TWI640103B - Solar cell manufacturing method - Google Patents

Abstract

The present invention relates to a method for producing a solar cell, and an object of the invention is to provide a method for producing a solar cell that can be efficiently produced.

The solution provides: engineering for forming a dielectric film on a portion of at least one side of the substrate, and engineering of the p-type diffusion dopant on a part or all of the dielectric film, and once through A method of manufacturing a solar cell characterized by heat treatment and diffusion of an n-type dopant and a p-type dopant. Before the above-mentioned process for diffusing, it is preferable to have a range in which a dielectric film is not formed in the germanium substrate, and an engineer who applies an n-type diffusion dopant is preferable.

Description

Solar cell manufacturing method

The present invention relates to a method of fabricating a solar cell, and more particularly to a pn junction forming process.

In recent years, in order to solve the environmental problems of depletion of energy resources or an increase in the amount of carbon dioxide in the atmosphere, the development of clean energy has been carried out prosperously. In particular, solar cells, which are capable of converting endless solar energy into electric energy, are expected to be high-efficiency and cost-reduced as a new generation of energy.

For the performance improvement of solar cells, it is important to efficiently introduce sunlight into the interior of the substrate. In the related art, a back-junction type solar cell in which an electrode is formed on the light-receiving surface of the ruthenium substrate and the electrode is formed only on the back surface, for example, is disclosed in Patent Document 1 or A method of manufacturing a solar cell described in Patent Document 2.

In the above-described manufacturing method, a diffusion-inhibiting mask such as a patterned SiO ₂ layer is formed on a germanium semiconductor substrate, and a patterned diffusion layer is formed by doping treatment to form a back-junction type solar cell.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2007-81300

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2012-94739

However, in the conventional solar cell manufacturing method, diffusion treatment of the n-type diffusion dopant and the p-type diffusion dopant is separately performed. That is, it is necessary to perform the diffusion heat treatment twice, each time including the process of forming the diffusion suppression mask and the process of removing the mask after the doping treatment. Therefore, the number of projects is complicated, and the problem of high manufacturing costs is burdened. The present invention has been made in view of such a problem, and provides a method for manufacturing a solar cell that can be efficiently manufactured by reducing the number of projects.

In order to solve the above problems, a method for manufacturing a solar cell according to an embodiment of the present invention includes a process of forming a dielectric film on at least one side of a single substrate, and a part or all of the dielectric film. Engineering for coating a p-type diffusion dopant, and engineering for diffusing an n-type dopant and a p-type dopant through one heat treatment.

In the present invention, it is more Preparation: In the range where the dielectric film is not formed in the germanium substrate, it is preferable to apply an n-type diffusion dopant. Further, the dielectric film is preferably an oxide film. Further, the thickness of the dielectric film is preferably from 10 to 150 nm.

In the present invention, it is preferred that the p-type dopant is boron and the n-type dopant is phosphorus.

In the present invention, it is preferable to include an engineer who removes a part of the dielectric film with an electric paste containing phosphoric acid.

In the present invention, it is preferred that the range in which the n-type dopant is diffused is the same as the range in which the p-type dopant is diffused on the same side of the tantalum substrate.

100, 200, 300‧‧‧ semiconductor substrates

101, 201, 301‧‧‧ solar cell substrates

102, 202, 302‧‧‧ dielectric film

103, 203, 303‧‧‧ etching paste

104, 204, 304‧‧‧ openings

105, 205, 305‧‧‧n type diffusion dopant

106, 206, 306‧‧‧p type diffusion dopant

107, 207, 307‧‧‧n type doping range

108, 208, 208‧‧‧p type doping range

109, 209, 309‧‧‧ anti-reflection film

110, 210, 310‧‧‧ protective film

111, 211, 311‧‧‧n type electrode

112, 212, 312‧‧‧p-type electrodes

Fig. 1 is a flow chart showing an example of a method of manufacturing a back junction type solar cell according to the first embodiment of the present invention.

Fig. 2 is a flow chart showing an example of a method of manufacturing a double-sided junction type solar cell according to a second embodiment of the present invention.

Fig. 3 is a flow chart showing the manufacturing process common to the embodiment and the comparative example.

