TW201331991A - N-type diffusion layer forming composition, n-type diffusion layer forming composition set, method for producing semiconductor substrate having n-type diffusion layer, and method for producing photovoltaic cell element - Google Patents

Abstract

The invention provides a n-type diffusion layer forming composition, including: a compound which contains a donor element; a metal compound that is different from the compound which contains a donor element, and contains at least one metal selected from a group consist of an alkali earth metal and an alkali metal; and a dispersion medium. The invention also provides a method for producing a semiconductor substrate having a n-type diffusion layer. The method includes applying the n-type diffusion layer forming composition on a semiconductor substrate to form a composition layer, and performing a heat-treating on the semiconductor substrate formed with the composition layer.

Description

N-type diffusion layer forming composition, n-type diffusion layer forming composition set, manufacturing method of semiconductor substrate with n-type diffusion layer, and manufacturing method of solar cell element

The present invention relates to an n-type diffusion layer forming composition, an n-type diffusion layer forming composition kit, a method of manufacturing a semiconductor substrate having an n-type diffusion layer, and a method of manufacturing a solar cell element.

The manufacturing steps of the prior 矽 solar cell element (solar cell) will be described.

First, in order to promote the light blocking effect and to improve the efficiency, a p-type germanium substrate having a texture structure formed on the light receiving surface, and then a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen gas, and oxygen is prepared. Next, the treatment was performed at 800 ° C to 900 ° C for several tens of minutes to form an n-type diffusion layer in the same manner. In this prior method, since phosphorus is diffused by using a mixed gas, an n-type diffusion layer is formed not only on the surface but also on the side surface and the back surface. Therefore, a side etching step for removing the side n-type diffusion layer is required. In addition, the n-type diffusion layer on the back side must 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, heat treatment is performed, and the n-type diffusion layer is converted into a p ⁺ -type diffusion layer by diffusion of aluminum while obtaining an ohmic contact. .

In the method for producing a solar cell element, a method of producing 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. An n-type diffusion layer is formed in a specific region without forming an unnecessary n-type diffusion layer on the side surface or the back surface of the semiconductor substrate (for example, refer to International Publication No. 2011/090216).

On the other hand, as a structure of a solar cell element for the purpose of improving conversion efficiency, a selective emitter structure is known which has a low diffusion concentration of a donor element in a region other than immediately below the electrode. The diffusion concentration of the donor element in the region directly under the electrode (hereinafter, also referred to as "diffusion concentration") (for example, refer to L. Debarge, M. Schott, J Culler, R. Monna, "Solar Materials and Solar Cells"). (Solar Energy Materials & Solar Cells) 74 (2002) 71-75.). In this configuration, since a region having a high diffusion concentration (hereinafter referred to as a "selective emitter") is formed directly under the electrode, the contact resistance between the electrode and the crucible can be reduced. Further, the diffusion concentration is relatively low in the region where the electrode is formed, so that the conversion efficiency of the solar cell element can be improved.

However, in order to form a selection using the formation method of the previous n-type diffusion layer The selective emitter structure requires a complicated step of combining multiple thermal diffusion processes with partial etching by masking or the like.

The present invention has been made in view of the above problems, and an object of the invention is to provide an n-type diffusion layer forming composition, a method for producing a semiconductor substrate with an n-type diffusion layer, and a method for manufacturing a solar cell element. The n-type diffusion layer forming composition can form an n-type diffusion layer in a specific region, and can easily adjust the diffusion concentration of the donor element in the formed n-type diffusion layer.

The specific means for solving the above problems are as follows.

<1> An n-type diffusion layer forming composition comprising: a compound containing a donor element; a metal compound which is a compound different from the above-described compound containing a donor element, and contains a compound selected from the group consisting of alkaline earth metals and alkali metals At least one metal element in the group; and a dispersion medium.

<2> The n-type diffusion layer forming composition according to the above <1>, wherein the compound containing the donor element is a compound containing P (phosphorus).

The n-type diffusion layer forming composition according to the above <1> or <2>, wherein the metal compound is selected from the group consisting of magnesium, calcium, sodium, potassium, lithium, cesium, lanthanum, cerium, lanthanum, cerium And a compound of at least one metal element in the group consisting of radium.

The n-type diffusion layer forming composition according to any one of the above-mentioned, wherein the content of the metal compound is 0.01% by mass or more. 50% by mass or less.

The n-type diffusion layer forming composition according to any one of the above-mentioned, wherein the metal compound is solid at a normal temperature, and the volume average particle diameter of the particles is 0.01 μm or more. , 30 μm or less.

The n-type diffusion layer forming composition according to any one of the above-mentioned, wherein the compound containing the donor element is selected from the group consisting of P ₂ O ₃ and P ₂ O ₅ . At least one compound in the group.

The n-type diffusion layer forming composition according to any one of the above-mentioned <1>, wherein the compound containing the donor element is in the form of glass particles.

The n-type diffusion layer forming composition according to the above <7>, wherein the glass particles contain at least one donor element-containing element selected from the group consisting of P ₂ O ₃ and P ₂ O ₅ . a substance, and selected from the group consisting of 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 and MoO ₃ At least one glass component substance in the group.

The n-type diffusion layer forming composition according to the above <7>, wherein the content of the glass particles is 1% by mass or more and 80% by mass or less.

The n-type diffusion layer forming composition according to any one of the above-mentioned <7>, wherein the total content of P ₂ O ₃ and P ₂ O ₅ in the glass particles is 0.01% by mass. Above 10% by mass.

The n-type diffusion layer forming composition according to any one of <1> to <10> above, further comprising an organic binder.

<12> A method of manufacturing a semiconductor substrate with an n-type diffusion layer, comprising: applying the n-type diffusion according to any one of the above <1> to <11> on the entire surface or a part of the semiconductor substrate a step of forming a composition to form a composition layer; and a step of performing heat treatment on the semiconductor substrate on which the composition layer is formed.

<13> The method of manufacturing a semiconductor substrate with an n-type diffusion layer according to the above <12>, further comprising applying a first n-type diffusion layer forming composition to form a first portion in a region of a portion of the semiconductor substrate In the step of constituting the material layer, the first n-type diffusion layer forming composition contains a compound containing a donor element and a dispersion medium, and the step of forming the n-type diffusion layer to form a composition layer is a step of: working with the semiconductor substrate The surface on which the surface of the first composition layer is formed on the same surface and in the region different from the region in which the first composition layer is formed, the content of the applied metal compound is larger than that of the first n-type diffusion layer forming composition The n-type diffusion layer forming composition, wherein the metal compound contains at least one metal element selected from the group consisting of alkaline earth metals and alkali metals.

<14> A method of manufacturing a solar cell element, comprising: a step of applying a first n-type diffusion layer forming composition to form a first composition layer in a portion of a region on a semiconductor substrate, the first n-type diffusion layer The formation composition contains a compound containing a donor element and a dispersion medium; in the same surface as the surface on which the first composition layer is formed on the semiconductor substrate, and in a region different from the region in which the first composition layer is formed a step of forming a second n-type diffusion layer forming composition to form a second composition layer, wherein the second n-type diffusion layer forming composition is the n-type according to any one of the above <1> to <11> a diffusion layer forming composition, and a content of the metal compound containing at least one metal element selected from the group consisting of an alkaline earth metal and an alkali metal is larger than the first n-type diffusion layer forming composition; embodiment a composition of the semiconductor substrate layer and the second composition layer is a thermal diffusion treatment, is formed on the semiconductor substrate, an n ⁺ -type diffusion layer region and the second composition layer formed in shape Has a smaller step than the n ⁺ -type diffusion layer of the surface sheet resistance (sheet resistance) n ⁺⁺ type diffusion layer region values of the first composition layer is formed; and is formed on the n ⁺⁺ type diffusion layer The steps of the electrode.

The method for producing a solar cell element according to the above <14>, wherein the first n-type diffusion layer forming composition contains at least one metal selected from the group consisting of alkaline earth metals and alkali metals. The content of the metal compound of the element is 10% by mass or less, and the content of the metal compound containing at least one metal element selected from the group consisting of an alkaline earth metal and an alkali metal in the second n-type diffusion layer forming composition The rate is 0.01% by mass or more and 50% by mass or less.

<16> A method for producing a solar cell element, comprising: forming at least one of the n-type diffusion layer forming compositions according to any one of the above <1> to <11> on a semiconductor substrate to form a composition a step of performing a thermal diffusion treatment on the semiconductor substrate on which the composition layer is formed to form an n-type diffusion layer, and a step of forming an electrode on the n-type diffusion layer.

<17> An n-type diffusion layer forming composition kit comprising: An n-type diffusion layer forming composition containing a compound containing a donor element and a dispersion medium, and a second n-type diffusion layer forming composition, which is any one of the above <1> to <11> The n-type diffusion layer forms a composition, and the content of the metal compound containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals is larger than that of the first n-type diffusion layer forming composition.

According to the present invention, there is provided an n-type diffusion layer forming composition, a method for producing a semiconductor substrate with an n-type diffusion layer, and a method for producing a solar cell element, wherein the n-type diffusion layer forming composition can be specific The region forms an n-type diffusion layer, and the diffusion concentration of the donor element in the formed n-type diffusion layer can be easily adjusted.

10‧‧‧p type semiconductor substrate

10A‧‧‧n type semiconductor substrate

11‧‧‧First composition layer

11A‧‧‧ Heat treatment layer

12‧‧‧Second composition layer (n-type diffusion layer forming composition layer)

12A‧‧‧ Heat treated layer

13‧‧‧n ⁺⁺ type diffusion layer

14‧‧‧n ⁺ type diffusion layer

15‧‧‧Anti-reflective film

16‧‧‧ surface electrode

16A‧‧‧metal paste layer for surface electrodes

17‧‧‧Back electrode

17A‧‧‧metal paste layer for back electrode

18‧‧‧p ⁺ type diffusion layer (high concentration electric field layer)

19‧‧‧p-type diffusion layer forming composition layer

19A‧‧‧ Heat treated layer

20‧‧‧passivation film

30‧‧‧Bus Bar Electrode

32‧‧‧ finger electrode

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

2A is a plan view conceptually showing an arrangement of electrodes when a solar cell element is viewed from a light receiving surface.

Fig. 2B is a perspective view showing a part of Fig. 2A in an enlarged manner.

3 is a cross-sectional view conceptually showing another example of a manufacturing procedure of the solar cell element of the embodiment.

First, the n-type diffusion layer forming composition of the present invention will be described. Next, a semiconductor substrate with an n-type diffusion layer and a method for producing a solar cell element using the n-type diffusion layer forming composition will be described.

Furthermore, in the present specification, the term "step" means not only an independent step, but also cannot be clearly distinguished from other steps, and is included in the term as long as the intended purpose of the step is achieved. Further, the numerical range indicated by "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. Further, when the amount of each component in the composition is such that a plurality of substances corresponding to the respective components are present in the composition, unless otherwise specified, the total amount of the plurality of substances present in the composition is indicated.

In addition, in the present specification, the "content ratio" means the mass % of the component which is 100 mass % of the composition of the n-type diffusion layer, unless otherwise specified.

<n type diffusion layer forming composition>

The n-type diffusion layer forming composition of the present invention comprises: a compound (A) comprising a donor element; a metal compound (B) which is a compound different from the above-mentioned compound containing a donor element, and which is selected from the group consisting of alkaline earth metals and alkalis. At least one metal element in the group consisting of metals; and a dispersion medium (C). Further, the coating property and the like are considered, and other additives may be contained as needed.

