol% of memts/PhTMS (50 mol%). Using the obtained impurity diffusion composition N, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2.

Example 12

The p-type impurity diffusion component (B) is R in the general formula (2)⁵An impurity diffusion composition O was obtained in the same manner as in example 1, except that in the form of the diffusion component in which the molar ratio of methyl groups to phenyl groups in the raw material was changed to memts (80 mol%)/PhTMS (20 mol%) so that the molar ratio of methyl groups to phenyl groups in the raw material was 80: 20. Using the obtained impuritiesThe diffusion composition O was measured for releasability, sheet resistance value, diffusion uniformity and barrier property, and all the results showed good results as shown in table 2.

Example 13

The p-type impurity diffusion component (B) is R in the general formula (2)⁵An impurity diffusion composition P was obtained in the same manner as in example 1, except that the molar ratio of methyl groups to phenyl groups in the diffusion composition (b) was 95: 5, and the raw material was changed to memts (95 mol%)/PhTMS (5 mol%). Using the obtained impurity diffusion composition P, the peelability, sheet resistance value, diffusion uniformity, and barrier property were measured, and all of the results showed good results as shown in table 2.

Comparative example 1

An impurity diffusion composition H was obtained in the same manner as in example 1, except that boric acid was used as the (B) p-type impurity diffusion component. Boric acid has low solubility in polysiloxane solution a, resulting in a white precipitate. Using the obtained impurity diffusion composition H, the peeling property, sheet resistance value, diffusion uniformity, and barrier property were measured, and as shown in table 2, the sheet resistance value was high, and the diffusion uniformity was also poor.

Comparative example 2

An impurity diffusion composition I was obtained in the same manner as in example 1, except that phenylboronic acid was used as the (B) p-type impurity diffusion component. The solubility of phenylboronic acid in polysiloxane solution A was good. Using the obtained impurity diffusion composition I, the peeling property, sheet resistance value, diffusion uniformity, and barrier property were measured, and as shown in table 2, the sheet resistance value was high, and the diffusion uniformity was also poor.

Comparative example 3

An impurity diffusion composition J was obtained in the same manner as in example 1, except that polysiloxane was not used. Using the obtained impurity diffusion composition J, the peeling property, sheet resistance value, diffusion uniformity, and barrier property were measured, and the results are shown in table 2 as the results of poor barrier property.

[ Table 2]

Description of the reference numerals

1 semiconductor substrate

2 p-type impurity diffusion composition film

3 p type impurity diffusion layer

4 n-type impurity diffusion composition film

5 n type impurity diffusion layer

6 protective film

6a protective film opening

7p type contact electrode

8 n type contact electrode

9 back-junction solar cell

61 n type silicon wafer

62 p type impurity diffusion composition film

63 p type impurity diffusion layer

64 n type impurity diffusion composition film

65 n type impurity diffusion layer

Claims

A p-type impurity diffusion composition comprising (A) a polysiloxane and (B) a p-type impurity diffusion component having an Si-O-B bond,

wherein (A) the polysiloxane is represented by the following general formula (1),

in the formula (1), R¹A plurality of R represents an aryl group having 6 to 15 carbon atoms¹Each of which may be the same or different,

R²represents a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carbon atomA plurality of R, at least one selected from the group consisting of 1 to 6 acyloxy groups, 2 to 10 carbon alkenyl groups and 6 to 15 carbon aryl groups²Each of which may be the same or different,

R³and R⁴A plurality of R's each representing one of a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms and an alkenyl group having 2 to 10 carbon atoms³And R⁴Each of which may be the same or different,

wherein R is²～R⁴The hydroxyl group, alkoxy group having 1 to 6 carbon atoms, acyloxy group having 1 to 6 carbon atoms and other R in the above formula²～R⁴Wherein any one of a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms and an acyloxy group having 1 to 6 carbon atoms is condensed to form a crosslinked structure,

x represents any one of a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms and an aryl group having 6 to 15 carbon atoms, Y represents any one of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms and an acyl group having 1 to 6 carbon atoms,

n：m＝95：5～25：75，

(B) the p-type impurity diffusion component having an Si-O-B bond comprises a partial structure represented by the following general formula (2),

in the formula (2), R⁵R represents any one of an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 15 carbon atoms⁵Wherein the molar ratio of the alkyl with 1-6 carbon atoms to the aryl with 6-15 carbon atoms is the alkyl with 1-6 carbon atoms: 20-C6-15 aryl: 80-80: 20; r⁶Represents any one of a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or an acyloxy group having 1 to 6 carbon atoms; plural R⁵And R⁶Each may be the same or different.
2. Such as rightThe p-type impurity diffusion composition according to claim 1, wherein R²And R⁴R represents any one of a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms or an acyloxy group having 1 to 6 carbon atoms³Represents an alkyl group having 1 to 4 carbon atoms or an alkenyl group having 2 to 4 carbon atoms.
3. The p-type impurity diffusion composition according to claim 1 or 2, wherein n: m is 80: 20-40: 60.
4. a method for manufacturing a semiconductor device, comprising the steps of:

a step of applying the p-type impurity diffusion composition according to any one of claims 1 to 3 onto a semiconductor substrate to form a p-type impurity diffusion composition film; and

and a step of forming a p-type impurity diffusion layer by diffusing a p-type impurity from the p-type impurity diffusion composition film.
5. A method for manufacturing a semiconductor device, comprising the steps of:

a step of coating the n-type impurity diffusion composition on a semiconductor substrate to form an n-type impurity diffusion composition film;

a step of applying the p-type impurity diffusion composition according to any one of claims 1 to 3 after the above step to form a p-type impurity diffusion composition film; and

and a step of simultaneously forming an n-type impurity diffusion layer and a p-type impurity diffusion layer by heating the semiconductor substrate.
6. A method for manufacturing a semiconductor device, comprising the steps of:

a step of applying the p-type impurity diffusion composition according to any one of claims 1 to 3 to one surface of a semiconductor substrate to form a p-type impurity diffusion composition film;

a step of coating the other surface of the semiconductor substrate with an n-type impurity diffusion composition to form an n-type impurity diffusion composition film; and

and a step of simultaneously forming a p-type impurity diffusion layer and an n-type impurity diffusion layer by heating the semiconductor substrate.
7. A method for manufacturing a solar cell, comprising a step of manufacturing a semiconductor device by the method for manufacturing a semiconductor device according to any one of claims 4 to 6.