Figure 4 is a flow chart showing the subsequent processing of the process of Figure 3 of the embodiment.

Fig. 5 is a flow chart showing the subsequent processing of the processing of Fig. 3 of the comparative example.

Fig. 6 is a flow chart showing the processing subsequent to Fig. 4 or Fig. 5, common to the processing of the embodiment and the comparative example.

As described above, in the conventional solar cell manufacturing method, since the diffusion treatment of the n-type diffusion dopant and the p-type diffusion dopant is separately performed, it is necessary to perform the diffusion heat treatment twice, and each time the diffusion suppression mask is formed. After the engineering and the doping treatment, the work of removing the mask is carried out, and the number of engineering becomes complicated, and the problem that the manufacturing cost becomes high is burdened.

As a result of intensive research, the inventors have made a p-type diffusion dopant containing boron (boron) and an n-type diffusion containing phosphorus in a state in which a dielectric film of 10 to 150 nm is formed on a germanium substrate. When the dopant is thermally diffused, the boron dopant diffuses into the germanium substrate even if the dielectric film is present, but the phosphorous dopant is inhibited from being diffused by the dielectric film, and it is found that the germanium substrate does not cause diffusion. By. In the case of utilizing this phenomenon, the diffusion heat treatment which is required twice in the past can be completed by one diffusion heat treatment, and the number of the engineering can be omitted as much as possible.

[First Embodiment]

Hereinafter, a method of manufacturing a solar cell according to a first embodiment of the present invention will be described with reference to Fig. 1, but the present invention is not limited thereto.

First, the semiconductor substrate 100 is prepared (Fig. 1 (a)). The semiconductor substrate 100 can be, for example, a high-purity germanium, doped with a group 3 element such as boron or gallium, as a specific impedance of 0.1 to 5 Ω. The original cut of cm is a single crystal {100} p type tantalum substrate.

The semiconductor substrate 100 is not only a single crystal but also a multi-crystal substrate, and an n-type germanium substrate can be used even for a non-p-type germanium substrate.

The surface of the semiconductor substrate 100 is cut and damaged, and is etched using a high concentration alkali such as sodium hydroxide or potassium hydroxide at a concentration of 5 to 60%, or a mixed acid of hydrofluoric acid and nitric acid, and then formed on the surface of the substrate. Texture with a random cone construction (Fig. 1(b)). However, in the figure, the texture concavo-convex structure is omitted from the drawing.

Texture is an effective method for reducing the reflectance of a solar cell. The texture is applied to an alkaline solution (concentration: 1 to 10%, temperature: 60 to 100 ° C) of heated sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium hydrogencarbonate, etc., by immersion for 10 minutes to 30 minutes. To the extent that it is formed. In the above solution, a specific amount of 2-propanol is dissolved, and it is preferred to promote the reaction. After forming the texture, it is washed with pure water and transferred to the next project.

After the texture is formed, the substrate is washed in hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, or the like, or an acidic aqueous solution of the mixed solution. From the perspective of economy and efficiency, it is better to wash it in hydrochloric acid. In order to improve the degree of cleansing, 0.5 to 5% of hydrogen peroxide is mixed in a hydrochloric acid solution, and the mixture may be heated to 60 to 90 ° C for washing. Thereafter, the substrate is washed with pure water, and the substrate for drying the substrate is obtained by drying the substrate.

Next, a dielectric film 102 is formed on both surfaces of the solar cell substrate 101 (FIG. 1(c)). As the dielectric film 102, for example, a tantalum oxide film subjected to thermal oxidation treatment is used. For example, in an oxygen environment In a high-temperature heat treatment furnace at 900 to 1100 ° C, a heat-oxidation film having a thickness of 10 to 150 nm is formed on a substrate 101 for a solar cell, after heat treatment for 4 minutes to 7 hours.

The method for forming the oxide film may be any method other than wet oxidation using oxygen, wet oxidation, high temperature oxidation, or a method of introducing a gas such as HCl or Cl ₂ .

Further, the dielectric film 102 is, for example, a coating of siloxane, tetramethoxy decane, tetraethoxy decane, tetrapropoxy decane, tetraethyl decane, or the like, alone or in combination. The agent may be applied to the entire substrate and dried by a heating plate of about 100 to 300 ° C for several minutes, and an oxide film may be formed by atmospheric pressure CVD or the like.

