JP5186673B2 - Manufacturing method of solar cell - Google Patents

Description

The present invention relates to a method for manufacturing a solar cell using a silicon single crystal.

  In a solar cell using a silicon single crystal, how to efficiently convert irradiated light energy into electric energy is one of the important technical issues. In general, the surface of a silicon single crystal substrate that has been smoothed by polishing has a high light reflectivity and causes a loss of light energy (hereinafter referred to as reflection loss). On the other hand, a silicon single crystal substrate having a not high dopant concentration has a relatively high light transmittance, and light incident on the substrate from the light receiving surface (in this specification, the second main surface of the substrate) If the light is transmitted (in this specification, the first main surface of the substrate), this also becomes a light energy loss factor (hereinafter referred to as transmission loss).

  Among them, as an improvement for reducing the reflection loss on the light receiving surface side, there is a method of forming an antireflection film on the light receiving surface side, but recently, the surface of a silicon single crystal substrate using anisotropic etching is used. Roughening, so-called texture processing is often used. This is because the (111) plane of various orientations was preferentially exposed by anisotropically etching the (100) plane of silicon single crystal using an etching solution such as hydrazine aqueous solution or sodium hydroxide. It has a rough surface structure (hereinafter referred to as texture). Incident light is irregularly reflected by the unevenness of the texture, and the light flux that satisfies the total reflection condition with the light receiving surface is reduced. As a result, the light incident efficiency into the substrate is increased, and the reflection loss on the light receiving surface side can be reduced. Note that the texture can also be formed on the back surface side, whereby it is possible to suppress the loss caused by scattering the reflected light on the back surface side and coming out of the battery again from the light receiving surface side.

  On the other hand, as an improvement for reducing transmission loss, a method has been proposed in which a reflective film is formed on the back surface side, and light that is about to escape from the back surface is reflected back into the substrate. As such a reflective film, a metal electrode layer (hereinafter referred to as a back metal electrode layer) covering the entire back surface is used. However, when the metal electrode layer is brought into direct contact with the main surface of the silicon single crystal substrate, the loss due to the surface recombination of photogenerated carriers becomes large. Therefore, a passivation film is formed between the metal electrode layer and the silicon single crystal substrate. For example, a silicon nitride film is formed. In this case, the contact between the metal electrode layer and the underlying silicon single crystal substrate is ensured through a conductive through-hole formed in the silicon nitride film by photolithography or mechanical processing.

  Here, the light incident from the light receiving surface side is reflected on the two surfaces of the back surface metal electrode layer and the silicon single crystal substrate / silicon nitride film boundary. Of these, the light reflected on the back surface metal electrode layer is After being refracted at the boundary, the light passes through the silicon nitride film once at the time of incidence and once at the time of reflection. As a result, an optical path difference occurs between the reflected light and the interference. Conventionally, no technical consideration has been paid to the influence of the interference on the conversion efficiency of the solar cell.

  An object of the present invention is to form a silicon nitride film formed as a back surface passivation film in consideration of interference between reflected light at the back surface metal electrode layer and reflected light at the silicon single crystal substrate / silicon nitride film boundary. By devising, it is to implement a more efficient solar cell.

Means for Solving the Problems and Effects of the Invention

In order to solve the above problems, the configuration related to the solar cell of the present invention is as follows.
In a solar cell that forms an emitter layer by vapor phase diffusion using phosphorus oxychloride,
Second main surface of a silicon single crystal substrate having a crystal principal axis direction of <100> and a texture mainly composed of {111} planes formed on neither the first main surface nor the second main surface Is formed on the first main surface, which is the back surface side, with a thickness of 40 to 220 nm, and a back metal electrode layer is formed to cover the silicon nitride film. Become
The nitrided silicon film having improved effect and diffusion masking effect of internal reflection efficiency due to the back surface metal electrode layer is Ru is assumed.

