TW201401533A - Solar cell and producing method therefor - Google Patents

Abstract

The purpose of the present invention is to improve the power generation efficiency of a back-junction solar cell. In order to achieve this purpose, an ONO multilayer film in contact with the backside of a substrate, an n+-layer side electrode penetrating through the ONO multilayer film and contacting the n+ layer, and a p+-layer side electrode penetrating through the ONO multilayer film and contacting the p+ layer are formed so as to cover the n+ layer and the p+ layer provided on the backside of the substrate. In this case, the silicon nitride film in the ONO multilayer film in contact with the n+ layer acts as a positive charge storage film, while the silicon nitride film in the ONO multilayer film in contact with the p+ layer acts as a negative charge storage film irradiated by UV light.

Description

Solar cell and method of manufacturing same

The present invention relates to a solar cell and a method of manufacturing the same, and more particularly to a technique suitable for a back junction type solar cell and a method of manufacturing the same.

In recent years, in the structure of a solar cell, the surface (main surface) on the front side of the substrate, that is, the electrode is not present on the light-irradiating surface, and only the back surface, that is, the surface opposite to the light-irradiating surface is disposed. The back-joining type solar cell among the back electrode type solar cell is prevalent in development research. In the back surface bonding type solar cell, the front surface electrode and the back surface electrode of the former solar cell are disposed on the back surface. The maximum effect of the back surface bonding type structure is that the light shielding loss due to the surface electrode can be eliminated. Therefore, by using the back surface bonding type structure, the solar cell can be made more efficient.

On the other hand, regarding passivation of solar cells, field effect passivation technology has attracted attention in recent years. The field effect passivation is a technique of reducing the asymmetry of the electron density and the positive hole density of the semiconductor layer by the fixed charge of the passivation film, and improving the probability of recombination in the vicinity of the interface between the passivation film and the semiconductor layer. For example, as the Si (矽) sun A passivation film of a battery cell, a SiN (tantalum nitride) film which is now widely used, usually has a positive charge. Therefore, in the vicinity of the interface between the tantalum substrate and the tantalum nitride film constituting the solar cell, electrons in the tantalum substrate are attracted by the positive charge in the tantalum nitride film, and the positive holes in the tantalum substrate are in the tantalum nitride film. The positive charge causes rejection, so the electron density in the germanium substrate is higher than the positive hole density.

The recombination of electrons and positive holes has the highest probability of occurrence when the number density of the two is the same, so as described above, the electron density and the positive hole density are asymmetric, that is, by increasing the electron density and positive The difference in pore density can suppress recombination. The passivation film should be connected to the emitter layer of the solar cell, that is, the p ⁺ layer or the n ⁺ layer doped with a high concentration. In this case, by the field effect passivation, the asymmetry of the electron density and the positive hole density is increased. Therefore, it is necessary that the passivation film connected to the n ⁺ layer has a positive charge, and the passivation film connected to the p ⁺ layer has a negative charge.

Make contact with the n ⁺ layer of the passivation film charging a positive charge, in order to make the electrons in the n ⁺ layer, by the positive charge in the passivation film, it is attracted to the n ⁺ layer near the interface of the passivation film, on the contrary, the n The positive hole of the ⁺ layer is made to repel the positive charge in the passivation film, so that the electron density is higher than the positive hole density, and the recombination probability is reduced. Similarly, the passivation film on the p ⁺ contact layer pads with negative charge, for the passivation film by negative charges, the positive holes in the p ⁺ layer, is attracted to the vicinity of the p ⁺ layer and the interface of the passivation film, Conversely, by making the electrons in the p ⁺ layer repel the negative charge in the passivation film, the positive hole density is higher than the electron density to reduce the recombination probability. In this manner, a passivation film in which electric charges corresponding to the n ⁺ layer and the p ⁺ layer are accumulated is formed, and by performing field effect passivation, the solar cell can be made more efficient.

For example, in the case of a Si solar cell, it is conceivable that a negatively charged Al ₂ O ₃ (alumina) film is adjacent to the p ⁺ layer to perform field effect passivation on the p ⁺ layer.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2008-10746

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2005-322780

As described above, in recent years, the back surface bonding type which is a structure of a solar cell or the field effect passivation which is a passivation technique of a solar cell is attracting attention in a structure which can improve the power generation efficiency of a solar cell. However, combining these two technologies will cause the following problems. That is, in the back-junction type solar cell, the p ⁺ layer and the n ⁺ layer exist on the same surface (for example, the back surface of the substrate), so when field effect passivation is applied, it is necessary to make a positively charged film and a negatively charged film. The film is formed in the same plane so as to be connected to the same surface (for example, the back surface of the substrate).

As a method of forming the same, the following method is disclosed in Patent Document 1 (JP-A-2008-10746). First, after forming a p ⁺ layer and an n ⁺ layer on the back surface of the germanium substrate, a passivation film having a positive or negative charge, for example, a positively charged film, is formed on the back surface by a film formation method or the like. comprehensive. Thereafter, among the passivation films, only the film in the region in contact with the p ⁺ layer is removed by patterning. Next, the passivation film having a negative charge is formed in a comprehensive manner by a film formation method.

By the above steps, a structure in which an n ⁺ layer is in contact with a film having a positive charge and a p ⁺ layer is in contact with a film having a negative charge is obtained, and field effect passivation becomes possible. However, the method described in Patent Document 1 includes a step of removing the passivation film by patterning and a secondary film formation step, which causes a problem of an increase in manufacturing cost.

On the other hand, in the method of applying field effect passivation to the back junction type solar cell, the following method is disclosed in the patent document 2 (JP-A-2005-322780). First, after the p ⁺ layer and the n ⁺ layer are formed on the back surface of the substrate, a passivation film having a positive or negative charge, for example, a positively charged film, is formed on the entire back surface. Thereafter, the passivation film in the aforementioned, only the ion implantation region of the membrane in contact with the p ⁺ layer. In this case, the ion species to be implanted is such that a negative charge is generated in the passivation film. In Patent Document 2, a method of injecting Cu (copper) into a SiN (tantalum nitride) film to generate a negative charge is exemplified. In the case of using this method, ion implantation is used. Therefore, unlike the method described in Patent Document 1, there is an advantage that it is not necessary to use pattern removal and a complicated process of forming a film twice.

However, the method described in the above Patent Document 2 has the following three problems. First, ions that are implanted into the passivation film reach the substrate, and damage due to ion implantation occurs on the substrate, and the substrate can be predicted to be amorphous. When ion implantation is performed under the conditions described in Patent Document 2, since the implantation dose is high, it is predicted that the electrical insulation of the passivation film is impaired.

Further, in Patent Document 2, the ion implantation step is not explicitly described, and which electrode is to be formed first in the electrode formation step, and electrode formation is performed first. In the case where ion implantation is performed under the conditions described in Patent Document 2, it is predicted that damage to the electrode may be caused by ion implantation, and the contact resistance between the electrode and the external wiring is increased. In other words, as described in Patent Document 2, as described above, there is a problem in that damage is caused by ion implantation.

