JP6090209B2 - Solar cell and method for manufacturing solar cell - Google Patents

Description

The present invention relates to a cell structure for improving light utilization efficiency and a method for manufacturing the same for solar cells.

  In a solar cell, it is necessary to ensure electrical continuity by connecting an electrode on a light incident surface (hereinafter also referred to as a light receiving surface) or an electrode opposite to the light receiving surface (hereinafter referred to as a back surface) and a semiconductor substrate of the solar cell. In a diffusion type solar cell in which a diffusion layer is formed by diffusing impurities to form a pn junction, since the conductivity of the diffusion layer is low, a large amount of impurities are in contact with the aluminum (Al) electrode of the semiconductor substrate. There is a method in which a diffused low resistance layer is formed, and then an electrode is formed so as to overlap the low resistance layer region. By this method, low resistance electrical connection can be ensured between the metal electrode and the semiconductor substrate (see, for example, Patent Document 1).

  In such a solar cell, it is necessary to form a high-concentration impurity diffusion layer serving as a low-resistance contact region and an Al electrode so as to overlap each other at the same position. Therefore, in the Al electrode formation process, alignment with a high concentration impurity diffusion layer that is difficult to discriminate by observation is necessary, and a special apparatus is required, which complicates the process.

Therefore, after boron (B) is diffused into the semiconductor substrate, the boron silicate glass (BSG) film generated on the substrate surface is left and a silicon nitride (SiN _x ) film is laminated on the BSG layer, and then a boron-containing glass frit There has been proposed a method of penetrating a BSG film and a silicon nitride (SiN _x ) film by a fire-through method using an aluminum-containing paste mixed with. This is to form a low-resistance field effect layer containing boron and aluminum in BSG inside the cell (see, for example, Patent Document 2). The Al electrode thus fabricated forms a field effect layer in which aluminum and boron are diffused to a depth of about 10 times the boron diffusion layer of the semiconductor substrate after penetrating the silicon nitride film and the BSG film.

JP 2010-118473 A JP 2013-143459

  In a solar cell as shown in Patent Document 2, an alignment process with a high-concentration impurity diffusion layer is not required for electrode formation, but the thickness of the BSG layer formed during boron diffusion is about 50 nm. Since the thickness is an obstacle to the diffusion phenomenon of hydrogen, the defect termination (passivation) effect near the substrate surface by hydrogen supplied from the silicon nitride film formed by the CVD method at the time of electrode firing cannot be obtained. There is a problem that application is difficult in a configuration in which a passivation effect by a film formed by the method is essential.

  The present invention has been made in order to solve the above-described problems, and a solar cell that exhibits high photoelectric conversion efficiency by securing a defect termination effect while eliminating the above-described alignment step when forming an electrode. The purpose is to obtain.

A solar cell according to the present invention includes a first conductivity type semiconductor substrate, a second conductivity type layer formed on the first surface of the first conductivity type semiconductor substrate, and a first passivation formed on the second conductivity type layer. A first functional layer formed on the first passivation layer and including a component capable of adding conductivity to the second conductive type layer ; and a first antireflection formed on the first functional layer. A first electrode formed so as to penetrate from the first antireflection film to the first passivation film and reach the second conductivity type layer, and within the second conductivity type layer, the first electrode And a first conductive layer including the same component as the component capable of adding conductivity to the second conductive type layer included in the first functional layer.

  According to the present invention, while ensuring the passivation effect in the vicinity of the substrate surface, the electrode incorporating the component contained in the functional layer at the time of fire-through reaches the second conductivity type layer that is the low-concentration impurity diffusion region. A conductive state having a low resistance can be obtained by a conductive layer including a component.

It is sectional drawing which shows the structure of the solar cell of Embodiment 1 of this invention. It is a flowchart which shows the process of forming the structure by the side of the light-receiving surface of Embodiment 1 of this invention. It is a top view which shows the example of arrangement | positioning of the light-receiving surface electrode of the solar cell of Embodiment 1 of this invention. It is sectional drawing which shows the structure of the solar cell of Embodiment 2 of this invention. It is sectional drawing which shows the structure of the solar cell of Embodiment 3 of this invention. It is a top view which shows the example of arrangement | positioning of the light-receiving surface electrode of the solar cell of Embodiment 3 of this invention. It is a top view which shows the structure of the light-receiving surface electrode of the solar cell of Embodiment 3 of this invention.