In order to solve the above problems, the configuration of the method for manufacturing a solar cell of the present invention is as follows.
In a method of manufacturing a solar cell in which an emitter layer is formed by a vapor phase diffusion method using phosphorus oxychloride,
The crystals in the principal axis direction is <100> Der Ru first main surface of the silicon single crystal substrate without forming a texture mainly composed of {111} plane, the texture on the second main surface of the silicon single crystal substrate A texture forming step in which the surface roughness is 0.5 to 50 μm at the center line average roughness Ra;
A silicon nitride film forming step of forming a silicon nitride film on the first main surface;
Using the silicon nitride film as a phosphorus diffusion mask, an emitter layer forming step of forming the emitter layer on the light receiving surface which is the second main surface ;
A back metal electrode layer forming step of forming a back metal electrode layer having a thickness of 0.5~2μm as to cover the silicon nitride film,
Have
The silicon nitride film has a thickness of 100 nm to 100 nm so that the metal surface reflected light reflected by the back surface metal electrode layer and the boundary reflected light reflected at the boundary between the silicon single crystal substrate and the silicon nitride film are mutually intensified by interference. 300 nm (except for 200 nm) in Rukoto such formed at a thickness of the silicon nitride film and having improved effectiveness and diffusion masking effect of internal reflection efficiency due to the back metal electrode layer.

Other configurations in the solar cell of the present invention are as follows:
In a method of manufacturing a solar cell in which an emitter layer is formed by a vapor phase diffusion method using phosphorus oxychloride,
Texture principal crystal axis direction is mainly one to be {111} plane of the <100> of the silicon single crystal substrate Ru der first main surface and second main surface, the surface roughness center line average roughness Ra At 0.5 to 50 μm and a formation texture forming step ,
A silicon nitride film forming step of forming a silicon nitride film on the first main surface;
Using the silicon nitride film as a phosphorus diffusion mask, an emitter layer forming step of forming the emitter layer on the light receiving surface which is the second main surface ;
A back metal electrode layer forming step of forming a back metal electrode layer having a thickness of 0.5~2μm as to cover the silicon nitride film,
Have
The silicon nitride film has a thickness of 40 nm to 40 nm so that the metal surface reflected light reflected by the back metal electrode layer and the boundary reflected light reflected at the boundary between the silicon single crystal substrate and the silicon nitride film are mutually intensified by interference. Formed with a thickness of 230 nm,
The silicon nitride film has an effect of improving internal reflection efficiency and a diffusion mask effect by the back surface metal electrode layer.

  In the case of a solar cell using a silicon single crystal substrate whose crystal principal axis direction is <100>, the film thickness of the silicon nitride film formed on the back surface is selected to be sufficient to ensure the function as a passivation film. Of course you have to. The lower limit of the thickness can be estimated to be approximately 20 nm from the viewpoint of suppressing the surface recombination of photogenerated carriers due to the tunnel current. However, when the present inventors examined in detail, by forming a silicon nitride film in a specific film thickness range determined irrespective of the lower limit value, the internal reflection efficiency by the back metal electrode layer and the light / The present inventors have found the fact that energy conversion efficiency can be improved and have completed the present invention.

  The specific film thickness range of the silicon nitride film differs depending on whether texture is formed on the first main surface (back surface side) and the second main surface (light receiving surface side) of the silicon single crystal substrate. Become. A 1st structure is a case where a texture is not formed in any of a 1st main surface and a 2nd main surface, and the optimal film thickness range of a silicon nitride film is 40-220 nm. Even if the film thickness exceeds the upper limit of this range or less than the lower limit, the effect of improving the internal reflection efficiency cannot be expected.

  In the second configuration, the texture is formed only on the second main surface side, and the optimum film thickness range of the silicon nitride film is 100 to 300 nm. When the film thickness is less than the lower limit of this range, the effect of improving internal reflection efficiency cannot be expected. On the other hand, the upper limit value is determined in consideration of the problem of the formation time and cost of the silicon nitride film.

  The third configuration is a case where texture is formed on both the first main surface and the second main surface, and the optimum film thickness range of the silicon nitride film is 40 to 230 nm. Even if the film thickness exceeds the upper limit of this range or less than the lower limit, the effect of improving the internal reflection efficiency cannot be expected.