As described above, in the back-junction type solar cell, when a negatively charged film is adjacent to the p ⁺ film, a positively charged film is adjacent to the n ⁺ film, and field effect passivation is performed. In the method of charging a film and a film having a negative charge, removal of the film by patterning, or formation of a film or the like across a plurality of times, the solar cell is damaged, and there is a problem that reliability is lowered. Further, when the film is removed by patterning, or when a film or the like is formed over a plurality of times, the manufacturing process becomes complicated, and there is a problem that the manufacturing cost of the solar cell increases.

It is an object of the invention to improve the performance of a solar cell.

Further, another object of the present invention is to improve the reliability of a solar cell.

Further, still another object of the present invention is to simplify the manufacturing steps of the solar cell.

The above objects and novel features of the present invention are apparent from the description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS A summary of representative forms of the embodiments disclosed in the present invention is as follows.

A solar cell according to an embodiment has an n-layer, a p-layer formed in the same plane as the n-layer, and a first hafnium oxide film or tantalum nitride which is sequentially laminated on the n-layer and the p-layer. A passivation film of the film and the second hafnium oxide film; a portion adjacent to the n layer of the tantalum nitride film has a positive charge, and a portion adjacent to the p layer has a negative charge.

Further, a solar cell according to another embodiment includes an n-layer, a p-layer formed in the same plane as the n-layer, and a first yttrium oxide film sequentially laminated on the n-layer and the p-layer, a passivation film of a tantalum nitride film and a second hafnium oxide film; the n layer and the p layer are different in width, and are connected to the n-layer side electrode of the n layer and the p-side electrode connected to the p layer The first tantalum nitride film adjacent to the n-layer portion has a positive charge, and among the tantalum nitride films adjacent to the p-layer portion, a part of the tantalum nitride film has a positive charge, and the remaining portion has a negative charge.

Further, a method for manufacturing a solar cell according to another embodiment includes: (a) a step of forming an n layer, (b) a step of forming a p layer in the same plane as the n layer, and (c) forming a sequential layer. a step of laminating the n-layer and the p-layer first passivation film, the tantalum nitride film, and the passivation film of the second hafnium oxide film, and (d) the passivation film adjacent to the n-layer a portion of the portion forming a contact hole, (e) a step of forming an n-layer side electrode in contact with the n-layer after the step (d), (f) a step of irradiating the aforementioned passivation film with UV light.

Briefly, the effects obtainable by the representative of the invention disclosed in the present invention are as follows.

According to the present invention, the performance of the solar cell can be further improved.

1‧‧‧矽 substrate

11 ‧ ‧ layer

12‧‧‧Contact hole

13‧‧‧Layer side electrode

21 ‧ ‧ layer

22‧‧‧Contact hole

23‧‧‧Layer side electrode

31‧‧‧ONO laminated film

32‧‧‧Oxide film

33‧‧‧ nitride film

34‧‧‧Oxide film

35‧‧‧ positive charge accumulation film

36‧‧‧Negative charge accumulation film

Fig. 1 is a plan view showing a solar cell of Embodiment 1 of the present invention.

Figure 2 is a cross-sectional view taken along line A-A of Figure 1.

Fig. 3 is a cross-sectional view showing a manufacturing step of a solar cell according to Embodiment 1 of the present invention.

Fig. 4 is a plan view showing the back side of the solar cell in the manufacturing step shown in Fig. 3.

Figure 5 is a cross-sectional view of the solar cell in the manufacturing step subsequent to Figure 3.

Fig. 6 is a plan view showing the back side of the solar cell in the manufacturing step shown in Fig. 5.

Figure 7 is a cross-sectional view of the solar cell in the manufacturing step subsequent to Figure 5.

Fig. 8 is a plan view showing the back side of the solar cell in the manufacturing step shown in Fig. 7.

Figure 9 is a cross-sectional view of the solar cell in the manufacturing step subsequent to Figure 7.

Fig. 10 is a plan view showing the back side of the solar cell in the manufacturing step shown in Fig. 9.

Figure 11 is a cross-sectional view of the solar cell in the manufacturing step subsequent to Figure 9.

Fig. 12 is a plan view showing the back side of the solar cell in the manufacturing step shown in Fig. 11.

Figure 13 is a cross-sectional view of the solar cell in the manufacturing step subsequent to Figure 11.

Fig. 14 is a plan view showing the back side of the solar cell in the manufacturing step shown in Fig. 13.

Figure 15 is a cross-sectional view of the solar cell in the manufacturing step subsequent to Figure 13.

Fig. 16 is a plan view showing the back side of the solar cell in the manufacturing step shown in Fig. 15.

Fig. 17 is an energy band structure of an interface between an ONO laminated film and a substrate.

Fig. 18 is a cross-sectional view showing a solar cell according to a modification of the first embodiment of the present invention.

Fig. 19 is a cross-sectional view showing a solar cell according to a modification of the first embodiment of the present invention.

Fig. 20 is a plan view showing a solar cell of Embodiment 2 of the present invention.

Figure 21 is an enlarged plan view showing an enlarged portion of Figure 20.

Figure 22 is a cross-sectional view taken along line B-B of Figures 20 and 21.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. also, In order to explain the entire drawings of the embodiments, the same reference numerals will be given to the components having the same functions, and the repeated description will be omitted. Further, in the following embodiments, the same or the same portions will not be repeatedly described in principle unless otherwise necessary.

Further, in the drawings used in the following embodiments, even if it is a plan view or a bird's-eye view, it is partially shaded in order to make the drawing easy to read.

[Implementation type 1]

Fig. 1 is a plan view showing the back side of a solar cell according to the present embodiment. The ruthenium oxide film 34 formed on the lower surface of the ruthenium substrate and the p ⁺ layer side electrode 13 and the n ⁺ layer side electrode 23 formed on the lower portion of the ruthenium oxide film 34 are shown in FIG. Each of the p ⁺ layer side electrode 13 and the n ⁺ layer side electrode 23 has a pattern extending in the first direction along the back surface of the ruthenium substrate. The patterns extending in the first direction of the p ⁺ layer side electrode 13 and the n ⁺ layer side electrode 23 are arranged in a second direction orthogonal to the first direction, and each of the patterns extends between the second pattern The pattern of the p ⁺ layer side electrode 13 and the n ⁺ layer side electrode 23 in the direction is alternately arranged in the first direction.

In short, each of the p ⁺ layer side electrode 13 and the n ⁺ layer side electrode 23 has a comb-shaped shape including a pattern extending in the first direction and a plurality of patterns extending in the second direction from the pattern. Further, in FIG. 1, a structure having a comb-shaped electrode pattern is displayed on the back surface bonding type solar cell, but in the present embodiment, another electrode pattern may be used.