After the dielectric film 102 is formed, for example, the etching paste 103 containing phosphoric acid is applied using a dispenser (Fig. 1 (d)), and an opening portion 104 is formed in a portion of the dielectric film 102 (Fig. 1) 1(e)). However, the etching paste 103 may be applied by printing.

Further, the formation of the opening portion 104 may be performed by photolithography, and the opening portion 104 may be formed by inkjet printing a coating liquid containing a trace amount of hydrogen fluoride. However, the opening portion 104 is preferably about 50 to 400 μm in width, and is preferably formed at intervals of 1 to 5 mm.

Thereafter, the range of the opening portion 104 is not provided in the dielectric film 102, and the p-type diffusion dopant 106 containing boron is applied, for example, via a dispenser or printing. Here, the electric paste can also be applied by printing. For boron In addition, a p-type diffusion dopant containing a trivalent element such as gallium or indium may be used. However, it is preferable to use a p-type diffusion dopant containing boron from the cost side.

The p-type diffusion dopant 106 preferably has a width of about 50 to 1000 μm, and is preferably formed at intervals of 1 to 5 mm. Further, it is preferable that the printing position of the p-type diffusion dopant 106 is at least 10 μm from the opening portion 104.

Further, on the opening portion 104, for example, an n-type diffusion dopant 105 containing phosphorus is applied via a dispenser or printing (Fig. 1 (f)). In addition to phosphorus, an n-type diffusion dopant 105 containing a pentavalent element such as arsenic or antimony may be used. However, from the viewpoint of the cost surface or the ease of handling of the material, an n-type diffusion dopant 105 containing phosphorus is used. It is better.

Next, in the state of Fig. 1 (f), diffusion heat treatment is performed. The dielectric film 102 is present directly under the p-type diffusion dopant 106, but is a dielectric film thickness of up to 150 nm, and a trivalent p-type dopant such as boron is permeable during thermal diffusion. The dielectric film 102 is diffused into the semiconductor substrate to form a p-type doping range 108.

On the other hand, a 5-valent n-type diffusion dopant 105 such as phosphorus has an oxide containing an n-type dopant such as phosphorus pentoxide, which is scattered from the electric paste during heat treatment, and is other than the electric paste printing unit. In the case of the range, the n-type doping range is formed, but as in the present invention, when the dielectric film 102 is formed outside the range in which the n-type diffusion dopant 105 is applied, the dielectric film 102 can hinder the p. For the diffusion of the type dopant to the substrate, as shown in FIG. 1(g), the p-type doping range 108 and the n-type doping range 107 may be formed only in the lower portion of the paste application.

However, the heat treatment is preferably performed by a heat treatment furnace of 800 to 1000 degrees in an inert gas atmosphere such as argon or nitrogen, and a mixed gas of mixed oxygen may be used for the gas system.

Further, the n-type diffusion dopant 105 having phosphorus may be formed by a vapor phase diffusion method using phosphorus oxychloride or the like, or may be formed by spin-coating an n-type diffusion dopant 105 containing phosphorus and then performing heat treatment. By.

After the diffusion process, the glass layer and the dielectric film 102 including the p-type dopant and/or the n-type dopant formed on the surface are removed by a few hundred to tens of percent of fluoric acid or the like (FIG. 1(h)). .

Next, the anti-reflection film 109 is formed on the surface (light-receiving surface) of the substrate, and the protective film 110 is formed on the back surface (non-light-receiving surface) (Fig. 1 (i)). As the anti-reflection film 109 and the protective film 110, for example, a thermal oxide film is used. By using a thermal oxide film, the surface protection effect is improved, and the conversion efficiency is also contributed. The method of forming the thermal oxide film is not limited to dry oxidation, wet oxidation, or high-temperature oxidation of 5 to 120 minutes at 950 to 1100 ° C, and may be any method such as introduction of a gas such as HCl or Cl ₂ . By the method of any of the above, a tantalum oxide film of 90 to 150 nm is formed on the light receiving surface. When it deviates from this range, there arises a problem that the reflectance becomes high and the short-circuit current decreases.

