TW201031009A - Manufacturing method of solar cell - Google Patents

Abstract

This invention is a manufacturing method of a high efficiency solar cell using a simple manufacturing process. This manufacturing method is applicable in producing solar cell of textured silicon substrate surface. This manufacturing method comprises the following steps: step 1, submerging a silicon substrate into an aqueous solution which is a mixture of oxidant metal ion and hydrofluoric acid, and forming a porous layer on the surface of the aforementioned silicon substrate; step 2, submerging the surface of the aforementioned silicon substrate after processed in step 1 into a mixture of mainly hydrofluoric acid and nitric acid and etching to form texture.

Description

201031009 Η 发明 发明 发明 发明 发明 发明 发明 发明 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 [Prior Art] Conventionally, in order to suppress surface reflection ', minute irregularities are formed on the surface of a solar cell. Due to this minute unevenness, the incident light is subjected to multiple reflections and is effectively absorbed inside the solar cell. This tiny bump is called a texture. Generally, in a single crystal germanium solar cell, the texture is formed by wet etching using an alkaline aqueous solution of NaOH, KOfi or the like and isopropyl alcohol (is〇pr〇pyl alc〇h〇1; ιρΑ). Since this technique utilizes the difference in etching speed of the crystal face, it is effective for a case where a wafer such as a single crystal germanium is constituted by a single crystal face, but for a state such as polysilicon, there are various types in the plane. In the case of the crystal face, the reflectance cannot be sufficiently reduced. Therefore, a texture forming method which does not depend on the crystal plane orientation, such as a mechanical processing method (for example, Patent Document 1) or a reactive ion method (for example, 2), is being studied. In the case of using a mechanical processing method, in order to perform sheet processing and a reactive ion etching method, in order to use a vacuum apparatus capable of processing a certain number of sheets, the problem is that considerable processing cost is required. . Here, a method of forming a texture (Patent Document 3) has been proposed. * Patent application' is a method of immersing a ruthenium substrate with a metal ion-containing oxidant and

2111-10310-PF 3 201031009 A mixed aqueous solution of fluorofluoric acid' forms a porous layer on the surface of the substrate, and then is immersed in an alkaline liquid to form a texture. The principle of completing the hole (pit) in the metal-attached crucible is disclosed in Patent Document 4. Patent Document 1: Japanese Patent Laid-Open No. 3189201 Patent Document 2: Japanese Patent Laid-Open Publication No. Hei No. Hei 9 - 1 No. 2 6 2 5 Patent Document 3: Japanese Patent No. 3925867 Patent Document 4: Japanese Patent Publication No. 2 0 〇 4 - 71 6 2 6 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION 1. However, the porous fracture layer ruthenium substrate produced by the method proposed in Patent Document 3 exhibits low reflection. The value of the rate, but the surface of the wafer is discolored, and the hydrophobicity of the characteristics of the clean surface of the crucible is not shown. The reason is generally considered to be that this method not only forms holes in the surface of the crucible, but also degrades the surface of the dream. In addition, the wafer was immersed in 6〇% nitric acid for one hour after the silver was attached, and the wafer was fabricated into a solar cell unit, and the characteristics were judged, and it was learned and used with an alkaline aqueous solution. The solar cell of the texture formed by isopropyl alcohol (hereinafter simply referred to as "etching texture") is greatly deteriorated in characteristics. The reason for this is that it is generally considered that even after the process of immersing in 60% nitric acid for one hour, the metal cannot be completely removed, and the metal diffuses in the solar cell fabrication process to lower the crystal quality, so that the characteristics of the solar cell are greatly deteriorated. ♦- Therefore, in order to use the oxidant containing metal ions and hydrofluoric acid to make 211M0310-PF 4 201031009 porous stone layer to effectively complete the solar cell, the problem is that a process is required, which is in the formation of porous After the enamel layer, the cleaned surface of the crucible is exposed and the residual metal is removed. In view of the present invention, a method for manufacturing a solar cell having high characteristics is to use a metal ion-containing oxidizing agent and hydrofluoric acid to form a porous layer, and to expose the clean surface of the crucible and remove the residual layer. metal. [Means to solve problems]

