JP2007049079A - Masking paste, method for manufacturing same, and method for manufacturing solar cell using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease a manufacturing cost by conveniently performing a fine patterning of doped regions in a manufacturing process of a backside solar cell. <P>SOLUTION: In the masking paste used as a diffusion-controlling mask in diffusing a dopant over a semiconductor substrate to form the doped regions, the masking paste includes at least a solvent, a thickener, and a SiO<SB>2</SB>precursor, and/or a TiO<SB>2</SB>precursor is provided. In addition, the method is provided for manufacturing the solar cell by diffusing the dopant after the masking paste is pattern-formed on the substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a masking paste used as a diffusion control mask when a dopant is diffused into a semiconductor substrate. By using the masking paste, fine patterning of the doping region can be performed easily and inexpensively. And it can provide the method of manufacturing a back-electrode-type solar cell with high efficiency and low cost by performing fine patterning simply.

  In recent years, photoelectric power technologies and power semiconductors, including solar cells that directly convert solar energy into electrical energy, have been rapidly expected as next-generation energy sources, particularly from the viewpoint of global environmental problems. There are various types of solar cells, such as those using compound semiconductors or organic materials. Currently, the mainstream is the one using silicon crystals. The solar cells currently produced and sold most often have an n-electrode on the light-receiving surface that receives sunlight and a p-electrode on the back surface. The n-electrode provided on the light-receiving surface side is indispensable for taking out the current. However, since sunlight does not enter the substrate under the electrode, no power is generated in that portion. Therefore, if the electrode area is large, the conversion efficiency decreases. Such loss due to the electrode on the light receiving surface side is called shadow loss.

  A back electrode type solar cell having no electrode on the light receiving surface has no shadow loss due to the electrode, and 100% of incident sunlight can be taken into the solar cell, so that high efficiency can be realized in principle. In patent document 1, one form of the back electrode type solar cell suitable for the concentrating type is disclosed. FIG. 1 shows an outline of the structure.

  High-concentration p-doped regions 12 and high-concentration n-doped regions 13 are alternately provided on the back side of the semiconductor substrate 10. Further, a texture etched surface 18 is formed on the light receiving surface of the semiconductor substrate 10. A passivation layer 11 is formed on the surface of the semiconductor substrate 10, thereby suppressing surface recombination. A p-electrode 14 is connected to the high-concentration p-doped region 12 and an n-electrode 15 is connected to the high-concentration n-doped region 13 through a p-region contact hole 16 or an n-region contact hole 17 provided on the back surface. The current is taken out from. The passivation layer 11 on the light receiving surface also serves as an antireflection film. As can be seen from this figure, the high-concentration p and n doping regions and the respective electrodes are all formed on the back surface, and there is nothing to block the light on the front surface (light receiving surface), so that 100% of sunlight is taken in. Can do.

  The back electrode structure of the back electrode solar cell is a precise patterning in which high-concentration n-doped regions 13 and high-concentration p-doped regions 12 are alternately formed. The manufacturing process of the solar cell will be described below with reference to FIG.

First, after forming an oxide film, a nitride film is deposited to form a passivation layer 11. Next, an n-region contact hole 17 is opened by a photolithography technique, and a glass layer containing an n-type dopant is deposited by CVD (chemical vapor deposition). After removing the portion corresponding to the high-concentration p-doped region of the glass layer, a p-region contact hole 16 is formed by photolithography, and a glass layer containing a p-type dopant is deposited. When this is heated at 900 ° C., a high concentration p-doped region 12 and a high concentration n-doped region 13 are formed. Thereafter, all the glass layer remaining on the surface is removed, and heat treatment is performed at a high temperature of 900 ° C. or higher in H ₂ to hydrogenate the Si—SiO ₂ interface. After removing the two glass layers that have become the diffusion source, Al is deposited by sputtering or the like, and patterned by a photolithography technique to form the p electrode 14 and the n electrode 15.