The n-type diffusion layer forming composition of the present invention includes, in addition to the compound containing the donor element, a metal compound containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals (hereinafter, also referred to as "specific compound"), thereby forming a composition using an n-type diffusion layer containing no specific compound The ratio of the donor element to the diffusibility of the semiconductor substrate can be suppressed. Therefore, for example, in a semiconductor substrate, the n-type diffusion layer forming composition of the present invention is applied in a region where the diffusion concentration of the donor element is adjusted to be lower than other regions, and n without a specific compound is applied in other regions. The type diffusion layer forms a composition and then performs a thermal diffusion treatment, whereby the diffusion concentration of the donor element in the desired region can be easily lowered. That is, it is possible to selectively form regions of different diffusion densities of the donor elements in the same plane of the semiconductor substrate. The reason for this can be considered as follows.

In general, P ₂ O ₅ (or a material which changes to a compound containing P ₂ O ₅ when it is 800 ° C or more) and P ₂ O ₃ are all used as an acidic oxide, which is suitably used as a compound containing a donor element. These compounds are generally considered to diffuse into the semiconductor substrate as P ₂ O ₅ or P ₂ O ₃ . It is considered that when the specific compound is contained in the n-type diffusion layer forming composition, the reactivity of the compound containing the donor element and the specific compound is higher than that of the compound containing the donor element and the semiconductor substrate, so that the donor can be inhibited. The diffusivity of the element toward the semiconductor substrate. In particular, it is considered that when the specific compound is a basic compound, an acid-base reaction occurs between the specific compound and the compound containing the donor element, and the reactivity of the acid-base reaction is high, so that the donor element can be more effectively inhibited. Diffusion in a semiconductor substrate.

Further, unlike the organic compound, the specific compound is stable at a high temperature (for example, 500 ° C or higher). Therefore, when the donor element is diffused into the semiconductor substrate, the effects of the present invention can be sufficiently exhibited.

Further, even when a specific compound is dissolved in a semiconductor substrate In the case where the semiconductor substrate does not function as a recombination center of the carrier, it is possible to suppress the occurrence of a problem that the conversion efficiency is lowered when the semiconductor substrate is applied to the solar cell.

Further, by appropriately adjusting the content of the specific compound in the n-type diffusion layer forming composition, the diffusion concentration of the donor element into the semiconductor substrate can be more precisely adjusted. Further, by containing a specific compound, even if the compound containing the donor element is a highly volatile compound, out diffusion can be suppressed. The reason can be considered as follows: For example, a specific compound chemically interacts with a compound containing a donor element, whereby the volatility of the compound containing the donor element is suppressed.

Further, the present invention has an effect that it is possible to form a selective shot of a complicated manufacturing step in which a plurality of thermal diffusion treatments are required to be combined with partial etching by masking or the like in a simple manufacturing step, for example, primary thermal diffusion treatment. Polar structure.

(A) a compound containing a donor element

The donor element refers to an element which can form an n-type diffusion layer by thermal diffusion in a semiconductor substrate. An element of Group 15 can be used as the donor element, and from the viewpoint of safety and the like, P (phosphorus) is suitable.

The compound containing a donor element is not particularly limited. Examples of the metal oxide containing a donor element include individual metal oxides such as P ₂ O ₅ and P ₂ O ₃ ; bismuth phosphorus, cerium particles doped with phosphorus, calcium phosphate, phosphoric acid, glass particles containing phosphorus, and the like. Inorganic phosphorus compounds; phosphonic acid, phosphonous acid, phosphinic acid, phosphinous acid, phosphine, phosphine oxide, phosphate, phosphite, etc. Compounds, etc.

Among these compounds, the organophosphorus compound is a compound which can be changed to a compound containing P ₂ O ₅ at a high temperature (for example, 800 ° C or higher) at which the donor element is thermally diffused toward the semiconductor substrate.

Among these, it is preferable to use P ₂ O ₃ , P ₂ O ₅ , and a high temperature (for example, 800 ° C or higher) which can thermally diffuse the donor element toward the semiconductor substrate, and change to include P ₂ O _{5 .} At least one of a group consisting of a compound of a compound (for example, ammonium dihydrogen phosphate, phosphoric acid, phosphinic acid, phosphinic acid, trivalent phosphonic acid, phosphine, phosphine oxide, phosphate, phosphite), Among them, a compound having a melting point of 1000 ° C or less is more preferably used. The reason for this is that when thermal diffusion is performed in the semiconductor substrate, it tends to be in a molten state, and the donor element can be uniformly thermally diffused toward the semiconductor substrate. Further, even if the compound having a melting point of more than 1000 ° C is further added with a compound having a melting point of less than 1000 ° C, the donor element may be transferred from the compound containing the donor element to the semiconductor substrate via a compound having a melting point of less than 1000 ° C. Thermal diffusion.

When the compound containing the donor element in the n-type diffusion layer forming composition is in the form of particles at normal temperature (25° C.), the shape in the case of particles is substantially spherical, flat, or blocky. Plate shape, scale shape, etc. From the viewpoint of the coating property and uniform diffusibility of the substrate when forming the composition of the n-type diffusion layer, it is preferably substantially spherical, flat or plate-shaped. When the compound containing the donor element is in the form of a solid particle, the particle diameter of the particle is preferably 100 μm or less. When used with When particles having a particle diameter of 100 μm or less are used, a smooth composition layer is easily obtained. Further, when the compound containing the donor element is in the form of solid particles, the particle diameter of the particles is more preferably 50 μm or less. Further, the lower limit is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.1 μm or more. Further, when the compound containing the donor element is in the form of solid particles, the particle diameter of the particles represents a volume average particle diameter, and can be measured by a laser scattering diffraction particle size distribution measuring apparatus or the like.

The relationship between the intensity of scattered light of the laser light irradiated to the particles and the angle can be detected, and the volume average particle diameter can be calculated from the Mie scattering theory. The dispersion medium at the time of measurement is not particularly limited, but it is preferably a dispersion medium in which particles to be measured are not dissolved.

The compound containing the donor element may be in a state of being dissolved in the dispersion medium. In this case, the shape and particle diameter of the compound containing the donor element used for the preparation of the n-type diffusion layer forming composition are not particularly limited.

The content of the compound containing the donor element in the n-type diffusion layer forming composition is determined in consideration of coatability, diffusibility of the donor element, and the like. In the n-type diffusion layer forming composition, the content of the compound containing the donor element 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. 90% by mass or less, more preferably 1% by mass or more and 80% by mass or less, still 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 compound containing the donor element is 0.1% by mass or more, Then, an n-type diffusion layer can be sufficiently formed. When the content is 95% by mass or less, the dispersibility of the compound containing the donor element in the n-type diffusion layer forming composition is improved, and the coatability to the semiconductor substrate is improved.

The compound containing the donor element is preferably in the form of a glass particle containing a donor element. Here, the glass refers to a substance which does not have a clear crystal state in its atomic arrangement in the X-ray diffraction spectrum, has an irregular network structure, and exhibits a glass transition phenomenon. By using the glass particles containing the donor element, there is a tendency to more effectively suppress diffusion of the donor element outside the region where the composition is formed by applying the n-type diffusion layer (referred to as outward diffusion), and can be suppressed to the back surface. Or an undesired n-type diffusion layer is formed on the side. That is, the n-type diffusion layer can be formed more selectively by containing the glass particles containing the donor element.

The glass particles containing the donor element will be described in detail. Further, the glass particles contained in the n-type diffusion layer forming composition of the present invention are melted at a calcination temperature (about 800 ° C to 2000 ° C) at the time of thermal diffusion, and a glass layer is formed on the n-type diffusion layer. Therefore, outward diffusion can be further suppressed. After the formation of the n-type diffusion layer, the glass layer formed on the n-type diffusion layer can be removed by etching (aqueous solution of hydrofluoric acid or the like).

The glass particles containing the donor element may contain, for example, a substance containing a donor element and a glass component substance. The substance containing the donor element for introducing the donor element into the glass particles is preferably a compound containing P (phosphorus), more preferably selected from the group consisting of P ₂ O ₃ and P ₂ O ₅ . At least one of them.

The content rate of the substance containing the donor element in the glass particles containing the donor element is not particularly limited. For example, from the viewpoint of the diffusibility of the donor element, it is preferably 0.5% by mass or more and 100% by mass or less, more preferably 2% by mass or more and 80% by mass or less. Further, from the viewpoint of the diffusibility of the donor element, the glass particles containing the donor element preferably contain 0.5% by mass or more and 100% by mass or less, and are selected from the group consisting of P ₂ O ₃ and P ₂ O ₅ . At least one of the group is a substance containing a donor element, and more preferably contains at least one selected from the group consisting of P ₂ O ₃ and P ₂ O ₅ in an amount of 2% by mass or more and 80% by mass or less. As a substance containing a donor element.

Further, the glass particles containing the donor element can be controlled to have a melting temperature, a softening point, a glass transition point, chemical durability, and the like, as needed, by adjusting the composition ratio thereof. Further, it is preferable to contain at least one of the glass component materials described below.

Examples of the glass component substance include SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, Tl ₂ O, V ₂ O ₅ , and SnO. 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 , ZrO ₂ , GeO ₂ , TeO ₂ , Lu ₂ O _{3 ,} or the like. Preferably, it is selected from the group consisting of 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 , at least one of the group consisting of GeO ₂ , Y ₂ O ₃ , CsO ₂ and TiO ₂ , more preferably selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO At least one of the group consisting of CaO, MgO, BeO, ZnO, PbO, CdO, V ₂ O ₅ , SnO, ZrO ₂ and MoO ₃ .

Specific examples of the glass particles containing the donor element include a system containing both the above-described donor element-containing material and the above-described glass component material. Specific examples include P ₂ O ₅ -SiO ₂ (described in the order of the substance containing the donor element - the glass component, the same applies hereinafter), P ₂ O ₅ -K ₂ O, and P ₂ O ₅ - Na ₂ O system, P ₂ O ₅ -Li ₂ O system, P ₂ O ₅ -BaO system, P ₂ O ₅ -SrO system, P ₂ O ₅ -CaO system, P ₂ O ₅ -MgO system, P ₂ O ₅ -BeO system, P ₂ O ₅ -ZnO system, P ₂ O ₅ -CdO system, P ₂ O ₅ -PbO system, P ₂ O ₅ -V ₂ O ₅ system, P ₂ O ₅ -SnO system, P ₂ Glass particles containing a system of P ₂ O ₅ as a substance containing a donor element, such as O ₅ -GeO ₂ or P ₂ O ₅ -TeO ₂ , containing P ₂ O ₃ instead of P ₂ O ₅ as a donor-containing element The material of the system of glass particles and the like.

Further, it may be a glass particle containing two or more substances containing a donor element, such as a P ₂ O ₅ -Sb ₂ O ₃ system or a P ₂ O ₅ -As ₂ O ₃ system.

In the above, a composite glass containing two components is exemplified, but 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 preferably contain at least one substance containing a donor element selected from the group consisting of P ₂ O ₃ and P ₂ O ₅ , and are selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, and Li. a group consisting of 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 TiO ₂ At least one of the glass component substances, more preferably at least one substance containing a donor element selected from the group consisting of P ₂ O ₃ and P ₂ O ₅ , and selected from the group consisting of SiO ₂ and K ₂ O At least one glass component substance in the group consisting of Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V ₂ O ₅ , SnO, ZrO ₂ and MoO ₃ More preferably, it contains a substance containing a donor element as P ₂ O ₅ , and at least one glass component selected from the group consisting of SiO ₂ , ZnO, CaO, Na ₂ O, Li ₂ O, and BaO. substance. Thereby, the sheet resistance of the formed n-type diffusion layer can be further reduced.

The content ratio of the glass component (hereinafter also referred to as "specific glass component") selected from the group consisting of SiO ₂ and GeO ₂ in the glass particles is preferably a melting temperature, a softening point, and a glass transition point. It is suitable for chemical durability. In the case of 100% by mass of the glass particles, the specific glass component is preferably 0.01% by mass or more and 80% by mass or less, more preferably 0.1% by mass or more and 50% by mass or less. When it is 0.01% by mass or more, the n-type diffusion layer can be formed efficiently. In addition, when it is 80% by mass or less, formation of a portion where the n-type diffusion layer is formed without applying the n-type diffusion layer can be more effectively suppressed.