In order to solve the above problems, the present invention achieves the above object, and is a method for manufacturing a solar cell having a texture on the surface of a stone substrate, which comprises the following steps: a first step of immersing a substrate in a substrate a mixed aqueous solution of a metal-containing hetero oxidant and hydrofluoric acid to form a porous layer on the surface of the ruthenium substrate; and a second step of immersing the surface of the ruthenium substrate having undergone the first step of the process Etching is carried out by etching a mixed acid mainly composed of chlorine: fluoric acid and nitric acid to form an identifiable structure. According to the present invention, the porous layer (tetrazed) using metal ions is a mixed acid mainly composed of fluoric acid and nitric acid, so that the effect of reducing the reflectance is not lost, whereby the decrease in reflectance can be retained. The effect is to get a clean dream surface, and (4) to remove the metal from the hole, thus achieving the effect of manufacturing a solar cell with high sorghum. In addition, the effect of simplification of the process is achieved by the removal of the true rhyme and the metal. [Embodiment] and advantages can be made clear for the above and other objects and features of the present invention.

2111-10310-PF 5 201031009 It is easy to understand, the following is a better example of the best and better, and with the accompanying drawings, the following is a detailed description: In this specification, after the numerical description, the above In the case of the range of the following descriptions of the "following", unless otherwise noted, the relevant numerical range is the value of the preceding words including the above "above" and "below". [Best Mode for Carrying Out the Invention] The inventors of the present invention have made a texture according to the embodiment described in Patent Document 3 and judged the characteristics thereof, and found the problem of the technique of Patent Document 3. First, detailed steps and problems to be implemented according to the embodiment of Patent Document 3 will be described. First, the inventors of the present invention prepared a polycrystalline substrate which removed the damage I generated when cutting out from the bulk, and then contained silver ions containing (1E-4) m (M'l/L). A mixed aqueous solution of hydrogen peroxide and hydrofluoric acid is used for button etching. Figure 5 蚤#+ S Η! ΛΑ ^ , a photograph taken of a test piece that has been etched on the lower half of the circle. 'In addition, 笙β. Surface ββ Fig. 6 shows a graph showing the measurement result of the reflectance as shown in Fig. 6, and the value of the reflectance of the portion where the porous layer is formed by the above-mentioned surname is lower than the test. (4) The reflectivity of the texture processing m; but as shown in Fig. 5, the surface of the wafer is discolored, and the hydrophobicity D of the characteristic of the broken clean surface is not shown.

Further, after that, a 1% hydrogen hydroxide aqueous solution was used to carry out a 1 knives clock, but the surface of the wafer did not show hydrophobicity even after passing through the HF:net step of removing the natural oxide film. According to the case where the porous layer cannot be transported to the hydrophobic surface after the formation of the porous layer, it can be considered that not only the value of the twin crystal is formed into a hole, but the surface of the dream is deteriorated, and even if the surname is applied, it cannot be removed.

2111-10310-PF 201031009 Deterioration of deterioration. In addition, in order to remove the adhered silver, the inventors of the present invention immersed the wafer in 60% of the niobium for 1 hour, and then performed the steps shown in Fig. 7, and fabricated a solar cell from the wafer (unit size: 2x2 cm). ). In Fig. 7, 'the thermal diffusion treatment is performed in order to form the PN junction (step. Next, a tantalum nitride film as an antireflection film is deposited on the surface of the wafer using a battery growth device (step S12). Electrode printing (step si3), sintering to adhere the electrode (step S14), and forming a solar cell. Fig. 8 is a graph for explaining the short-circuit photocurrent density Jsc of the solar cell fabricated above. In the eighth circle, the characteristics of the solar cell to which the alkali etching texture treatment is applied are also considered. As a result, it is understood that the solar cell of the above-mentioned inventors of the present invention has a 'skin' ratio than the alkali etching texture. The characteristics of the battery unit have been greatly improved, and the solar battery manufactured by the original technology disclosed in Japanese Patent Application No. 3 has problems in use. In the manufacture of the semiconductor package, the helmet T is right, and the method is paid. It is impossible to produce a high-quality solar cell by showing at least the π clean surface of the degree of hydrophobicity of the characteristics of the dream. The patent is the method disclosed in the literature. The alkali etching etched by the 3μ item of the patent 'Document 3' still fails to make the wafer hydrophobic. For example, the 芸 曰 认 认 认 认 认 认 认 认 认 认 认 认 认 认 认 认 认 认 认 认 认Etching can of course obtain a hydrophobic surface, but the porous layer can be completely removed, and only the same level of reflectivity as that of the (four) texture can be obtained, and the effect of reducing the reflectance is lost. "The metal is deposited on the surface of the dream substrate. Only disclosed in Document 3