  From the viewpoint of improving internal reflection efficiency, the fact that there is an optimum film thickness range for the silicon nitride film on the back surface side is that, as described above, each surface between the back surface metal electrode layer and the silicon single crystal substrate / silicon nitride film boundary This is related to the interference effect of light reflected by the light (hereinafter referred to as metal surface reflected light and film boundary reflected light). That is, when the metal surface reflected light and the film boundary reflected light cause interference in the silicon nitride film, the interference state between the two lights is silicon nitride due to the difference in refractive index between the silicon single crystal substrate and the silicon nitride film. It varies depending on the film thickness. Then, in a specific film thickness range, it is considered that a condition for strengthening the metal surface reflected light and the film boundary reflected light is established, and the internal reflection efficiency is improved.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the solar cell of the present invention. The solar cell 1 has a second main surface MPS of a p-type silicon single crystal substrate 3 having a crystal main axis of <100> as a light-receiving surface side, and an emitter layer 42 in which n-type dopants are diffused is formed here. An −n junction 48 is formed, and an oxide film 43, an electrode 44, and an antireflection film 47 are formed in this order. The electrode 44 on the light-receiving surface side is, for example, a finger electrode as shown in FIG. 2 in order to increase the efficiency of light incident on the pn junction 48, and further, a thick bus bar at an appropriate interval for reducing internal resistance. An electrode is provided.

  On the other hand, as shown in FIG. 3, a silicon nitride film 4 is formed on the first main surface MPP on the back side, and a back metal electrode layer 5 is formed so as to cover the silicon nitride film 4. The back metal electrode layer 5 covers substantially the entire surface of the first main surface MPP, and is configured as an aluminum vapor deposition layer, for example. The back metal electrode layer 5 is electrically connected to the underlying silicon single crystal substrate 3 (silicon semiconductor layer) through a contact penetration 6 that penetrates the silicon nitride film 4 in the film thickness direction. The contact penetrating portion 6 may be formed by photolithography, but in this embodiment, it is a groove portion by machining or a hole by laser processing.

  An antireflection texture can be formed on one or both of the first main surface MPP and the second main surface MPS of the silicon single crystal substrate 3. For example, as shown in FIG. 5, the texture is a random texture composed of a large number of pyramidal protrusions whose outer surface is a (111) plane. However, this texture can of course be omitted. The surface roughness of the textured main surface of the silicon single crystal substrate 3 is about 0.5 to 50 μm at the center line average roughness Ra defined in JIS: B0601 (1982). On the other hand, when not formed, it is, for example, a chemically polished surface, and the center line average roughness Ra is 0.5 μm or less.

  As described above, in the case where no texture is formed on either the first main surface MPP or the second main surface MPS in FIG. 1, the optimum film thickness t of the silicon nitride film is 40 to 220 nm in FIG. is there. When the texture is formed only on the second main surface MPS side, the optimum film thickness range t of the silicon nitride film 3 is 100 to 300 nm. Furthermore, when a texture is formed on both the first main surface MPP and the second main surface MPS, the optimum film thickness range of the silicon nitride film is 40 to 230 nm.

  Hereinafter, the manufacturing process of the solar cell 1 will be described mainly on the back surface side. However, the present invention is not limited to the solar cell produced by this method. First, as shown in FIG. 4A, a high-purity silicon is doped with a group III element such as boron or gallium to have a specific resistance of 0.5 to 5 Ω · cm. On the other hand, by immersing in a potassium hydroxide aqueous solution or a sodium hydroxide aqueous solution for a certain time by a known method to remove the damaged layer, texture formation is performed. The silicon single crystal substrate 3 may be manufactured by either the CZ method or the FZ method, but is preferably manufactured by the CZ method from the viewpoint of mechanical strength.

  After the formation of the texture, the silicon single crystal substrate 3 is washed in an acidic aqueous solution of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, etc., or a mixture thereof. From the economical and efficient viewpoint, washing in hydrochloric acid is preferable. In some cases, this texture forming step may be omitted. Next, as shown in FIG. 4B, a silicon nitride film 4 is formed on the first main surface (hereinafter referred to as the back surface) of the substrate 3 by a known method. The silicon nitride film forming process can be any method such as atmospheric pressure CVD, reduced pressure CVD, photo CVD, etc., but it is a low temperature process of about 350 to 400 ° C. and has a small surface recombination rate. It is preferable to produce it by a plasma CVD method that can be achieved.

  Since this silicon nitride film 4 is also effective as a phosphorus diffusion mask, at this stage, an emitter layer is formed on the second main surface MPS of this substrate by vapor phase diffusion using phosphorus oxychloride. May be. In order to enhance the effect as a diffusion mask, it is preferable that the surfaces of the two silicon single crystal substrates 3 on which the silicon nitride film 4 is formed are overlapped and arranged in a diffusion boat as a pair and vapor phase diffusion is performed. Then, heat treatment is performed at about 850 ° C. in a phosphorus oxychloride atmosphere to form an n-type emitter layer on the second main surface MPS. The depth of the formed emitter layer is about 0.5 μm, and the sheet resistance is 40 to 100Ω / □.