In addition, regarding semiconductor doping technology, a screen-printable dopant paste for forming p, p +, n, and n + regions on single crystal and polycrystalline silicon substrates at low cost and easily, and also controls dopant diffusion during semiconductor manufacturing. Research on masking paste is underway (see Patent Document 2).
U.S. Pat. No. 4,927,770 JP 2002-539615A

  However, the back electrode type solar cell was originally developed as a concentrating solar cell, and complicated photolithography technology, high-quality doping technology, and passivation technology were used for its production. As a result, the cost is increased and it is not suitable as a general ground solar cell, that is, a residential solar cell. Therefore, in order to reduce the manufacturing cost of the back electrode type solar cell as shown in FIG. 1, it is necessary to simplify the manufacturing process of the solar cell. For this purpose, it is desirable to form a fine patterning of the n-doped region and the p-doped region without using a complicated photolithography technique or the like.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a masking paste having a diffusion control function and a coating and printing characteristic used as a diffusion control mask when a dopant is diffused into a semiconductor substrate. . By using the masking paste according to the present invention, the fine patterning of the doping region can be performed easily and inexpensively. And it provides the method of manufacturing a back electrode type solar cell at low cost by enabling simple and fine patterning.

The present invention relates to a masking paste used as a diffusion control mask when a dopant is diffused in a semiconductor substrate to form a doping region, and includes at least a solvent, a thickener, and a SiO ₂ precursor and / or a TiO ₂ precursor. It is related with the masking paste characterized by including. In the present invention, the solvent is preferably butyl cellosolve and / or N-methyl-2-pyrrolidone. In the present invention, it is desirable that the thickener is ethyl cellulose and / or polyvinyl pyrrolidone. In the present invention, the SiO ₂ precursor has the general formula R ′ _n Si (OR) _{4 -n} (R ′ is methyl, ethyl or phenyl, R is methyl, ethyl, n-propyl or i-propyl, and n is 0) 1) or 2), preferably formed by silanes selected individually or as a mixture from the group consisting of tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetrapropoxysilane, tetramethoxysilane Is desirable. In the present invention, the SiO ₂ precursor is preferably formed of siloxane and polysiloxane. In the present invention, the TiO ₂ precursor is represented by the general formula R ′ _n Ti (OR) _{4 -n} (R ′ is methyl, ethyl or phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2). In the present invention, the TiO ₂ precursor is preferably formed individually or in a mixture from the group consisting of tetraisopropoxy titanium, TiCl ₄ , TiF ₄ and TiOSO ₄ . In the present invention, the concentration of the SiO ₂ precursor and / or TiO ₂ precursor in the masking paste is preferably 5 to 15% by mass. Moreover, as for this invention, it is desirable for the density | concentration in the masking paste of the said thickener to be 5-15 mass%.

Further, the present invention relates to a method for producing a masking paste used as a diffusion control mask when a dopant is diffused in a semiconductor substrate to form a doping region, and the general formula R ′ _n Si (OR) _4-n (R ′ Is methyl, ethyl or phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2), a mixture containing a solvent and a thickener is prepared, and then the general formula R ′ _n Si (OR) _4-n (R ′ is methyl, ethyl or phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2) It is related with the manufacturing method of the said masking paste characterized by evaporating alcohol by heating at the temperature below the boiling point of this.

  The present invention also relates to a method for manufacturing a solar cell, wherein the masking paste is patterned on a semiconductor substrate, and then a dopant is diffused.

  By using the masking paste, fine patterning of the n-doped region and the p-doped region can be easily performed, and a low-cost back electrode type solar cell can be manufactured.

<Role of masking paste>
The masking paste is used to form a diffusion control mask on the semiconductor substrate. The diffusion control mask refers to a film having a control function such as suppressing or stopping the diffusion of the dopant. The masking paste is applied to the semiconductor substrate, and the dopant diffuses only in the unprinted portion. Therefore, by using the masking paste, it is possible to easily manufacture a region that is not a doping region, and as a result, a fine patterning of the n doping region and the p doping region can be easily performed.