2111-10310-PF 201031009 " "To remove silver remaining on the surface". However, in Patent Document 4, which discloses a ruthenium which has been adhered to a metal, it is revealed that the metal-attached portion and its periphery are etched, that is, a mechanism for opening a hole in the ruthenium substrate by a metal as a hole. Etched. Therefore, it can be said that if the method of Patent Document 3 is used, the metal which remains in the bottom of the hole is diffused in the process of producing the solar cell, and the crystal quality is lowered, and the characteristics of the solar cell are largely deteriorated. In the internal quantum efficiency shown in Fig. 8, the sensitivity is lowered to 8 〇〇 to 12 〇〇 nffi and the reaction crystallization quality also illustrates this. As a result, in the method described in the examples of Patent Document 3, the genus of gold is precipitated and exists at the bottom of the pore of the crystal face. In order to prevent the above-mentioned wafer from being dissipated and to reduce the effect of the reflectance, the porous body is removed by the alkali solution. However, it is extremely difficult to remove the metal at the bottom of the hole by acid. The reason is that if the degree of etching is insufficient, the chemical liquid (acid) hardly touches the bottom of the hole 'and thus it is difficult to remove the metal; or if the amount of alkali etching is increased for easy removal of the metal, the etching speed is due to the crystal face The characteristics of the etching are remarkable when they are different, and the effect of lowering the reflectance is lost when compared with the alkali etching texture processing. Further, if the porous material is removed by the test liquid without losing the effect of lowering the reflectance, and the metal at the bottom of the hole can be removed by the subsequent acid treatment, even if the porous layer is removed and the metal is removed, A necessary step to complicate the manufacturing process. Here, a method for producing a solar cell having a low reflectance and a clean wafer surface by removing the porous ruthenium removing metal in one step is proposed as an embodiment of the present invention. The following is a detailed description of the hair

2111-10310-PF 8 201031009 An embodiment of a method for producing a solar cell. However, the present invention is not limited to these embodiments. (Embodiment 1) Next, a method of manufacturing a Taichung battery according to Embodiment 1 of the present invention will be described. Fig. 1 is a flow chart for explaining the manufacturing method of the embodiment. Hereinafter, a method of manufacturing a solar battery according to the present embodiment will be described based on the flowchart of Fig. 1. ❿ Prepare P-type polycrystalline wafers (doping, 1~3 Ω cm, 15 X15 cm angle, thickness 280# m). Since the polycrystalline germanium wafer is manufactured by cooling and solidifying a molten tungsten crucible, a tungsten ingot is sliced through a wire saw, and the surface thereof is damaged during slicing. First, the damaged layer is removed with an alkali solution. Thereafter, a silver nitrate aqueous solution is added to a mixed chemical solution of hydrofluoric acid, hydrogen peroxide, and water to obtain a chemical solution having a predetermined silver ion concentration (described by scarring [蜍+]). The wafer is immersed in the above liquid solution to form a porous layer on the surface thereof (step S1) » Actually, HF (50%): H2 〇 2 (60%): H2 〇: AgN 〇 3 (〇. lM)=400ml : 200ml: 1 600 ml : 4. 4ml '(U g + Μ 2E - 4) Μ) The liquid is placed in the tank, and the wafer is straight in the tank. Make a 3-minute button. The porous layer formed at this time is shown in Fig. 2. In this case, the wafer is stored in a cassette and is erected. The layer is formed by placing the wafer horizontally in a mat-like flat shape. Quality layer. Subtraction, as described above - in the case of a porous layer, the conditions of the end of the layer, the hydrogen generated during the etching will be blocked and the sputum will be rounded down to make the squat; * the etching uniformity is poor, so it is better to etch t