As the anti-reflection film 109, in addition to the thermal oxide film, a SiN _x (tantalum nitride) film can also be used. As a method of forming a SiN _x film, for example, there is a method of forming a SiN _x film into a film of about 100 nm using a plasma CVD apparatus. As the reaction gas, there are many cases in which methotane (SiH ₄ ) and ammonia (NH ₃ ) are mixed, but nitrogen may be used instead of NH ₃ .

From the viewpoint of the protective effect and the prevention of reflection, it is also possible to form an oxide film that functions as a protective film and a SiN _x film that functions as an anti-reflection film.

Next, electrode formation is performed (Fig. 1 (j)). An n-type electrode 111 is formed on the n-type doping range 107, and a p-type electrode 112 is formed on the p-type doping range 108. These electrodes can be formed by any method of vapor deposition, sputtering, electroplating, inkjet, or screen printing. In the case of the screen printing method, a silver (Ag) powder, a glass powder, and a silver paste mixed with an organic binder are screen-printed, and then the silver powder is passed through a SiN _x film (fired through) by heat treatment. The electrode is electrically connected to the crucible.

As described above, in the present embodiment, in the thermal diffusion treatment, the dielectric film 102 is covered with a range other than the opening 104, and an n-type doping range is formed in a range other than the opening 104. The situation is not caused at all. Therefore, in the conventional solar cell manufacturing method, diffusion heat treatment for dividing the n-type diffusion dopant 105 and the p-type diffusion dopant 106 twice is required as the primary diffusion heat treatment.

[Second Embodiment]

In the first embodiment, the manufacturing method of the present invention is applied to the manufacturing process of the back junction type solar cell in which the electrode is not formed on the light receiving surface of the germanium substrate and the electrode is formed only on the back surface, but other examples are applied. The method for manufacturing the solar cell of the present invention is based on a single side The manufacturing process of a solar cell in which the opposite side is composed of a base is also applicable. Hereinafter, a second embodiment of the present invention will be described with reference to Fig. 2 .

In the same manner as the one described in the first embodiment, the semiconductor substrate 200 is formed on both surfaces of the solar cell substrate 201 obtained by removing the damaged layer and the texture structure, and the dielectric film 202 is formed (Fig. 2(a)~(c)).

Next, an opening portion 204 is formed in one portion of one surface of the dielectric film 202. However, the surface on which the opening 204 is provided is then referred to as a back surface (non-light-receiving surface), and the opposite surface is represented as a surface (light-receiving surface). Here, the etched paste 203 containing phosphoric acid (FIG. 2(d)) is applied or printed using a dispenser, and the opening 204 may be formed in one portion of the dielectric film 202 (FIG. 2(e)). . The opening 204 may be formed by photolithography, and inkjet printing may be carried out by coating a coating liquid containing a trace amount of hydrogen fluoride. However, the width of the opening portion 204 is preferably about 50 to 400 μm, and is preferably formed at intervals of 1 to 5 mm.

Next, on the formed opening portion 204, it is applied by a dispenser or printed with, for example, an n-type diffusion dopant 205 containing phosphorus (Fig. 2(f)). In addition to phosphorus, an n-type diffusion dopant 205 containing a pentavalent element such as arsenic or antimony may be used. However, from the viewpoint of the cost surface or the ease of handling of the material, an n-type diffusion dopant 205 containing phosphorus is used. It is better.

The printing process here is not a pattern, or the n-type diffusion dopant 205 may be printed on the back surface (non-light-receiving surface), or the n-type diffusion dopant 205 may be spin-coated on the back side (non- Light surface) surface.

In addition, in this case, the n-type diffusion dopant 205 is not applied to the back surface, and only the opening portion 204 is provided, and in the subsequent process, vapor phase diffusion may be performed using phosphorus oxychloride or the like.

On the other hand, for the surface (light-receiving surface), a dispenser is used for coating, or a p-type diffusion dopant 206 containing boron, for example, is printed. In addition to boron, a p-type diffusion dopant 206 containing a trivalent element such as gallium or indium may be used. However, it is preferable to use a boron-containing p-type diffusion dopant 206 from the cost side.