  Embodiments of a solar cell manufacturing apparatus according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably. In the drawings shown below, the scale of each member may be different from the actual scale for easy understanding. The same applies between the drawings.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing the structure of a solar cell according to Embodiment 1 for carrying out the present invention. In the solar cell according to the first embodiment, the second conductivity type layer 2 is formed by impurity diffusion on the first surface side which is the light receiving surface of the first conductivity type substrate 1 made of the first conductivity type semiconductor, A passivation layer 3 formed directly on the second conductivity type layer 2, a functional layer 4 containing a functional substance, and an antireflection film 5 are sequentially laminated. The functional substance has an effect of adding conductivity when diffused into the second conductivity type layer 2.
Further, a light receiving surface electrode 6 is formed at an appropriate position on the light receiving surface from above the antireflection film 5, and when the light receiving surface electrode 6 is baked, it penetrates each layer and is in contact with the second conductivity type layer 2. In the vicinity of the interface where the light-receiving surface electrode 6 is in contact with the second conductivity type layer 2, a conductive layer 7 in which the functional substance of the functional layer 4 is diffused as a result of firing is formed. A first conductive type layer 8 formed by impurity diffusion, a passivation layer 9 and an antireflection film 10 are formed in this order on the second surface which is the back surface of the first conductive type substrate 1. The back electrode 11 is formed at an appropriate location.

  Note that a fine concavo-convex structure called a texture is usually formed on the light receiving surface of the first conductivity type substrate 1 (not shown) in order to reduce light reflection. Therefore, a layer structure such as the second conductivity type layer 2 is formed on the texture. In addition, a texture may be formed on the back surface as well as the light receiving surface. It is preferable that the light receiving surface and the back surface of the first conductivity type substrate 1 have a texture in order to reduce the reflectance. However, a flat surface structure or a combination of a concavo-convex structure and a flat structure may be used according to the application. Good.

As the first conductivity type substrate 1 according to the present embodiment, for example, a single crystal or polycrystalline silicon substrate that is an n-type containing a small amount of phosphorus or the like can be used. In this case, the second conductivity type layer 2 may be a p-type impurity diffusion layer in which, for example, boron is diffused with an impurity concentration of less than 1 × 10 ²⁰ cm ⁻³ . For the functional layer 4 in that case, for example, a boron silicate glass (BSG) layer containing boron may be used. The light-receiving surface electrode 6 is formed using, for example, a thick film material in which aluminum particles and silver particles are mixed. The passivation layer 3 is, for example, a silicon oxide film, and the antireflection film 5 is, for example, a silicon nitride (SiN _x ) film. A low pressure CVD method or a normal pressure CVD method can be used to form the silicon oxide film, silicon nitride film, and BSG layer.

  On the other hand, the first conductivity type layer 8 on the back surface is, for example, an n-type impurity diffusion layer in which phosphorus is diffused. For example, a silicon oxide film is used for the passivation layer 9, and a silicon nitride film is used for the antireflection film 10, for example. The back electrode 11 is formed using, for example, a material mainly composed of silver particles.

  In addition to boron, the component contained in the functional layer 4 that acts as a conductive material functions as an acceptor in the n-type first conductivity type substrate 1 such as aluminum, gallium, or indium. I just need it. Alternatively, a metal such as gold, silver, copper, or nickel can be used.

  The first conductivity type substrate 1 is not limited to the n-type described above, and a p-type silicon substrate may be used. In that case, for example, phosphorus may be diffused into the second conductivity type layer 2 to form an n-type layer, and boron may be diffused into the first conductivity type layer 8 to form a p-type layer. The component for adding conductivity contained in the functional layer 4 may be any component that functions as a donor, such as arsenic and antimony.