In addition to the specific glass component material, the glass particles may also contain Network Modifying Oxides (for example, alkali oxides, alkaline earth oxides) or intermediate oxides which are not vitrified when used alone. Specifically, in the case of P ₂ O ₅ -SiO ₂ -CaO-based glass, the content ratio of CaO as the network-shaped modified oxide is preferably 1% by mass or more, 30% by mass or less, and more preferably 5% by mass. The above is 20% by mass or less.

The softening point of the glass particles is preferably from 200 ° C to 1000 ° C, more preferably from 300 ° C to 900 ° C from the viewpoint of diffusibility at the time of diffusion treatment and dripping. Furthermore, the softening point of the glass particles can be used as the differential heat. Thermogravimetric simultaneous determination of the device and by differential thermal analysis (Differential Thermal Analysis (DTA)) Find the curve. Specifically, the value of the third peak from the low temperature of the DTA curve can be set as the softening point.

The glass particles containing the donor element are produced by the following procedure.

First, the raw material is weighed, for example, the above-mentioned substance containing the donor element and the glass component substance are weighed, and then filled into a crucible. Examples of the material of the crucible include platinum, platinum-rhodium, iridium, aluminum oxide, quartz, carbon, and the like, and are appropriately selected in consideration of the melting temperature, the environment, and the reactivity with the molten material.

Next, a molten metal is prepared by heating in an electric furnace at a temperature corresponding to the composition of the glass. At this time, it is preferable to stir so that the melt becomes uniform. Then, the obtained melt flows out onto a zirconia substrate, a carbon substrate or the like to vitrify the melt. Finally, the glass is pulverized to form a powder. A known method such as a jet mill, a bead mill, or a ball mill can be applied to the pulverization.

When the glass particles containing the donor element are used as the compound containing the donor element, the content of the donor element in the glass particles is preferably 0.01% by mass or more and 40% in terms of the diffusion performance. The mass% or less is more preferably 0.1% by mass or more and 35% by mass or less, and still more preferably 1% by mass or more and 30% by mass or less.

Further, when a glass particle containing a donor element is used as a compound containing a donor element, the n-type diffusion layer forms a glass in the composition in the n-type diffusion layer forming composition from the viewpoint of uniformity of diffusion. The content of the particles is preferably 1% by mass or more and 80% by mass or less, more preferably 5% by mass or more and 60% by mass or less. Furthermore, it is more preferably 10% by mass or more and 40% by mass or less.

(B) a metal compound containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals

The n-type diffusion layer forming composition of the present invention contains at least one metal compound (specific compound) which is a compound different from the above-described compound containing a donor element and contains a group selected from the group consisting of alkaline earth metals and alkali metals. At least one metal element in the group. Thereby, the diffusion concentration of the donor element into the semiconductor substrate can be easily controlled. Specifically, in addition to the use of the compound containing the donor element, the composition is formed by using the n-type diffusion layer including the metal compound, compared with the case of forming the composition using the n-type diffusion layer not including the metal compound. An n-type diffusion layer having a low diffusion concentration of the donor element is formed, and the metal compound contains at least one metal element selected from the group consisting of alkaline earth metals and alkali metals.

Here, the specific compound (B) is a compound different from the compound (A) containing a donor element, and means that, for example, even if the compound (A) containing a donor element is glass particles, and contains an alkaline earth metal or When the alkali metal compound is a glass component material constituting the glass particles, the n-type diffusion layer forming composition of the present invention contains the specific compound (B) independently of the compound (A) containing the donor element.

The metal compound containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals may be a metal compound which is liquid at normal temperature (about 20 ° C), or may be at normal temperature (about 20 ° C). A solid metal compound. due to Since the heat diffusion temperature of the donor element is a high temperature, it is preferably a compound which is solid at a high temperature (for example, 500 ° C or higher) at which thermal diffusion treatment is performed. Here, for example, as the metal compound containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals, at least one metal selected from the group consisting of alkaline earth metals and alkali metals may be mentioned. A metal oxide of an element and a metal salt containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals.

The metal compound (specific compound) containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals is preferably changed to alkaline at a high temperature of 700 ° C or higher at which the donor element is thermally diffused. a compound of a compound. Wherein, the specific compound preferably contains at least 1 selected from the group consisting of magnesium, calcium, sodium, potassium, lithium, cesium, strontium, barium, strontium, strontium, and radium from the viewpoint of exhibiting strong alkalinity. The metal element is preferably a metal element, and more preferably contains at least one metal element selected from the group consisting of magnesium, calcium, potassium and strontium as a metal element, and more preferably contains at least one selected from the group consisting of magnesium, calcium and potassium. At least one metal element in the group is a metal element. Further, in terms of chemical stability, the specific compound is preferably at least one selected from the group consisting of metal oxides, metal carbonates, metal nitrates, metal sulfates, and metal hydroxides, and At least one selected from the group consisting of the metal elements is contained, and the specific compound is particularly preferably at least one selected from the group consisting of metal oxides, metal carbonates, and metal hydroxides.

As a specific compound, it is particularly preferred to use sodium oxide, potassium oxide, or oxygen. Metal oxides such as lithium, calcium oxide, magnesium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, and radium oxide, and composite oxides thereof; sodium hydroxide, potassium hydroxide, lithium hydroxide, Metal hydroxides such as calcium hydroxide, magnesium hydroxide, barium hydroxide, barium hydroxide, barium hydroxide, barium hydroxide, barium hydroxide, and radium hydroxide; sodium carbonate, potassium carbonate, lithium carbonate, calcium carbonate, carbonic acid Metal carbonates such as magnesium, barium carbonate, barium carbonate, barium carbonate, barium carbonate, barium carbonate, and radium carbonate; sodium nitrate, potassium nitrate, lithium nitrate, calcium nitrate, magnesium nitrate, barium nitrate, barium nitrate, barium nitrate, barium nitrate Metal nitrates such as barium nitrate and radium nitrate; metal sulfates such as sodium sulfate, potassium sulfate, lithium sulfate, calcium sulfate, magnesium sulfate, barium sulfate, barium sulfate, barium sulfate, barium sulfate, barium sulfate, and radium sulfate.

The specific compound is preferably at least one selected from the group consisting of the above metal oxides, and the composite oxides, metal hydroxides, and metal carbonates.

Among these, in view of low toxicity and ease of availability, the specific compound is preferably selected from the group consisting of sodium carbonate, sodium oxide, potassium carbonate, potassium oxide, calcium carbonate, calcium hydroxide, calcium oxide, and carbonic acid. At least one selected from the group consisting of magnesium, magnesium hydroxide, magnesium sulfate, calcium sulfate, magnesium nitrate, calcium nitrate, and magnesium oxide, more preferably selected from the group consisting of potassium carbonate, potassium oxide, magnesium oxide, calcium oxide, and carbonic acid. At least one selected from the group consisting of magnesium, calcium carbonate, magnesium sulfate, calcium sulfate, magnesium nitrate, calcium nitrate, magnesium hydroxide, and calcium hydroxide, and more preferably selected from the group consisting of potassium carbonate, potassium oxide, and calcium carbonate. , calcium oxide, calcium hydroxide, magnesium carbonate, magnesium oxide and magnesium hydroxide At least one selected from the group consisting of at least one selected from the group consisting of potassium oxide, calcium carbonate, calcium oxide, calcium hydroxide, magnesium carbonate, magnesium oxide, and magnesium hydroxide is particularly preferred.

When the specific compound is in the form of solid particles at normal temperature, the particle diameter of the particles is preferably 0.01 μm or more and 30 μm or less, more preferably 0.02 μm or more and 10 μm or less, and still more preferably 0.03 μm or more and 5 μm. the following. When the particle diameter is 30 μm or less, the donor element can be more uniformly diffused (doped) in the application region of the n-type diffusion layer forming composition on the semiconductor substrate. On the other hand, when it is 0.01 μm or more, the specific compound tends to be more uniformly dispersed in the n-type layer forming composition. In addition, specific compounds can also be dissolved in the dispersion medium.

Further, the particle diameter indicates a volume average particle diameter, which can be measured by a laser scattering diffraction particle size distribution measuring apparatus or the like.

The method of obtaining solid particles of a specific compound having a particle diameter within a desired range, for example, 0.01 μm or more and 30 μm or less is not particularly limited. For example, it can be obtained by pulverizing treatment. As the pulverization method, a dry pulverization method and a wet pulverization method can be employed. As the dry pulverization method, a jet mill, a vibration mill, a ball mill, or the like can be used. As the wet pulverization method, a bead mill, a ball mill or the like can be used.

When the impurities due to the pulverizing device are mixed into the n-type diffusion layer forming composition during the pulverization treatment, the life of the carrier in the semiconductor substrate may be lowered. Therefore, the material of the pulverization container, the beads, the balls, and the like is preferably A material having a small influence on the semiconductor substrate is selected. Specifically, partially stabilized zirconia or the like can be used. In addition, In addition to the pulverization method, a gas phase oxidation method, a hydrolysis method, or the like can also be used to obtain a desired specific compound.

The shape of the specific compound is not particularly limited, and may be any of a substantially spherical shape, a flat shape, a scale shape, a block shape, an ellipsoid shape, a plate shape, and a rod shape. Further, the shape of a specific compound can be observed and determined using a scanning electron microscope.

Alternatively, a specific compound may be reacted with a compound containing a donor element in advance. Specifically, for example, the following materials may be used as a compound containing a donor element and a specific compound which is obtained by immersing calcium oxide in an aqueous phosphoric acid solution and fixing the phosphorus compound on the surface of calcium oxide by filtration. A material obtained by separating calcium oxide having a phosphorus compound.

The content ratio of the specific compound in the n-type diffusion layer forming composition is determined in consideration of coatability, diffusion concentration of the donor element into the semiconductor substrate, and the like. In the n-type diffusion layer forming composition, the content of the specific compound in the n-type diffusion layer forming composition is preferably 0.01% by mass or more and 50% by mass or less, more preferably 0.02% by mass or more and 30% by mass. In the following, it is more preferably 0.1% by mass or more and 20% by mass or less, and particularly preferably 0.1% by mass or more and 5% by mass or less.

When the content of the specific compound is 0.01% by mass or more, thermal diffusion of the donor element contained in the compound containing the donor element into the semiconductor substrate can be appropriately suppressed. In addition, when the content of the specific compound is 50% by mass or less, the tendency of the donor element contained in the compound containing the donor element to thermally diffuse into the semiconductor substrate is not excessively inhibited.

The content ratio of the above specific compound in the n-type diffusion layer forming composition to the compound containing the donor element is not particularly limited. From the viewpoint of uniformity of diffusion of the donor element into the semiconductor substrate, it is preferably 0.01% by mass or more, 10% by mass or less, and more preferably 0.1% by mass or more based on 100% by mass of the compound containing the donor element. 8% by mass or less, more preferably 0.5% by mass or more and 6% by mass or less.

(C) Dispersing media

The n-type diffusion layer forming composition of the present invention contains a dispersing medium.

The dispersion medium refers to a medium in which the compound containing the donor element and the metal compound containing at least one metal element selected from the group consisting of an alkaline earth metal and an alkali metal are dispersed or dissolved in the composition. Specifically, the dispersion medium preferably contains at least a solvent or water. Further, the dispersion medium may be a dispersion medium containing an organic binder to be described later, in addition to a solvent or water.