Fig. 2 is a cross-sectional view showing a back junction type solar cell of an important portion of the solar cell of the embodiment, and Fig. 2 is a cross section taken along line A-A of Fig. 1. Figure. The surface of the back-junction type solar cell should be subjected to texture processing to form a doped layer for preventing surface recombination, that is, a so-called FSF (Front Surface Field) layer is formed, and further A surface passivation film, an anti-reflection film, or the like is formed, but these are not shown in FIG. 2, and only the structure of the crucible substrate 1 and its vicinity of the back surface is shown. Further, in Fig. 2, a structure in which the back surface is not subjected to texturing processing is shown, but here, texture processing may be applied to the back surface. In addition, the texture processing is to form irregularities on the surface of the solar cell for the purpose of preventing the reflection of light on the surface of the solar cell, and more efficiently taking light into the cell of the solar cell.

As shown in FIG. 2, the back surface bonding type solar cell constituting the solar cell of the present embodiment has a ruthenium substrate (semiconductor substrate) 1 on which a p ⁺ layer 11 and an n ⁺ layer 21 are formed. The ONO laminated film 31 is formed on the back surface of the ruthenium substrate 1 so as to cover the back surfaces of the ruthenium substrate 1, the p ⁺ layer 11, and the n ⁺ layer 21, and is formed on the back surface of the ONO laminated film 31. The p ⁺ layer side electrode 13 of the p ⁺ layer 11 and the n ⁺ layer side electrode 23 connected to the n ⁺ layer 21.

The ruthenium substrate 1 is more effective than the p-type substrate in that an n-type substrate having a long carrier life is used, and the power generation efficiency of the solar cell is increased. However, in the present embodiment, the ruthenium substrate 1 may be p-type. The substrate may also be an n-type substrate. Further, since the p ⁺ layer 11 and the n ⁺ layer 21 are higher in the impurity concentration than the substrate 1 , they are not referred to as a p layer or an n layer, and are referred to as a p ⁺ layer and an n ⁺ layer.

Feature of the present embodiment is configured patterns, as a passivation film, a SiO ₂ (silicon oxide) / SiN (silicon nitride) / SiO ₂ (silicon oxide) layer of the laminated film 3 (hereinafter referred to as this laminated film ONO The laminated film 31) and the fixed charge of the tantalum nitride film 33 in the ONO laminated film 31 are negatively charged in a region in contact with the p ⁺ layer, and positive in a region in contact with the n ⁺ layer. Charge this.

The ONO laminated film 31 is composed of a yttrium oxide film 32, a tantalum nitride film 33, and a yttrium oxide film 34, wherein the yttrium oxide film 32 is located at a position in contact with the p ⁺ layer and the n ⁺ layer, and the yttrium oxide film 34 is located. A position that does not connect to the p ⁺ layer and the n ⁺ layer. In short, the yttrium oxide film 32, the tantalum nitride film, and the hafnium oxide film 34 are sequentially formed from the back surface of the substrate 1 toward the lower side, and the three layers of the insulating film constitute the ONO laminated film 31. Further, the tantalum nitride film 33 in the ONO laminated film 31 that is in contact with the p ⁺ layer 11 serves as the negative charge storage film 36, and the tantalum nitride film in the ONO laminated film 31 in the region in contact with the n ⁺ layer 21 33 becomes the positive charge storage film 35. Here, the ONO laminated film 31 including the tantalum nitride film 33 is a field effect passivation film, and by forming the ONO laminated film 31 adjacent to the p ⁺ layer 11 and the n ⁺ layer 21, field effect passivation effect can be obtained. .

As described above, the field effect passivation is such that the p ⁺ layer is in contact with the negatively charged film, and the n ⁺ layer is in contact with the positively charged film. The structure is most effective, and the configuration of the present embodiment satisfies condition. As the back surface electrode, a p ⁺ layer side electrode 13 that is in contact with the p ⁺ layer 11 and an n ⁺ layer side electrode 23 that is in contact with the n ⁺ layer 21 are formed. The ONO laminated film 31 connected to the p ⁺ layer 11 is formed so as to expose the contact hole 22 on the lower surface of the p ⁺ layer 11, and in the contact hole 22, the ONO laminated film 31 is interposed under the p ⁺ layer 11 A part of the formed p ⁺ layer side electrode 13 is buried. Similarly, in contact with the n ⁺ ONO laminated film layer 21 and 31, is formed of the exposed contact holes below the n ⁺ layer 21 and 12, the contact hole 12, on the n ⁺ directly below the interposer 21 of the ONO layer A part of the n ⁺ layer side electrode 23 formed by the film 31 is buried. The depth and diameter of the contact hole should be optimized in consideration of processing accuracy, contact resistance, and interface recombination speed.

As described above, the solar electrode of the present embodiment has the ruthenium substrate 1 and the p ⁺ layer 11 and the n ⁺ layer 21 formed in the semiconductor region on the back surface of the ruthenium substrate 1 so as to cover the back surface of the ruthenium substrate 1 . The ONO laminated film 31, the p ⁺ layer side electrode 13 which is electrically connected to the p ⁺ layer 11 through the ONO laminated film 31, and the through-ON multilayer film 31 are electrically connected to the n ⁺ layer side of the n ⁺ layer 21 Electrode 23. The ONO laminated film 31 has a tantalum nitride film 33 sandwiched by the yttrium oxide films 32 and 34 in a direction perpendicular to the back surface of the tantalum substrate 1.

The tantalum nitride film 33 has a positive charge storage film 35 in a region overlapping the n ⁺ layer side electrode 23 in plan view, and has a negative charge storage film 36 in a region overlapping the n ⁺ layer side electrode 23 in plan view. In short, the tantalum nitride film 33 in the ONO laminated film 31 in the region not in contact with the p ⁺ layer 11 and the n ⁺ layer 21 has the negative charge storage film 36. Negative charge storage film 36, as described later, for the silicon nitride film 33 based originally having a positive charge to the n ⁺ layer 23 as a mask-side electrode irradiating UV (ultraviolet) light, so that the n ⁺ layer is exposed from the side electrode 23 The tantalum nitride film 33 in the ONO laminated film 31 in the region is a film formed by charging negative. Further, the positive charge storage film 35 is covered with the n ⁺ layer side electrode 23 in the irradiation step of the UV light, and is a film having a residual positive charge in a region not irradiated with the UV light.

In the solar cell of the present embodiment, by using the configuration as described above, electrons in the substrate 1 can be pulled to the side of the n ⁺ layer side electrode 23 by the positive charge in the positive charge storage film 35. The positive hole is not brought close to the side of the n ⁺ layer side electrode 23. Similarly, the positive hole in the ruthenium substrate 1 can be pulled toward the p ⁺ layer side electrode 13 side by the negative charge in the negative charge storage film 36 so that the electrons are not close to the p ⁺ layer side electrode 13 side.