The light-receiving surface electrode 6 is formed by a process of penetrating the antireflection film 5, the functional layer 4, and the passivation layer 3 by a fire-through method in the baking step after the printing. As the material of the light-receiving surface electrode 6, glass frit particles, thick film printing paste in which metal particles are dispersed in an organic binder and an organic solvent are used, and the metal particles are aluminum or a mixture of silver and aluminum. Can do.
The pattern formation of the electrode on the antireflection film 5 may be performed by a screen printing method using, for example, the above-described thick film printing paste and a screen mask corresponding to the pattern. FIG. 2 is a flowchart showing a process of forming the structure on the light receiving surface side in the first embodiment.

  FIG. 3 is a plan view showing an arrangement example of the light-receiving surface electrodes of the solar cell of the first embodiment. FIG. 1 is a vertical cross-section of a region illustrated as region A in FIG. The cross section of the direction to do is shown. The light-receiving surface electrode 6 is a grid electrode 14 which is a large number of linear thin line electrodes extending in the horizontal direction in FIG. 3, and is connected to the bus bar electrode 15 which is two thick line electrodes extending in the vertical direction in FIG. ing. In general, as shown in FIG. 3, the grid electrode 14 and the bus bar electrode 15 are formed to be orthogonal to each other. The number of grid electrodes 14 and bus bar electrodes 15 is appropriately determined and may be larger than the number shown in FIG. The fire-through method described above is applied to the grid electrode 14, but may be applied to the bus bar electrode 15.

  In the solar cell according to the first embodiment, the concavo-convex structure on the back surface side, the first conductivity type layer 8, the passivation layer 9, the antireflection film 10, and the back electrode 11 explain the function as a solar cell. For this purpose, an example is shown, and the present invention is not limited. The structure other than the structure of the light receiving surface may be appropriately configured to function as a solar cell.

  The thicknesses of the passivation layer 3, the functional layer 4, and the antireflection film 5 are optically designed so as to maximize the antireflection effect. However, the layers depend on each other and have the following limitations.

The thickness of the functional layer 4 can be in the range of 1 nm to 40 nm, and is preferably about 5 nm to 20 nm. More preferably, when the thickness is from 1 nm to 10 nm, the thickness of the passivation layer 3 can be increased, and the passivation effect can be sufficiently obtained. When a layer thicker than 40 nm is formed, hydrogen incidence from the silicon nitride film used as the antireflection film 5 to the first conductivity type substrate 1 is hindered, and a sufficient passivation effect for the first conductivity type substrate 1 is obtained. I can't. The passivation effect by the silicon nitride film formed by the CVD method cannot be obtained gradually as the thickness of the functional layer 4 increases.

  Further, as the thickness of the functional layer 4 increases, the contact resistance between the light-receiving surface electrode 6 and the first conductivity type substrate 1 tends to gradually increase. When the thickness of the functional layer 4 is 40 nm or more, the through connection of the light receiving surface electrode 6 by fire-through becomes difficult.

  The thickness of the passivation layer 3 is 1 nm to 40 nm, preferably 5 nm to 20 nm. If it is 20 nm or less, the fire-through of the electrode is not restricted, and even if it is combined with the thickness of the functional layer 4, the fire-through is not restricted. In addition, if the thickness is 5 nm or more, an appropriate passivation effect can be obtained.

  The film thickness of the antireflection film 5 may be a thickness that provides a sufficient antireflection effect in consideration of the thickness and refractive index of the passivation layer 3 and the functional layer 4, and is, for example, 20 nm to 50 nm. Note that the refractive indexes of the BSG film and the Si oxide film are almost equal. Furthermore, the total thickness of the passivation film 3 and the functional layer 4 is more than a certain degree in order to suppress the depth of penetration through the second conductivity type layer 2 of the first conductivity type substrate 1 by the above-described fire-through of the light receiving surface electrode 6. It is necessary to secure. Although different depending on the electrode material, the total thickness is preferably in the range of 10 nm to 40 nm.