2111-10310-PF 201031009 The upward facing surface is used as a light receiving surface to make a solar cell. After the step si is performed, the surface of the wafer is etched by washing and drying (step S2) of the wafer to the extent that the effect of reducing the reflectance is not lost, and the surface of the wafer is etched using a mixed acid mainly composed of hydrofluoric acid and nitric acid (step S3). ). Actually, a mixed acid having a capacity ratio of HF (5〇%): HN〇3 (69%): H2〇 = 1:9:15 was used for etching for 3 minutes. The person-in-law puts the liquid into a flat container with a cushion-like shape, and the level is rounded, but the wafer is shaken in the liquid medicine so that the unevenness of the liquid medicine does not occur during the remaining process. . Here, the chlorine generated by the button is also trapped under the wafer and the silver engraving uniformity of the lower surface is poor. Therefore, it is preferable to form the solar cell as the light-receiving surface at the time of etching. Of course, the wafer can be placed in the wafer and the money can be engraved in an upright state. = An etching device for transporting wafers horizontally in the liquid medicine is already being sold, = important. In the case of using the device of this type, the upper surface of the etching is used as the light receiving surface of the solar cell; The rhythm of the rhyme is uniformly performed in the form of (4), (10) and (4) (row (4), or the wafer is not placed, and the crystal is transported horizontally in the chemical solution for etching). After oxidation, water washing (step (4), followed by thymidine (tetra) stone ^ 10 seconds (four) engraved (step S5) ° with ammonia acid and nitric acid because of the ratio of chlorine acid and acid solution used and its membrane It is called the case where the surface of the wafer is discolored. It is a thin acid rabbit material that causes discoloration. When the multi-layer is etched by the hydrofluoric acid and the acid-based mixed acid in the step S3, the dye film is formed on the surface of the wafer 2111-1〇3 j〇.pp 201031009. In the step 55, etching using a 1% aqueous sodium hydroxide solution was carried out for the purpose of removing the dye film. Here, a 1% aqueous sodium hydroxide solution is used at room temperature, but the type of the chemical liquid is not limited as long as it is an alkaline aqueous solution. The concentration of the alkaline aqueous solution is at most 5%, and the temperature of the chemical solution is around room temperature. After the step S5, if the wafer is washed (step S6) and the natural oxide film on the surface of the wafer is removed by hydrofluoric acid (step S7), a water surface is formed on the surface of the wafer. Finally, the water is washed (step S8), and the completed wafer is used as the wafer to which the embodiment is applied. The texture formed by the above process is shown in Fig. 3. As can be seen from comparison with Fig. 2, the wafer surface to which the present embodiment is applied as shown in Fig. 3 has a large aperture ', which is advantageous for removing the bottom metal. Fig. 4 is a sinogram showing a comparison of the reflectance of the wafer to which the wafer of the present embodiment is applied and the texture of the application. For comparison, the texture of the test (4) was obtained by applying the same town bond slice of the wafer of the present embodiment, and removing the damage layer, and adding 600 ml to the aqueous sodium hydroxide solution (6.3%, 80 ° C). A solution of iso-alcohol was prepared by performing (four) for 9 minutes. As is understood from Fig. 2, the reflectance of the surface of the crystal to which the present embodiment is applied is lower than the reflectance of the alkali etching texture of the object to be compared. Next, the wafer to which the present embodiment is applied and the wafer subjected to the alkali etching texture treatment are applied, and the process shown in FIG. 7 is performed to produce a solar energy=cell (unit β size: 15×15 cm), and the short-circuit light of the solar cell is used. The current * is shown in Figure 20. As shown in Figure 20, you can understand the application.

