JP5610100B2 - N-type diffusion layer forming composition, n-type diffusion layer manufacturing method, and solar cell manufacturing method - Google Patents

Description

  The present invention relates to a solar cell n-type diffusion layer forming composition, a method for manufacturing an n-type diffusion layer, and a method for manufacturing a solar cell, and more specifically, a specific portion of a silicon substrate that is a semiconductor substrate. The present invention relates to a technique that makes it possible to form an n-type diffusion layer.

The manufacturing process of the conventional silicon solar cell element (solar cell) will be described.
First, a p-type semiconductor substrate having a texture structure formed on the light-receiving surface (surface) is prepared to promote the light confinement effect, and then a mixed gas of phosphorus oxychloride (POCl ₃ ), nitrogen and oxygen. In an atmosphere, the p-type semiconductor substrate is treated for several tens of minutes at 800 ° C. to 900 ° C. to uniformly form an n-type diffusion layer. In this conventional method, phosphorus is diffused into the p-type semiconductor substrate using a mixed gas, so that n-type diffusion layers are formed not only on the surface of the p-type semiconductor substrate, but also on the side and back surfaces. Therefore, a side etching step for removing the n-type diffusion layer formed on the side surface is necessary. Further, the n-type diffusion layer formed on the back surface needs to be converted into a p ⁺ -type diffusion layer. Therefore, after applying an aluminum paste containing aluminum as a group 13 element on the n-type diffusion layer on the back surface, a thermal diffusion treatment is performed to convert the n-type diffusion layer into a p ⁺ -type diffusion layer by aluminum diffusion. At the same time, I was getting ohmic contact.
In addition, a method of forming an n-type diffusion layer by applying a solution containing a phosphate such as ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ) has also been proposed (for example, JP-A-2002-75894). reference).
However, even in this method, since the phosphorus compound is volatilized during diffusion, the donor element is not selectively diffused, and an n-type diffusion layer is formed on the entire surface of the p-type semiconductor substrate.

  In relation to the above, an n-type diffusion layer forming composition containing a glass powder containing a donor element and a dispersion medium is applied to a semiconductor substrate and subjected to thermal diffusion treatment, so that it is unnecessary on the side and back surfaces of the semiconductor substrate. A method for manufacturing a solar cell element in which an n-type diffusion layer is formed in a specific region without forming an n-type diffusion layer has been proposed (see, for example, International Publication No. 11/090216 pamphlet).

  On the other hand, as a structure of a solar cell element for the purpose of increasing the conversion efficiency, the diffusion in the region other than directly under the electrode is compared with the diffusion concentration of the donor element in the region directly under the electrode (hereinafter also simply referred to as “diffusion concentration”). A selective emitter structure with a low concentration is known (see, for example, L. Debarge, M. Schott, JCMuller, R. Monna, Solar Energy Materials & Solar Cells 74 (2002) 71-75). In this structure, a region having a high diffusion concentration immediately below the electrode (hereinafter, this region is also referred to as “selective emitter”) is formed, so that the contact resistance between the electrode and silicon can be reduced. Furthermore, since the diffusion concentration is relatively low except in the region where the electrode is formed, the conversion efficiency of the solar cell element can be improved. In order to construct such a selective emitter structure, it is required to form an n-type diffusion layer in a thin line shape within a width of several hundred μm (about 50 μm to 200 μm).

  However, when the n-type diffusion layer forming composition described in the pamphlet of International Publication No. 11/090216 is used, the line width is expanded even if the n-type diffusion layer forming composition is applied in a thin line shape on a semiconductor substrate, There was a tendency that a desired thin line width could not be obtained. In order to solve this problem, when the content of the dispersion medium in the n-type diffusion layer forming composition is changed to increase the viscosity of the n-type diffusion layer forming composition, the handling property of the n-type diffusion layer forming composition is improved. There was a tendency that application to the semiconductor substrate itself could not be performed.

  The present invention has been made in view of the above-described conventional problems, and can be applied to a semiconductor substrate while suppressing an increase in the line width of a thin line pattern in a manufacturing process of a solar battery cell. Furthermore, an n-type diffusion layer forming composition capable of forming an n-type diffusion layer with a specific size in a desired specific region, a method for manufacturing the n-type diffusion layer, and a method for manufacturing a solar battery cell are provided. For the purpose.

  Means for solving the problems are as follows.

<1> An n-type diffusion layer forming composition containing glass particles containing a donor element, a dispersion medium, a gelling agent, a compound having an ester bond, and at least one selected from a compound having a urea group.

<2> The n-type diffusion layer forming composition part according to <1>, which contains the gelling agent, and the gelling agent is an organic compound represented by the following structural formula (1).

In the structural formula (1), R ¹ and R ² each independently represent H or CH ₃ .

<3> The content of the glass particles containing the gelling agent and containing the donor element is 1% by mass or more and 80% by mass or less, and the content of the gelling agent is 0.01% by mass or more and 5% or less. The n-type diffusion layer forming composition according to <1> or <2>, wherein the composition is at most% by mass.

<4> The compound according to <1>, wherein the compound having the ester bond or the compound having the urea group is contained, and the decomposition temperature of the compound having the ester bond or the compound having the urea group is 400 ° C. or lower. n-type diffusion layer forming composition.

<5> A compound having an ester bond or a compound having a urea group, the content of the glass particles containing the donor element being 1% by mass or more and 80% by mass or less, and the compound having the ester bond or The composition for forming an n-type diffusion layer according to <1> or <4>, wherein the content of the compound having a urea group is 0.1% by mass or more and 10% by mass or less.

<6> The composition for forming an n-type diffusion layer according to <1>, which contains a compound having a urea group, and the compound having the urea group is a urea compound having a medium polar group at its terminal.

<7> The glass particles containing the donor element include at least one donor element-containing material selected from P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ , SiO ₂ , K ₂ O, and Na ₂ O. And at least one glass component material selected from Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V ₂ O ₅ , SnO, ZrO ₂ and MoO _3. The n-type diffusion layer forming composition according to any one of <1> to <6>.

<8> The n-type diffusion layer forming composition according to any one of <1> to <7>, further including at least one thickener selected from a cellulose derivative, an acrylic resin, and an alkyd resin.

<9> The n-type diffusion layer forming composition according to any one of <1> to <8>, further including an inorganic filler.

<10> The n-type diffusion layer forming composition according to <9>, wherein the inorganic filler is fumed silica.

<11> The n-type diffusion layer forming composition according to any one of <1> to <10>, wherein the glass particles containing the donor element have a volume average particle size of 0.1 μm or more and 10 μm or less. .

<12> A step of applying the n-type diffusion layer forming composition according to any one of the above <1> and <11> on a semiconductor substrate; and heating the semiconductor substrate provided with the n-type diffusion layer forming composition. And a step of performing a diffusion treatment.

<13> A step of applying the n-type diffusion layer forming composition according to any one of <1> to <11> on a semiconductor substrate, and a semiconductor substrate provided with the n-type diffusion layer forming composition The manufacturing method of the photovoltaic cell which has the process of forming a n-type diffused layer by performing a thermal diffusion process, and the process of forming an electrode on the formed n-type diffused layer.

  According to the present invention, in the manufacturing process of a solar battery cell, it is possible to suppress the expansion of the line width of the fine line pattern on the semiconductor substrate, and further to a specific area in a specific size. It is possible to provide an n-type diffusion layer forming composition capable of forming an n-type diffusion layer, a method for producing an n-type diffusion layer using the composition, and a method for producing a solar battery cell.

It is sectional drawing which shows notionally an example of the manufacturing process of a photovoltaic cell. It is the top view which looked at the photovoltaic cell from the surface. It is a perspective view which expands and shows a part of FIG. 2A. It is sectional drawing which shows notionally an example of the manufacturing process of a back contact type photovoltaic cell.

First, the n-type diffusion layer forming composition of the present invention will be described, and then an n-type diffusion layer using the n-type diffusion layer forming composition and a method for producing a solar battery cell will be described.
In the present specification, the term “process” is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term “process” is used as long as the intended purpose of the process is achieved. included.
In the present specification, “to” indicates a range including the numerical values described before and after the values as a minimum value and a maximum value, respectively. Moreover, in this specification, "content rate" represents the mass% of a component with respect to 100 mass% of n type diffused layer formation compositions unless there is particular description.

<N-type diffusion layer forming composition>
The composition for forming an n-type diffusion layer of the present invention comprises glass particles containing at least a donor element (hereinafter sometimes simply referred to as “glass particles”), a gelling agent, a compound having an ester bond, and a compound having a urea group. And at least one selected from the group consisting of a dispersion medium. Furthermore, in consideration of applicability and the like, other additives may be contained as necessary.

Here, the n-type diffusion layer forming composition contains glass particles containing a donor element, and after applying to the semiconductor substrate, the donor element is thermally diffused to form an n-type diffusion layer on the semiconductor substrate. A material that can be used.
Since the donor element in the glass particles is difficult to volatilize even during the thermal diffusion treatment (firing), it is suppressed that the n-type diffusion layer is formed not only on the surface but also on the back surface and side surfaces due to the generation of the volatilizing gas. Therefore, by using an n-type diffusion layer forming composition containing a donor element in glass particles, an n-type diffusion layer is formed in a desired region in the semiconductor substrate, and unnecessary n-type diffusion layers are formed on the back surface and side surfaces. Not.