If the functional layer 4 is a BSG film, boron diffuses in addition to aluminum in the substrate in the conductive layer 7, so that the boron doping concentration at the interface is superimposed on the impurity concentration contained in the second conductivity type layer 2. It becomes a layer with high concentration. Therefore, even if the second conductivity type layer 2 is an impurity diffusion layer having a low concentration of less than 1 × 10 ²⁰ cm ^−3, by adding a conductive component contained in the functional layer 4, the interface region has high conductivity. Since the conductive layer 7 is formed, the light-receiving surface electrode 6 and the first conductivity type substrate 1 can be conducted with low contact resistance.

Furthermore, the conductive layer 7 is preferably formed so as to remain inside the second conductivity type layer 2 as shown in FIG. That is, it is preferable that the first conductivity type region does not penetrate through the second conductivity type layer 2 and the interface of the second conductivity type layer 2 in the first conductivity type substrate 1 is not affected.

  As a method for forming the light-receiving surface electrode 6, for example, a mixed electrode paste of aluminum and silver containing glass frit and containing 20% or less and 1% or more of aluminum with respect to the total amount excluding organic components is used as an antireflection film. Print on top of 5 When the aluminum content excluding the organic components of the electrode paste is 5% or less and 1% or more, the amount of aluminum penetration can be controlled to a permissible amount or less. After the drying process, a firing process is performed in which the peak temperature is set to 700 ° C. or more and 830 ° C. or less and the holding time at the peak temperature is set to 10 seconds or less so that only the outermost surface of the semiconductor substrate 1 is affected. The penetration depth can be limited. The holding time can be 1 to 10 seconds, but preferably 2 to 5 seconds. If the holding time is too long, erosion of aluminum will proceed too much.

  As a result of the firing, the organic components of the electrode paste disappear, the glass frit melts and penetrates, breaks through the antireflection film 5, the functional layer 4, and the passivation layer 3, and the electrode paste becomes the passivation layer 2 and the passivation. The interface of layer 3 is reached. Since the electrode paste reaching the interface contains a small amount of an aluminum component, it melts with silicon near the surface of the substrate and forms a conductive layer 7 near the surface together with the component taken in by the functional layer 4. Since the aluminum content in the paste is limited to the above amount and the firing temperature is also limited to the temperature or lower, the eutectic reaction between aluminum and silicon is suppressed.

Moreover, since the excessive penetration | invasion can be suppressed by forming the passivation film 3 in which aluminum is hard to fire through under the functional layer 4, the conductive layer 7 seems to be formed inside the 2nd conductivity type layer 2. It is possible to find process conditions that are appropriate for the process.
In the solar cell of Patent Document 2 described above, since the fire through due to the Al electrode reaches about 10 times the depth of the boron diffusion layer, the field effect in which minority carriers in the vicinity of the electrode diffuse high-concentration Al. There is a problem of deactivation in the layer (BSF layer). In addition, since a high-concentration boron diffusion layer of about 4 × 10 ¹⁹ cm ⁻³ to 1 × 10 ²⁰ cm ⁻³ is formed, there is a problem that minority carriers are easily deactivated.

If the configuration of the present embodiment is used, the diffusion of impurities in the formation of the second conductivity type layer 2 is reduced to a minimum concentration of about 1 × 10 ¹⁸ cm ⁻³ to about 4 × 10 ¹⁹ cm ⁻³ . It is possible to suppress the deactivation of carriers in the second conductivity type layer 2 and realize a long carrier life. In addition, since the formation depth of the second conductive type layer 2 can be increased while maintaining the deactivation of carriers at a low level, the conductive layer 7 is formed while being held inside the second type conductive layer 2. Becomes easier.