At this time, the width of the p-type diffusion dopant 206 is preferably about 50 to 1000 μm, and is preferably formed at intervals of 1 to 5 mm. However, in this case, the electric paste may be applied to the surface (light-receiving surface) in a comprehensive manner, and the p-type diffusion dopant 206 may be spin-coated on the surface (light-receiving surface).

Through the above treatment, as shown in FIG. 2(f), diffusion heat treatment is performed in a state where the n-type diffusion dopant 205 and the p-type diffusion dopant 206 are applied. The dielectric film 202 is present directly under the p-type diffusion dopant 206, but as described above, the film thickness is up to 150 nm, and when thermally diffused, a trivalent p-type dopant such as boron is permeable. The dielectric film 202 is diffused into the semiconductor substrate to form a p-type doping range 208. On the other hand, for the portion where the dielectric film 202 is not formed, the n-type doping range 207 can be formed (Fig. 2(g)).

As described above, the 5-valent n-type diffusion dopant 205 such as phosphorus has an oxide containing an n-type dopant and is flung from the electric paste during heat treatment. The n-type doping range 207 is formed in a range other than the electric paste application portion. However, in the present embodiment, the dielectric film 202 is formed outside the range in which the n-type diffusion dopant 205 is printed. The dielectric film 202 can block the diffusion of the n-type dopant to the substrate.

However, the heat treatment is preferably performed by a heat treatment furnace of 800 to 1000 degrees in an inert gas atmosphere such as argon or nitrogen, and a mixed gas of mixed oxygen may be used for the gas system.

After the diffusion process, the glass layer and the dielectric film 202 including the p-type dopant and/or the n-type dopant formed on the surface are removed by a few hundred to tens of percent of fluoric acid or the like (Fig. 2(h)). .

Next, the formation of the anti-reflection film 209 is performed on the surface of the substrate, and the formation of the protective film 210 is performed on the back surface (Fig. 2(i)). As the anti-reflection film 209, for example, a thermal oxide film may be used. By using a thermal oxide film, the protection effect is improved, and the conversion efficiency is improved. The method of forming the thermal oxide film is not limited to dry oxidation of 5 to 120 minutes at 950 to 1100 ° C, wet oxidation, or high temperature oxidation, and may be any method of introducing a gas such as HCl or Cl ₂ . By the method of any of the above, a tantalum oxide film of 90 to 150 nm is formed on the light receiving surface. When it deviates from this range, there arises a problem that the reflectance becomes high and the short-circuit current decreases.

As the anti-reflection film 209, in addition to the thermal oxide film, a SiN _x film can also be used. As a method of forming a SiN _x film, for example, there is a method of forming a SiN _x film into a film of about 100 nm using a plasma CVD apparatus. As the reaction gas, there are many cases in which methotane (SiH ₄ ) and ammonia (NH ₃ ) are mixed, but nitrogen may be used instead of NH ₃ . From the viewpoint of the protection effect and the prevention of the reflection, it is also possible to form a highly efficient solar cell by forming an oxide film that functions as a protective film and a SiN _x film that functions as an antireflection film.

Next, electrode formation is performed (Fig. 2 (j)). An n-type electrode 211 is formed on the n-type doping range 207, and a p-type electrode 212 is formed on the p-type doping range 208. These may be formed by any of an evaporation method, a sputtering method, a plating method, an inkjet method, or a screen printing method. In the case of the screen printing method, a silver powder mixed with a glass powder and an organic binder is screen-printed, and then the silver powder is passed through a SiN _x film (fired through) by heat treatment to form an electrode and a crucible. Turn on.

If the back surface (non-light-receiving surface) is provided as a comb-shaped electrode similar to the light-receiving surface, it can also be used as a two-sided solar cell. As described above, the present invention is not only a back-junction type solar cell but also a manufacturer of a solar cell in which one surface is made of an emitter and the other surface is made of a base.

As described above, in the conventional method for manufacturing a solar cell, it is necessary to perform diffusion heat treatment for the n-type diffusion dopant 205 and the p-type diffusion dopant 206 twice as a primary diffusion heat treatment. In this manufacturing method, in the thermal diffusion treatment, the range other than the opening portion 204 is covered by the dielectric film 202, and the range in which the n-type doping range is formed outside the opening portion 204 is not caused at all, and is not caused. By this characteristic decline.