211M0310-PF 11 201031009 The short-circuit photocurrent density of the solar cell of the wafer of the present embodiment is improved compared to the wafer subjected to the alkali etching texture treatment. Here, it is explained that silver is used as the metal ion in the step S1, and in other examples, the copper may be used instead of the silver. Among the metal ions (silver, copper, nickel, ruthenium, gold, and gold) exemplified in Patent Document 3, the metal platinum and gold other than the above cannot be removed in the process of step S3. The (four) in step S3 is caused by the mechanism of oxidation of tartaric acid (tetra) and removal of hydrazine by hydrofluoric acid. Therefore, if the capacity of nitric acid is large, the oxidation rate of niobium is greater than the removal rate, and the etching rate of niobium is slowed. Therefore, the ratio of the chemical solution of hydrofluoric acid or tannic acid determines the rate of etching. Also, water can be added to adjust the etch rate. Here, it is a liquid solution using HF (50%): HN〇3 (69%): .H2 (M: 9:15), but since the amount of added water or etching time can be adjusted, if it is relative to When the capacity of the hydrofluoric acid is 1 and the capacity of the nitric acid is 6 or more, the ratio of nitric acid in the relevant chemical solution may be changed. If the volume ratio of nitric acid to 1 is less than 6 with respect to the hydrofluoric acid, the case may be different. The first, the completion, the first and third are pictures of the appearance of the wafer, which have been passed through HF (50%): H2〇2 (6〇%): H2〇: AgN 〇3(〇iM) = 40〇ml: 20〇ml: 1600inl: 4,4inl ([Ag+] = (2E_4)M) is etched for 3 minutes to form a porous layer of wafer, and then the above wafer The solution of liver (5〇%): ΗΝ〇3 (69%): Η2〇=:ι:x: 15 with a change in the amount of nitric acid X to 4, 5, 6, and 9 was performed for 3 minutes of etching β ( Similarly, in order to remove the dyed film, etching with 1% NaOH for 10 seconds was performed as a comparison object, and Fig. 9 shows HF (50%): H2〇2 (60%): H2〇: AgN〇3 (〇 1M) = 4〇〇nii: 2〇〇mi: 2111-10310-PF 12 201031009 Appearance of the porous layer wafer Photographs: Compared to the case where the hydrofluoric acid is 1 and the nitric acid is 4, since the nitric acid is too small, the mass of the layer is extremely slow. If the nitric acid is increased to 5, the niobium layer can be removed, but the niobium is formed. The dyed film cannot be removed by the alkali solution, and as shown in Fig. 12, the dyed film remains at the end of the wafer. The figure is shown, HF (5(U).HN〇3(69%): H2〇= l : a mixed photograph of a capacity ratio of 5:15 is a photograph of a dyed film formed at the end of the wafer 3 minutes after the porous guest layer shown in Fig. 9. In contrast, if the nitric acid is 6 or more, The dyed film may be completely removed. Therefore, the mixed acid to be used is preferably a mixed acid having a capacity of 6 or more in a case where the capacity of the hydrofluoric acid (5 % by mass) is 1 or more. 'In the process shown in Fig. 7, a solar cell is fabricated by forming a PN junction by a thermal diffusion method using a polycrystalline wafer as a substrate. However, it is of course possible to use a single crystal substrate, but also a CVD method. Sink (4) ΡΝ to form a 太阳能 joint to make a solar cell. • So, if the implementation of the present invention, the state 1 The degree of the effect of lowering the reflectance is lost, and the porous layer mainly composed of hydrofluoric acid and nitric acid is used to contact the porous layer formed of the metal ions, whereby the effect of reducing the reflectance can be retained and the cleaned stone surface is obtained. At the same time, the metal at the bottom of the hole can be removed, and the effect of manufacturing a highly efficient solar cell can be achieved. In addition, the effect of simplifying the manufacturing process can be simplified by the simultaneous implementation of the removal of the metal and the removal of the metal [others on the hydrofluoric acid and indeed In the case of a mixed acid having a main acid as the main component, a mixed acid having a capacity of 50% of the hydrofluoric acid and a capacity of 6 or more of nitric acid is used, thereby achieving a rapid progress in the 211M0310-PF 13 201031009. The etching rate and the effect of the etching step which is easy to perform surface treatment after etching. In addition, when etching is performed using a mixed acid mainly composed of hydrofluoric acid and nitric acid, the etching is performed while stirring the mixed acid, thereby achieving a mixed acid solution on the surface of the wafer which prevents the etching from proceeding. The effect of uneven concentration. In addition, in the process of forming a porous layer using metal ions and etching a mixed acid mainly composed of hydrofluoric acid and nitric acid, the substrate is horizontally disposed, or the surface of the substrate is horizontally transported while impregnating the substrate. The upward facing surface serves as a light-receiving surface of the solar cell to achieve an effect of preventing unevenness of the rice caused by the influence of hydrogen generated on the light-receiving surface. Embodiment 2 Next, the inventors of the present invention changed the metal ion concentration to form a porous layer on the tantalum substrate and mounted a light substrate to fabricate the solar cell, and studied the metal ion infiltration caused by the characteristics of the solar cell. The influence "is taken as the second embodiment, and will be described in detail below. The manufacturing method r in the present embodiment is carried out in the same manner as in the first embodiment, as shown in Fig. 1. In step S1 of Fig. 1, for two wafers cut out from one ingot and having the damaged layer removed, in HF (50%): H2〇2 (10): : 2〇〇ml:} 6 _ The liquid solution of the _ solution is added to 2. (5) ([Ag+] = (1E-4)M), 1· lnil ([Ag+] = (5E_5)M) 〇. 3 minutes of narration. In step s3, a mixed acid having a capacity ratio of HF (50%):HN〇3 (69%):H2〇=1:9:15 was subjected to a 3-minute surname. After the process of step 58 is ±, according to the seventh figure