<Composition of masking paste>
The masking paste of the present invention contains at least a solvent, a thickener, a SiO ₂ precursor and / or a TiO ₂ precursor. Suitable ethylene glycol, methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve, diethyl cellosolve, cellosolve acetate, ethylene glycol monophenyl ether, methoxymethoxyethanol, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol Monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol acetate, triethyl glycol, triethylene glycol Monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, liquid polyethylene glycol, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, 1-butoxyethoxypropanol, dipropyl glycol, diethylene glycol Propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, polypropylene glycol, trimethylene glycol, butane dial, 1,5-pentane dial, hexylene glycol, glycerin, glyceryl acetate, glyceryl diacetate, glyceryl triacetate , Trimethylol propi , 1,2,6-hexanetriol or hydrophilic derivatives thereof, and aliphatic and aromatic such as 1,2-propanediol, 1,5-pentanediol, octanediol, etc. Polyhydric alcohols, esters and ethers thereof, 1,2-butanediol, 1,4-butanediol, 1,3-butanediol, and hydrophilic ethers such as dioxane, trioxane, tetrahydrofuran, tetrahydropyran, methylal, diethyl acetal , Methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, acetonyl acetone, diacetone alcohol, or hydrophilic esters such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate or mixtures of these solvents It is also possible to use butyl cellosolve or N-methyl-2-pyrrolidone or a mixture of both. And it is desirable to use ethylcellulose or polyvinylpyrrolidone or a mixture of both as thickener, but various quality and properties of bentonite, generally inorganic rheological additives for various polar solvent mixtures, nitrocellulose and other cellulose compounds , Starch, gelatin, alginic acid, highly dispersible amorphous silicic acid (Aerosil®), polyvinyl butyral (Mowital®), sodium carboxymethylcellulose (vivistar), thermoplastic polyamide resin (Eurelon®) ), Organic castor oil derivative (Thixin R (registered trademark)), diamide wax (Thixatrol plus (registered trademark)), swollen polyacrylate (Rheolate (registered trademark)), poly Ether urea - polyurethane, polyether - polyol can be used, and the like.

  In particular, when masking with the masking paste according to the present invention on an n-type substrate, a combination of butyl cellosolve and ethylcellulose is used for masking n-type diffusion, and N-methyl-2pyrrolidone and polyvinylpyrrolidone are used for masking p-type diffusion. In combination, it is desirable to use a solvent and a thickener.

Further, if the viscosity of the paste is too small, the paste leaks from the gap between the printing screens. Conversely, if the viscosity is too large, the paste becomes difficult to adhere to the semiconductor substrate. The mass is set to be 8% by mass, more desirably 8 to 12% by mass. The main component of the diffusion control mask made of the masking paste is SiO ₂ and / or TiO ₂ , but a thickness of about 300 nm is required to exhibit the diffusion mask property. However, if a film having a thickness of 1000 nm or more is formed with a masking paste, it may crack. Therefore, the concentration of the SiO ₂ precursor and / or TiO ₂ precursor contained in the masking paste is 5 to 15% by mass, more preferably 5 to 8% by mass.

It is considered that the SiO ₂ precursor is usually present in the form of Si (OH) _{4 in} the masking paste, and is changed to SiO ₂ by the drying process and serves as a diffusion protection mask. The SiO ₂ precursor is also formed by substances such as TE ′ (tetraethylorthosilicate) represented by R ′ _n Si (OR) _4-n , siloxane, and polysiloxane (R ′ is methyl, ethyl). Or phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2).

In addition to Ti (OH) ₄ , a TiO ₂ precursor is formed by a substance represented by R ′ _n Ti (OR) _4-n such as TPT (tetraisopropoxytitanium) (R ′ is methyl, ethyl or Phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2), and TiCl ₄ , TiF ₄ , TiOSO _{4 and the} like are also included.

<Manufacturing method of masking paste using SiO ₂ precursor>
First, in a glass bottle, a general formula R ′ _n Si (OR) _{4 -n} such as TEOS (tetraethyl orthosilicate) (R ′ is methyl, ethyl or phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2) (hereinafter, TEOS will be described as an example), a solvent, water and hydrochloric acid are added, and the mixture is stirred well for about 10 minutes and then allowed to stand for about 6 hours. Through this process, TEOS and water undergo a chemical reaction using hydrochloric acid as a catalyst to generate ethyl alcohol and Si (OH) ₄ . The above reaction is shown in chemical formula (1).

  However, when the paste is produced as it is, it becomes a paste that is very easy to solidify due to the high volatility of ethyl alcohol. Therefore, in order to perform printing smoothly, it is effective to heat the solution at about 80 ° C. (above the boiling point of the generated ethyl alcohol and below the boiling point of the solvent) to evaporate the ethyl alcohol in the solution. It is.

  Moreover, the above hydrolysis is not necessary when producing a masking paste using siloxane and polysiloxane.

  Finally, the thickener is mixed in an amount of 5 to 15% by mass, more preferably 8 to 12% by mass with respect to the amount of the masking paste, and sufficiently stirred to complete the masking paste. However, the thickener may be mixed before the ethyl alcohol evaporation step.