Thereby, it is possible to prevent the electron density and the positive hole density from being in the vicinity of the interface between the n ⁺ layer 21 and the n ⁺ layer side electrode 23 or in the vicinity of the interface between the p ⁺ layer 11 and the p ⁺ layer side electrode 13, so that it can be prevented. Recombination of electrons with positive holes. This is because the recombination of electrons and positive holes has the highest probability of occurrence when the number density of the two is the same. Therefore, in the present embodiment, the ONO laminated film 31 of the field effect passivation film is used to increase the number of electrons and positive The difference in the number of holes to prevent the aforementioned recombination. That is, in the back junction type solar cell of the present embodiment, the power generation efficiency can be further improved. Thereby, the performance of the solar cell can be improved.

Next, a method of manufacturing the solar cell of the present embodiment will be described with reference to Figs. 3 to 16 . 3, 5, 7, 9, 9, 13, and 15 are cross-sectional views for explaining a method of manufacturing a solar cell of the present embodiment, which corresponds to the line AA of Fig. 1. section. 4, 6, 8, 8, 10, 14, and 16, respectively, using FIG. 3, FIG. 5, FIG. 7, FIG. 9, FIG. 11, FIG. 13, and FIG. A plan view of the back side of the solar cell in the manufacturing step of the step.

First, as shown in FIGS. 3 and 4, a p ⁺ layer 11 and an n ⁺ layer 21 of a semiconductor layer are formed on the back surface of the germanium substrate 1. A cross-sectional view of the structure after formation of the p ⁺ layer 11 and the n ⁺ layer 21 is shown in Fig. 3, and a plan view is shown in Fig. 4. A method of forming the p ⁺ layer 11 and the n ⁺ layer 21, using a conventional gas phase diffusion method or the like, first forming the p ⁺ layer 11 in its entirety, then partially forming the n ⁺ layer 21, or making the p ⁺ layer A method in which 11 and n ⁺ layers 21 are partially formed, and the like.

As a method of partially forming the p ⁺ layer 11 or the n ⁺ layer 21, it is conceivable to perform vapor phase diffusion after patterning the diffusion preventing layer on the back surface of the tantalum substrate 1, or to spread the paste to the tantalum substrate 1. The method of forming the back surface is followed by patterning, and then solid layer diffusion is performed. The second layer is a solid layer diffusion, for example, a diffusion paste containing a p-type impurity (for example, B (boron)) is formed on a germanium substrate, and the impurities are diffused into the germanium substrate by heat treatment to form on the surface of the germanium substrate. The method of the p-type layer.

In this manner, the p ⁺ layer 11 is formed by introducing a p-type impurity (for example, B (boron)) to the back surface of the counter substrate 1, and the n ⁺ layer 21 is introduced with an n-type impurity (for example, P (phosphorus) on the back surface of the counter substrate 1 . )) formed. Further, in FIG. 3 and FIG. 4, a p ⁺ contact layer 11 and the n ⁺ layer 21 different from each other, the case of the present configuration of the silicon substrate 1 therebetween, the p ⁺ layer 11 and n ⁺ layer 21 may contact each other .

Each of the p ⁺ layer 11 and the n ⁺ layer 21 is alternately arranged in the first direction along the back surface of the tantalum substrate 1 to form a plurality of layers. Further, the p ⁺ layer 11 and the n ⁺ layer 21 are formed so as to extend in the second direction orthogonal to the first direction.

Next, as shown in FIGS. 5 and 6, an ONO laminated film 31 covering the back surface of the ruthenium substrate 1 is formed. A cross-sectional view of the structure after formation of the ONO laminated film 31 is shown in Fig. 5, and a plan view is shown in Fig. 6. The ONO laminated film 31 is formed on the back surface of the ruthenium substrate 1 and sequentially laminates the ruthenium oxide film 32, the tantalum nitride film 33, and the ruthenium oxide film 34 so as to cover the p ⁺ layer 11 and the n ⁺ layer 21 . .

Among the films constituting the ONO laminated film 31, the formation of the yttrium oxide film 32 may be performed by oxidation of the ruthenium substrate 1, the p ⁺ layer 11 and the n ⁺ layer 21, or by CVD (Chemical Vapor Deposition) method. It may be carried out by a film formation method. As a property required for the ruthenium oxide film 32, the interface state density density with the ruthenium substrate 1, the p ⁺ layer 11, and the n ⁺ layer 21 is small. In order to satisfy this requirement, the formation of the ruthenium oxide film 32 is preferably carried out by thermal oxidation. Further, as will be described later, the ruthenium oxide film 32 is responsible for preventing the barrier layer in which the carrier between the ruthenium substrate 1, the p ⁺ layer 11 and the n ⁺ layer 21 and the tantalum nitride film 33 is moved, and therefore it is required to pass. The leakage current of the ruthenium oxide film 32 is as small as possible. That is, the film thickness of the yttrium oxide film 32 is preferably 5 nm or more.

The formation of the tantalum nitride film 33 is performed by a reduced pressure CVD method (LPCVD method) or a plasma enhanced CVD method (PECVD method). The film formation by the LPCVD method is carried out, for example, at a temperature of 750 ° C to 800 ° C, using SiH ₂ + Cl ₂ (chlorinated alkane) and NH ₃ (ammonia) as a material gas. The film formation by the PECVD method is carried out, for example, at a temperature of 250 ° C or more and 450 ° C or less, using SiH ₄ (monodecane) NH ₃ (ammonia) and N ₂ (nitrogen) as raw material gases. The tantalum nitride film 33 formed under these conditions becomes a tantalum nitride film 33 having a positive charge. Further, the formation of the ruthenium oxide film 34 is performed by a film formation method such as a CVD method.

Then, 7 and 8, in the laminated film in the ONO layer 31, connected to a portion of the n ⁺ layer region 21, a contact hole so that the n ⁺ layer 21 beneath the exposed side of the n ⁺ layer 22 is formed. A cross-sectional view of the structure after the opening of the contact hole 22 is shown in Fig. 7, and a plan view is shown in Fig. 8. The formation of the contact hole 22 may be performed by laser irradiation, or may be performed by an etching method or the like using an etching paste or a photo etching technique. It is necessary for the contact hole 22 to pass through the yttrium oxide film 32 at least through the yttrium oxide film 32. When the contact hole 22 is formed by the above-described method, a part of the n ⁺ layer 21 may be etched. When the n ⁺ layer 21 is etched, the concentration of the outermost surface impurity of the n ⁺ layer 21 is lowered, and the contact resistance with the electrode formed later is increased. Therefore, it is preferable to suppress the etching amount to a minimum. Further, it is preferable to form the contact hole 22 for laser irradiation in a space where vacuum is applied without causing burrs.

Next, as shown in FIGS. 9 and 10, the n ⁺ layer side electrode 23 is formed under the ONO laminated film 31 so as to be buried in the contact hole 22. A cross-sectional view of the structure after formation of the n ⁺ layer side electrode 23 is shown in Fig. 9, and a plan view is shown in Fig. 10. The material of the n ⁺ layer side electrode 23 is Ag (silver), Al (aluminum), Ti (titanium), Cu (copper) or a compound containing these as a main component. In addition, the n ⁺ layer side electrode 23 may be a film obtained by laminating a plurality of films of a film formed of a layered Ag film, an Al film, a Ti film, a Cu film, and a compound containing these as a main component. The formation of the n ⁺ layer side electrode 23 is performed, for example, by a printing method, a vapor deposition method, a plating method, a sputtering method, a CVD method, or the like.