[Examples]

In order to confirm the effectiveness of the present invention, a back junction type solar cell was actually produced by using the method for producing a solar cell described in the above embodiment. The production processes common to the examples and comparative examples are shown in Fig. 3. In addition, the subsequent processing of the process of FIG. 3 of the embodiment is shown in FIG. In addition, the subsequent processing of the process of FIG. 3 of the comparative example is shown in FIG. Further, subsequent to the processing of FIG. 4 or FIG. 5, the processing common to the embodiment and the comparative example is shown in FIG. 6. Hereinafter, descriptions of the examples and comparative examples will be made with reference to FIGS. 3 to 6.

Prepare a thickness of 200μm and a specific impedance of 1Ω. The cm-doped phosphorus is doped with the {100}n-type original dicing substrate 300, and after removing the damaged layer via the hot concentrated potassium hydroxide aqueous solution (Fig. 3(a)), the substrate 300 is immersed in potassium hydroxide/2-propanol. The aqueous solution forms a texture. However, in the figure, the texture concavo-convex structure is omitted from the drawing. Next, the substrate 300 is washed in a hydrochloric acid/hydrogen peroxide mixed solution to prepare 100 solar battery substrates 301 (Fig. 3(b)).

Thereafter, the obtained solar cell substrate 301 was heat-treated in a heat treatment furnace at 1000 ° C for 90 minutes in an oxygen atmosphere to form a 70 nm tantalum oxide film 302 on both surfaces of the substrate (Fig. 3(c)).

Next, an etching paste 303 containing phosphoric acid (Fig. 3 (d)) is applied using a dispenser to form an opening portion 304. The opening portion 304 is formed in a line shape having a width of 200 μm and a space of 1.5 mm (Fig. 3(e)).

Then, the same type of phosphorus is used to coat the n-type containing phosphorus. The diffusion dopant 305 is in the opening portion 304 (Fig. 3(f)).

Among the substrates processed so far, 50 sheets of the substrate 300 were processed by the method of the examples (Figs. 4 (a), (b)), and the remaining 50 sheets were compared with the comparative examples. The method was carried out (Fig. 5 (a) to (g)), and 50 solar cells produced by the production methods of the examples and the comparative examples were produced. Hereinafter, each manufacturing method will be described using the drawings.

[Examples]

Based on the 50 substrates 300 processed up to FIG. 3(f), a boron-containing p-type diffusion dopant 306 is applied using a dispenser. Further, the p-type diffusion dopant 306 is formed to have a width of 400 μm and a pitch of 1.5 mm, and is formed by opening the interval of 200 μm with the n-type diffusion dopant 305 (Fig. 4(a) ).

Thermal diffusion treatment is performed in this state (Fig. 4(b)). The thermal diffusion treatment was carried out for 30 minutes in a heat treatment furnace at 950 ° C in an argon atmosphere.

[Comparative Example]

In the comparative example, 50 sheets of the substrate processed up to FIG. 3(f) were temporarily subjected to thermal diffusion treatment to form an n-type doping range 307 (FIG. 5(a)). The thermal diffusion treatment was carried out for 30 minutes in a heat treatment furnace at 950 ° C in an argon atmosphere.

Next, the phosphor glass formed by thermal diffusion treatment The layer was immersed in a 10% fluoric acid solution and removed (Fig. 5(b)).

Thereafter, the formation of the thermal oxide film 302 is performed again. This treatment was carried out in the same manner as in Fig. 3(c), and a 70 nm tantalum oxide film 302 was formed again on both surfaces of the substrate (Fig. 5(c)).

Next, the etching paste 303 containing phosphorus is applied again using a dispenser (Fig. 5(d)) to form an opening 304 (Fig. 5(e)). However, here, as the opening portion 304, a configuration is adopted in which the width is 400 μm and the interval is made 1.5 mm, and the interval of the n-type doping region 307 formed in FIG. 5(a) is 200 μm. And formed.