  In the solar cell according to the first embodiment, the conductive layer 7 is formed so as to remain inside the second conductive layer type layer 2, and the minority carriers are subjected to the electric field effect of the second conductive type layer to be conductive. It has the effect of being kept away from the layer 7. Therefore, minority carriers approaching the second conductivity type layer can return to the inside of the first conductivity type substrate 1 without reaching the conductive layer 7, and the sun whose carrier deactivation is maintained at a low level. A battery can be realized. The deep second conductivity type layer is formed with a thickness of, for example, 500 nm to 2 μm, preferably 800 nm to 2 μm, and more preferably 1 μm to 2 μm. If the thickness is 1 μm or more, conditions that do not affect the conductivity can be obtained even if the second conductivity type layer 2 is formed at a low concentration, and if it is 2 μm or less, conditions that can be formed by thermal diffusion are easily found. be able to. Since the conductive layer 7 is formed by the fire-through method, it is thinly formed only in a region where the electrode paste and the substrate react in the baking process, and it is not necessary to previously form a low resistance diffusion layer.

  As described above, according to the first embodiment, even if the second conductive type layer is formed of a high-resistance low-concentration diffusion layer, the light-receiving surface electrode 6 and the first conductive type substrate 1 are connected with a low contact resistance. can do. Furthermore, in addition to suppressing the area of the conductive layer 7 to the necessary minimum, the deep second conductivity type layer is provided, so that a long carrier life is realized and high light utilization efficiency and high open circuit voltage are provided. A solar battery cell having excellent photoelectric conversion efficiency is realized.

  When the characteristic difference was simulated by PC1D, which is a software tool that is generally used when calculating the characteristics of solar cells, the result of an improvement in photoelectric conversion efficiency of 0.28% was obtained as shown below. At this time, the sheet resistance of the low resistance region was 20Ω / □ (Ω / sq.), And the sheet resistance of the high resistance region was 80Ω / □. The solar cell used in Comparative Example 1 in Table 1 was the same as Example 1 except for the structure of the second conductivity type layer formed on the light receiving surface. The second conductivity type layer of Comparative Example 1 had the same depth as that of Example 1, but the impurity was diffused at a high concentration over the entire surface and exhibited a sheet resistance of 50Ω / □. Since PC1D is a one-dimensional simulation, the sheet resistance value used when calculating the photoelectric conversion efficiency of Example 1 is the area of the light receiving surface electrode region and the region other than the light receiving surface electrode (described as the light receiving region in Table 1). The sheet resistance synthesized based on the above was used.

(Table 1) Photoelectric conversion efficiency when only the sheet resistance of the second conductivity type layer is changed

  In addition, although the solar cell concerning Embodiment 1 showed the structure containing the 2nd conductivity type layer 2 and the functional layer 4 in the light-receiving surface, it is also possible to use it by inverting the surface of the solar cell of this structure. What is necessary is just to change and interpret the names of a light-receiving surface and a back surface.

  According to this invention, since the passivation layer can be formed on the surface of the semiconductor substrate, the deactivation of carriers can be suppressed, and the carrier life can be extended.

  Furthermore, since the conductive layer 7 is formed while remaining in the second conductivity type layer 2, minority carriers do not reach the conductive layer 7 rich in electrode components and functional layer components that are liable to be deactivated. Therefore, an effect that a long carrier life can be maintained is obtained. In addition, since there is no need to previously form a high-concentration second conductivity type layer in the semiconductor substrate region that is in contact with the electrode, alignment is not necessary when the electrode is formed.

  Due to these effects, a solar cell having an unprecedented high photoelectric conversion efficiency with a long carrier life can be obtained without deteriorating the ease of manufacture without requiring an alignment mechanism.

Embodiment 2. FIG.
Since the solar cell according to the second embodiment is the same as that of the first embodiment except for the back surface structure of the first conductivity type substrate, detailed description regarding the light receiving surface is omitted. FIG. 4 is a cross-sectional view for explaining the structure of the solar cell according to the second embodiment. In the second embodiment, a structure similar to the structure on the light receiving surface side of the first embodiment is formed on the back surface.

  A first conductive type thick first conductive type layer 16 formed by impurity diffusion and a passivation layer 17 formed so as to be in contact with the first conductive type layer 16 are provided on the back side of the first conductive type substrate 22. The thickness of the first conductivity type layer 16 can be 500 nm to 2 μm, and preferably 800 nm to 2 μm. Further, even if the first conductivity type layer 16 is formed at a low concentration, if the thickness of the first conductivity type layer 16 is 1 μm or more, a condition that does not affect the conductivity can be obtained, and if it is 2 μm or less. In this case, formation by simple thermal diffusion is possible.