Therefore, if the composition for forming an n-type diffusion layer of the present invention is applied, the side etching step that is essential in the gas phase reaction method that has been widely employed is not required, and the process is simplified. In addition, the step of converting the n-type diffusion layer formed on the back surface into the p ⁺ -type diffusion layer is not necessary. Therefore, the method for forming the p ⁺ -type diffusion layer on the back surface and the material, shape, and thickness of the back electrode are not limited, and the choice of manufacturing method, material, and shape to be applied is widened. Moreover, although mentioned later for details, generation | occurrence | production of the internal stress in the semiconductor substrate resulting from the thickness of a back surface electrode is suppressed, and the curvature of a semiconductor substrate is also suppressed.

  The glass particles contained in the n-type diffusion layer forming composition of the present invention are melted by a thermal diffusion process to form a glass layer on the n-type diffusion layer. However, the glass layer is formed on the n-type diffusion layer also in the conventional gas phase reaction method and the method of applying a phosphate-containing solution or paste. Therefore, the glass layer produced | generated in this invention can be removed by an etching similarly to the conventional method. Therefore, the n-type diffusion layer forming composition of the present invention does not generate unnecessary products and does not increase the number of steps as compared with the conventional method.

  Further, since the n-type diffusion layer forming composition containing a gelling agent has high thixotropy, the semiconductor can be formed by suppressing an increase in line width when a thin line pattern is formed by the n-type diffusion layer forming composition. It can be applied on the substrate, and an n-type diffusion layer having a specific size can be formed in a desired specific region. In the present invention, the fine line shape means a pattern shape having a set width of 200 μm or less.

  Further, when a compound having an ester bond or a compound having a urea group is contained in the n-type diffusion layer forming composition, thixotropic properties can be imparted. That is, the n-type diffusion layer forming composition containing a compound having an ester bond or a compound having a urea group exhibits a high viscosity when the shearing force is low, and exhibits a low viscosity when the shearing force is high. Exhibits sex. Thereby, for example, when printing the n-type diffusion layer forming composition on a semiconductor substrate with a screen printer, when the stress is applied to the n-type diffusion layer forming composition in contact with the scraper or the squeegee by the operation of the scraper or the squeegee, The n-type diffusion layer forming composition has low viscosity and fluidity, and passes through the mesh of the screen plate to form a print on the semiconductor substrate. In addition, the n-type diffusion layer forming composition once formed as a printed material on the semiconductor substrate is in a state where the shape can be maintained without lowering the viscosity unless stress is applied. In other words, by using a compound having an ester bond or a compound having a urea group, it is possible to suppress the expansion of the line width of the fine line-shaped pattern shape on the semiconductor substrate, and further to a desired specific region. In addition, it is possible to form an n-type diffusion layer with a specific size.

As described above, the n-type diffusion layer forming composition of the present invention can form an n-type diffusion layer having a desired concentration in a desired portion of the semiconductor substrate. It is possible to form a selective region having a high (element) concentration. In particular, using the n-type diffusion layer forming composition of the present invention, a selective region having a high n-type dopant concentration (hereinafter, this region may be referred to as “selective emitter”) is formed immediately below the electrode. Te with n ⁺ -type diffusion layer or n ⁺⁺ type diffusion layer, it is possible to reduce the contact resistance between the n-type diffusion layer and the electrode.
Since the selective emitter increases the n-type dopant concentration in a selective region of the semiconductor substrate, a gas phase reaction method, which is a general manufacturing method of an n-type diffusion layer, and a phosphate-containing solution are used. It is difficult to form by the method used.

  The diffusion layer in the present invention includes not only the case where it is formed on the entire surface but also a case where it is formed on a part when the semiconductor substrate is observed as a plan view.

(Glass particles containing donor elements)
The glass particles containing the donor element according to the present invention will be described in detail.
A donor element is an element that can form an n-type diffusion layer by diffusing into a silicon substrate, which is a semiconductor substrate. As the donor element, a Group 15 element can be used, and examples thereof include P (phosphorus), Sb (antimony), As (arsenic), and the like. From the viewpoints of safety, ease of vitrification, etc., P or Sb is preferred.

Examples of the donor element-containing material used for introducing the donor element into the glass particles include P ₂ O ₃ , P ₂ O ₅ , Sb ₂ O ₃ , Sb ₂ O ₅ , Bi ₂ O ₃ , Bi ₂ O ₅ , As _2. O ₃ and As ₂ O ₅ may be mentioned, and it is preferable to use at least one selected from P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ .

Moreover, the glass particle containing a donor element can control a melting temperature, a softening point, a glass transition temperature, chemical durability, etc. by adjusting a component ratio as needed. Furthermore, it is preferable that the glass particle containing a donor element contains the glass component substance described below. _Since P 2 _{O 5} forms the glass _alone, the P 2 _{O 5} is not used in conjunction with the glass component _material, it may be used in P 2 _{O 5} alone.

Examples of glass component materials include SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V ₂ O ₅ , SnO, ZrO ₂ , WO ₃ , _{MoO 3, MnO, La 2 O} 3, Nb 2 O 5, Ta 2 O 5, Y 2 O 3, CsO 2, TiO 2, GeO 2, TeO 2 , and _Lu 2 _{O 3} and the like, _SiO 2, K _{2 O, Na 2 O, Li} 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5, SnO, ZrO 2, MoO 3, GeO 2, Y 2 O 3, CsO 2 And at least one selected from TiO ₂ , SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO It is more preferable to use at least one selected from CdO, V ₂ O ₅ , SnO, ZrO ₂ and MoO _3, and at least selected from SiO ₂ , ZnO, CaO, Na ₂ O, Li ₂ O and BaO. More preferably, one type is used.

Specific examples of the glass particles containing a donor element include a system containing both the donor element-containing substance and the glass component substance, and a P ₂ O ₅ —SiO ₂ system (in order of donor element-containing substance-glass component substance). in described, the same applies _{hereinafter), P 2 O 5 -K 2} O _based, P ₂ O 5 -Na _{2 O-based,} P ₂ O 5 -Li ₂ O _system, P ₂ O 5 _-BaO-based, P 2 _{O 5} - _SrO-based, P ₂ O 5 _-CaO-based, P ₂ O 5 _-MgO-based, P ₂ O 5 -BeO _based, P ₂ O 5 _-ZnO-based, P ₂ O 5 -CdO _based, P ₂ O 5 -PbO system , including _P 2 _O 5 _-V 2 _{O 5 system,} P ₂ O 5 _-SnO-based, P ₂ O 5 -GeO _{2 system,} a _P 2 _{O 5} as a donor element-containing material of P ₂ O 5 -TeO ₂ system, etc. system; and donor element-containing material instead of _P 2 _{O 5} of system containing _P 2 _{O 5} of the And glass particles such as a system containing Sb ₂ O ₃ or P ₂ O ₃ .
Note that glass particles containing two or more kinds of donor element-containing substances may be used, such as P ₂ O ₅ —Sb ₂ O ₃ system and P ₂ O ₅ —As ₂ O ₃ system.
Although the composite glass containing two components was illustrated above, glass particles containing three or more components such as P ₂ O ₅ —SiO ₂ —V ₂ O ₅ and P ₂ O ₅ —SiO ₂ —CaO may be used.

The glass particles include at least one donor element-containing material selected from P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ , SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, _{SrO, CaO, MgO, BeO,} ZnO, PbO, CdO, V 2 O 5, SnO, ZrO 2, MoO 3, GeO 2, Y 2 O 3, at least one glass component is selected from CsO ₂ and TiO ₂ And at least one donor element-containing material selected from P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ , and SiO ₂ , K ₂ O, Na ₂ O, Li _At least one glass component material selected from ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V ₂ O ₅ , SnO, ZrO ₂ and MoO ₃ ; A donor element-containing material that is P ₂ O ₅ and at least one glass component material selected from SiO ₂ , ZnO, CaO, Na ₂ O, Li ₂ O, and BaO. It is more preferable to contain. Thereby, the sheet resistance of the n-type diffusion layer to be formed can be further reduced.

  Examples of the shape of the glass particles include a spherical shape, a flat shape, a block shape, a plate shape, a scale shape, and the like, from the viewpoint of application property to a semiconductor substrate and a uniform diffusibility when it is an n-type diffusion layer forming composition, A spherical shape, a flat shape, or a plate shape is preferable.

The particle diameter of the glass particles is preferably 100 μm or less. When an n-type diffusion layer forming composition containing glass particles having a particle size of 100 μm or less is applied to a semiconductor substrate, a smooth coating film is easily obtained. Furthermore, the particle diameter of the glass particles is more preferably 50 μm or less, and further preferably 10 μm or less. The lower limit of the particle size of the glass particles is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.1 μm or more.
Here, the particle diameter of the glass particles represents a volume average particle diameter, and can be measured by a laser scattering diffraction method particle size distribution measuring apparatus or the like.

Glass particles containing a donor element are produced by the following procedure.
First, raw materials, for example, the donor element-containing material and the glass component material are weighed and filled in a crucible. Examples of the material for the crucible include platinum, platinum-rhodium, iridium, alumina, quartz, carbon and the like, which are appropriately selected in consideration of the melting temperature, atmosphere, reactivity with the molten material, and the like.