Examples of the solvent include a ketone solvent; an ether solvent; an ester solvent such as 2-(2-butoxyethoxy)ethyl acetate; an aprotic polar solvent; an alcohol solvent; diethylene glycol mono-n-butyl ether; Glycol monoether solvent; terpenoids such as α-terpinene, terpineol such as α-terpineol, terpene such as α-pinene and β-pinene, laurel Iridene (myrcene), allo-ocimene, limonene, dipentene, carvone, ocimene, phellandrene, etc. (terpene) solvent, etc. Further, as described in JP-A-2012-084830, a solvent can also be used. Some of these The solvent may be used singly or in combination of two or more.

When the n-type diffusion layer forming composition is formed, it is preferably at least 1 selected from the group consisting of a terpene solvent, a glycol monoether solvent, and an ester solvent from the viewpoint of coatability of the substrate. More preferably, it is terpineol, diethylene glycol mono-n-butyl ether or 2-(2-butoxyethoxy)ethyl acetate.

The content of the dispersion medium in the n-type diffusion layer forming composition is determined in consideration of coatability and concentration of the donor element. For example, the n-type diffusion layer forming composition is preferably 5% by mass or more and 99% by mass or less, more preferably 20% by mass or more and 95% by mass or less, still more preferably 40% by mass or more and 90% by mass. the following.

The n-type diffusion layer forming composition of the present invention, in addition to the compound containing the donor element, the metal compound containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals, and the dispersion medium, It may contain an organic binder, a surfactant, an inorganic powder, a resin containing a ruthenium atom, a reducing additive, a thixotropic agent, or the like.

The n-type diffusion layer forming composition may further contain at least one organic binder. By containing an organic binder, viscosity adjustment and thixotropy can be applied as an n-type diffusion layer forming composition, and the applicability to a semiconductor substrate is further improved. As the organic binder, for example, polyvinyl alcohol; polypropylene decylamine resin; polyvinyl decylamine resin; polyvinylpyrrolidone resin; polyethylene oxide resin; polyfluorene resin; acrylamide alkyl hydrazine Resin; cellulose derivatives such as cellulose ether, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose; gelatin and gelatin derivatives; starch And starch derivatives; sodium alginate and sodium alginate derivatives; Sanxian gum and Sanxian gum derivatives; guar gum and guar gum derivatives; scleroglucans and scleroglucan derivatives; And xanthan gum derivatives; dextrin and dextrin derivatives; (meth)acrylic resin; (meth)acrylic acid alkyl ester resin, (meth)acrylic acid dimethylaminoethyl ester resin (meth)acrylic acid Ester resin; butadiene resin; styrene resin; and copolymers thereof. These organic binders may be used alone or in combination of two or more. When an organic binder is used, a cellulose derivative, an acrylic resin derivative, or a polyethylene oxide resin is preferably used from the viewpoint of decomposability and ease of handling.

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

Examples of the surfactant include a nonionic surfactant, a cationic surfactant, an anionic surfactant, and the like. Among them, in the case where the introduction of impurities such as heavy metals into the semiconductor substrate is small, a nonionic surfactant or a cationic surfactant is preferable.

Examples of the nonionic surfactant include a lanthanoid surfactant, a fluorine surfactant, a hydrocarbon surfactant, and the like. Among them, a hydrocarbon-based surfactant is preferred in that it is rapidly calcined during heating such as diffusion.

As the hydrocarbon-based surfactant, ethylene oxide-propylene oxide can be exemplified Segment copolymer, acetylene glycol compound, and the like. From the viewpoint of further reducing variations in the sheet resistance value of the semiconductor substrate, an acetylene glycol compound is preferred.

As the inorganic powder, a substance which functions as a filler is preferable. Examples of the inorganic powder include powders of cerium oxide, titanium oxide, cerium nitride, and cerium carbide.

The n-type diffusion layer forming composition may further contain a reducing compound. Examples of the reducing compound include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, terminal alkylates of polyalkylene glycols, monosaccharides such as glucose, fructose and galactose, and derivatives of monosaccharides; sucrose and maltose. Such as disaccharides and disaccharide derivatives; polysaccharides and polysaccharide derivatives. Among these organic compounds, a polyalkylene glycol is preferred, and polypropylene glycol is more preferred. Further, by further containing a reducing compound, it tends to facilitate diffusion of the donor element into the semiconductor substrate.

The n-type diffusion layer forming composition may further comprise a thixotropic agent containing a solid component. Thereby, thixotropy can be easily controlled, and an n-type diffusion layer forming composition for screen printing having a viscosity suitable for printing can be formed. Further, since the thixotropy is controlled, it is possible to suppress bleeding or dripping of the n-type diffusion layer forming composition from the printed pattern during printing.

The method for producing the n-type diffusion layer forming composition of the present invention is not particularly limited. For example, a compound containing a donor element, a metal compound containing at least one metal element selected from the group consisting of an alkaline earth metal and an alkali metal, or the like, may be used by using a stirrer, a mixer, a mortar, a rotor, or the like. The dispersion medium and the components added as needed are obtained by mixing. In addition, when mixing is carried out, it may be heated as needed. Mixed When heating is performed at the same time, the temperature can be, for example, 30 ° C to 100 ° C.

Further, the content of the component contained in the n-type diffusion layer forming composition and the content of each component may be thermal analysis using a thermogravimetric/differential thermal analysis (TG/DTA) or the like, and nuclear magnetic resonance (Nuclear) Magnetic Resonance (NMR), Infrared (IR), Matrix Assisted Laser Desorption Ionization-Mass Spectrometry (MALDI-MS), Gas Chromatography-Mass Spectrometry , GC-MS) and other spectral analysis, high performance liquid chromatography (HPLC), gel permeation chromatography (GPC) and other chromatographic analysis.

In the n-type diffusion layer forming composition, the n-type diffusion layer of the present invention forms a compound containing a donor element in the composition, and contains at least one metal element selected from the group consisting of an alkaline earth metal and an alkali metal. The total content of the metal compound and the dispersion medium is preferably 1% by mass or more, and more preferably 5% by mass or more.

A preferred embodiment of the n-type diffusion layer forming composition of the present invention is as follows, for example.

(1) An n-type diffusion layer forming composition comprising: a compound containing at least one selected from the group consisting of P ₂ O ₅ and P ₂ O ₃ as a donor element; a metal compound, the metal compound Containing at least one metal element selected from the group consisting of magnesium, calcium, sodium, potassium, lithium, cesium, lanthanum, cerium, lanthanum, cerium, and radium; and a dispersing medium.

(2) An n-type diffusion layer forming composition comprising: glass particles comprising at least one selected from the group consisting of P ₂ O ₅ and P ₂ O ₃ as a donor element; a metal compound The metal compound is at least one selected from the group consisting of metal oxides, metal carbonates, metal nitrates, metal sulfates, and metal hydroxides, and is selected from the group consisting of magnesium, calcium, sodium, potassium, At least one metal element in the group consisting of lithium, lanthanum, cerium, lanthanum, cerium, lanthanum, and radium; and a dispersing medium.

(3) An n-type diffusion layer forming composition comprising: glass particles, wherein the glass particles comprise at least one selected from the group consisting of P ₂ O ₅ and P ₂ O ₃ as a donor element, and the particles The diameter is 0.01 μm or more and 100 μm or less; the metal compound particles are at least 1 selected from the group consisting of metal oxides, metal carbonates, metal nitrates, metal sulfates, and metal hydroxides. a particle size of 0.01 μm or more and 30 μm or less and containing at least one metal element selected from the group consisting of magnesium, calcium, sodium, potassium, lithium, cesium, rubidium, cesium, strontium, strontium, and radium ; and dispersing media.

(4) An n-type diffusion layer forming composition comprising: glass particles comprising at least one selected from the group consisting of P ₂ O ₅ and P ₂ O ₃ as a donor element, particle diameter The content is 0.01 μm or more and 100 μm or less, and the content is 0.1% by mass or more and 95% by mass or less; and the metal compound particles are selected from the group consisting of metal oxides, metal carbonates, metal nitrates, metal sulfates, and At least one of the group consisting of metal hydroxides has a particle diameter of 0.01 μm or more and 30 μm or less, a content ratio of 0.01% by mass or more, 50% by mass or less, and a content selected from the group consisting of magnesium, calcium, sodium, and potassium. At least one metal element in the group consisting of lithium, lanthanum, cerium, lanthanum, cerium, lanthanum, and radium; and a dispersing medium.

(5) An n-type diffusion layer forming composition comprising: glass particles comprising at least one selected from the group consisting of P ₂ O ₅ and P ₂ O ₃ as a donor element; a metal compound The metal compound is at least one selected from the group consisting of metal oxides, metal carbonates, metal nitrates, metal sulfates, and metal hydroxides, and is selected from the group consisting of magnesium, calcium, sodium, potassium, At least one metal element in the group consisting of lithium, lanthanum, cerium, lanthanum, cerium, lanthanum, and radium; and a dispersing medium; and the content ratio of the above metal compound to the glass particles containing the donor element is 0.01 mass % or more and 10% by mass or less.

The n-type diffusion layer forming composition of the present invention preferably contains no metal other than the metal contained in the compound containing the donor element and the metal contained in the specific compound (0.5% by mass or less), more preferably It is metal free (0% by mass).

<n type diffusion layer forming composition set>

The n-type diffusion layer forming composition kit of the present invention includes: a first n-type diffusion layer forming composition containing a compound containing a donor element and a dispersion medium; and a second n-type diffusion layer forming composition containing the inclusion a compound of a donor element, a metal compound (specific compound) containing at least one metal element selected from the group consisting of an alkaline earth metal and an alkali metal, and a dispersion medium, and the content of the specific compound described above The probability is greater than the first n-type diffusion layer forming composition described above. That is, the n-type diffusion layer forming composition set is a combination (set) of the first n-type diffusion layer forming composition and the second n-type diffusion layer forming composition. By forming a composition including two or more types of n-type diffusion layers having different contents of a specific compound, it can be suitably used for the production of a semiconductor substrate having a region in which the diffusion concentration of the donor element is different.

The details of the second n-type diffusion layer forming composition described above are as described above.

The content of the specific compound in the first n-type diffusion layer forming composition is not particularly limited as long as it is lower than the content of the specific compound in the second n-type diffusion layer forming composition. The content of the specific compound can be, for example, 10% by mass or less, preferably 1% by mass or less, and more preferably substantially no specific compound, in the first n-type diffusion layer forming composition. Here, the term "substantially free of a specific compound" means that unavoidable incorporation of a specific compound is allowed.

The content of the specific compound in the second n-type diffusion layer forming composition is preferably 5 or more, more preferably 10 or more, based on the content of the specific compound in the first n-type diffusion layer forming composition.

<Method of Manufacturing Semiconductor Substrate with n-Type Diffusion Layer>

A method of manufacturing a semiconductor substrate with an n-type diffusion layer of the present invention includes the steps of: applying an n-type diffusion layer forming composition of the present invention to form a composition layer on a semiconductor substrate; and forming a semiconductor layer having the above composition layer The step of performing heat treatment on the substrate. The method of manufacturing the semiconductor substrate with the n-type diffusion layer described above may further have other steps as needed.

The above semiconductor substrate can be suitably selected from semiconductor substrates that are generally used depending on the purpose. Among them, a tantalum substrate is preferred. Further, the semiconductor substrate may be a p-type semiconductor substrate or an n-type semiconductor substrate.

The method of applying the n-type diffusion layer forming composition of the present invention to a semiconductor substrate is not particularly limited, and can be suitably selected from the usual coating methods. Examples of the application method include a printing method, a spinning method, a brush coating method, a spray method, a doctor blade method, a roll coater method, and an inkjet method.

The application amount of the above-described n-type diffusion layer forming composition is not particularly limited. For example, the amount of the compound containing the donor element is preferably from 0.01 g/m ² to 100 g/m ² , more preferably from 0.1 g/m ² to 10 g/m ² .