  Furthermore, a functional layer 18 and an antireflection film 19 are formed in this order on the passivation layer 17. Here, the first conductivity type is described as n-type. For example, the first conductivity type layer 16 is a layer formed by diffusing phosphorus into the first conductivity type substrate 22. The passivation layer 17 is a silicon oxide film, for example. The functional layer 18 is a layer containing a component that can form a conductive region when diffused into the first conductivity type substrate 22, and for example, a silicon oxide film containing a high concentration of phosphorus can be used.

  The back electrode 20 is formed on the antireflection film 19, penetrates the passivation layer 17, the functional layer 18, and the antireflection film 19 using the fire-through method and reaches the first conductivity type layer 16 to reach the first conductivity type. Conductivity with the substrate 22 is secured. Similar to the light receiving surface of the first embodiment, the conductive layer 21 generated at the interface between the back electrode 20 and the first conductive type layer 16 by the fire-through method is formed inside the first conductive type diffusion layer 16 and has a low contact resistance. Is realized. The antireflection film 19 is used when a double-sided light-receiving solar cell is manufactured. When a single-sided light-receiving solar cell is used, the antireflection film 19 may be replaced with an insulating layer.

  As a material for the back electrode 20, for example, a silver paste containing glass frit can be used. It is also possible to perform the baking of the back electrode simultaneously with the baking of the light receiving surface electrode. In that case, it is necessary to adjust the amount of glass frit or silver in order to match the firing conditions of the light-receiving surface electrode. If the firing step is performed with the peak temperature of the firing step set to 700 ° C. or more and 830 ° C. or less and the holding time at the peak temperature set to 10 seconds or less (1 to 10 seconds is possible, preferably 2 to 5 seconds), It is possible to form the back surface conductive layer 21 so as to remain inside the first conductivity type layer 16 on the back surface.

  In the solar cell according to the second embodiment, since the functional layer 17 is also included on the back surface, electrode connection with low contact resistance can be realized without using an alignment mechanism when forming both electrodes on the light receiving surface and the back surface. . In addition, by forming the back surface conductive layer 21 so as to remain inside the first conductivity type layer 16 on the back surface, the deactivation of carriers in the conductive layer is minimized, and the photoelectric conversion efficiency is further improved. A solar cell is realized.

Embodiment 3 FIG.
FIG. 5 is a cross-sectional view showing the electrode structure of the solar cell according to the third embodiment, and shows a cross section along the grid electrode of the portion exemplified by the region B of the light-receiving surface electrode shown in the plan view of the solar cell of FIG. Show. In the solar cell according to the third embodiment, the electrodes formed by the fire-through method are arranged in a dot shape, and the point electrodes 23 are arranged at regular intervals. FIG. 7 is a plan view showing the structure of the light-receiving surface electrode of the solar cell according to the third embodiment of the present invention, in which the linear bridge girder electrode 24 is covered so as to connect the point electrodes 23 spaced apart at a constant interval. It has a configuration. In this example, the point electrodes 23 having a circular region are discretely formed and connected by bridge girder electrodes 24 formed long in a band shape to constitute grid electrodes. Needless to say, a similar configuration may be used on the back side.

  As described in the first embodiment, the point electrode 23 in which the light receiving surface electrode generates fire-through is in contact with the first conductivity type substrate 25 with a low contact resistance. Therefore, fire-through occurs in the entire grid electrode of the light receiving surface electrode. The carrier can be taken out without making it. Furthermore, since the area of the conductive layer 26 that generates a large amount of carrier deactivation at the interface can be reduced, it is possible to suppress the carrier deactivation in the conductive layer.