<Manufacturing Method of Masking Paste Using TiO ₂ Precursor>
By using TiO ₂ , it is possible to form a strong diffusion mask that hardly dissolves in the hydrofluoric acid aqueous solution.

First, in a glass bottle, a general formula R ′ _n Ti (OR) _{4 -n} such as TPT (tetraisopropoxy titanium) (R ′ is methyl, ethyl or phenyl, R is methyl, ethyl, n-propyl or i-propyl, n Is a substance represented by 0, 1 or 2) (hereinafter, TPT will be described as an example) and a solvent. Stir well for about 10 minutes. Since TPT reacts easily with water and forms TiO ₂ immediately, it is not necessary to add water or hydrochloric acid unlike the SiO ₂ precursor. Further, since no alcohol is generated by hydrolysis, there is no need to add a heating step as in the case of using a SiO ₂ precursor. Finally, the thickener is mixed in an amount of 5 to 15% by mass, more preferably 8 to 12% by mass with respect to the amount of the masking paste, and sufficiently stirred to complete the masking paste. In addition to TPT, TiCl ₄ , TiF ₄ , TiOSO _{4 and the} like can be used as the TiO ₂ precursor.

<Method for producing solar cell using masking paste containing SiO ₂ precursor>
A method for producing a back electrode type solar cell using the SiO ₂ precursor-containing masking paste produced by the above method will be described with reference to FIG. First, the masking paste 30 is screen-printed on the entire light receiving surface side of the semiconductor substrate 10 and dried at about 300 ° C. for several tens of minutes using an oven. Next, an opening is partially provided on the back side, and the masking paste 30 is screen-printed (FIG. 2 (a)).

Next, this substrate is heated at 800 to 1000 ° C. for 10 to 60 minutes to sinter SiO ₂ which is a material of the diffusion control mask 33 included in the masking paste 30. Thereafter, by diffusing the p-type dopant 31 at 800 to 1000 ° C. for 30 to 100 minutes, only the portion corresponding to the opening of the diffusion control mask 33 diffuses into the semiconductor substrate 10, A concentration p-doped region 12 is formed (FIG. 2B).

  Examples of the diffusion method include a vapor phase diffusion method and an ion implantation method. Thereafter, the diffusion control mask 33 can be removed by immersing in a hydrofluoric acid aqueous solution having a concentration of about 10% for about 1 minute.

  Also for n-type diffusion, the masking paste 30 is again screen-printed with openings partially provided on the back side of the semiconductor substrate 10 and fired under the same conditions as above (FIG. 2C).

  Then, the n-type dopant 32 is diffused by applying the same process as described above, whereby the high-concentration n-doped region 13 can be formed (FIG. 2D).

  After forming each doping region as described above, the substrate is kept at about 75 to 85 ° C., and 1 to 10% by mass of isopropyl alcohol as a surfactant is added to 1 to 10% by mass with respect to an aqueous potassium hydroxide solution or the like. The texture etched surface 18 is formed on the light receiving surface by immersing it in an aqueous solution of potassium hydroxide or sodium hydroxide for 10 to 60 minutes. As a method for forming texture etching, there is a method using a hydrazine aqueous solution or the like, but any method can be used as long as a texture structure capable of suppressing reflection of incident light on the light receiving surface can be formed.

  Next, a silicon nitride film is formed on both surfaces of the semiconductor substrate 10 to form a passivation layer 11 and perform passivation (FIG. 2E).

  Then, the back surface passivation layer 11 is punched to provide the p region contact hole 16 and the n region contact hole 17, and then the p electrode 14 and the n electrode 15 are formed to manufacture a back electrode type solar cell ( FIG. 2 (f)).

<Method for producing solar cell using masking paste containing TiO ₂ precursor>
Except for using the TiO ₂ precursor-containing masking paste produced by the above method, it can be carried out in the same manner as in the solar cell production method. However, since a strong TiO ₂ -containing diffusion control mask that is difficult to dissolve in a hydrofluoric acid aqueous solution is used, when removing the diffusion control mask, it is immersed in a 10% aqueous hydrogen fluoride solution for about 60 minutes. There is a need.