The composition of the n-type diffusion layer forming composition is preferably a drying step for volatilizing a solvent or the like sometimes contained in the composition after being applied to the semiconductor substrate. For example, drying can be carried out at a temperature of about 80 ° C to 300 ° C. The drying time can be, for example, 1 minute to 10 minutes in the case of using a hot plate, and can be set to 10 minutes to 30 minutes in the case of using a dryer. The drying conditions can be appropriately selected in accordance with the solvent composition of the n-type diffusion layer forming composition, etc., and are not particularly limited to the above conditions in the present invention.

Then, the semiconductor substrate on which the above composition layer is formed is subjected to heat treatment. The temperature of the heat treatment can be, for example, 600 ° C to 1200 ° C. By this heat treatment, the donor element is thermally diffused into the semiconductor substrate to form an n-type diffusion layer. A known continuous furnace, a batch furnace, or the like can be applied to the heat treatment. In addition, the furnace environment during heat treatment It can also be suitably adjusted to air, oxygen, nitrogen, and the like.

The heat treatment time can be appropriately selected in accordance with the content ratio of the donor element contained in the n-type diffusion layer forming composition. The heat treatment time is preferably, for example, 1 minute to 60 minutes, more preferably 2 minutes to 30 minutes.

A glass layer such as phosphoric acid glass derived from a compound containing a donor element may be formed on the surface of the formed n-type diffusion layer. In this case, it is preferred to remove the glass layer by etching. As the etching method, 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.

Preferably, the method for fabricating a semiconductor substrate with an n-type diffusion layer further includes the step of applying a first n-type diffusion layer forming composition to form a first composition layer in a portion of the semiconductor substrate, the first The n-type diffusion layer forming composition contains a compound containing a donor element and a dispersion medium, and the step of forming the n-type diffusion layer forming the composition layer is a step of forming the first composition layer on the semiconductor substrate The n-type diffusion layer having a higher content of the metal compound (specific compound) than the first n-type diffusion layer forming composition in a region different from the surface on which the first composition layer is formed The composition is formed, and the metal compound contains at least one metal element selected from the group consisting of alkaline earth metals and alkali metals.

That is, the method of manufacturing a semiconductor substrate with an n-type diffusion layer is preferably a method of manufacturing a semiconductor substrate with an n-type diffusion layer, the method comprising: applying a first portion in a region on a portion of the semiconductor substrate N-type diffusion layer a step of forming a composition to form a first composition layer, wherein the first n-type diffusion layer forming composition contains a compound containing a donor element and a dispersion medium; and is the same as a surface on which the first composition layer is formed on the semiconductor substrate a step of applying a second n-type diffusion layer forming composition to form a second composition layer in a region different from a region forming the first composition layer, wherein the second n-type diffusion layer is formed The n-type diffusion layer forming composition of the present invention, and the content of the metal compound containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals is larger than the first n-type diffusion layer forming composition. And a step of performing heat treatment on the semiconductor substrate on which the first composition layer and the second composition layer are formed.

Thereby, a semiconductor substrate in which two or more types of n-type diffusion layer regions having different diffusion densities of the donor elements are formed on the same surface can be manufactured by a simple method. Specifically, compared with the diffusion concentration of the donor atoms in the n ⁺ -type diffusion layer formed in the region in which the first composition layer is formed, the formation of the region in which the second composition layer is formed can be improved. The diffusion concentration of the donor atoms in the n ⁺⁺ type diffusion layer.

Further, in addition to the region different from the region in which the first composition layer is formed, the second composition layer may be further formed on the first composition layer.

<Method of Manufacturing Solar Cell Element>

The first aspect of the method for producing a solar cell element of the present invention includes the step of using at least one selected from the group consisting of alkaline earth metals and alkali metals, and a compound containing a donor element and a dispersion medium. Two or more types of n-type diffusion layer forming compositions having different metal compounds of metal elements, Two or more regions in which the diffusion concentration of the donor element is different are formed on the semiconductor substrate.

Specifically, a first aspect of the method for producing a solar cell element of the present invention is a method of manufacturing a solar cell element, comprising: applying a first n-type diffusion layer forming composition to a portion of a region on a semiconductor substrate a step of forming a first composition layer, the first n-type diffusion layer forming composition containing a compound containing a donor element and a dispersing medium; and a surface identical to a surface on which the first composition layer is formed on the semiconductor substrate And a step of forming a second n-type diffusion layer forming composition to form a second composition layer in a region different from a region in which the first composition layer is formed, wherein the second n-type diffusion layer is formed into a composition, a metal compound (specific compound) containing at least one metal element selected from the group consisting of an alkaline earth metal and an alkali metal is larger than the first n-type diffusion layer forming composition; and the first composition is formed heat treatment of the semiconductor substrate layer and the second composition layer, formed on said semiconductor substrate region and the second composition layer of n ⁺ -type expansion Layer, there is the step of forming the n ⁺⁺ -type diffusion layer has a sheet resistance value of the surface layer is smaller than the n ⁺ -type diffusion region of said first composition layer is formed; and is formed on the n ⁺⁺ type diffusion layer The steps of the electrode.

When the content of the specific compound in the second n-type diffusion layer forming composition is larger than the content of the specific compound in the first n-type diffusion layer forming composition, the first n-type diffusion layer forming composition and the first The content rate of the specific compound in the two n-type diffusion layer forming composition is not particularly limited. It is preferable that the content of the specific compound in the first n-type diffusion layer forming composition is 10% by mass or less. The content of the specific compound in the second n-type diffusion layer forming composition is 0.01% by mass or more and 50% by mass or less, and more preferably the content of the specific compound in the first n-type diffusion layer forming composition is 1 The content of the specific compound in the second n-type diffusion layer forming composition is 0.01% by mass or more and 50% by mass or less, and more preferably the specific compound in the first n-type diffusion layer forming composition. The content of the specific compound in the second n-type diffusion layer forming composition is 0.5% by mass or more and 30% by mass or less.

The diffusion concentration of the donor element in the n ⁺⁺ type diffusion layer and the n ⁺ type diffusion layer formed by the above production method is not particularly limited, and may be appropriately selected depending on the purpose. For example, it is preferable that the surface resistance value of the surface of the n ⁺⁺ type diffusion layer is 10 Ω/□ or more and 80 Ω/□ or less, and the sheet resistance of the surface of the n ⁺ type diffusion layer is larger than that of the n ⁺⁺ type diffusion layer. The sheet resistance value is 60 Ω/□ or more and 150 Ω/□ or less, and more preferably the surface resistance of the surface of the n ⁺⁺ type diffusion layer is 10 Ω/□ or more, less than 70 Ω/□, n ⁺ The sheet resistance value of the surface of the diffusion layer is 70 Ω/□ or more and 150 Ω/□ or less, and more preferably the sheet resistance of the surface of the n ⁺⁺ type diffusion layer is 30 Ω/□ or more and 60 Ω/□ or less. The sheet resistance value of the surface of the n ⁺ -type diffusion layer is 80 Ω/□ or more and 120 Ω/□ or less.

Further, the sheet resistance value of the surface of the semiconductor substrate is measured by a four-probe method which is generally used. The four-probe method can be carried out, for example, using a Loresta-EP MCP-T360 type low resistivity meter manufactured by Mitsubishi Chemical Corporation.

Applying the first n-type diffusion layer forming composition on the semiconductor substrate and The shape of the first composition layer and the second composition layer formed by forming the composition of the second n-type diffusion layer is not particularly limited, and is appropriately selected depending on the purpose. For example, it is preferable that the first composition layer is formed in a region corresponding to a region where the electrode is formed, and the second composition layer is formed in a region other than the region where the electrode is formed. Further, after the first composition layer is formed in a region corresponding to the region where the electrode is formed, the second composition layer may be formed on the entire surface of the semiconductor substrate surface including the region in which the first composition layer is formed. on. By forming the first composition layer and the second composition layer as described above, it is possible to efficiently manufacture a solar cell element having a selective emitter structure.

The details of the method of applying the first n-type diffusion layer forming composition and the second n-type diffusion layer forming composition and the heat treatment are as described above, and the preferred embodiments are also the same.

Then, an electrode is formed on the n ⁺⁺ type diffusion layer formed by thermal diffusion treatment. The method for forming the electrode is not particularly limited, and can be appropriately selected from the electrode forming methods generally used. For example, an electrode forming method using a commercially available silver paste can be applied.

Preferably, the method of manufacturing a solar cell element further includes the step of forming an electrode on a p-type diffusion layer on a semiconductor substrate. The method of forming the electrode on the p-type diffusion layer is not particularly limited, and can be suitably selected from the electrode formation methods generally used. For example, an electrode forming method using a commercially available aluminum paste can be applied.

A second aspect of the method for producing a solar cell element of the present invention is the method for producing a solar cell element, comprising: applying at least one n-type diffusion layer forming composition on a semiconductor substrate to form an n-type diffusion layer forming composition Layer In the step, the n-type diffusion layer forming composition includes a compound containing a donor element, a metal compound containing at least one metal element selected from the group consisting of an alkaline earth metal and an alkali metal, and a dispersion medium; The n-type diffusion layer forms a semiconductor layer of the composition layer to perform heat treatment to form an n-type diffusion layer, and a step of forming an electrode on the formed n-type diffusion layer.

Preferably, in the manufacturing method of the second aspect, before the step of forming the n-type diffusion layer, the method further includes the step of applying the inclusion on the same surface as the surface on which the n-type diffusion layer forming composition layer is formed on the semiconductor substrate. The compound of the acceptor element and the p-type diffusion layer of the dispersion medium form a composition to form a p-type diffusion layer forming composition layer. Thereby, for example, a back contact type solar cell element can be efficiently manufactured.

The shape and size of the solar cell element manufactured by the method for producing a solar cell element described above are not limited. For example, a square having a side of 125 mm to 156 mm is preferred.

<solar battery>

The solar cell element manufactured by the above-described method for manufacturing a solar cell element can be used for the manufacture of a solar cell. The solar cell includes at least one of the solar cell elements manufactured by the above-described manufacturing method, and is configured by disposing a wiring material (bonding wire or the like) on the electrode of the solar cell element. Further, the solar cell may be connected to a plurality of solar cell elements via a wiring material as needed, and further sealed by a sealing material.

The wiring material and the sealing material are not particularly limited and can be generally used in the field. The wiring material and the sealing material to be used are suitably selected.

The shape and size of the solar cell are not particularly limited. For example, it is preferably 0.5 m ² to 3 m ² .

Next, a method of manufacturing a semiconductor substrate with an n-type diffusion layer and a solar cell element according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view conceptually showing an example of a manufacturing procedure of a solar cell element of the present embodiment. In the following drawings, the same components are denoted by the same reference numerals. In addition, the size of each component shown in the drawing is an example, and the relative relationship between the sizes of the components is not limited.

In (1) of FIG. 1, an alkaline solution is applied to a crystalline germanium substrate as the p-type semiconductor substrate 10 to remove the damaged layer, and a texture structure is obtained by etching (the description of the texture structure is omitted in the drawing).

Specifically, the damaged layer of the crucible surface generated when slicing from the ingot was removed using 20% by mass of caustic soda. Then, etching was performed using a mixed solution of 1% by mass of caustic soda and 10% by mass of isopropyl alcohol to form a texture structure. The solar cell element forms a texture structure on the light-receiving surface (hereinafter also referred to as "surface") side, thereby promoting the light confinement effect and achieving high efficiency.

In (2) of FIG. 1, the first n-type diffusion layer forming composition is applied to the surface of the p-type semiconductor substrate 10 which is the light-receiving surface, and the first composition layer 11 is formed. In the present invention, the application method is not limited. Examples of the application method include a printing method, a spinning method, a brush coating method, a spray method, a doctor blade method, a roll coater method, and an inkjet method.

The coating amount of the first n-type diffusion layer forming composition is not particularly limited. For example, the amount of the glass powder is preferably from 0.01 g/m ² to 100 g/m ² , more preferably from 0.1 g/m ² to 10 g/m ² .