  Then, as shown in FIG. 4C, grooves or holes as contact penetrating portions are formed on the back surface of the substrate 3. For example, when the groove 6 is formed, it is engraved using the high-speed rotary blade 13. The high-speed rotary blade has 100 to 200 uneven forming blades attached to a cylindrical portion having a diameter of 103 mm and a length of 165 mm. The height of the blade is, for example, 50 to 100 μm, and the width of the blade and the interval between the blades are about several hundred μm. Diamond abrasive grains having a diameter of 5 μm to 10 μm are uniformly electrodeposited on the surface of the blade. Using this high-speed rotary blade 13, grooving is performed on the substrate at a speed of about 1 to 4 cm per second while spraying the cutting fluid. The high-speed rotary blade 13 can be replaced with a dicer or a wire saw. The rotary blade device is finely adjusted so that the depth of the groove 6 is approximately 5 to 50 μm.

  On the other hand, when forming a hole instead of the groove 6, a laser beam is preferably used. As the laser, a carbon dioxide laser, an argon laser, a YAG laser, a ruby laser, an excimer laser, or the like is easily used. Of these, excimer lasers such as KrF and Nd: YAG lasers are most suitable. As the planar shape of the hole, a circle, an ellipse, a rectangle or the like can be adopted. Note that the laser irradiation condition for providing the opening is appropriately determined depending on the type of laser, the thickness of the insulating layer, the diameter of the opening, and the like. For example, when using pulse oscillation, the frequency is preferably 1 Hz to 100 kHz, and the average laser output is preferably in the range of 10 mW to 1 kW.

  After forming the contact through portion such as the groove 6 and the hole, as shown in FIG. 4D, the back metal electrode layer 5 is formed on the same surface (first main surface side) by 0.5 to 2 μm, for example. A metal such as silver or copper can be used for the electrode, but aluminum is most preferable from the viewpoint of economy and workability. The metal layer can be deposited by any method such as sputtering, vacuum evaporation, and screen printing. Back metal electrode layer 5 is uniformly deposited on first main surface MPP while filling the contact through portion.

  Thereafter, the antireflection film 47 and the electrode 44 on the second main surface MPS (light receiving surface) side in FIG. 1 are formed by a known method. As the antireflection film 47, a silicon oxide, silicon nitride, cerium oxide, alumina, tin dioxide, titanium dioxide, magnesium fluoride, tantalum oxide, and the like, and a two-layer film combining these two are used. There is no problem even if it is used. For the film formation, a PVD method, a CVD method or the like is used, and any method is possible. In order to produce a high-efficiency solar cell, silicon nitride formed by remote plasma CVD is preferable because a small surface recombination rate can be achieved. On the other hand, the electrode 44 is produced by vapor deposition, plating, printing, or the like. Either method may be used, but the printing method is preferable for low cost and high throughput. For example, an electrode pattern is screen-printed using a silver paste in which silver powder and glass frit are mixed with an organic binder, and then heat-treated to form an electrode. Note that there is no problem even if the processing order on the first main surface MPP side and the processing on the second main surface MPS side are reversed.

The thickness of the silicon nitride film 4 on the first main surface MPP side is adjusted to each optimum film thickness range according to the presence or absence of texture formation on the silicon single crystal substrate 3. The validity of this film thickness range is supported not only by the experimental results described later, but also by the calculation results based on the following refraction / reflection theory. First, the reflectance on the first main surface MPP side of the light incident from the second main surface MPS side is calculated by the refraction / reflection theory. The outline is as follows. First, the light propagating in two different media, namely the electromagnetic wave reflection law and the refraction law, are derived from the boundary conditions of the electric flux density, magnetic flux density, electric field and magnetic field that Maxwell's equations must satisfy at the boundary of the medium. Can be derived uniquely. The derivation process is shown in general optical or electromagnetic textbooks and is very well known, so a detailed description is omitted (for example, Asakura Modern Physics Course 2: Electromagnetics I (Hisashi Matsuda (1980: Asakura Shoten) See pages 63-68). If we show the result, if the incident angle, refraction angle and reflection angle of light are θ, β and γ, respectively, the law of reflection is
θ = γ (1)
And the law of refraction (so-called Snell's law) is
sin θ / sin β = n2 / n1 (2)
It is. Note that a medium (in this case, a silicon single crystal) on the light incident side across the boundary is a medium 1, a medium (in this case, silicon nitride) on the transmission side is a medium 2, and n1 and n2 are the medium 1 and This is the refractive index of the medium 2. The refractive index n1 of silicon single crystal is 3.52, and the refractive index n2 of silicon nitride is 2.00.