Example 1
First, 30 g of TEOS (tetraethylorthosilicate), 100 g of butyl cellosolve as a solvent, 10 g of water and 0.1% by mass of hydrochloric acid were placed in a glass bottle and stirred for 10 minutes, and then allowed to stand for 6 hours. Through this process, TEOS and water caused a chemical reaction using hydrochloric acid as a catalyst to generate ethyl alcohol and Si (OH) ₄ .

  Further, in order to smoothly print the resulting masking paste on the semiconductor substrate, the solution is heated at about 80 ° C. (above the boiling point of the generated ethyl alcohol and below the boiling point of the solvent) for 60 minutes. A step of evaporating ethyl alcohol was performed. Finally, 10 g of the thickening agent ethylcellulose was mixed and stirred sufficiently to produce a masking paste.

(Example 2)
First, 30 g of TPT (tetraisopropoxytitanium) and 100 g of butyl cellosolve as a solvent were put in a glass bottle and stirred well for 10 minutes. Finally, 15 g of thickener ethylcellulose was mixed and stirred well to produce a masking paste.

(Example 3)
The masking paste obtained in Example 1 was screen-printed on the entire light-receiving surface side of the silicon substrate, and dried at about 300 ° C. for 20 minutes using an oven. Next, by partially providing screen openings on the back side, the masking paste was screen-printed with a width of 0.75 mm and a height of 10 μm with a design with a width of 0.75 mm at intervals of 1.5 mm. . Next, this substrate was heated at 900 ° C. for 60 minutes to sinter SiO ₂ which is a material for the diffusion control mask. Thereafter, the p-type dopant is diffused by the thermal diffusion method at 1000 ° C. for 30 minutes, so that the p-type dopant is diffused into the silicon substrate only in the portion corresponding to the opening portion of the diffusion control mask, and the high-concentration p-doped region. Formed. Thereafter, the diffusion control mask was removed by immersing in a 10% concentration hydrofluoric acid aqueous solution for about 1 minute.

  FIG. 3 is a graph showing the voltage distribution under light irradiation of the n-type silicon substrate in which the p-doping region is patterned using the masking paste by the above method. In the region where the masking paste is not printed, p-type doping is performed and a voltage is generated because the pn junction is formed. However, in the region where the masking paste is printed, p-type doping is not performed and the pn junction is not formed. It was found that no voltage was generated.

  Also for n-type diffusion, the masking paste is again screen-printed with a partial opening on the screen on the back side of the silicon substrate, and then a high-concentration n-doped region is formed by applying the same process as above. did.

  After each doping region is formed as described above, this substrate is kept at 80 ° C., and a 3% by weight potassium hydroxide aqueous solution in which 6% by weight isopropyl alcohol is added as a surfactant to a potassium hydroxide aqueous solution or the like is added. A texture etched surface was formed on the light receiving surface by infiltration for 40 minutes. In order to form texture etching, an anisotropic etching method using an alkaline aqueous solution was used.

  Next, a silicon nitride film is formed on both sides of the silicon substrate by PECVD (Plasma Enhanced Chemical Vapor Deposition), thereby forming a passivation layer and performing passivation, and making holes in the backside passivation layer. A p-electrode and an n-electrode were formed after processing to provide a p-region contact hole and an n-region contact hole, and a back electrode type solar cell was manufactured.

Example 4
The masking paste obtained in Example 2 was screen-printed on the entire light-receiving surface side of the silicon substrate, and dried at about 300 ° C. for 20 minutes using an oven. Next, by partially providing screen openings on the back side, the masking paste was screen-printed with a width of 0.75 mm and a height of 10 μm with a design with a width of 0.75 mm at intervals of 1.5 mm. . Next, this substrate is heated at 900 ° C. for 60 minutes to sinter TiO ₂ which is a material for the diffusion control mask. Thereafter, the p-type dopant is diffused by the thermal diffusion method at 1000 ° C. for 30 minutes, so that the p-type dopant is diffused into the silicon substrate only in the portion corresponding to the opening portion of the diffusion control mask, and the high-concentration p-doped region. Formed. After diffusion, the diffusion control mask was removed by immersing in an aqueous solution of about 10% hydrofluoric acid for about 60 minutes.

  Also for n-type diffusion, the masking paste is again screen-printed with a partial opening on the screen on the back side of the silicon substrate, and then a high-concentration n-doped region is formed by applying the same process as above. did.