  Next, it heats with the temperature according to a glass composition with an electric furnace, and is set as a melt. At this time, it is desirable to stir the melt uniformly. Subsequently, the melt is poured onto a zirconia substrate or a carbon substrate to vitrify the melt. Finally, the glass is crushed into particles. A known method such as a jet mill, a bead mill, or a ball mill can be applied to the pulverization.

The content rate of the glass particle containing the donor element in the n-type diffusion layer forming composition is determined in consideration of the coating property, the diffusibility of the donor element, and the like. In general, the content of the glass particles in the n-type diffusion layer forming composition is preferably 0.1% by mass or more and 95% by mass or less, more preferably 1% by mass or more and 90% by mass or less. It is preferably 1% by mass or more and 80% by mass or less, more preferably 2% by mass or more and 80% by mass or less, and particularly preferably 5% by mass or more and 20% by mass or less.
When the content of the glass particles containing the donor element in the n-type diffusion layer forming composition is 0.1% by mass or more, the n-type diffusion layer can be sufficiently formed on the semiconductor substrate. When the content is 95% by mass or less, the dispersibility of the glass particles in the n-type diffusion layer forming composition is improved, and the coating property of the n-type diffusion layer forming composition to the semiconductor substrate is improved.

(Gelling agent)
The gelling agent as used in the field of this invention means the compound which can gelatinize and solidify a liquid. Generally, whether or not to solidify is greatly influenced by the ratio of the liquid and the gelling agent, but the gelling agent in the composition for forming an n-type diffusion layer of the present invention does not necessarily contain an amount of gelling agent to solidify. The thixotropy can be improved by including a small amount of the gelling agent.

  The content of the gelling agent is preferably 0.01% by mass or more and 5% by mass or less, and preferably 0.1% by mass or more and 3% by mass or less in the n-type diffusion layer forming composition. Is more preferably 0.2% by mass or more and 2% by mass or less, particularly preferably 0.3% by mass or more and 1% by mass or less, 0.4% by mass or more, and 0.7% by mass or more. It is very preferable that the content is not more than mass%. When the content of the gelling agent is 0.01% by mass or more, a sufficient effect of improving printability can be obtained. Further, when the content of the gelling agent is 5% by mass or less, the viscosity or thixotropy does not become too high, and the screen printing workability is improved.

  There is no restriction | limiting in particular in a gelling agent, Either a physical gelling agent and a chemical gelling agent may be sufficient, and it is preferable to use a physical gelling agent. By using a physical gelling agent, the thixotropy tends to be easily adjusted. Among physical gelling agents, it is preferable to use an organic compound that gels by intermolecular hydrogen bonding.

  Physical gelling agents include butyric acid (butyric acid), valeric acid (valeric acid), caproic acid, enanthic acid (heptylic acid), caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid Carboxylic acids such as margaric acid, stearic acid, tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, melicic acid, octylic acid, oleic acid, ricinoleic acid, hydroxystearic acid, isostearic acid; Compound of the carboxylic acid and any one of sodium, potassium, lithium, calcium, barium, zinc, magnesium, aluminum and lead; sorbitol-based organic compound; fine particle silica such as Aerosil (manufactured by Nippon Aerosil Co., Ltd.) Dispalon 305 ( Hydrogenated castor oil type such as Honkasei Co., Ltd .; Cellulose type such as Soroid (Sanki Co., Ltd., quaternary ammonium salt of cellulose sulfate); Leopard KE (Chiba Milling Co., Ltd., dextrin palmitate) Examples thereof include dextrin fatty acid esters such as acid esters); bentonite; and the like.

  As the chemical gelling agent, for example, a monomer, oligomer, polymer or the like having a functional group that can be polymerized or cross-linked represented by an acryloyl group and an epoxy group can be used. The chemical gelling agent is preferably a copolymer containing a cyano group.

A gelling agent may be used individually by 1 type, or may use 2 or more types together.
As the gelling agent, it is more preferable to use hydrogenated castor oil-based, fine-particle silica, or sorbitol-based organic compound, and it is more preferable to use a sorbitol-based organic compound. The sorbitol-based organic compound has a hydroxyl group and an ether bond, and an appropriate thixotropy can be imparted to the n-type diffusion layer forming composition by hydrogen bonding between molecules due to the hydroxyl group and the ether bond. As a result, when an n-type diffusion layer forming composition containing a sorbitol-based organic compound is used to form a fine line-shaped pattern shape on a semiconductor substrate, the line width is prevented from increasing and applied to the semiconductor substrate. It becomes possible.

  As the sorbitol-based organic compound, a compound represented by the following structural formula (1) is preferably used.

In the structural formula (1), R ¹ and R ² each independently represent H or CH ₃ .

  The gelling agent is preferably dissolved in the n-type diffusion layer forming composition. When the gelling agent is dissolved, the effects of the present invention can be expressed more effectively.

The decomposition temperature of the gelling agent is preferably 800 ° C. or lower, and more preferably 400 ° C. or lower. Generation | occurrence | production of a residue after a thermal diffusion process can be suppressed because the decomposition temperature of a gelatinizer is 800 degrees C or less. If the gelling agent, which is a polymer compound, remains on the semiconductor substrate as a residue, it causes a reduction in power generation performance of the solar cell.
The decomposition temperature of the gelling agent can be measured using differential thermal scanning calorimetry (DSC) or simultaneous differential thermal calorimetry (TG / DTA).

(Compound having ester bond or compound having urea group)
When the n-type diffusion layer forming composition contains a compound having an ester bond or a compound having a urea group, the n-type diffusion layer forming composition can have an appropriate shear viscosity, and the printability is improved.
Specifically, the n-type diffusion layer forming composition containing a compound having an ester bond or a compound having a urea group has a shear viscosity at η (D = 0.01 s ⁻¹ and 10 s ⁻¹⁾ , respectively. 0.01s ⁻¹ ) and η (D = 10 s ⁻¹ ), log [η (D = 0.01 s ⁻¹ )] − log [η (D = 10 ⁻¹ )] ≧ 0.3 It is preferable to be prepared as follows.

  In addition, since the n-type diffusion layer forming composition containing a compound having an ester bond or a compound having a urea group has high thixotropy, a thin line pattern is formed on the semiconductor substrate by the n-type diffusion layer forming composition. In this case, the expansion of the line width is suppressed, and the generation of residues on the semiconductor substrate during the thermal diffusion process is suppressed. When an inorganic material is used for the n-type diffusion layer forming composition in order to suppress the expansion of the line width of the pattern, the organic component is removed through drying and degreasing after applying the n-type diffusion layer forming composition to the semiconductor substrate. In some cases, inorganic materials may remain. When the inorganic material remains, the composition of the glass particles containing the donor element is changed by the inorganic material during the thermal diffusion treatment, and as a result, the doping of the donor element may be affected.

  Examples of the compound having an ester bond include compounds such as hydrogenated castor oil, beeswax and carnauba wax (ITOWAX CO-FA (castor oil fatty acid) manufactured by Ito Oil Co., Ltd.); DCO-FA (dehydrated castor oil fatty acid); E-210, E-230, E-250, E-270, E-70G (hydroxystearic acid ester wax); J-50, J-420, J-500, J-550S, J-530.J-630, J -700 (hydroxy fatty acid amide type)).

  As the compound having a urea group, for example, a compound having a medium polar group or a low polar group at its terminal (BIC Chemie Japan, trade name: BYK-410 (special modified urea), 411 (modified urea), 420 (modified) Urea), 425 (urea modified urethane), 428 (polyurethane), 430 (urea modified polyamide), 431 (urea modified polyamide), LPR20320 (special modified urea), P104, P105 and the like.

  From the viewpoint of giving a better pattern shape, it is preferable to use a compound having a urea group among a compound having an ester bond and a compound having a urea group. The reason is considered as follows. When the n-type diffusion layer forming composition contains a compound having a urea group, if no stress is applied to the n-type diffusion layer forming composition, a hydrogen bond is formed between the urea groups of individual molecules to form a network structure. Thus, it is possible to prevent the line width from increasing when the n-type diffusion layer forming composition is applied to the semiconductor substrate in a thin line shape. On the other hand, when stress is applied to the n-type diffusion layer forming composition, the hydrogen bond between urea groups is broken and fluidity is generated, so that the viscosity of the n-type diffusion layer forming composition is lowered and the printability is improved. To do.

  From the viewpoint of more manifesting the effects of the present invention, the compound having a urea group is preferably a urea compound having a medium polar group or a low polarity group at the terminal, and preferably a urea compound having a medium polar group at the terminal. More preferred. BYK-410 etc. are mentioned as a commercial item of the urea compound which has a medium polar group at the terminal.

  The low polar group is a molecular chain having an alkyl group derived from fat or oil or an alkenyl group derived from fat or oil; a molecular chain having an alkyl group having 6 or more carbon atoms or an alkenyl group having 6 or more carbon atoms; a molecular unit having 4 or more carbon atoms A molecular chain having a repeating unit; a molecular chain composed of a rosin skeleton or a hydrogenated rosin skeleton; and the like are preferable. The low polarity group may be one kind of these groups or a combination of two or more kinds. The alkyl group having 6 or more carbon atoms or the alkenyl group having 6 or more carbon atoms related to the low polar molecular chain may be linear, branched or cyclic.