Further, the size of the contact hole 22, that is, the diameter of the contact hole 22, is as small as possible in the contact resistance of the n ⁺ layer 21 and the n ⁺ layer side electrode 23 in a range which does not cause a decrease in the efficiency of the solar cell. It is better. The reason for this is that the recombination speed of the interface between the n ⁺ layer 21 and the n ⁺ layer side electrode 23 is greater than the recombination speed of the interface between the n ⁺ layer 21 and the hafnium oxide film 32, by reducing the n ⁺ layer 21 and n ⁺ The area of the interface between the layer side electrodes 23 can suppress recombination and improve the characteristics of the solar cell. In short, between the semiconductor layer such as bismuth (Si) and the metal film, the recombination is more remarkable than that between the semiconductor layer and the ruthenium oxide film, so that the diameter of the contact hole 22 is reduced, and the buried contact hole 22 is reduced. The contact area of the n ⁺ layer side electrode 23 and the germanium substrate 1 can prevent recombination of electrons and positive holes. The diameter of the contact hole 22 is, for example, 10 to 100 μm.

Next, as shown in FIGS. 11 and 12, the UV light is irradiated to the ONO laminated film 31 from the back side of the ruthenium substrate 1. As the UV light, it is preferable to use light having a wavelength of 310 nm or less and energy of 4 eV or more for the reason described later.

A cross-sectional view of the solar cell in the manufacturing step of the step of irradiating the UV light is shown in Fig. 11, and a plan view is shown in Fig. 12. As indicated by an arrow in FIG. 11, the UV light is irradiated from the lower side (back side) of the ruthenium substrate 1 toward the ONO laminated film 31 on the back surface of the ruthenium substrate 1. At this time, the n ⁺ layer side electrode 23 reflects the UV light, but in the region where the n ⁺ layer side electrode 23 does not exist, that is, the region which is not covered by the n ⁺ layer side electrode 23, the ONO laminated film 31 is irradiated with UV light. . In the region irradiated with the UV light, the tantalum nitride film 33 in the ONO laminated film 31 is formed by the positively charged tantalum nitride film 33 after the film formation, and the negatively charged tantalum nitride film 33 is also negative. The charge accumulation film 36 changes.

Here, the tantalum nitride film 33 having a positive charge is not referred to as the positive charge storage film 35, and is not irradiated with the UV light. In other words, the tantalum nitride film 33 after the UV light irradiation is a positive charge storage film 35 which is superposed on the n ⁺ layer side electrode 23 in plan view, and a negative charge storage film 36 which is not overlapped with the n ⁺ layer side electrode 23 in plan view. Composition. Hereinafter, this phenomenon will be described.

17 shows a four-layer energy band structure of the base substrate 1, the yttrium oxide film 32, the tantalum nitride film 33, and the yttrium oxide film 34. Since the tantalum oxide film 32 and the tantalum oxide film 34 form an energy barrier by the tantalum nitride film 33, the electric charge of the tantalum nitride film 33 cannot move freely and remains in the tantalum nitride film 33.

As described above, the tantalum nitride film 33 in the ONO laminated film 31 retains the charge property and is applied to a nonvolatile memory such as a MONOS (Metal Oxide Nitride Oxide Semiconductor) type memory. In the MONOS-type memory, by carrying out carrier injection according to a tunneling current or the like from the germanium substrate 1 to the tantalum nitride film 33, even if the tantalum nitride film 33 accumulates electrons, the positive holes can be accumulated. When the charge sign and the charge amount of the tantalum nitride film 33 are changed, the threshold voltage of the transistor is changed, and reading is performed to realize the operation as a memory.

When the MONOS type memory is irradiated with UV light, the threshold voltage change is uniquely determined regardless of the value of the threshold voltage before the irradiation. The value of the threshold voltage after the irradiation is about 1 V when the ruthenium substrate 1 is a p-type substrate. This value means that the ruthenium nitride film 33 has a negative charge state. The reason why the tantalum nitride film 33 has a negative charge by UV light irradiation can be explained by the energy band structure of FIG.

From the viewpoint of the substrate 1, the yttrium oxide film 32 forms an energy barrier, the conduction band barrier height X is about 3 eV, and the valence electron band barrier height Y is about 4 eV. The foregoing The energy of the UV light is a higher value than these barriers. That is, the electrons and the positive holes excited by the UV light move between the ruthenium substrate 1 and the tantalum nitride film 33 over the barrier ribs of the ruthenium oxide film 32. At this time, by making the valence electron band gap height between the ruthenium substrate 1 and the ruthenium oxide film 32 higher than the height of the conduction band barrier, the electrons from the ruthenium substrate 1 to the ruthenium nitride film 33 are excessively supplied, in the case of In the state, the number of electrons existing in the tantalum nitride film 33 is larger than the number of positive holes. In summary, the tantalum nitride film 33 is changed to a state having a negative charge by irradiation with UV light.

In the present embodiment, after the UV light is irradiated, the carrier barrier between the ruthenium substrate 1 and the ruthenium oxide film 32 is hindered by the energy barrier of the ruthenium oxide film 32, so that the negative charge accumulated in the tantalum nitride film 33 is accumulated. It continues to exist in peace. Internally, the positive charge storage film 35 having a positive charge is adjacent to the negative charge storage film 36 having a negative charge, so that the distance between the positive charge storage film 35 and the negative charge storage film 36 is short enough, there are both. The possibility of offsetting the charge, but in the solar cell, can be said without this concern.

In the MONOS-type memory, a large number of memory cells are formed in the same faded ruthenium film 33, but the inter-cell charge interference does not affect the memory at least when the distance between the memory cells is 0.1 μm or more. action. In the solar cell, the distance between the positive charge storage film 35 and the negative charge storage film 36 corresponds to the distance between the p ⁺ layer 11 and the n ⁺ layer 21, and is about several tens of μm to several mm, so there is no such thing as described above. The charge is offset between the positive charge storage film 35 and the negative charge storage film 36.

Here, the distance between the p ⁺ layer 11 and the n ⁺ layer 21 refers to the arrangement interval of the p ⁺ layer 11 and the n ⁺ layer 21 which are alternately arranged in the second direction described above, and is not the adjacent p ⁺ layers 11 and n. ⁺ The shortest distance between the opposite ends of layer 21 from each other. In short, the pitch is, for example, the distance between the central portion of the p ⁺ layer 11 in the second direction and the central portion of the n ⁺ layer 21 adjacent to the p ⁺ layer 11 .