  By applying the above Snell's law to the well-known Fresnel formula and calculating the intensity of incident light and reflected light (which can be expressed as either electric field or magnetic field intensity), the silicon single crystal substrate 3 and the silicon nitride film 4 can be obtained. On the other hand, the influence of light penetration and refraction on the back metal electrode layer 5 side at the boundary between the back metal electrode layer 5 and the silicon nitride film 4 is considered to be small, but here the complex refractive index (absorption coefficient) is Introduced and fine-tuned.

  FIG. 6 shows a result of calculating how the reflectance of the boundary reflection between the silicon single crystal substrate 3 and the silicon nitride film 4 changes according to the thickness of the silicon nitride film using the incident angle θ as a parameter. Yes (incident wavelength is 1200 nm). When θ is a critical angle of total reflection of 34.6 ° or less, a maximum value occurs in the reflectance due to the interference effect with the reflected light from the metal surface. A part of the long wavelength light reaching the second main surface MPS is returned again to the inside of the silicon single crystal substrate 3 with this reflectance. Next, FIG. 7 shows the result of calculating the dependence of the optical carrier generation ratio on the internal reflectance using the thickness of the silicon single crystal substrate 3 as a parameter. The smaller the substrate thickness, the more remarkable is the effect of internal reflectivity. When the internal reflectivity exceeds 93%, the photocarrier generation rate increases rapidly. That is, for a high-power solar cell, a structure having an internal reflectance of 93% or more may be provided on the back surface of the solar cell, and the corresponding silicon nitride film thickness can be obtained from FIG. That is, in the case of a silicon solar cell that does not have a texture, it can be understood that the silicon nitride film thickness may be in the range of 40 to 220 nm, corresponding to θ = 0 ° in FIG.

  Next, consider a case where there is a texture on the second main surface (light receiving surface) MPS side. The texture is formed by utilizing the difference in etching rate between the {100} plane and the {111} plane of the silicon single crystal. As shown in FIG. 5, the regular pyramid having a size of several μm to several tens of μm. The structure is randomly formed. Since this structure is composed of an equivalent {111} plane of silicon single crystal, the angle α formed by the slope of the pyramid with the second main surface MPS is 54.7 °. On the other hand, since the refractive index of silicon is 3.52 at a long wavelength, it is possible to derive from a simple calculation that the incident light is incident on the back surface at an incident angle θ = 41.3 ° by using Snell's law. . Therefore, the optimum silicon nitride film thickness range of a solar cell having a texture on the second main surface (light-receiving surface) MPS and a flat first main surface (back surface) MPP is θ = 41.3 ° in FIG. Correspondingly, it can be seen that it should be approximately 100 nm or more.

  Finally, when textures are present on both sides, the texture of the second main surface (light-receiving surface) MPS is uniformly distributed due to the random arrangement, and light enters the first main surface (back surface) MPP. Assume that the incidence is uniform at an angle of 41.3 °. On each surface of the pyramid of the texture of the first main surface MPP, 55.4% of incident light is incident at an incident angle of 13.4 ° and 44.6% at an angle of 64.3 °. It can be calculated by considering a simple square pyramid standing upright. From FIG. 6, it can be seen that the silicon nitride film thickness in which both θ = 13.4 ° and θ = 64.3 ° exceed 93% is in the range of approximately 40 to 230 nm.