The medium polar group is a group having a polar group in the low polar group or a group having a polar group in a nonpolar group.
Examples of the polar group include a heterocyclic group, a carboxyl group, a hydroxyl group, an amide group, an imide group, a nitro group, an amino group, an ammonium group, a sulfonyl group, a thiol group, a phosphoric acid group, a sulfonic acid group, and a sulfide group. An amide group is preferred. Amide groups are preferred because they are less polar than carboxyl groups, hydroxyl groups and amino groups. The polar group may be a single type of these groups or a combination of two or more types. Examples of the nonpolar group include an alkyl group. The nonpolar group may be a single type of these groups or a combination of two or more types.

  A compound having a low-polar group at the terminal is defined as one that does not cause turbidity or separation when mixed with a low-polarity compound that serves as an index. A compound having a medium polar group at the end is defined as a compound that does not cause turbidity or separation even when mixed with a low-polarity compound serving as an index and a polar compound serving as an index.

  For example, an alkyd resin is obtained by modifying a condensate of a polybasic acid and a polyhydric alcohol with a fatty oil or a fatty acid, and is generally a low polarity compound. A compound which is compatible with the alkyd resin, becomes turbid and does not separate is a compound having a medium polar group or a low polar group at the terminal.

Examples of the low polar compound that serves as an index include nonpolar solvents such as hexane, benzene, toluene, diethyl ether, ethyl acetate, chloroform, and methylene chloride.
Examples of polar compounds that serve as indicators include polar aprotic solvents such as tetrahydrofuran, acetone, acetonitrile, N, N-dimethylformamide, and dimethyl sulfoxide; acetic acid, 1-butanol, 2-propanol, 1-propanol, ethanol, methanol, formic acid, Polar proton solvents such as water; and the like.

The decomposition temperature of the compound having an ester bond or the compound having a urea group is preferably 400 ° C. or lower, more preferably 300 ° C. or lower, and further preferably 250 ° C. or lower.
The decomposition temperature of a compound having an ester bond or a compound having a urea group can be measured using a differential thermal scanning calorimetry (DSC) or a simultaneous differential calorific value calorimeter (TG / DTA).

  The content of the compound having an ester bond or the compound having a urea group is preferably 0.1% by mass or more and 10% by mass or less with respect to 100 parts by mass of the n-type diffusion layer forming composition. More preferably, the content is from 5% by mass to 5% by mass, and further preferably from 1% by mass to 3% by mass. By setting the content of the compound having an ester bond or the compound having a urea group to be 0.1% by mass or more and 10% by mass or less, high thixotropy can be imparted to the n-type diffusion layer forming composition.

(Dispersion medium)
The n-type diffusion layer forming composition of the present invention contains a dispersion medium. The dispersion medium is a medium in which the glass particles are dispersed in the n-type diffusion layer forming composition. Specifically, the dispersion medium includes at least a solvent or water, and includes a thickener as necessary.

  Solvents include acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, methyl n-hexyl ketone, diethyl ketone, dipropyl ketone, Ketone solvents such as diisobutylketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, γ-butyrolactone, γ-valerolactone; diethyl ether, methyl ethyl ether, methyl- n-propyl ether, diisopropyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethylene glycol dimethyl ether, ethylene glycol die Chill ether, ethylene glycol di-n-propyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl n-propyl ether, diethylene glycol methyl n-butyl ether, diethylene glycol di-n-propyl ether , Diethylene glycol di-n-butyl ether, diethylene glycol methyl-n-hexyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol methyl n-butyl ether, triethylene glycol di-n- Butyl ether , Triethylene glycol methyl-n-hexyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetradiethylene glycol methyl ethyl ether, tetraethylene glycol methyl n-butyl ether, diethylene glycol di-n-butyl ether, tetraethylene glycol methyl-n -Hexyl ether, tetraethylene glycol di-n-butyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol dibutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol Methyl ethyl ether , Dipropylene glycol methyl-n-butyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl-n-hexyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, Tripropylene glycol methyl ethyl ether, tripropylene glycol methyl-n-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl-n-hexyl ether, tetrapropylene glycol dimethyl ether, tetrapropylene glycol diethyl ether, tetradipropylene glycol Methyl ethyl ether, tetrapropylene glycol methyl-n-butyl ether Ether solvents such as ether, tetrapropylene glycol di-n-butyl ether, tetrapropylene glycol methyl n-hexyl ether, tetrapropylene glycol di-n-butyl ether; methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, acetic acid n-butyl, isobutyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, 2- (2-butoxyethoxy acetate) ) Ethyl, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diacetate Tylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, isoamyl propionate, diethyl oxalate, Esters such as di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate; ethylene glycol methyl ether propionate, ethylene glycol ethyl ether propionate, ethylene glycol methyl ether acetate , Ethylene glycol ethyl ether acetate, diethylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol-n Ether acetate solvents such as butyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl ether acetate; acetonitrile, N-methylpyrrolidinone, N- Aprotic polar solvents such as ethylpyrrolidinone, N-propylpyrrolidinone, N-butylpyrrolidinone, N-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide; methanol, ethanol , N-propanol, isopropanol, n-butanol, isobutanol, sec -Butanol, t-butanol, n-pentanol, isopentanol, 2-methylbutanol, sec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-hepta Decyl alcohol, phenol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, diethylene glycol, dip Alcohol solvents such as pyrene glycol, triethylene glycol, tripropylene glycol; ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono -Glycol monoether solvents such as n-hexyl ether, ethoxytriglycol, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether; α-terpinene, α-te And the like; Pineoru, myrcene, alloocimene, limonene, dipentene, alpha-pinene, beta-pinene, terpineol, carvone, ocimene, terpene solvent such as phellandrene. These are used singly or in combination of two or more.

  In the case of an n-type diffusion layer forming composition, from the viewpoint of applicability to a semiconductor substrate, the solvent is preferably a terpene solvent, glycol monoether solvent or ester solvent, such as terpineol such as α-terpineol, diethylene glycol mono -N-butyl ether (butyl carbitol) or acetic acid diethylene glycol mono-n-butyl ether (butyl carbitol acetate) is more preferred, α-terpineol or diethylene glycol mono-n-butyl ether is more preferred, and diethylene glycol acetate mono-n-butyl ether is particularly preferred. preferable. When these dispersion media are used, the gelling agent and the thickeners described later (cellulose derivatives, acrylic resins, alkyd resins, etc.) tend to be easily dissolved.

  The composition of the dispersion medium and the content of the dispersion medium in the n-type diffusion layer forming composition are determined in consideration of coating properties and donor concentration. For example, in the n-type diffusion layer forming composition, the content of the solvent can be 10% by mass to 95% by mass, and preferably 50% by mass to 90% by mass.

The n-type diffusion layer forming composition preferably contains a thickener.
Thickeners include polyvinyl alcohol, polyacrylamides, polyvinylamides, polyvinylpyrrolidone, polyethylene oxides, polysulfonic acid, acrylamide alkylsulfonic acid, cellulose ethers, cellulose derivatives, carboxymethylcellulose, hydroxyethylcellulose, ethylcellulose, gelatin, starch , Starch derivatives, sodium alginate, xanthan, guar, guar derivatives, scleroglucan, scleroglucan derivative, tragacanth, tragacanth derivative, dextrin, dextrin derivative, acrylic resin [(meth) acrylic acid resin, (meth) acrylic acid ester Resin (for example, alkyl (meth) acrylate resin and dimethylaminoethyl (meth) acrylate resin), etc.], alkyd resin, Tajien resins, styrene resins, may select and copolymers thereof as appropriate. These are used singly or in combination of two or more.
Among these, it is preferable that the thickener contains at least one selected from cellulose derivatives, acrylic resins, and alkyd resins.

  The molecular weight of the thickener is not particularly limited, and it is desirable to adjust appropriately in view of the desired viscosity as the composition. Further, the constitution of the thickener and the content of the thickener in the n-type diffusion layer forming composition are determined in consideration of coating properties and a desired donor concentration in the semiconductor substrate.

(Inorganic filler)
The n-type diffusion layer forming composition of the present invention may contain an inorganic filler. Examples of the inorganic filler include silica, clay, silicon carbide and the like. Among these, the inorganic filler preferably contains silica. The n-type diffusion layer imparted on the semiconductor substrate in the drying process in which the dispersion medium, the gelling agent, etc. in the n-type diffusion layer formation composition are decomposed or volatilized because the n-type diffusion layer formation composition contains an inorganic filler. Thermal sagging of the layer forming composition can be suppressed. The cause of the thermal sag is considered to be that the viscosity of the dispersion medium, the gelling agent and the like is lowered at a temperature of about 100 ° C. to 500 ° C. at which the dispersion medium, the gelling agent and the like are decomposed or volatilized. In the case where the n-type diffusion layer forming composition contains an inorganic filler, it is considered that since the decrease in the viscosity of the n-type diffusion layer forming composition can be suppressed, thermal sag can be suppressed.