Thereafter, a boron-containing p-type diffusion dopant 306 was applied to the opening 304 (Fig. 5 (f)) using a dispenser, and thermal diffusion treatment was performed (Fig. 5 (g)). The thermal diffusion treatment was carried out for 30 minutes in a heat treatment furnace at 950 ° C in an argon atmosphere.

Thus, 50 sheets of each of the substrates treated by the methods of the examples and the comparative examples were immersed in a 10% fluoric acid solution to remove the oxide film 302 remaining on the surface of the substrate, and the phosphor glass layer and the borosilicate layer were removed. The n-type doping range 307 and the p-type doping range 308 are prepared to be formed on the same substrate (Fig. 6(a)).

Thereafter, the anti-reflection film 309 and the protective film 310 are formed on all the substrates (FIG. 6(b)). First, heat treatment is performed for 40 minutes in a heat treatment furnace at 900 ° C in an oxygen atmosphere to form a thermal oxide film on both surfaces of the substrate. An anti-reflection film 309 and a protective film 310 were formed by depositing a SiN _x film of about 80 nm on both surfaces of the substrate by using a plasma CVD apparatus.

Next, an n-type electrode 311 is formed on the n-type doping range 307, and a p-type electrode 312 is formed on the p-type doping range 308 (FIG. 6(c)). Electrode paste containing silver powder and glass powder is screen-printed, and silver powder is passed through a SiN _x film (baking through) by heat treatment, and an electrode and a ruthenium are turned on to form an n-type electrode 311 and P-type electrode 312.

The solar cell produced as described above was subjected to measurement of electrical characteristics at 25 ° C, 100 mW/cm ² , and spectral AM 1.5, and the results of electrical characteristics (average of 50 sheets) are shown in Table 1. .

By using the method for producing a solar cell described in the present application, the open voltage is greatly improved, and a solar cell having high conversion efficiency is produced. This is compared with the comparative example. In the examples, the number of times of high-temperature heat treatment is small, and it is difficult to cause a decrease in the overall life cycle.

In addition, when the n-type doping range is protected by the dielectric film during the heat treatment, the n-type doping range can be prevented from being formed outside the n-type doping range, and the form factor can be increased and increased. Conversion efficiency.

When using the manufacturer of the solar cell described above In the case of the law, not only the engineering can be largely omitted, but also the conversion efficiency of the solar cell can be improved.

That is, the manufacturing process can be greatly shortened. In particular, the number of times of the high-temperature heat treatment process is reduced, the overall life cycle can be prevented from decreasing, the open voltage is increased, and the conversion efficiency can be improved.

Further, in general, when the n-type doping range and the p-type doping range are to be formed by one thermal diffusion treatment, the formation of the diffusion pattern cannot be controlled by the automatic doping of the dopant, and the solar cell characteristics are remarkably lowered. However, in the method for manufacturing a solar cell according to the present application, the p-type and n-type dopants can be selectively diffused into the substrate by protecting the surface of the n-type doping range by the dielectric film. . Thereby, it contributes to the increase of the shape factor, and the conversion efficiency can be increased.

[Industrial use possibility]

The method for producing a solar cell according to the invention of the present application is efficiently manufactured as a number of engineering reductions.

Claims (6)

A method of manufacturing a solar cell, comprising: engineering a dielectric film on at least one side of a germanium substrate, and coating a p-type diffusion doping on a portion or all of the dielectric film Engineering of the agent, and the process of diffusing the n-type dopant and the p-type dopant through one-time heat treatment; before the above-mentioned diffusion process, further comprising: not forming the dielectric film in the germanium substrate Range, the engineer who applies the n-type diffusion dopant. The method for producing a solar cell according to the first aspect of the invention, wherein the dielectric film is an oxide film. The method for producing a solar cell according to the first aspect of the invention, wherein the thickness of the dielectric film is 10 to 150 nm. The method for producing a solar cell according to claim 1, wherein the p-type dopant is boron and the n-type dopant is phosphorus. The method for producing a solar cell according to claim 1, further comprising: an engineer who removes one of the dielectric films by using an electric paste containing phosphoric acid. The method for producing a solar cell according to claim 1, wherein a range in which the n-type dopant is diffused and a range in which the p-type dopant is diffused are located on a same surface of the tantalum substrate.