Example 1
Two p-type silicon single crystal substrates (crystal principal axis direction <100>: cut-up state: specific resistance 1 Ω · cm) with a thickness of 150 μm and boron as a dopant are immersed in an aqueous potassium hydroxide solution, and textures are formed on both sides. Formed. Next, on the first main surface (back surface), a silicon nitride film was formed to a thickness of 150 nm and 300 nm, respectively, and then a parallel groove as a contact penetrating portion was formed using a commercially available dicer. On this, aluminum was deposited on the entire surface to form a back metal electrode layer. On the other hand, an emitter layer, an antireflection film, a finger electrode, and a bus bar electrode were sequentially formed on the second main surface (light receiving surface) by the above-described method, and a solar cell test product was produced.

  The obtained solar cell test products were measured for IV characteristics of these solar cells under standard conditions using a solar simulator (YSS-80) manufactured by Yamashita Denso Co., Ltd., and the conversion efficiency was determined. The results are shown in Table 1.

  It can be seen that in the solar cell having a silicon nitride film thickness of 150 nm, the short-circuit current is increased and the conversion efficiency is higher than in the case of 300 nm.

(Example 2)
A solar cell test product prepared in the same manner as in Example 1 was prepared except that a silicon single crystal substrate having no texture on both sides was used, and the same measurement was performed. The results are shown in Table 2.

  It can be seen that the solar cell having a silicon nitride thickness of 150 nm exhibits higher conversion efficiency than the case of 300 nm.

The cross-sectional schematic diagram which shows an example of the solar cell of this invention. The perspective view which shows an example of the electrode formation form by the side of a light-receiving surface. The cross-sectional schematic diagram which expands and shows the structure of the back surface side of the solar cell of FIG. Explanatory drawing which shows the formation process of the back surface structure of FIG. The perspective view which shows an example of the form of a texture. The figure which shows the result of having calculated the relationship between the back surface internal reflectance in various incident angles, and a silicon nitride film thickness. The figure which shows the result of having calculated the relationship between a back surface internal reflectance and a photocarrier production | generation ratio about the various thickness of a silicon single crystal substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solar cell MPP 1st main surface MPS 2nd main surface 4 Silicon nitride film 5 Back surface metal electrode layer

Claims (2)

In a method of manufacturing a solar cell in which an emitter layer is formed by a vapor phase diffusion method using phosphorus oxychloride,
The crystals in the principal axis direction is <100> Der Ru first main surface of the silicon single crystal substrate without forming a texture mainly composed of {111} plane, the texture on the second main surface of the silicon single crystal substrate A texture forming step in which the surface roughness is 0.5 to 50 μm at the center line average roughness Ra;
A silicon nitride film forming step of forming a silicon nitride film on the first main surface;
Using the silicon nitride film as a phosphorus diffusion mask, an emitter layer forming step of forming the emitter layer on the light receiving surface which is the second main surface ;
A back metal electrode layer forming step of forming a back metal electrode layer having a thickness of 0.5~2μm as to cover the silicon nitride film,
Have
The silicon nitride film has a thickness of 100 nm to 100 nm so that the metal surface reflected light reflected by the back surface metal electrode layer and the boundary reflected light reflected at the boundary between the silicon single crystal substrate and the silicon nitride film are mutually intensified by interference. 300 nm (except for 200 nm) in Rukoto such formed at a thickness of, sun said silicon nitride film and having improved effectiveness and diffusion masking effect of internal reflection efficiency due to the back metal electrode layer Battery manufacturing method . In a method of manufacturing a solar cell in which an emitter layer is formed by a vapor phase diffusion method using phosphorus oxychloride,
Texture principal crystal axis direction is mainly one to be {111} plane of the <100> of the silicon single crystal substrate Ru der first main surface and second main surface, the surface roughness center line average roughness Ra At 0.5 to 50 μm and a formation texture forming step ,
A silicon nitride film forming step of forming a silicon nitride film on the first main surface;
Using the silicon nitride film as a phosphorus diffusion mask, an emitter layer forming step of forming the emitter layer on the light receiving surface which is the second main surface ;
A back metal electrode layer forming step of forming a back metal electrode layer having a thickness of 0.5~2μm as to cover the silicon nitride film,
Have
The silicon nitride film has a thickness of 40 nm to 40 nm so that the metal surface reflected light reflected by the back metal electrode layer and the boundary reflected light reflected at the boundary between the silicon single crystal substrate and the silicon nitride film are mutually intensified by interference. Formed with a thickness of 230 nm,
The method of manufacturing a solar cell , wherein the silicon nitride film has an effect of improving internal reflection efficiency and a diffusion mask effect by the back metal electrode layer.

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