  In the manufacturing process of the solar cell according to the third embodiment, an operation of aligning the bridge electrode 24 with the position of the point electrode 23 is required. In the conventional method of separately forming the diffusion layer, since there is no difference in appearance and shape of the diffusion layer, precise alignment has been difficult, but the point electrode 23 has a color different from that of the substrate and has a convex shape. Therefore, it can be easily confirmed visually. In the production line, for example, by detecting the contrast using a CCD camera, the position of the point electrode 23 can be easily recognized and the formation position of the bridge electrode 24 can be adjusted. The bridge girder electrode 24 can be formed on the first conductivity type substrate 25 without causing a fire-through by using a silver paste that can be fired at a low temperature of 400 ° C. or lower, for example.

  Therefore, in the solar cell according to the third embodiment, the effect of maintaining a longer carrier life with suppressed carrier deactivation is obtained, and a solar cell exhibiting high photoelectric conversion efficiency is realized.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 1st conductivity type board | substrate 2 2nd conductivity type layer 3 Passivation layer 4 Functional layer 5 Antireflection film 6 Light reception surface electrode 7 Conductive layer 8 1 conductivity type layer 9 Passivation layer 10 Antireflection film 11 Back surface electrode 14 Grid electrode 15 Bus bar electrode 16 First conductivity type layer 17 Passivation layer 18 Functional layer 19 Antireflection film 20 Back electrode 21 Conductive layer 22 First conductivity type substrate 23 Point electrode 24 Bridge girder electrode 25 First conductivity type substrate 26 Conductive layer

Claims (8)

A first conductivity type semiconductor substrate;
A second conductivity type layer formed on the first surface of the first conductivity type semiconductor substrate;
A first passivation film formed on the second conductivity type layer;
A first functional layer formed on the first passivation film and including a component capable of adding conductivity to the second conductivity type layer ;
A first antireflection film formed on the first functional layer;
A first electrode formed so as to penetrate from the first antireflection film to the first passivation film and reach the second conductivity type layer;
A second electrode formed on a second surface which is a surface opposite to the first surface of the first conductivity type semiconductor substrate,
The second conductive type layer is in contact with the first electrode and includes the same component as the component that can add conductivity to the second conductive type layer included in the first functional layer. A solar cell comprising one conductive layer. 2. The sun according to claim 1, wherein the first passivation film does not include the same component as a component capable of adding conductivity to the second conductivity type layer included in the first functional layer. battery.   In the first conductive layer, when the first electrode takes in the component in the first functional layer by fire-through and reaches the second conductive type layer, the component diffuses into the second conductive type layer. The solar cell according to claim 1, wherein the solar cell is formed. The first conductive semiconductor substrate is an n-type silicon crystal substrate;
The solar cell according to any one of claims 1 to 3, wherein the first functional layer is a film containing boron silicate glass as a main component. The thickness of the first functional layer is 1 nm to 20 nm,
The first antireflection film contains hydrogen;
The solar cell according to claim 4. A first conductivity type layer formed on the second surface;
A second passivation film formed on the first conductivity type layer;
A second functional layer formed on the second passivation film;
A second antireflection film formed on the second functional layer;
A second electrode formed so as to penetrate from the second antireflection film to the second passivation film and reach the first conductivity type layer;
Further comprising
2. A second conductive layer formed by diffusing components in the second functional layer from a boundary region between the second electrode and the first conductivity type layer inside the first conductivity type layer. The solar cell as described in any one of -5.   The at least one of the first electrode and the second electrode is formed discretely, and the plurality of first electrodes are connected by a bridge girder electrode. The solar cell described. Forming a second conductivity type layer on the first surface of the first conductivity type semiconductor substrate;
Forming a first passivation film on the second conductivity type layer;
Forming a first functional layer containing a component capable of adding conductivity to the second conductivity type layer on the first passivation film;
Forming a first antireflection film on the first functional layer;
Forming a first electrode by firing so as to penetrate from the first antireflection film to the first passivation film and reach the second conductivity type layer;
With
In the step of forming the first electrode by firing, from the boundary region between the first electrode and the second conductivity type layer to the second conductivity type layer in the first functional layer in the second conductivity type layer. The manufacturing method of the solar cell which the component which can add electroconductivity diffuses, and forms a 1st conductive layer.

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