In the present embodiment, an important point is that the UV light is irradiated from the side of the solar cell to which the n ⁺ layer side electrode is disposed, and the n ⁺ layer side electrode 23 reflects the UV light, so only the n ⁺ layer side electrode 23 The non-existing region, that is, the region not covered by the n ⁺ layer side electrode 23, the ONO laminated film 31 is irradiated with UV light.

As a result, among the ONO laminated films 31, the tantalum nitride film 33 has a positive charge in a region in contact with the n ⁺ layer 21, and the tantalum nitride film 33 has a negative charge in a region in contact with the p ⁺ layer 11. . In summary, it is possible to achieve a configuration in which field effect passivation works effectively.

Further, when the field effect passivation is realized, the passivation film having a positive charge is patterned in the p ⁺ layer, and then formed so as to be in contact with the n ⁺ layer provided in the same plane as the p ⁺ layer, without using In the complicated process such as a negatively-charged passivation film, the positive charge storage film 35 and the negative charge storage film 36 are separately formed by using an integrated process, which is an important point in this embodiment. In short, the n ⁺ layer side electrode 23 is irradiated with UV light as a mask, and the positive charge storage film 35 and the negative charge storage film 36 are integrally formed by itself. Therefore, the manufacturing process of the solar cell can be simplified, and the manufacturing cost of the solar cell can be reduced.

Further, a method of forming a negative charge storage film 36 by injecting a Cu (copper) plasma species into the passivation film to charge the passivation film with a negative charge can also be performed. In consideration of such a method, the tantalum substrate is damaged by ion implantation, and is amorphized to deteriorate the characteristics of the solar cell. Further, when the electrode is damaged by ion implantation, the wiring resistance of the electrode and other wirings is increased. As described above, when ion implantation is performed and a negative charge is charged in the passivation film, the solar cell is damaged and the reliability of the solar cell is lowered.

On the other hand, in the present embodiment, by forming the negative charge storage film 36 by irradiation of UV light, it is possible to prevent the ruthenium substrate 1 or the n ⁺ layer side electrode 23 from being damaged as in the case of performing ion implantation, so that the solar cell can be improved. Trustworthiness.

Next, as shown in FIG. 13 and FIG. 14, among the ONO laminated film 31, a contact hole 12 is formed (opened) in a part of the region of the p ⁺ layer 11. The configuration after the formation of the contact hole 22 is shown in Fig. 13, and the plan view is shown in Fig. 14. The formation of the contact hole 12 may be performed by laser irradiation as in the formation of the contact hole 22, or may be performed by etching or the like using an etching paste or a photo etching technique. Further, similarly to the contact hole 22, the contact hole 12 is opened so that the bottom surface of the p ⁺ layer 11 is exposed.

Further, in the present embodiment, a method of manufacturing the contact hole 12 after the UV light irradiation is described. However, when the contact hole 12 is formed, for example, when the sample temperature rises to 200 ° C or higher, the formation is performed. It is preferable to manufacture the solar cell in the order of the UV light irradiation after the contact hole 12. The reason is that the charge accumulated in the tantalum nitride film 33 increases the probability that the electric charge accumulated in the tantalum nitride film 33 passes over the energy barrier of the tantalum oxide film 32 due to thermal energy, and the negative charge storage film 36 formed by the UV light irradiation has return The possibility of a positively charged tantalum nitride film in the initial state.

Next, as shown in FIGS. 15 and 16, the p ⁺ layer side electrode 13 is formed so as to be buried in the contact hole 12. The material of the p ⁺ layer side electrode 13 may be the same as the material of the n ⁺ layer side electrode 23, and may be different. The metal in conductive contact with the p ⁺ layer 11 and the metal in conductive contact with the n ⁺ layer 21 have different optimum operating functions, so in order to reduce the contact resistance, the material of the p ⁺ layer side electrode 13 and the n ⁺ layer side are It is preferred that the work function of the material of the electrode 23 is optimized separately. Specifically, the metal that is in conductive contact with the p ⁺ layer 11 is preferably Al (aluminum), and the metal that is in conductive contact with the n ⁺ layer 21 is preferably Ag (silver). Further, the size (diameter) of the contact hole 12 is appropriately determined in the same manner as in the case of the contact hole 22 described above.

By the above, the solar cell of this embodiment is completed. Further, in addition to the above steps, in order to improve the crystallinity, the film quality, and the like of each film, or to improve the quality of the interface with the adjacent film, heat treatment, plasma treatment, or the like may be added.

Further, in Fig. 2, the widths of the p ⁺ layer 11 and the n ⁺ layer 21 are made the same, and the widths of the p ⁺ layer 11 and the p ⁺ layer side electrode 13 are made equal to each other, so that the n ⁺ layers 21 and n are made. width ⁺ side electrode layer 23 is constructed of the same degree as the case. However, in practice, the positive hole life in the substrate 1 of the back junction type solar cell is shorter than the electron lifetime, so it is conceivable that the width of the p ⁺ layer 11 is larger than the width of the n ⁺ layer 21. In this case, as shown in FIG. 18, the widths of the p ⁺ layer 11 and the p ⁺ layer side electrode 13 are the same, and the widths of the n ⁺ layer 21 and the n ⁺ layer side electrode 23 are also the same. structure. Further, as shown in Fig. 19, the widths of the p ⁺ layer 11 and the p ⁺ layer side electrode 13 may be different, and the widths of the n ⁺ layer 21 and the n ⁺ layer side electrode 23 may be different, and the p ⁺ layer side may be different. The width of the electrode 13 and the n ⁺ layer side electrode 23 is the same as that of the case. 18 and 19 are cross-sectional views showing a modification of the solar cell of the present embodiment.

Here, the wide width refers to the first direction in which the p ⁺ layer 11 or the n ⁺ layer 21 extending in the second direction along the back surface of the dam substrate 1 is orthogonal to the respective extending directions (second direction). The length of the p ⁺ layer 11 or the n ⁺ layer 21 . Similarly, the width of the p ⁺ layer side electrode 13 or the n ⁺ layer side electrode 23 means the length of each electrode in the first direction orthogonal to the extending direction (second direction) of the pattern extending in the second direction. . That is, the width of the p ⁺ layer side electrode 13 or the n ⁺ layer side electrode 23 does not mean the direction in which the p ⁺ layer side electrode 13 or the n ⁺ layer side electrode 23 extends in the region extending in the first direction (first The length of the direction).

Hereinafter, the effect of the case of applying the method of the present embodiment to the above two types of structures will be described.

First, as shown in FIG. 18, it is considered that the width of the p ⁺ layer 11 is larger than that of the n ⁺ layer 21, and the width of the p ⁺ layer 11 and the p ⁺ layer side electrode 13 are the same, n ⁺ layer 21 The width of the n ⁺ layer side electrode 23 is also the same. The negative charge storage film 36 is formed in a region not covered by the n ⁺ layer side electrode 23 by performing UV light irradiation using the steps described with reference to FIGS. 3 to 17 . Therefore, in the case of the structure shown in Fig. 18, among the regions of the ONO laminated film 31 that are in contact with the n ⁺ layer 21, the tantalum nitride film 33 has a positive charge, and a region in contact with the p ⁺ layer 11 is nitrided. Since the ruthenium film 33 has a negative electric charge, the above-described embodiment can obtain the same effects as those of the structure shown in Fig. 2 .