Preferably the BET specific surface area of the inorganic filler is ^{50m 2} / ^g~500m 2 / ^g, and more preferably 100m ² / g~300m 2 / g. As an inorganic filler having such a BET specific surface area, fumed silica can be exemplified. Here, fumed silica refers to ultrafine anhydrous silica, and is produced by hydrolyzing silanes such as silicon tetrachloride in a flame of oxygen and hydrogen. Since fumed silica is synthesized by a gas phase method, the primary particle size is small and the BET specific surface area is large. By using the inorganic filler having the BET specific surface area for the n-type diffusion layer forming composition, an interaction caused by physical and van der Waals forces occurs between the solvent and the inorganic filler whose viscosity is reduced in the drying step, It exists in the tendency which becomes easy to suppress the fall of the viscosity of n type diffused layer formation composition.
The BET specific surface area of the inorganic filler can be calculated by measuring the amount of nitrogen adsorbed at 77K.

  The fumed silica may be hydrophilic or hydrophobic. Hydrophobic fumed silica can be obtained by treating the surface of anhydrous silica with a silane coupling agent or the like.

  The content of the inorganic filler in the n-type diffusion layer forming composition is preferably 0.01% by mass to 40% by mass, more preferably 0.1% by mass to 20% by mass, and 0.2% More preferably, it is 5 mass%-5 mass%. By setting the content of the inorganic filler to 0.01% by mass or more, generation of thermal sag in the drying process is suppressed, and by setting the content to 40% by mass or less, it is possible to ensure the coating characteristics of the n-type diffusion layer forming composition. it can.

(Alkoxysilane)
The n-type diffusion layer forming composition of the present invention may further contain alkoxysilane. When the n-type diffusion layer forming composition contains alkoxysilane, the viscosity of the n-type diffusion layer forming composition tends to be maintained in the drying step after the n-type diffusion layer forming composition is applied to the semiconductor substrate. The alkoxy group constituting the alkoxysilane is preferably a linear or branched alkoxy group, and is a linear or branched alkoxy group having 1 to 24 carbon atoms. It is more preferable that it is a C1-C10 linear or C1-C10 branched alkoxy group, and it is C1-C4 linear or C1-C4. A branched alkoxy group is particularly preferred.

  Specific examples of the alkyl group of the alkoxy group include methyl group, ethyl group, propyl group, butyl group, isopropyl group, isobutyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, t-octyl group, decyl group. Group, dodecyl group, tetradecyl group, 2-hexyldecyl group, hexadecyl group, octadecyl group, cyclohexylmethyl group, octylcyclohexyl group and the like.

As the alkoxysilane, it is preferable to use at least one selected from tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane.
When the n-type diffusion layer forming composition of the present invention contains alkoxysilane, the content of alkoxysilane in the n-type diffusion layer forming composition is not particularly limited, and is preferably 30% by mass or less, and 20% by mass. % Or less is more preferable, and 10 mass% or less is still more preferable.

(Organic filler)
The n-type diffusion layer forming composition of the present invention may contain an organic filler. Organic fillers include urea formalin resin, phenol resin, polycarbonate resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin, polyurethane resin, polyolefin resin, acrylic resin, fluorine resin, polystyrene resin, cellulose, formaldehyde resin, A malon indene resin, lignin, petroleum resin, amino resin, polyester resin, polyether sulfone resin, butadiene resin, a copolymer thereof, and the like can be appropriately selected.
An organic filler is used individually by 1 type or in combination of 2 or more types.

  The molecular weight of the resin used as the organic filler is not particularly limited, and it is desirable to adjust appropriately in view of the desired viscosity as the n-type diffusion layer forming composition.

  Examples of the monomer constituting the acrylic resin include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, N-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, pentyl acrylate, methacryl Pentyl acid, hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate, acrylic Nonyl acid, nonyl methacrylate, decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tetradecyl acrylate, tetradecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, eicosyl acrylate , Eicosyl methacrylate, docosyl acrylate, docosyl methacrylate, cyclopentyl acrylate, cyclopentyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, cycloheptyl acrylate, cycloheptyl methacrylate, benzyl acrylate, benzyl methacrylate, phenyl acrylate , Phenyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, dimethyl methacrylate Aminoethyl, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, 2-chloroethyl acrylate, 2-chloroethyl methacrylate, 2-fluoroethyl acrylate, 2-fluoroethyl methacrylate, styrene, α-methylstyrene, cyclohexylmaleimide, dicyclopentanyl acrylate, dicyclopentanyl methacrylate, vinyl toluene, vinyl chloride, vinyl acetate, N-vinyl pyrrolidone, butadiene, isoprene, chloroprene Etc. These may be used alone or in combination of two or more.

  The particle diameter (volume average particle diameter) of the organic filler is preferably 10 μm or less, and more preferably 0.1 μm or less. When the particle size of the organic filler is 10 μm or less, precipitation of the organic filler is easily suppressed in the n-type diffusion layer forming composition, and clogging is suppressed when printing the n-type diffusion layer forming composition. .

(Other ingredients)
The composition for forming an n-type diffusion layer of the present invention preferably contains substantially no transition metal such as silver, copper, iron, zinc and the transition metal compound (for example, 5% by mass or less). When these transition metals and transition metal compounds are dissolved in the semiconductor substrate, they act as carrier recombination centers in the semiconductor substrate, resulting in a problem of reduced conversion efficiency when the semiconductor substrate is applied to a solar cell. there's a possibility that. As for the content rate of the transition metal and transition metal compound in an n type diffused layer formation composition, it is more preferable that it is 0.5 mass% or less.

(Physical property value)
The viscosity of the n-type diffusion layer forming composition is not particularly limited. For example, the shear viscosity when the shear rate is 10 [1 s ⁻¹ ] is preferably 1 Pa · s to 150 Pa · s (25 ° C.), It is more preferably 5 Pa · s to 100 Pa · s, and further preferably 7 Pa · s to 80 Pa · s. When the shear rate of the n-type diffusion layer forming composition when the shear rate is 10 [1 s ⁻¹ ] is 1 Pa · s or more, the thickness of the coating film in screen printing tends to be uniform, and 150 Pa · s or less. If this is the case, clogging of the screen mask plate tends to be difficult to occur.

The thixotropy of the n-type diffusion layer forming composition is not particularly limited. For example, the logarithm of the shear viscosity η ^x when the shear rate is x [1 / sec] is expressed as log ₁₀ (η ^x ), and the thixotropy is expressed. The TI value is preferably 0.3 to 2.5, and is 1 to 2.2, when the TI value indicating [log ₁₀ (η ^0.01 ) −log ₁₀ (η ¹⁰ )] is More preferably, it is more preferably 1.5 to 2.0. When the TI value is 0.3 or more, the dripping of the n-type diffusion layer forming composition after screen printing on the semiconductor substrate is difficult to occur, and when it is 2.5 or less, the coating amount at the time of continuous printing is stable. Tend to. This tendency is the same in other coating methods such as an ink jet method.

(Method for preparing n-type diffusion layer forming composition)
The method for preparing the n-type diffusion layer forming composition of the present invention is not particularly limited. For example, a blender containing glass particles containing a donor element, a dispersion medium, a gelling agent, at least one selected from a compound having an ester bond and a compound having a urea group, and other additives as necessary. The n-type diffusion layer forming composition of the present invention can be obtained by mixing using a mixer, a mortar or a rotor. Moreover, when mixing, you may heat as needed. When heating at the time of mixing, the temperature can be 30 degreeC-100 degreeC, for example.

  When using the said gelling agent, it is preferable to pass through the process of once melt | dissolving a gelling agent in a dispersion medium. Once dissolved, the n-type diffusion layer forming composition can be given more appropriate thixotropy. Once dissolved, the gelling agent may be in a dissolved state or in a precipitated state.

  The components contained in the n-type diffusion layer forming composition and the content of each component are confirmed using thermal analysis such as TG / DTA, NMR, HPLC, GPC, GC-MS, IR, MALDI-MS, etc. be able to.

<The manufacturing method of an n type diffused layer, and the manufacturing method of a photovoltaic cell>
The method for producing an n-type diffusion layer of the present invention includes a step of applying the n-type diffusion layer forming composition on a semiconductor substrate and a step of applying a thermal diffusion treatment to the semiconductor substrate to which the n-type diffusion layer forming composition is applied. And having.
Moreover, the manufacturing method of the positive battery cell of this invention performs the process of providing the said n type diffused layer formation composition on a semiconductor substrate, and a thermal diffusion process to the semiconductor substrate which provided the n type diffused layer formation composition. Forming an n-type diffusion layer and forming an electrode on the formed n-type diffusion layer.

  Next, the manufacturing method of the n type diffused layer and photovoltaic cell of this invention is demonstrated, referring FIG. FIG. 1 is a schematic cross-sectional view conceptually showing an example of the manufacturing process of the solar battery cell of the present invention. In the subsequent drawings, common constituent elements are denoted by the same reference numerals.

In FIG. 1A, an alkaline solution is applied to a silicon substrate that is a p-type semiconductor substrate 10 to remove a damaged layer, and a texture structure is obtained on the surface of the p-type semiconductor substrate 10 by etching.
Specifically, the damaged layer on the surface of the silicon substrate generated when slicing from the ingot is removed with 20% by mass caustic soda. Next, etching is performed with a mixed solution of 1% by mass caustic soda and 10% by mass isopropyl alcohol to form a texture structure (the description of the texture structure is omitted in the figure). In the solar battery cell, by forming a texture structure on the light receiving surface (front surface) side, a light confinement effect is promoted and high efficiency is achieved.