Further, depending on the composition of the first n-type diffusion layer forming composition, it is preferred to provide a drying step for volatilizing the solvent contained in the composition after coating. In this case, drying can be carried out at a temperature of about 80 ° C to 300 ° C. The drying time can be, for example, 1 minute to 10 minutes when a hot plate or the like is used, and can be set to about 10 minutes to 30 minutes when a dryer or the like is used. 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.

Then, a second n-type diffusion layer is formed on the entire surface of the light-receiving surface including the first composition layer 11 to form a composition, and the second composition layer 12 is formed. In this case, the second n-type diffusion layer forming composition contains a group selected from the group consisting of alkaline earth metals and alkali metals, as compared with the concentration of the specific compound contained in the first n-type diffusion layer forming composition. The concentration of the metal compound (specific compound) of at least one metal element in the group is relatively high. Thereby, the diffusion performance of each n-type diffusion layer forming composition can be controlled.

Specifically, a composition containing 10% by mass or less of a specific compound, preferably a first n-type diffusion layer containing no specific compound, is applied. Then, it is preferable to apply a second n-type diffusion layer forming composition on the entire surface of the light-receiving surface, and the second n-type diffusion layer forming composition contains 0.01% by mass or more and 50% by mass or less of specific composition. And the concentration of the specific compound is higher than that of the first n-type diffusion layer forming composition.

Further, the second composition layer 12 may be formed not in the first composition layer 11 but in the region of the light receiving surface other than the first composition layer.

Then, the semiconductor substrate 10 on which the first composition layer 11 and the second composition layer 12 are formed is subjected to heat treatment. The temperature of the heat treatment is not particularly limited, but is preferably from 600 ° C to 1200 ° C, more preferably from 750 ° C to 1050 ° C. In addition, the time of the heat treatment is not particularly limited. For example, it is preferably carried out for 1 minute to 30 minutes. By this heat treatment, the donor element is diffused into the semiconductor substrate as shown in (3) of FIG. 1 to form the n ⁺⁺ type diffusion layer 13 and the n ⁺ type diffusion layer 14, respectively. A known continuous furnace, a batch furnace, or the like can be applied to the heat treatment. In addition, the furnace environment during heat treatment may be suitably adjusted to air, oxygen, nitrogen, or the like.

The heat treatment time can be appropriately selected depending on the content ratio of the donor element contained in the first n-type diffusion layer forming composition and the second n-type diffusion layer forming composition. For example, it can be set to 1 minute to 60 minutes, more preferably 2 minutes to 30 minutes.

In the formed n ⁺⁺ type diffusion layer 13 and n ⁺ type diffusion layer 14, the diffusion concentration of the donor element is different. Specifically, compared with the diffusion concentration of the donor element of the n ⁺⁺ type diffusion layer 13 formed by forming the composition by the first n-type diffusion layer, the composition formed by the second n-type diffusion layer is formed. The diffusion concentration of the donor element of the n ⁺ -type diffusion layer 14 is small, and the second n-type diffusion layer formation composition contains a large amount of a metal compound containing at least a metal element selected from the group consisting of an alkaline earth metal and an alkali metal.

Conventionally, as a method of forming an n-type diffusion layer, there is a thermal diffusion treatment using a phosphorus oxychloride gas or the like. In this case, when two or more kinds of n-type diffusion layers having different diffusion concentrations of the donor elements are to be formed, it is necessary to combine the thermal diffusion treatment and the mask treatment a plurality of times. Further, since phosphorus chloride is a poison, it is necessary to replace it with an inert gas for about 1 hour after being treated with phosphorus oxychloride gas, and it is impossible to take out the semiconductor substrate on which the n-type diffusion layer is formed. Move to the next step immediately. However, when the first n-type diffusion layer forming composition and the second n-type diffusion layer forming composition are used to form the n ⁺⁺ -type diffusion layer 13 and the n ⁺ -type diffusion layer 14, the above-described simple method will be adopted. Since two or more kinds of n-type diffusion layers having different diffusion densities of the donor elements are selectively formed in the desired regions, the solar cell elements having the selective emitter structure can be efficiently produced.

The heat treatment layer 11A of the first n-type diffusion layer forming composition is formed on the surface of the n ⁺⁺ type diffusion layer 13 formed by the heat treatment, and the second n type diffusion layer is formed on the surface of the n ⁺ type diffusion layer 14 to form a composition. Heat treated material layer 12A. Since a glass layer such as phosphoric acid glass is formed in the heat-treated material layers, the phosphoric acid glass is removed by an etching treatment. As the etching method, 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. By the etching treatment, as shown in (5) of FIG. 1, two kinds of n-type diffusion layers of the n ⁺⁺ type diffusion layer 13 and the n ⁺ type diffusion layer 14 having different diffusion concentrations of the donor element can be easily produced.

Forming the composition and the second n by using the first n-type diffusion layer as described above The type of diffusion layer forms a composition, and it is possible to easily form two kinds of n-type diffusion layers having different diffusion concentrations of the donor elements by one heat treatment. Here, an example in which two kinds of n-type diffusion layers having different diffusion concentrations of the donor element are formed is formed, but a composition may be formed by preparing three or more types of n-type diffusion layers having different contents of specific compounds, and the composition may be formed. These compositions are selectively applied to a desired region, and three or more kinds of n-type diffusion layers having different diffusion concentrations of the donor elements are easily formed.

Then, as shown in (6) of FIG. 1, the anti-reflection film 15 is formed on the n ⁺⁺ type diffusion layer 13 and the n ⁺ type diffusion layer 14. The anti-reflection film 15 is formed using a well-known technique. For example, when the anti-reflection film 15 is a tantalum nitride film, it is formed by a plasma chemical vapor deposition (CVD) method using a mixed gas of SiH ₄ and NH ₃ as a raw material. At this time, hydrogen diffuses in the crystal, does not participate in the bond of the bond of the helium atom, that is, a dangling bond and hydrogen bond, and inactivates the defect (hydrogen passivation). More specifically, the flow rate of the mixed gas is 0.05 to 1.0 in NH ₃ /SiH ₄ , the pressure in the reaction chamber is 0.1 Torr (13.3 Pa) to 2 Torr (266.6 Pa), and the temperature at the time of film formation is 300 ° C. 550 ° C, used for the discharge of plasma at a frequency of 100 kHz or more. The film thickness of the antireflection film is not particularly limited. For example, it is preferably set to 10 nm to 300 nm, and more preferably set to 30 nm to 150 nm.

As shown in (7) of FIG. 1, the surface electrode metal paste is applied and dried by the screen printing method or the like on the anti-reflection film 15 formed on the region of the n ⁺⁺ type diffusion layer 13 on the light-receiving surface. Thereby, the metal paste layer 16A for surface electrodes is formed. The metal paste for surface electrodes contains (1) metal particles and (2) glass particles as essential components, and if necessary, (3) a resin binder, (4) other additives, and the like.

Then, a metal paste layer 17A for a back surface electrode is formed on the back side. In the present invention, the material and formation method of the back surface electrode 17 are not particularly limited. For example, a metal paste for a back surface electrode containing a metal such as aluminum, silver or copper may be applied and dried to form a metal paste layer 17A for a back surface electrode.

Usually, the metal paste layer 17A for a back surface electrode is formed using a metal paste for a back surface electrode containing aluminum, and is subjected to a calcination treatment, thereby forming the back surface electrode 17 and forming a p ⁺ -type diffusion layer (high-concentration electric field layer) on the back surface. 18. At this time, in order to connect the solar cell elements in the module process, a silver paste for silver electrode formation may be provided on a part of the back surface.

When the production method of the present invention is used, the method for producing the p ⁺ -type diffusion layer (high-concentration electric field layer) 18 on the back surface is not limited to the method using a metal paste for a back surface electrode containing aluminum, and any of the previously known ones may be employed. The method and the range of choice of manufacturing methods are expanded. For example, a p-type diffusion layer forming composition containing an element of Group 13 such as B (boron) may be applied to form the p ⁺ -type diffusion layer 18.

Further, the thickness of the surface electrode 17 on the back surface may be formed to be thinner than the previous thickness.

The semiconductor substrate on which the surface electrode metal paste layer 16A and the back surface metal paste layer 17A are formed is subjected to a firing treatment, and the surface electrode 16 and the back surface electrode 17 are formed as shown in FIG. 1 (8) to complete the solar cell element. The calcination treatment can be, for example, calcined in the range of 600 ° C to 900 ° C for several seconds to several minutes. At this time, on the surface side, the anti-reflection film 15 as an insulating film is melted by the glass particles contained in the surface electrode metal paste layer 16A, and a part of the surface of the p-type semiconductor substrate 10 is also melted, and the metal particles in the paste ( For example, silver particles are formed in contact with the n ⁺⁺ type diffusion layer 13 of the p-type semiconductor substrate 10 and solidified. Thereby, the surface electrode 16 and the p-type semiconductor substrate 10 are electrically connected. This is referred to as fire through. In the case where the back surface electrode metal paste layer 17A containing aluminum is formed on the back surface side, when the back surface electrode 17 is formed, the p ⁺ -type diffusion layer 18 in which aluminum has diffused into the p-type semiconductor substrate 10 is formed, and it appears that It is called the back surface field of the back surface field, which contributes to high efficiency.

Next, the shape of the surface electrode 16 will be described. As shown in FIGS. 2(A) and 2(B), the surface electrode 16 includes a bus bar electrode 30 and a finger electrode 32 that intersects the bus bar electrode 30. 2(A) is a plan view of a solar cell element viewed from a light receiving surface (surface), and the solar cell element is provided with a surface electrode 16 including a bus bar electrode 30 and a finger electrode 32 crossing the bus bar electrode 30. FIG. 2(B) is a perspective view showing a part of FIG. 2(A) in an enlarged manner.

Such a surface electrode 16 can be formed, for example, by applying a metal paste by screen printing or the like as described above and subjecting it to a calcination treatment. Further, it can be formed by a method such as plating of an electrode material or vapor deposition of an electrode material by electron beam heating in a high vacuum. As is well known, the surface including the bus bar electrode 30 and the finger electrode 32 The electrode 16 is generally used as an electrode on the light-receiving surface side, and a known method of forming a bus bar electrode and a finger electrode on the light-receiving surface side can be applied.

In the above, the n ⁺⁺ type diffusion layer 13 and the n ⁺ type diffusion layer 14 are formed on the surface, and the p ⁺ type diffusion layer 18 is formed on the back surface, and further on the n ⁺⁺ type diffusion layer 13 and the p ⁺ type diffusion layer 18. The solar cell elements in which the front surface electrode 16 and the back surface electrode 17 are provided, respectively, have been described. On the other hand, when the composition is formed using the n-type diffusion layer of the present invention, a back contact type solar cell element can be easily produced.

The back contact type solar cell element is a solar cell element in which all of the electrodes are provided on the back surface to increase the area of the light receiving surface. In other words, in the back contact type solar cell element, it is necessary to form both the n ⁺ -type diffusion layer portion and the p ⁺ -type diffusion layer portion on the back surface to form a pn junction structure. Since the n-type diffusion layer forming composition of the present invention can form an n ⁺ -type diffusion layer portion only at a specific portion, it can be suitably applied to the production of a back contact type solar cell element.

When both the n ⁺ -type diffusion layer portion and the p ⁺ -type diffusion layer portion are to be formed on the back surface, an n-type diffusion layer forming composition containing a donor element such as phosphorus and a p-type diffusion layer containing an acceptor element such as boron are formed. The composition is applied to a desired region and then heat-treated, whereby an n ⁺ -type diffusion layer portion and a p ⁺ -type diffusion layer portion can be formed, respectively.