Next, as shown in FIG. 19, it is considered that the widths of the p ⁺ layer 11 and the p ⁺ layer side electrode 13 are different, and the widths of the n ⁺ layer 21 and the n ⁺ layer side electrode 23 are different, and the p ⁺ layer side electrode 13 is different. The width of the n ⁺ layer side electrode 23 is the same. In this case, among the ONO laminated film 31, the tantalum nitride film 33 has a positive charge in a part of the region in contact with the p ⁺ layer 11. In short, there is a region where the p ⁺ layer 11 and the positive charge storage film 35 overlap each other in plan view.

In the case of the structure shown in Fig. 2 and Fig. 19, the width of the n ⁺ layer side electrode 23 is large as compared with the structure shown in Fig. 18, so that the wiring resistance can be reduced. Further, in the case where the value of the wiring resistance is large and the efficiency of the solar cell is lowered, in order to avoid this, a method of increasing the height (film thickness) of the n ⁺ layer side electrode 23 is preferable.

Further, in the case of the structure shown in FIG. 2 and FIG. 18, among the tantalum nitride film 33 in the ONO laminated film 31, only the positive charge storage film 35 is formed in the region in contact with the p ⁺ layer 11. The region where the n ⁺ layer 21 is in contact is formed only by the negative charge storage film 36, so that the effect of field effect passivation can be improved as compared with the configuration shown in FIG.

As described above, the characteristics of the solar cell of the present embodiment are different as the relationship between the size of the width of the p ⁺ layer 11, the n ⁺ layer 21, the p ⁺ layer side electrode 13, and the n ⁺ layer side electrode 23 is different. Differently, it is necessary to carry out the above-described increase in the height of the electrode, etc., depending on the occasion.

Further, in the solar cell of the present embodiment, as shown in Figs. 1 and 2, p ⁺ layer side electrodes 13 and n ⁺ layers corresponding to the planar shape of the p ⁺ layer 11 and the n ⁺ layer 21 are formed, respectively. Side electrode 23. In short, for example, the n ⁺ layer 21 is arranged in a matrix on the back surface of the tantalum substrate 1 to form a complex number, and the p ⁺ layer 11 is formed in other regions on the back surface of the tantalum substrate 1, and the position corresponding to each n ⁺ layer 21 is plural. The configuration in which the contact hole 22 is opened to the ONO laminated film 31 is not employed in this embodiment.

As described above, when the complex n ⁺ layer 21 is formed to form the p ⁺ layer 11 on a broad surface in such a manner as to surround it, a few of the n ⁺ layers 21 dispersed in a matrix form are extended in one direction. When the n ⁺ layer side electrode 23 is covered, the ONO laminated film 31 which is formed between the adjacent n ⁺ layers 21 and which is connected to the p ⁺ layer 11 is covered by the n ⁺ layer side electrode 23. In such a state, even if UV light is applied to the ONO laminated film 31, the charge inversion of the tantalum nitride film 33 in the region in contact with the p ⁺ layer 11 does not occur in the region covered by the n ⁺ layer side electrode 23 occur. That is, a portion of the tantalum nitride film 33 in the region in contact with the p ⁺ layer 11 becomes the positive charge storage layer 35. In short, there is a region where the p ⁺ layer 11 is passivated by the positive charge storage film 35.

On the other hand, in the back surface bonding type solar cell of the present embodiment, the structure in which the p ⁺ layer 11 is not present directly above the n ⁺ layer side electrode 23 can be realized. In short, it is possible to form a structure in which the p ⁺ layer 11 and the positive charge storage film 35 do not overlap each other in plan view. That is, in the present embodiment, the field effect passivation can be performed more effectively than in the solar cell in which the p ⁺ layer 11 and the positive charge storage film 35 are overlapped in plan view as described above. Improve the performance of solar cells.

[Implementation 2]

A solar cell according to the present embodiment will be described with reference to Figs. 20 to 22 . Fig. 20 is a plan view showing the back side of the solar cell of the embodiment. Figure 21 is a plan view showing an enlarged view of a portion of Figure 20. Figure 22 is a cross-sectional view taken along line B-B of Figures 20 and 21.

The difference from the foregoing embodiment 1 is that the configuration of the first embodiment is a back-junction type solar cell, and the configuration of the present embodiment is an emitter-wound through (EWT) solar cell. a little. As shown in FIG. 22, the EWT solar cell is formed through the through hole of the upper surface and the lower surface of the ruthenium substrate 1, and thereafter, after the n ⁺ layer 21 is formed on the inner wall of the through hole and the back surface of the ruthenium substrate 1, A solar cell of the n ⁺ layer side electrode 23 buried in the through hole is formed. Further, a p ⁺ layer 11 is formed on the back surface of the germanium substrate 1. The plan view shown in Fig. 20 is the same as the plan view of the back-junction type solar cell shown in Fig. 1, and the EWT solar cell is the p ⁺ layer side electrode 13 and the n ⁺ layer side electrode, similarly to the back surface bonding solar cell. 23 is one of the back electrode type solar cell cells disposed on the back side.

In the EWT solar cell, by forming the n ⁺ layer side electrode 23 penetrating the ruthenium substrate 1, the movement path of electrons in the ruthenium substrate 1 is shortened, and the electric resistance can be reduced. Further, the n ⁺ layer 21 is formed at a position away from the p ⁺ layer 11 in the positive hole concentration, so that electrons in the tantalum substrate 1 can be prevented from recombining with the positive holes in the vicinity of the p ⁺ layer 11.

As shown in Fig. 22, the solar cell structure of the present embodiment is also the same as the structure of the above-described embodiment 1, and the tantalum nitride film in the region where the n ⁺ layer 21 is in contact with the ONO laminated film 31. 33 is a positive charge storage film 35, and a tantalum nitride film 33 in a region in contact with the p ⁺ layer 11 is a negative charge storage film 36.

According to the present embodiment, as in the case of the back surface bonding type solar cell of the first embodiment, the EWT solar cell is not patterned, and the n ⁺ layer 21 is passivated to a film having a positive charge. The p ⁺ layer 11 is passivated to a film having a negative charge, and field effect passivation can be achieved. In the same manner as in the first embodiment, the effect of the present embodiment is different depending on the size relationship of the width of the p ⁺ layer 11, the n ⁺ layer 21, the p ⁺ layer side electrode 13, and the n ⁺ layer side electrode 23. Different, it is necessary to design according to the occasion.