In FIG. 1 (2), the n-type diffusion layer forming composition layer 11 is formed by applying the n-type diffusion layer forming composition to the surface of the p-type semiconductor substrate 10, that is, the surface serving as the light receiving surface. In this invention, there is no restriction | limiting in the application | coating method of n type diffused layer formation composition, For example, a printing method, a spin method, a brush coating method, a spray method, a doctor blade method, a roll coater method, and an inkjet method is mentioned.
Particular restriction on the application amount of the n-type diffusion layer forming composition is not, for example, as the application amount of the glass particles contained in the n-type diffusion layer forming ^composition, and 0.01g / ^{m 2} ~100g / m 2 it ^can, it is preferred that ^{0.1g / m 2 ~10g / m 2} .

  Depending on the composition of the n-type diffusion layer forming composition, the solvent contained in the n-type diffusion layer forming composition after being applied to the p-type semiconductor substrate 10 is volatilized, so that a drying step may be necessary. In this case, drying is performed at a temperature of about 80 ° C. to 300 ° C. for about 1 minute to 10 minutes when using a hot plate, and about 10 minutes to 30 minutes when using a dryer. The drying conditions depend on the solvent composition of the n-type diffusion layer forming composition, and are not particularly limited to the above conditions in the present invention.

When the manufacturing method of the present invention is used, the method for forming the p ⁺ -type diffusion layer (high-concentration electric field layer) 14 on the back surface is limited to a method by conversion from an n-type diffusion layer to a p-type diffusion layer using aluminum. In this case, any conventionally known method can be adopted, and the choice of forming method is expanded. Therefore, for example, the high-concentration electric field layer 14 can be formed by applying the composition 13 containing a Group 13 element such as B (boron).

Next, the p-type semiconductor substrate 10 on which the n-type diffusion layer forming composition layer 11 is formed is subjected to thermal diffusion treatment at 600 ° C. to 1200 ° C. By this thermal diffusion treatment, the donor element diffuses into the p-type semiconductor substrate 10 as shown in FIG. A known continuous furnace, batch furnace, or the like can be applied to the thermal diffusion treatment. Further, the furnace atmosphere during the thermal diffusion treatment can be appropriately adjusted to air, oxygen, nitrogen or the like.
The time for the thermal diffusion treatment can be appropriately selected according to the content of the donor element contained in the n-type diffusion layer forming composition. For example, it can be 1 minute to 60 minutes, and more preferably 2 minutes to 30 minutes.

  Since a glass layer (not shown) such as phosphate glass is formed on the surface of the formed n-type diffusion layer 12, this phosphate glass is removed by etching. As the etching, a known method such as a method of immersing in an acid such as hydrofluoric acid or a method of immersing in an alkali such as caustic soda can be applied.

In the method for producing an n-type diffusion layer of the present invention, in which the n-type diffusion layer 12 is formed using the n-type diffusion layer forming composition of the present invention shown in FIGS. The n-type diffusion layer 12 is formed in this part, and an unnecessary n-type diffusion layer is not formed on the back and side surfaces.
Therefore, in the conventional method of forming an n-type diffusion layer by a gas phase reaction method, a side etching process for removing an unnecessary n-type diffusion layer formed on a side surface is essential. According to the manufacturing method of the invention, the side etching process is not required, and the process is simplified.

Further, in the conventional manufacturing method, it is necessary to convert an unnecessary n-type diffusion layer formed on the back surface into a p-type diffusion layer. As this conversion method, a group 13 element is added to the n-type diffusion layer on the back surface. A method is adopted in which a certain aluminum paste is applied and baked to diffuse aluminum into the n-type diffusion layer and convert it into a p-type diffusion layer. In this method, conversion to the p-type diffusion layer is sufficient, and in order to form a high-concentration electric field layer of the p ⁺ -type diffusion layer, a certain amount of aluminum is required. There was a need to form. However, the thermal expansion coefficient of aluminum is greatly different from the thermal expansion coefficient of silicon used as a semiconductor substrate. Therefore, a large internal stress is generated in the semiconductor substrate during the firing and cooling process, which causes warpage of the semiconductor substrate. It was.
This internal stress damages the crystal grain boundary when crystalline silicon is used as the semiconductor substrate, and there is a problem that power loss increases in a solar cell using this semiconductor substrate. Further, the warpage of the semiconductor substrate easily damages the solar battery cell when the solar battery cell is transported in the module process and when it is connected to a copper wire called a tab wire. In recent years, the thickness of a silicon substrate, which is a semiconductor substrate, is being made thinner due to improvements in slicing technology, and solar cells tend to be easily broken.

  However, according to the manufacturing method of the present invention, since an unnecessary n-type diffusion layer is not formed on the back surface, it is not necessary to perform conversion from the n-type diffusion layer to the p-type diffusion layer, and it is necessary to increase the thickness of the aluminum layer. Disappear. As a result, generation of internal stress in the semiconductor substrate and warpage of the semiconductor substrate can be suppressed. As a result, it is possible to suppress an increase in power loss and damage of the solar battery cell in the solar battery using this semiconductor substrate.

Further, when the manufacturing method of the present invention is used, the manufacturing method of the p ⁺ -type diffusion layer (high concentration electric field layer) 14 on the back surface is limited to a method by conversion from an n-type diffusion layer to a p-type diffusion layer by aluminum. However, either method can be adopted, and the choice of manufacturing method is expanded.
Further, as will be described later, the material used for the front surface electrode (back surface electrode) 20 on the back surface is not limited to Group 13 aluminum, and Ag (silver), Cu (copper), etc. can be applied. It is possible to form a thinner thickness than the conventional one.

In FIG. 1 (4), an antireflection film 16 is formed on the n-type diffusion layer 12. The antireflection film 16 is formed by applying a known technique. For example, when the antireflection film 16 is a silicon nitride film, it is formed by a plasma CVD method using a mixed gas of SiH ₄ and NH ₃ as a raw material. At this time, hydrogen diffuses into the silicon crystal, which is a semiconductor substrate, and orbitals (ie, dangling bonds) that do not contribute to bonding of silicon atoms are combined with hydrogen to inactivate defects (hydrogen passivation) of the silicon crystal.
More specifically, the mixed gas flow ratio NH ₃ / SiH ₄ is 0.05 to 1.0, the reaction chamber pressure is 13.3 Pa to 266.6 Pa (0.1 Torr to 2 Torr), The silicon nitride film is formed under conditions where the temperature is 300 ° C. to 550 ° C. and the frequency for plasma discharge is 100 kHz or more.

  In FIG. 1 (5), a surface electrode metal paste is printed on the surface (light receiving surface) of the antireflection film 16 by a screen printing method and then dried to form the surface electrode 18. The metal paste for a surface electrode includes (1) metal particles and (2) glass particles as essential components, and includes (3) a resin binder, (4) other additives, and the like as necessary.

  Next, the back electrode 20 is also formed on the high-concentration electric field layer 14 on the back surface. As described above, the material and the forming method of the back electrode 20 are not particularly limited in the present invention. For example, the back electrode 20 may be formed by applying a metal paste for the back electrode including a metal such as aluminum, silver, or copper, and drying the paste. At this time, you may provide the silver paste for silver electrode formation in a part of back surface for the connection between the photovoltaic cells in a module process.

  In FIG. 1 (6), an electrode is baked and a photovoltaic cell is completed. When firing for several seconds to several minutes in the range of 600 ° C. to 900 ° C., the antireflection film 16 that is an insulating film is melted by the glass particles contained in the metal paste for the surface electrode on the surface side, and the surface of the p-type semiconductor substrate 10 is also one. The metal particles (for example, silver particles) in the paste form a contact portion with the p-type semiconductor substrate 10 and are solidified. Thereby, the formed surface electrode 18 and the p-type semiconductor substrate 10 are electrically connected. This is called fire-through.

  The shape of the surface electrode 18 will be described. The surface electrode 18 includes a bus bar electrode 30 and finger electrodes 32 intersecting with the bus bar electrode 30. FIG. 2A is a plan view of a solar cell in which the surface electrode 18 includes a bus bar electrode 30 and a finger electrode 32 intersecting with the bus bar electrode 30 as viewed from the light receiving surface (front surface). FIG. 2B is an enlarged perspective view showing a part of FIG.

  Such a surface electrode 18 can be formed, for example, by means such as screen printing of the above-described metal paste for surface electrode, plating of the electrode material, or vapor deposition of the electrode material by electron beam heating in a high vacuum. The surface electrode 18 composed of the bus bar electrode 30 and the finger electrode 32 is generally used as an electrode on the light receiving surface side and is well known, and it is possible to apply known forming means for the bus bar electrode and finger electrode on the light receiving surface side. it can.