Here, in general, diffusion of a donor element such as phosphorus is easier than diffusion of an acceptor element such as boron. Therefore, when the heat treatment is simultaneously performed at the same diffusion temperature, the sheet resistance of the n ⁺ -type diffusion layer portion tends to be too small as compared with the sheet resistance of the p ⁺ -type diffusion portion. The n-type diffusion layer forming composition of the present invention can adjust the diffusibility of the donor element by containing a specific compound, and thus the diffusion concentration of the n-type diffusion layer forming composition into the semiconductor substrate can be adjusted. Thereby, the n ⁺ -type diffusion layer portion and the p ⁺ -type diffusion layer portion can be simultaneously formed, and the process time can be shortened.

Specifically, for example, a back contact type solar cell element can be produced by a manufacturing method including a manufacturing step as an example of which is schematically shown in FIG. 3 .

First, as shown in (1) of FIG. 3, a texture structure (the description of the texture structure is omitted in FIG. 3) is formed on the light-receiving surface (surface) of the n-type semiconductor substrate 10A, and the back surface is made into a low-defect structure such as a mirror shape. Specifically, the n-type semiconductor substrate is immersed in a mixed acid containing nitric acid, hydrofluoric acid, acetic acid, or the like, and the defects are removed. Then, a texture structure is formed only on the light receiving surface by alkali etching, plasma etching, or the like. The light confinement effect is promoted by forming a texture structure on the light receiving surface. In addition, by changing the back surface into a mirror shape or the like, recombination of carriers on the back surface surface can be suppressed, and the efficiency of the solar cell element can be improved.

Then, the n-type diffusion layer forming composition and the p-type diffusion layer forming composition of the present invention are partially applied to the back surface of the n-type semiconductor substrate 10A, respectively, and dried, thereby forming separately as shown in (2) of FIG. The n-type diffusion layer forms the composition layer 12 and the p-type diffusion layer formation composition layer 19. The p-type diffusion layer forming composition includes a compound containing a compound of Group 13 such as B (boron) (preferably in the form of glass particles) and a composition of a dispersion medium.

The n-type diffusion layer forming composition and the p-type diffusion layer forming composition The application method is not particularly limited. For example, there are a printing method, a spinning method, a brush coating method, a spray method, a doctor blade method, a roll coater method, and an inkjet method. The drying method is not particularly limited. For example, it can be dried using a hot plate or a dryer.

Then, the semiconductor substrate on which the n-type diffusion layer forming composition layer 12 and the p-type diffusion layer forming composition layer 19 are formed is subjected to heat treatment, whereby the p ⁺ -type diffusion layers 18 and n are formed as shown in (3) of FIG. 3 . ^{The +} type diffusion layers 14 are formed in specific regions, respectively. The conditions of the heat treatment are not particularly limited. For example, it is preferable that the surface sheet resistance value of the p ⁺ -type diffusion layer becomes 30 Ω/□ to 140 Ω/□, and the surface sheet resistance value of the n ⁺ type diffusion layer becomes 30 Ω/□ to 100 Ω/□. Heat treatment. Specifically, it is preferred to carry out heat treatment at 800 ° C to 1000 ° C for 5 minutes to 120 minutes. Since the n-type diffusion layer forming composition contains a specific compound, the diffusion ability of the donor element is controlled, so that the p ⁺ -type diffusion layer and the n ⁺ -type diffusion layer can be simultaneously formed, and the manufacturing steps can be simplified. Further, the furnace environment during heat treatment can be suitably adjusted to air, oxygen, nitrogen, or the like.

After the heat treatment, a glass layer such as a phosphoric acid glass layer is formed on the formed n ⁺ -type diffusion layer as a heat-treated material layer 12A of the n-type diffusion layer forming composition. Further, a glass layer such as a borosilicate glass layer is formed on the p ⁺ -type diffusion layer as a heat-treated material layer 19A of a p-type diffusion layer forming composition. As shown in (4) of FIG. 3, the glass layers are removed by an etching treatment such as hydrofluoric acid treatment. After the etching treatment, ultrasonic cleaning, spray cleaning, foam cleaning, and the like are performed as needed, whereby unnecessary garbage or the like derived from hydrofluoric acid treatment can be removed.

Then, as shown in (5) of FIG. 3, the anti-reflection film 15 is formed on the light-receiving surface, and the passivation film 20 is formed on the back surface. The anti-reflection film 15 is formed using a well-known technique. For example, when the anti-reflection film 15 is a tantalum 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 in the crystal, and does not participate in the bond of the bond of the ruthenium atom, that is, the dangling bond and the hydrogen bond, and passivate the defect (hydrogen passivation).

More specifically, the flow rate of the mixed gas is 0.05 to 1.0 in NH ₃ /SiH ₄ , the pressure in the reaction chamber is 0.1 Torr (13.3 Pa) to 2 Torr (266.6 Pa), and the temperature at the time of film formation is 300 ° C. 550 ° C, used for the discharge of plasma at a frequency of 100 kHz or more.

The passivation film on the back surface may be a tantalum nitride film in the same manner as the light receiving surface, and a ruthenium oxide (SiO ₂ ) film or an amorphous germanium film may be formed by a CVD method or the like.

Further, each of the antireflection film and the passivation film may have a two-layer structure including a ruthenium oxide (SiO ₂ ) film or a tantalum nitride film.

Thereafter, an electrode is formed on each of the n ⁺ -type diffusion layer and the p ⁺ -type diffusion layer formed on the semiconductor substrate. For the formation of the electrode, for example, a metal paste layer 17A for electrode formation containing glass powder having a calcination penetration property is formed on the passivation film 20. Then, this is subjected to a calcination treatment, whereby the back surface electrode 17 penetrating the passivation film 20 can be formed as shown in (7) of FIG. The composition of the metal paste for electrode formation is not particularly limited. A metal containing aluminum, silver, copper, or the like and a glass powder having calcination penetration can be used.

Manufactured by the manufacturing method including the manufacturing steps shown in FIG. In the solar cell element, since there is no electrode on the light receiving surface, sunlight can be efficiently received.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the invention is not limited to the examples. In addition, "%" means "% by mass" unless otherwise specified.

<Example 1> (Preparation of n-type diffusion layer forming composition)

A terpineol solution (Terpineol-LW, manufactured by Nippon Terpene Chemicals Co., Ltd.) containing 3.8% by mass of ethyl cellulose (manufactured by Dow Chemical Co., Ltd., Ethocel "STD200") was prepared. 9 g of this solution was mixed with 1 g of phosphorus pentoxide as a compound containing a donor element using a mortar, and it was made into a paste. Then, 0.1 g of magnesium oxide (manufactured by Wako Pure Chemical Industries, volume average particle diameter: 0.2 μm, substantially spherical) was added to 10 g of the paste, and mixed with a mortar to prepare an n-type diffusion layer forming composition. The composition is formed as a second n-type diffusion layer.

(Evaluation of preparation of composition α by diffusion layer of n ⁺⁺ type)

A solution of terpineol (Terpineol-LW, manufactured by Nippon Chemical Co., Ltd.) containing 3.8% of ethyl cellulose (manufactured by The Dow Chemical Co., Ltd., Ethocel "STD200") was prepared. 9 g of this solution was mixed with 1 g of phosphorus pentoxide (manufactured by High Purity Chemical Research Institute) as a compound containing a donor element by using a mortar to prepare a n ⁺⁺ type diffusion layer forming composition α as a first The n-type diffusion layer forms a composition.

(Manufacture of semiconductor substrate with n-type diffusion layer)

On the surface of a p-type germanium substrate having a texture structure (hereinafter, also simply referred to as "p-type germanium substrate"), a n ⁺⁺ type diffusion layer is partially applied by screen printing to form a composition α, and then at 150 ° C. The hot plate was dried for 1 minute to form a first composition layer. Then, the n-type diffusion layer forming composition obtained in the preparation of the above-described n-type diffusion layer forming composition is applied to the entire surface of the p-type tantalum substrate surface including the first composition layer, and then heated at 150 ° C. The upper layer was formed by drying on for 1 minute.

The 950 ° C tunnel furnace (transverse tube diffusion furnace ACCURON CQ-1200, manufactured by International Electric Co., Ltd.) in which air was flowed at 5 L/min. was subjected to thermal diffusion treatment for 10 minutes. Thereafter, in order to remove the glass layer formed on the surface of the p-type germanium substrate, the substrate was immersed in a 2.5 mass% hydrofluoric acid aqueous solution for 5 minutes, followed by running water washing, ultrasonic cleaning, and drying, respectively, to obtain A p-type germanium substrate of a n ⁺⁺ type diffusion layer and an n ⁺ type diffusion layer.

[Evaluation] (Measurement of sheet resistance)

For each region coated with the n ⁺⁺ type diffusion layer forming composition α and the n-type diffusion layer forming composition, a Loresta-EP MCP-T360 type low resistivity meter manufactured by Mitsubishi Chemical Corporation was used, and four The sheet resistance value of the surface of the p-type ruthenium substrate was measured by a probe method.

A region (n ⁺⁺ type diffusion layer) coated with the n ⁺⁺ type diffusion layer forming composition α has a surface sheet resistance value of 35 Ω/□, and a region coated with an n-type diffusion layer to form a composition (n ⁺ type) The diffusion sheet has a sheet resistance value of 55 Ω/□. That is, a p-type germanium substrate in which two kinds of n-type diffusion layers having different diffusion densities of phosphorus as a donor element are selectively formed is obtained.

(production of solar cell components)

The upper portion of the region where the n ⁺⁺ diffusion layer is formed on the light-receiving surface of the p-type germanium substrate on which the n ⁺ -type diffusion layer and the n ⁺⁺ diffusion layer are formed, and the Ag electrode paste is applied by screen printing to form an inclusion A composition layer for forming an electrode of Ag. Further, an Al electrode paste was screen-printed on the entire surface of the back surface to form an electrode forming composition layer containing Al.

Then, after the first region: 400 ° C, the second region: 850 ° C, the third region: 650 ° C, using a calcining furnace to perform calcination treatment at a takt time of 10 seconds, the edge is cut off to obtain a solar cell. element.

With respect to the obtained solar cell element, the solar cell evaluation system (NF Circuit Design, NF CORPORATION, As-510-PV) was used to evaluate the I-V characteristics, and as a result, the conversion efficiency was 9.2%.

<Example 2> (Preparation of n-type diffusion layer forming composition)

Using SiO ₂ (manufactured by Wako Pure Chemical Industries, Ltd.), P ₂ O ₅ (manufactured by Wako Pure Chemical Industries, Ltd.), and CaCO ₃ (manufactured by Wako Pure Chemical Industries, Ltd.) as raw materials, the respective molar ratios are changed to SiO ₂ :P ₂ O _{5 .} : CaCO ₃ = 30: 60: 10 was mixed and added to an alumina crucible, and heated at room temperature to 1400 ° C at 400 ° C / h, and then kept for 1 hour, followed by rapid cooling to obtain P ₂ O ₅ - SiO ₂ -CaO-based glass. The obtained glass was pulverized using an automatic mortar mixing device, and glass particles containing P (phosphorus) as a donor element were obtained in a powder state.

The X-ray Diffraction (XRD) pattern of the obtained glass particles was measured by using an Cu-Kα ray using a Ni filter and by an X-ray diffraction apparatus (RIT-2000). As a result, it was confirmed to be amorphous.

Further, the particle diameter of the obtained glass particles was substantially spherical, and the volume average particle diameter was measured by a laser diffraction type particle size distribution measuring apparatus, and it was 8 μm. Here, the relationship between the intensity of scattered light of the laser light irradiated to the particles and the angle is detected, and the volume average particle diameter is calculated from the Mie scattering theory. 0.1 g of the sample was dispersed in 10 g of terpineol as a dispersion medium, and was used as a measurement sample. The laser light has a wavelength of 750 nm.

Further, the shape of the glass particles was observed and judged using a TM-1000 scanning electron microscope manufactured by Hitachi High-Technologies Co., Ltd.