  After each doping region was formed as described above, this substrate was kept at 80 ° C., and a 3% by weight potassium hydroxide aqueous solution in which 6% by weight isopropyl alcohol was added as a surfactant to the potassium hydroxide aqueous solution or the like was added. A texture etched surface was formed on the light receiving surface by infiltration for 40 minutes. In order to form texture etching, an anisotropic etching method using an alkaline aqueous solution was used.

  Next, a silicon nitride film is formed on both sides of the silicon substrate by PECVD (Plasma Enhanced Chemical Vapor Deposition), thereby forming a passivation layer and performing passivation, and making holes in the backside passivation layer. A p-electrode and an n-electrode were formed after processing to provide a p-region contact hole and an n-region contact hole, and a back electrode type solar cell was manufactured.

  The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  By using the masking paste according to the present invention, fine patterning of the n-doping region and the p-doping region can be easily and inexpensively performed, and a low-cost back electrode type solar cell can be manufactured.

It is a schematic sectional drawing of a back electrode type solar cell. It is a schematic sectional drawing which shows the solar cell manufacturing method by this invention. It is a figure which shows the voltage distribution under light irradiation of the n-type silicon substrate which patterned the p doping area | region using the masking paste by the method of Example 3. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Semiconductor substrate, 11 Passivation layer, 12 High concentration p doping area | region, 13 High concentration n doping area | region, 14 p electrode, 15 n electrode, 16 p area contact hole, 17 n area contact hole, 18 Texture etching surface, 30 Masking paste , 31 p-type dopant, 32 n-type dopant, 33 Diffusion control mask.

Claims (13)

In a masking paste used as a diffusion control mask when a dopant is diffused in a semiconductor substrate and a doping region is formed,
A masking paste comprising at least a solvent, a thickener, and a SiO ₂ precursor and / or a TiO ₂ precursor.   The masking paste according to claim 1, wherein the solvent is butyl cellosolve and / or N-methyl-2-pyrrolidone.   The masking paste according to claim 1 or 2, wherein the thickener is ethyl cellulose and / or polyvinyl pyrrolidone. The SiO ₂ precursor has the general formula R ′ _n Si (OR) _4-n (R ′ is methyl, ethyl or phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2) The masking paste according to claim 1, wherein the masking paste is formed by: The SiO ₂ precursor tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetrapropoxysilane, claim characterized in that it is formed by the selected silane from the group consisting of tetramethoxysilane individually or as a mixture 1 4. The masking paste according to any one of 3. The masking paste according to claim 1, wherein the SiO ₂ precursor is formed of siloxane and polysiloxane. The TiO ₂ precursor has the general formula R ′ _n Ti (OR) _{4 -n} (R ′ is methyl, ethyl or phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2) The masking paste according to claim 1, wherein the masking paste is formed by: The masking paste according to claim 1, wherein the TiO ₂ precursor is formed individually or in a mixture from the group consisting of tetraisopropoxy titanium, TiCl ₄ , TiF ₄ , TiOSO ₄ . The masking paste according to claim 1, wherein the concentration of the SiO ₂ precursor and / or the TiO ₂ precursor in the masking paste is 5 to 15% by mass.   The masking paste according to claim 1, wherein a concentration of the thickener in the masking paste is 5 to 15% by mass. In a manufacturing method of a masking paste used as a diffusion control mask when a dopant is diffused in a semiconductor substrate and a doping region is formed,
(A) General formula R ′ _n Si (OR) _4-n (R ′ is methyl, ethyl or phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2)
(B) solvent,
(C) a thickener,
(D) acid,
(E) water,
A method for producing a masking paste, comprising: preparing a mixed solution comprising: and evaporating the alcohol by heating at a temperature not lower than the boiling point of the alcohol generated by the hydrolysis reaction of (a) and not higher than the boiling point of the solvent. In a manufacturing method of a masking paste used as a diffusion control mask when a dopant is diffused in a semiconductor substrate and a doping region is formed,
(A) General formula R ′ _n Si (OR) _4-n (R ′ is methyl, ethyl or phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2)
(B) solvent,
(D) acid,
(E) water,
And (c) adding a thickener after the alcohol is evaporated by heating at a temperature not lower than the boiling point of the alcohol generated by the hydrolysis reaction of (a) and not higher than the boiling point of the solvent. A manufacturing method of a masking paste characterized.   A method for producing a solar cell, comprising: patterning the masking paste according to claim 1 on a substrate, and then diffusing a dopant.

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