In the above description, the solar cell in which the n-type diffusion layer is formed on the front surface, the p ⁺ -type diffusion layer is formed on the back surface, and the front electrode and the back electrode are further provided on the respective diffusion layers has been described. If the diffusion layer forming composition is used, a back contact type solar battery cell can be produced.
The back contact type solar battery cell has all electrodes provided on the back surface to increase the area of the light receiving surface. That is, in the back contact solar cell, it is necessary to form both the n-type diffusion region and the p ⁺ -type diffusion region on the back surface to form a pn junction structure. The composition for forming an n-type diffusion layer of the present invention can form an n-type diffusion site in a specific region of a p-type semiconductor substrate, and is therefore preferably applied to the production of a back-contact type solar cell. Can do. Specifically, FIG. 3 is a cross-sectional view conceptually showing an example of the manufacturing process of the back contact solar cell according to the present invention.

A p-type diffusion layer forming composition and an n-type diffusion layer forming composition are partially applied to the surface of one surface of the p-type semiconductor substrate 1, respectively, and subjected to thermal diffusion treatment, whereby a p ⁺ -type diffusion layer is formed. The 3 and n type diffusion layers 6 can be formed in specific regions, respectively. Examples of a method for applying the p-type diffusion layer forming composition and the n-type diffusion layer forming composition include an ink jet method or a pattern printing method.
As a result, as shown in FIG. 3A, the heat-treated material layer 2 of the p-type diffusion layer forming composition is formed on the p ⁺ -type diffusion layer 3 of the p-type semiconductor substrate 1. A heat-treated product layer 5 of the n-type diffusion layer forming composition is formed thereon.

Next, as shown in FIG. 3B, the p-type diffusion layer forming composition formed on the p ⁺ -type diffusion layer 3 was formed on the heat-treated product layer 2 and the n-type diffusion layer 6. The heat-treated product layer 5 of the n-type diffusion layer forming composition is removed by etching or the like. Thereby, the p ⁺ -type diffusion layer 3 and the n-type diffusion layer 6 are selectively formed in the vicinity of the surface of the p-type semiconductor substrate 1.

Next, an antireflection film or a surface protective film 7 is formed on the p-type semiconductor substrate 1 by a conventional method. At this time, as shown in FIG. 3C1, an antireflection film or a surface protection film 7 is partially formed so that at least a part of the p ⁺ type diffusion layer 3 and the n type diffusion layer 6 is exposed on the surface. May be. Alternatively, as shown in FIG. 3 (c2), an antireflection film or a surface protective film 7 may be formed so as to cover the p ⁺ type diffusion layer 3 and the n type diffusion layer 6.

Next, by selectively applying an electrode paste on the p ⁺ -type diffusion layer 3 and the n-type diffusion layer 6 and performing thermal diffusion treatment, as shown in FIG. 3D, the p ⁺ -type diffusion layer 3 and n The electrode 4 and the electrode 8 can be formed on the mold diffusion layer 6, respectively.
In the case where an antireflection film or a surface protective film 7 is formed so as to cover the p ⁺ type diffusion layer 3 and the n type diffusion layer 6 as shown in FIG. By using the one containing particles, the electrode 4 and the electrode 8 can be formed on the p ⁺ -type diffusion layer 3 and the n-type diffusion layer 6 as shown in FIG.

  In the solar cell manufactured by the manufacturing method including the manufacturing process shown in FIG. 3, since no electrode exists on the light receiving surface, sunlight can be taken in effectively.

The entire disclosures of Japanese applications 2012-043445 and 2012-040994 are incorporated herein by reference.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

  Examples of the present invention will be described more specifically below, but the present invention is not limited to these examples. Unless otherwise stated, all chemicals used reagents. “%” Means “% by mass” unless otherwise specified.

<Example 1>
(Synthesis of glass particles)
SiO ₂ (manufactured by Wako Pure Chemical Industries, Ltd.), P ₂ O ₅ (manufactured by Wako Pure Chemical Industries, Ltd.), CaCO ₃ (manufactured by Wako Pure Chemical Industries, Ltd.) are used as raw materials, and the respective molar ratios are SiO ₂ : _{P 2 O 5: CaO = 30} : 60: 10 were mixed so that, placed in an alumina crucible, after heating at 400 ° C. / h up to 1400 ° C., held for 1 hour and then quenched. This was pulverized by an automatic mortar kneader to obtain glass particles containing a donor element.
When the powder X-ray diffraction (XRD) pattern of the obtained glass particles was measured with an X-ray diffractometer (RINT-2000, manufactured by Rigaku Corporation) using Cu-Kα rays using a Ni filter, it was obtained. The glass particles were confirmed to be amorphous.

(Preparation of solution containing glass particles)
30 g of glass particles containing a donor element, terpineol (Nippon Terpene Chemical Co., Ltd.) as a dispersion medium, 30% by mass glass particle / terpineol solution (solution containing 30% by mass of glass particles with respect to 100 parts by mass of the total amount of terpineol and glass particles) ) And ground in a planetary ball mill (manufactured by Fritsch) using 1 mm yttria-stabilized zirconia beads. The obtained product is a solution containing glass particles. The volume average particle size of the glass particles at this time was measured by a laser diffraction particle size distribution measuring device and found to be 0.3 μm.

(Preparation of solution containing gelling agent)
3% by mass of ethyl cellulose (Etocel STD300 manufactured by Nihon Kasei Co., Ltd., ethylation rate 50%) and Gelol D (manufactured by Shin Nippon Chemical Co., Ltd., the following structural formula (2), 1, 3: 2, A terpineol (Nihon Terpene Chemical Co., Ltd.) solution containing 0.9% by mass of 4-bis-O-benzylidene-D-glucitol (dibenzylidene sorbitol) was dissolved at 160 ° C. over 30 minutes, and then cooled to 25 ° C. 3 mass% ethyl cellulose / 0.9 mass% gelol D / terpineol solution (solution containing 3 mass% ethyl cellulose and 0.9 mass% gelol D with respect to 100 mass parts of the total amount of terpineol, ethyl cellulose and gelol D) Was prepared. This is a solution containing a gelling agent.

(Preparation of n-type diffusion layer forming composition)
10 g of a solution containing glass particles and 20 g of a solution containing a gelling agent were mixed in a mortar to prepare an n-type diffusion layer forming composition (hereinafter also simply referred to as “paste”).

(Thermal diffusion and etching process)
The obtained paste was applied by screen printing on the surface of a sliced p-type silicon substrate (hereinafter also referred to as “p-type slice silicon substrate”). The squeegee speed and scraper speed during screen printing were both 300 mm / sec. The printing pattern was printed with two types of masks: a solid pattern of 45 mm × 45 mm and a linear pattern with a width of 150 μm. After application, the paste on the p-type silicon substrate was dried on a hot plate at 150 ° C. for 5 minutes, and then air was supplied at 5 L / min. Thermal diffusion treatment was performed for 10 minutes in a 900 ° C. tunnel furnace flowed in Thereafter, in order to remove the glass layer formed on the surface of the p-type silicon substrate, the p-type silicon substrate is immersed in a 2.5 mass% HF aqueous solution for 6 minutes, and then washed with running water and ultrasonically. And drying was performed to obtain a p-type silicon substrate on which an n-type diffusion layer was formed.
Further, a p-type mirror wafer having a p-type diffusion layer formed was obtained in the same manner except that a p-type mirror wafer was used instead of the p-type slice silicon substrate. Table 1 shows the evaluation results when using a p-type slice silicon substrate.

[Evaluation]
(Evaluation of thixotropy of n-type diffusion layer forming composition)
Using a viscoelasticity measuring device (MCR-301, manufactured by Anton-Parr), the shear viscosity of the n-type diffusion layer forming composition is 25 ° C. within a shear rate range of 0.01 to 10 [s ⁻¹ ]. Measured with The results are shown in Table 1. In addition, the logarithm of the shear viscosity η ^x when the shear rate is x [1 / sec] is expressed as log ₁₀ (η ^x ), and the TI value indicating thixotropy is [log ₁₀ (η ^0.01 ) −log _10. (Η ¹⁰ )].

(Measurement of printing width)
The n-type diffusion layer forming composition is applied to the surface of the p-type slice silicon substrate in a linear pattern having a width of 150 μm, and the linear pattern width after drying at 150 ° C. is measured with an optical microscope (Olympus Corporation, MX-51) Observed. The linear pattern width after drying was 170 μm, and the print width increase rate with respect to the mask setting width of 150 μm was 113%.

(Sheet resistance measurement)
The sheet resistance of the surface of the p-type slice silicon substrate on which the n-type diffusion layer was formed was measured by a four-probe method using a Loresta-EP MCP-T360 type low resistivity meter manufactured by Mitsubishi Chemical Corporation. The sheet resistance of the portion where the n-type diffusion layer forming composition was applied was 40Ω / □.

<Examples 2 to 5, Comparative Examples 1 and 2>
An n-type diffusion layer forming composition was prepared so as to have the composition shown in Table 1, and evaluation was performed in the same manner as in Example 1 except that each n-type diffusion layer forming composition was used. In Table 1, the numerical value described in the column of composition indicates mass% with respect to the total amount of the n-type diffusion layer forming composition. The evaluation results are shown in Table 1. In addition, the used component is as follows.