Then, a terpineol solution containing 3.8% of ethyl cellulose was prepared. 9 g of this solution was mixed with 1 g of the above-obtained glass particles as a compound containing a donor element using a mortar, and it was made into a paste shape. Then, magnesium oxide (manufactured by Wako Pure Chemical Industries, Ltd., volume average particle diameter of 0.2 μm, substantially spherical) was added to 10 g of the paste. g and mixing were carried out to prepare an n-type diffusion layer forming composition as the n-type diffusion layer forming composition of Example 2.

(Preparation of n ⁺⁺ type diffusion layer forming composition β)

A terpineol solution containing 3.8% ethylcellulose was prepared. 9 g of this solution was mixed with 1 g of the above-obtained glass powder as a compound containing a donor element by using a mortar to prepare an n ⁺⁺ type diffusion layer forming composition β as a first n-type diffusion layer forming composition. .

The n-type diffusion layer forming composition of Example 2 was evaluated in the same manner as in Example 1 except that the composition β was formed using the n ⁺⁺ type diffusion layer instead of the n ⁺⁺ type diffusion layer forming composition α.

[Evaluation] (Measurement of sheet resistance)

The surface sheet resistance value of the region (n ⁺⁺ type diffusion layer) to which the n ⁺⁺ type diffusion layer was formed to form the composition β was 30 Ω/□, and the region where the n-type diffusion layer was formed to form the composition (n ⁺ type diffusion layer) was applied. The surface sheet resistance value is 50 Ω/□. That is, a p-type germanium substrate in which two kinds of n-type diffusion layers having different diffusion densities of phosphorus as a donor element are selectively formed is obtained.

(production of solar cell components)

Further, using the obtained p-type ruthenium substrate, a solar cell element was produced and evaluated in the same manner as in Example 1, and as a result, the conversion efficiency was 9.6%.

<Example 3 to Example 10, Comparative Example 1 to Comparative Example 3> (Preparation of n-type diffusion layer forming composition)

The n-types of Examples 3 to 10 and Comparative Examples 1 to 3 were prepared in the same manner as in Example 2 except that the materials for the preparation of the n-type diffusion layer forming composition were changed as shown in Table 1. The diffusion layer forms a composition. Further, the numerical values in Table 1 indicate the blending amount (g), and "-" indicates that the blending amount is not adjusted.

[Evaluation]

Evaluation was performed in the same manner as in Example 2 except that the n-type diffusion layer forming compositions of Examples 3 to 10 and Comparative Examples 1 to 3 were used. The results are shown in Table 1.

Further, the compounds used in Examples 3 to 10 and Comparative Examples 1 to 3 described in Table 1 are as follows.

. Magnesium oxide (manufactured by Wako Pure Chemical Industries, Ltd., volume average particle size is 0.2 μm)

. Calcium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., volume average particle size 1.5 μm)

. Calcium carbonate (manufactured by High Purity Chemical Company, 2.0 μm)

. Magnesium carbonate (manufactured by Wako Pure Chemical Industries, Ltd., volume average particle size of 2.0 μm)

. Potassium Oxide (manufactured by Wako Pure Chemical Industries, Ltd., volume average particle size of 3.5 μm)

. Yttrium oxide (manufactured by High Purity Chemical Research Institute, volume average particle size of 1.0 μm)

. Polyethyleneimine (manufactured by Wako Pure Chemical Industries, Inc., volume average particle size of 1.0 μm)

. Iron oxide (manufactured by Wako Pure Chemical Industries, Ltd., volume average particle size is 1.0 μm)

By forming the composition using the n-type diffusion layers of Examples 1 to 10, an n-type diffusion layer can be formed in a specific region. Further, by using the n-type diffusion layer forming compositions of Examples 1 to 10 and the n ⁺⁺ type diffusion layer forming composition α or the n ⁺⁺ type diffusion layer forming composition β, it is possible to perform primary thermal diffusion treatment. A diffusion layer having a different diffusion concentration is formed. Further, the sheet resistance value of the sample of Example 4 in which the amount of calcium hydroxide was 1 g was 95 Ω, and the sheet resistance of Example 4 in which the amount of calcium hydroxide was 0.5 g was 85 Ω, and the amount of calcium hydroxide was adjusted. The sheet resistance value of Example 4 of 0.01 g was 40 Ω. Thus, the n-type diffusion layer forming composition of the present invention can be adjusted by adjusting the amount of the metal compound (specific compound) containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals. The diffusion concentration is easily adjusted. Further, the conversion efficiency of the solar cell element produced by using the n-type diffusion layer forming compositions of Examples 1 to 10 was good.

On the other hand, when the composition is formed using the n-type diffusion layer of Comparative Example 1 to Comparative Example 3 containing no specific compound, the region where the first n-type diffusion layer is formed is applied, and the second n-type diffusion is applied. The surface sheet resistance value of the region where the layer was formed into the composition did not show a clear difference. That is, it is understood that the n-type diffusion layer forming composition containing no metal compound having an alkaline earth metal or an alkali metal has an effect of adjusting the diffusion concentration. Further, the solar cell elements produced by using the n-type diffusion layers of Comparative Examples 1 to 3 were all low in conversion efficiency.

In Comparative Example 2, since polyethyleneimine was decomposed at a high temperature (in this case, 950 ° C) subjected to thermal diffusion treatment, it was considered that the adjusted diffusion concentration was not obtained. effect. In Comparative Example 3, the iron element diffused into the substrate became a recombination center of the carrier (electrons, holes) in the semiconductor substrate, and the life of the carrier was shortened, so that the conversion efficiency was considered to be lowered.

According to the above, it is understood that the n-type diffusion layer can be formed in a specific region by using the n-type diffusion layer forming composition of the present invention, and the diffusion of the donor element in the formed n-type diffusion layer can be easily adjusted. concentration.

The entire contents disclosed in Japanese Patent Application No. 2012-002632 are incorporated herein by reference.

All the documents, patent applications, and technical specifications described in the specification are incorporated herein by reference to the same extent as the following, which is specifically and individually described by reference. The status of each document, patent application, and technical specifications.

10‧‧‧p type semiconductor substrate

11‧‧‧First composition layer

11A‧‧‧ Heat treatment layer

12‧‧‧Second composition layer

12A‧‧‧ Heat treated layer

13‧‧‧n ⁺⁺ type diffusion layer

14‧‧‧n ⁺ type diffusion layer

15‧‧‧Anti-reflective film

16‧‧‧ surface electrode

16A‧‧‧metal paste layer for surface electrodes

17‧‧‧Back electrode

17A‧‧‧metal paste layer for back electrode

18‧‧‧p ⁺ type diffusion layer (high concentration electric field layer)

Claims (17)

An n-type diffusion layer forming composition comprising: a compound containing a donor element; a metal compound which is a compound different from the above-described compound containing a donor element, and contains a group selected from the group consisting of alkaline earth metals and alkali metals At least one metal element in the medium; and a dispersing medium. The n-type diffusion layer forming composition according to claim 1, wherein the compound containing the donor element is a compound containing P (phosphorus). The n-type diffusion layer forming composition according to claim 1 or 2, wherein the metal compound is selected from the group consisting of magnesium, calcium, sodium, potassium, lithium, cesium, lanthanum, cerium, lanthanum, cerium, and A compound of at least one metal element in a group consisting of radium. The n-type diffusion layer forming composition according to any one of the items 1 to 3, wherein the content of the metal compound is 0.01% by mass or more and 50% by mass or less. The n-type diffusion layer forming composition according to any one of claims 1 to 4, wherein the metal compound is solid particles at a normal temperature, and the volume average particle diameter of the particles is 0.01 μm or more. Below 30 μm. The n-type diffusion layer forming composition according to any one of claims 1 to 5, wherein the compound containing the donor element is selected from the group consisting of P ₂ O ₃ and P ₂ O ₅ . At least one compound in the group. The n-type diffusion layer forming composition according to any one of claims 1 to 6, wherein the compound containing the donor element is in the form of glass particles. The n-type diffusion layer forming composition according to claim 7, wherein the glass particles contain at least one substance containing a donor element selected from the group consisting of P ₂ O ₃ and P ₂ O ₅ And selected from the group consisting of 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 and MoO ₃ At least one glass component substance in the group. The n-type diffusion layer forming composition according to the seventh or eighth aspect of the invention, wherein the content of the glass particles is 1% by mass or more and 80% by mass or less. The n-type diffusion layer forming composition according to any one of the items 7 to 9 wherein the total content of P ₂ O ₃ and P ₂ O ₅ in the glass particles is 0.01% by mass or more. 10% by mass or less. The n-type diffusion layer forming composition according to any one of claims 1 to 10, further comprising an organic binder. A method of manufacturing a semiconductor substrate with an n-type diffusion layer, comprising: applying an n-type diffusion layer according to any one of claims 1 to 11 on the entire surface or a portion of the semiconductor substrate. a step of forming a composition to form an n-type diffusion layer forming composition layer; and a step of performing heat treatment on the semiconductor substrate on which the composition layer is formed. A semiconductor with an n-type diffusion layer as described in claim 12 a method of manufacturing a substrate, further comprising the step of applying a first n-type diffusion layer forming composition to form a first composition layer in a portion of the semiconductor substrate, wherein the first n-type diffusion layer forming composition comprises a coating The compound of the bulk element and the dispersion medium, and the step of forming the n-type diffusion layer forming the composition layer is a step of forming the same surface on the surface of the semiconductor substrate on which the first composition layer is formed, and forming In the region where the region of the first composition layer is different, the content of the applied metal compound is larger than that of the n-type diffusion layer forming composition of the first n-type diffusion layer forming composition, and the metal compound contains a material selected from the group consisting of alkaline earth metals and alkalis. At least one metal element in the group consisting of metals. A method of manufacturing a solar cell element, comprising the steps of: applying a first n-type diffusion layer forming composition to form a first composition layer in a portion of a region on a semiconductor substrate, the first n-type diffusion layer forming composition a compound containing a donor element and a dispersion medium; the same surface as the surface on which the first composition layer is formed on the semiconductor substrate, and in a region different from the region in which the first composition layer is formed, a step of forming a composition of the second n-type diffusion layer to form a second composition layer, wherein the second n-type diffusion layer forming composition is the n-type diffusion according to any one of claims 1 to 11. a layer forming composition, and a content of the metal compound containing at least one metal element selected from the group consisting of an alkaline earth metal and an alkali metal is greater than the first n-type diffusion layer forming composition; heat treatment of the semiconductor substrate and the second composition layer of the composition layer, a region in which the second component layer on the semiconductor substrate, n ⁺ -type diffusion Step n ⁺⁺ type diffusion layer has a sheet resistance value of the surface layer is smaller than the n ⁺ -type diffusion region, are formed on the first composition layer is formed; and forming an electrode on said n ⁺⁺ type diffusion layer A step of. The method for producing a solar cell element according to claim 14, wherein the first n-type diffusion layer forming composition contains at least one metal element selected from the group consisting of alkaline earth metals and alkali metals. The content of the metal compound containing at least one metal element selected from the group consisting of alkaline earth metals and alkali metals in the second n-type diffusion layer forming composition is 10% by mass or less. It is 0.01% by mass or more and 50% by mass or less. A method of producing a solar cell element, comprising: forming at least one of the n-type diffusion layer forming compositions according to any one of claims 1 to 11 on a semiconductor substrate to form a composition layer a step of performing heat treatment on the semiconductor substrate on which the composition layer is formed to form an n-type diffusion layer, and a step of forming an electrode on the n-type diffusion layer. An n-type diffusion layer forming composition kit comprising: a first n-type diffusion layer forming composition containing a compound containing a donor element And a second n-type diffusion layer forming composition, which is an n-type diffusion layer forming composition according to any one of claims 1 to 11, and contains an alkali earth metal and The content of the metal compound of at least one metal element in the group consisting of alkali metals is larger than that of the first n-type diffusion layer forming composition.