The method for producing a solar cell of the present embodiment is almost the same as that of the first embodiment. That is, after the through hole penetrating the ruthenium substrate 1 is formed by laser irradiation, the n ⁺ layer 21 is formed on the inner wall of the through hole and the back surface of the ruthenium substrate 1, and the p ⁺ layer 11 is formed on the back surface of the ruthenium substrate 1. . Next, an ONO laminated film 31 is formed on the back surface of the germanium substrate 1, and thereafter, a contact hole 22 is formed, and then an n ⁺ layer side electrode 23 is formed. Then, by irradiating the ONO laminated film 31 with UV light, the positively charged tantalum nitride film in the region not covered by the n ⁺ layer side electrode 23 among the ONO laminated film 31 is changed to a negative charge storage film. After 36, the contact hole 12 is formed, and then the p ⁺ layer side electrode 13 is formed.

Further, the EWT solar cell is formed into a cylindrical shape along the inner wall of the through hole with respect to the n ⁺ layer 21 as viewed from above, and the n ⁺ layer side electrode 23 and the inner wall formed in each of the plurality of through holes The n ⁺ layer 21 is formed in a line shape overlapping the plan view. Fig. 21 is a plan view showing the ruthenium substrate 1 (see Fig. 22) as seen from the back side. In FIG. 21, the shapes of the n ⁺ layer side electrode 23 and the p ⁺ layer side electrode 13 which are formed on the lower side (back side) of the base substrate 1 are indicated by broken lines.

As shown in FIG. 21, the n ⁺ layer side electrode 23 is formed on the back side of the ruthenium substrate 1, and is exposed by a plurality of contact holes arranged in the second direction, and extends over the plurality of n ⁺ layers 21 so as to extend over Configured in the second direction. Further, the p ⁺ layer side electrode 13 is formed on the back surface of the ruthenium substrate 1, and is exposed by a plurality of contact holes arranged in the second direction, and is arranged to extend in the second direction so as to cover the plurality of p ⁺ layers 11 of. In a through hole at the center of the annular n ⁺ layer 21, a part of the n ⁺ layer side electrode 23 is buried so as to penetrate the ruthenium substrate 1. Further, in Fig. 21, a plurality of p ⁺ layers 11 exposed by the ONO laminated film 31 (see Fig. 22) containing the hafnium oxide film 34 are shown, but the p ⁺ layers 11 are not arranged in a matrix on the back surface of the tantalum substrate 1. The shape is actually formed in a wide range of the back surface of the ruthenium substrate 1, and is formed to surround each of the plurality of n ⁺ layers 21.

That is, on the back surface of the ruthenium substrate 1, the p ⁺ layer 11 exists in a region in which the n ⁺ layer 21 having an annular shape is not formed in a plan view, so that n is formed so as to overlap the plurality of n ⁺ layers 21 ⁺ layer portion directly above the side electrode 23, there must be a p ⁺ layer 11. In short, the n ⁺ layer side electrode 23 is formed to overlap not only the n ⁺ layer 21 but also the p ⁺ layer 11 . In other words, the tantalum nitride film 33 in the region covered by the n ⁺ layer side electrode 23 does not charge a negative charge even after the UV light irradiation step, and maintains a positive charge state, and the positive charge storage film 35 and p ⁺ The layer 11 has a structure in which the planes are arranged in a plan view and overlapped. This point is different from the back junction type solar cell described in the above first embodiment.

In such a solar cell, the line width of the n ⁺ layer side electrode 23 is set as close as possible to the value of the aperture of the n ⁺ layer 21, and the p ⁺ layer 11 and the positive charge storage film 35 can be reduced in plan view. The area, so the field effect passivation can be more effective, and the performance of the solar cell can be improved.

The invention made by the inventors of the present invention is specifically described above based on the embodiments, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the invention.

[Industrial use possibility]

The present invention is effectively applied to a manufacturing technique of a back junction type solar cell.

1‧‧‧矽 substrate

11 ‧ ‧ layer

12‧‧‧Contact hole

13‧‧‧Layer side electrode

21 ‧ ‧ layer

22‧‧‧Contact hole

23‧‧‧Layer side electrode

31‧‧‧ONO laminated film

32‧‧‧Oxide film

33‧‧‧ nitride film

34‧‧‧Oxide film

35‧‧‧ positive charge accumulation film

36‧‧‧Negative charge accumulation film

Claims (12)

A solar cell characterized by having an n-layer, a p-layer formed in the same plane as the n-layer, and a first yttrium oxide film and a tantalum nitride which are sequentially laminated on the n-layer and the p-layer A passivation film of the film and the second hafnium oxide film; a portion adjacent to the n layer of the tantalum nitride film has a positive charge, and a portion adjacent to the p layer has a negative charge. The solar cell according to claim 1, wherein the n layer and the p layer have the same width, and the n layer side electrode connected to the n layer is equal in width to the p layer side electrode connected to the p layer. . The solar cell according to claim 1, wherein the n layer and the p layer have different widths, and the n layer side electrode connected to the n layer is different from the p layer side electrode connected to the p layer. . The solar cell according to claim 3, wherein the width of the p-layer is larger than that of the n-layer, and the width of the p-side electrode is larger than the width of the n-layer side electrode. The solar cell according to claim 1, wherein the first yttria film has a film thickness of 5 nm or more. The solar cell of claim 1, wherein the n layer and the p layer are formed in the same plane of the substrate. A solar cell characterized by having an n-layer, a p-layer formed in the same plane as the n-layer, and a first yttrium oxide film and a tantalum nitride which are sequentially laminated on the n-layer and the p-layer a film and a passivation film of the second hafnium oxide film; wherein the n layer and the p layer have different widths, and the n layer side electrode connected to the n layer is equal in width to the p layer side electrode connected to the p layer; The tantalum nitride film adjacent to the n-layer portion has a positive charge, and a part of the tantalum nitride film adjacent to the p-layer portion has a positive charge and a negative charge. A method for manufacturing a solar cell, comprising: (a) a step of forming an n layer, (b) a step of forming a p layer in the same plane as the n layer, and (c) forming a layer by sequential bonding in the foregoing a step of the n-layer and the passivation film of the first yttrium oxide film, the tantalum nitride film, and the second yttrium oxide film of the p-layer, (d) forming a part of the portion adjacent to the n-layer among the passivation film a step of contacting a hole, (e) a step of forming an n-layer side electrode in contact with the n-layer after the step (d), and (f) a step of irradiating the passivation film with UV light. A method of manufacturing a solar cell according to item 8 of the patent application, wherein In the above step (f), the UV light is irradiated by the side where the n-layer side electrode is provided in the step (e). The method for producing a solar cell according to the eighth aspect of the invention, further comprising (g) the step of forming a contact hole in a portion adjacent to the p layer in the passivation film, (h) in (f) above After the step, and after the aforementioned step (g), a step of forming a p-layer side electrode in contact with the aforementioned p-layer is formed. The method for producing a solar cell according to the eighth aspect of the invention, wherein the wavelength of the UV light is 310 nm or less. The method of manufacturing a solar cell according to the eighth aspect of the invention, wherein in the step (a), the n layer is formed on one of the planes of the substrate, and in the step (b), the p layer is formed on the plane of the substrate.