Gelol MD; manufactured by Shin Nippon Rika Co., Ltd., the following structural formula (3), 1,3: 2,4-bis-O- (4-methylbenzylidene) -D-sorbitol fumed silica; manufactured by Nippon Aerosil Co., Ltd. AEROSIL 200 (BET specific surface area: 200 m ² / g)

  As shown in Examples 1 to 5, when an n-type diffusion layer forming composition containing a gelling agent was used, it was possible to suppress the expansion of the pattern line width in the surface direction on the semiconductor substrate after printing. . Also, good sheet resistance and TI value were given. On the other hand, in Comparative Examples 1 and 2 of the n-type diffusion layer forming composition containing no gelling agent, the printing width increase rate was large, and it was not possible to suppress the expansion of the pattern line width.

  As described above, by using the n-type diffusion layer forming composition containing the gelling agent, the printing width increase rate is close to 100%, and the expansion of the contact area of the pattern shape in the surface direction on the semiconductor substrate can be suppressed. it can.

[Example 6]
Glass particles (P ₂ O ₅ : 50%, SiO ₂ : 43%, CaO: 7%) 10%, ethyl cellulose 5%, α-terpineol 83.5%, and urea compound solution BYK-410 (BIC Chemie Japan Co., Ltd.) 1.5% of a compound having a medium polar group at the end) was mixed into a paste to prepare an n-type diffusion layer forming composition 6.
When the shear viscosity of the n-type diffusion layer forming composition 6 was examined in the same manner as in Example 1, the shear viscosity at a shear rate of 0.01 / s was 545 Pa · s, whereas the shear viscosity at a shear rate of 10 / s. Was 27 Pa · s, the TI value was 1.31, and high thixotropy was obtained.

  Further, in the same manner as in Example 1, except that instead of the n-type diffusion layer forming composition 6, screen printing was performed with a squeegee speed and a scraper speed of 300 mm / sec. The linear pattern width after coating with a linear pattern and drying at 50 ° C. was measured with an optical microscope manufactured by Olympus Corporation. The line width of the pattern was 180 μm, and the line thickness from the mask setting width of 150 μm was within 35 μm.

  The sheet resistance of the portion where the n-type diffusion layer forming composition 6 was applied was 40Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the back surface to which the n-type diffusion layer forming composition 6 was not applied was 1000000 Ω / □ or more, which was not measurable, and no n-type diffusion layer was formed.

[Example 7]
Glass particles (P ₂ O ₅ : 50%, SiO ₂ : 43%, CaO: 7%) 10%, ethyl cellulose 5%, α-terpineol 80%, and urea compound solution BYK-410 (manufactured by Big Chemie Japan) 5 % Was made into a paste to prepare an n-type diffusion layer forming composition 7.
When the shear viscosity of the n-type diffusion layer forming composition 7 was examined in the same manner as in Example 1, the shear viscosity at a shear rate of 0.01 / s was 580 Pa · s (25 ° C.), while the shear rate was 30 / The shear viscosity at s was 1.36 Pa · s, the TI value was 2.63, and high thixotropic properties were obtained.

  Using this n-type diffusion layer forming composition 7, as in Example 6, screen printing was performed with both the squeegee speed and the scraper speed being 300 mm / sec, and a linear pattern with a width of 150 μm was formed on the surface of the p-type silicon substrate. When the linear pattern width after coating at 50 ° C. and measuring with an optical microscope manufactured by Olympus Corporation was 185 μm, the line thickness from the mask setting width of 150 μm was within 35 μm.

  The sheet resistance of the portion where the n-type diffusion layer forming composition 7 was applied was 40Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the back surface to which the n-type diffusion layer forming composition 7 was not applied was 1000000 Ω / □ or more, which was not measurable, and no n-type diffusion layer was formed.

[Example 8]
Glass particles (P ₂ O ₅ : 50%, SiO ₂ : 43%, CaO: 7%) 10%, ethyl cellulose 5%, α-terpineol 80%, and urea compound solution BYK-411 (manufactured by Big Chemie Japan) 5 % Was made into a paste to prepare an n-type diffusion layer forming composition 8.
When the shear viscosity of the n-type diffusion layer forming composition 8 was examined in the same manner as in Example 1, the shear viscosity at a shear rate of 0.01 / s was 500 Pa · s (25 ° C.), while the shear rate was 30 / The shear viscosity at s was 10 Pa · s, the TI value was 1.70, and high thixotropy was obtained.

  Using this n-type diffusion layer forming composition 8, as in Example 6, screen printing with both the squeegee speed and scraper speed of 300 mm / sec was performed, and a 150 μm wide linear pattern was formed on the surface of the p-type silicon substrate. The linear pattern width after coating at 50 ° C. and measured with an optical microscope manufactured by Olympus Corporation was 190 μm, and the line thickness from the mask setting width of 150 μm was within 40 μm.

  The sheet resistance of the portion where the n-type diffusion layer forming composition 8 was applied was 40Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the back surface to which the n-type diffusion layer forming composition 8 was not applied was 1000000 Ω / □ or more, which was not measurable, and no n-type diffusion layer was formed.

[Comparative Example 3]
Glass particles (P ₂ O ₅ : 50%, SiO ₂ : 43%, CaO: 7%) 10%, ethyl cellulose 6.8%, and α-terpineol 83.2% were mixed to make a paste, and a comparative n-type A diffusion layer forming composition was prepared.
When the shear viscosity of the comparative n-type diffusion layer forming composition was examined in the same manner as in Example 1, the shear viscosity at a shear rate of 0.01 / s was 176 Pa · s (25 ° C.), while the shear rate was 10 The shear viscosity at / s was 68 Pa · s, the TI value was 0.41, and sufficient thixotropy was not obtained.

  Using this comparative n-type diffusion layer forming composition, as in Example 6, screen printing was performed with both the squeegee speed and scraper speed set to 300 mm / sec, and a 150 μm wide linear pattern was formed on the p-type silicon substrate surface. When it applied by the pattern, the comparative n type diffused layer formation composition was not printed in linear form, but the disconnection was seen in some places.

  An n-type diffusion layer forming composition containing a compound containing a donor element of the present invention, a dispersion medium, a gelling agent, at least one selected from a compound having an ester bond and a compound having a urea group, It is possible to suppress the expansion of the line width of the fine line pattern on the semiconductor substrate and to form an n-type diffusion layer with a specific size in a desired specific region of the semiconductor substrate. . In the present invention, by using at least one selected from a gelling agent, a compound having an ester bond, and a compound having a urea group, an appropriate shear viscosity can be imparted to the n-type diffusion layer forming composition, Good printability can be provided.

Claims (13)

  An n-type diffusion layer forming composition containing glass particles containing a donor element, a dispersion medium, a gelling agent, a compound having an ester bond, and at least one selected from a compound having a urea group. The composition for forming an n-type diffusion layer according to claim 1, comprising the gelling agent, wherein the gelling agent is an organic compound represented by the following structural formula (1).

[In Structural Formula (1), R ¹ and R ² each independently represent H or CH ₃ . ]   The content of the glass particles containing the gelling agent and containing the donor element is 1% by mass or more and 80% by mass or less, and the content of the gelling agent is 0.01% by mass or more and 5% by mass or less. The n-type diffusion layer forming composition according to claim 1 or 2, wherein   2. The n-type diffusion layer according to claim 1, comprising a compound having an ester bond or a compound having a urea group, wherein a decomposition temperature of the compound having an ester bond or the compound having a urea group is 400 ° C. or lower. Forming composition.   The compound having the ester bond or the compound having the urea group, the content of the glass particles containing the donor element is 1% by mass or more and 80% by mass or less, and the compound or urea group having the ester bond is 5. The n-type diffusion layer forming composition according to claim 1, wherein the content of the compound is 0.1% by mass or more and 10% by mass or less.   The composition for forming an n-type diffusion layer according to claim 1, which contains a compound having a urea group, and the compound having a urea group is a urea compound having a medium polar group at its terminal. The glass particles containing the donor element include at least one donor element-containing material selected from P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ , SiO ₂ , K ₂ O, Na ₂ O, Li _2. And at least one glass component material selected from O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V ₂ O ₅ , SnO, ZrO ₂ and MoO ₃ . The n type diffused layer formation composition of any one of Claim 6.   Furthermore, the n-type diffused layer formation composition of any one of Claims 1-7 containing the at least 1 type of thickener chosen from a cellulose derivative, an acrylic resin, and an alkyd resin.   Furthermore, the n type diffused layer formation composition of any one of Claims 1-8 containing an inorganic filler.   The n-type diffusion layer forming composition according to claim 9, wherein the inorganic filler is fumed silica.   The n-type diffused layer formation composition of any one of Claims 1-10 whose volume average particle diameters of the glass particle containing the said donor element are 0.1 micrometer or more and 10 micrometers or less.   A step of applying the n-type diffusion layer forming composition according to any one of claims 1 to 11 on the semiconductor substrate, and applying a thermal diffusion treatment to the semiconductor substrate to which the n-type diffusion layer forming composition has been applied. And a step of applying the n-type diffusion layer.   A step of applying the n-type diffusion layer forming composition according to any one of claims 1 to 11 on the semiconductor substrate, and applying a thermal diffusion treatment to the semiconductor substrate to which the n-type diffusion layer forming composition has been applied. The manufacturing method of the photovoltaic cell which has the process of forming and forming an n-type diffused layer and forming an electrode on the formed n-type diffused layer.