2111-10310-PF 14 201031009 The process shown is to make a solar cell (unit size: 2 x 2 cm). Fig. 21 is a diagram showing the short-circuit photocurrent density Jsc of the above two solar cells and the short-circuit photocurrent density JSC of the alkali-etched texture produced by cutting out from the same ingot. In the case of [Ag+] = (1E_4)M, Jsc is the same degree as the alkali etching texture, but once g[Ag+] = (5E_5)M, a significant drop in jsc is seen. The same etching time, [wire +] is lower, the result is that the characteristics of the solar cell are lower. φ Fig. 15 shows a comparison of the internal quantum efficiencies of the battery cells fabricated by [Ag+] = (1E-4)M, (5E-5)M and the alkali-etched textured cells. According to Fig. 15, compared with the battery unit treated with alkali etching or texture, the battery cells fabricated with [Ag+] = (1E-4)M and (5E-5)M are in the wavelength region of 8 〇〇 nm or more. The sensitivity is lower. It is revealed that the metal precipitated at the time of forming the porous layer is completely removed, and the lower the metal concentration, the higher the sensitivity in the wavelength region of 8 or more is lowered. The 16th step combines the solar cells fabricated by the same method in the mixed solution of [Ag+M2E_4)M in the step S1 to compare the short-circuit photocurrent density. However, in the solar cell produced by using the mixed solution of [Ag+M2E-4)M, the pound key of the wafer is cut out from the source, and the user of the embodiment 1 and the above-described embodiment are different from the above. The town bond of two-plate crystal κ. In Fig. 16, in order to compare the characteristics of solar cells fabricated using wafers cut from different ingots, alkali etching texture processing is separately performed from the same ingots as the wafers of the respective solar cells. For the battery cell, the value of the short-circuit photocurrent density of the battery cell treated by the above-described alkali etching texture is used as a normalized value. In 篦 1 R El ^ ^ ^ .

211M0310-PF 15 201031009 (1E-4) M or more The characteristics of the solar cell are raised to the same level as the battery unit treated with the alkali etching texture. Therefore, it is understood that in order to obtain a solar cell which is still efficient, the metal ion concentration of the mixed solution used in the step S1 is necessary to be at least (1E-4) M or more. Further, when the concentration of the right metal ion is lowered, the precipitation rate of the metal is slow, and variation in the size of the precipitated metal is likely to occur. On the other hand, according to Patent Document 4', since the hole is opened by the contact action of the metal, the depth of the hole is greatly affected by the size of the precipitated metal. Therefore, the first precipitated metal particles will first reach a size sufficient to form pores in the crucible, and the pores formed will be deeper, but the late-precipitated metal particles will reach a size sufficient to form pores in the crucible, so the pores formed are also The result is shallow, and the result is a crater layer with a large variation in the depth of the hole. After that, the effect of the effect of lowering the reflectance is not lost, and the removal of the porous layer by the mixed acid mainly composed of sulphuric acid and acid is here, because it is desirable to distribute as much as possible in a large proportion of regions. The embossing is carried out while the surname of the shallower hole is left. If there are deep holes at this time, the metal forming the deep holes cannot be completely removed, which adversely affects the characteristics of the solar cell. Therefore, the smaller the size of the precipitated metal $ is, the better. That is, it is easier to produce a highly efficient solar cell than the case where etching with a low metal ion concentration is carried out for a long time to etch with a mixed solution of a high metal ion concentration. ,, ',, if the metal ion concentration is too high, the amount of metal deposited on the wafer is too large' and the wafer will have the color of the metal used. Figures 17 and 18 are rainbow (5〇%): H2〇2 (6〇%): H2〇= 4〇〇ml: 2〇〇ml: 16〇〇mi liquid 213 l-103]〇* Pp 201031009 Adding a solution of 8.8 ml ([Ag+M4E-4)M), l7.6miaAg+] = (8E_4)M) of 0. 1M silver nitrate aqueous solution to the wafer obtained by etching for 3 minutes Appearance photography photos. Comparing these photos, we know that if you use [Ag+] = (8Έ-4)Μ, the deposited silver will give the wafer a silver color (white). If such a wafer is etched with a mixed acid mainly composed of hydrofluoric acid and nitric acid, there is still no problem in the characteristics of the solar cell, but a large amount of metal ions are required to form a porous layer. In addition, in order to remove a large amount of metal, the cost disadvantage of the mixed acid solution life and the like is shortened. As apparent from the above, the metal concentration in the metal-containing mixed solution is preferably (1E-4) M or more and less than (h4) m. According to the method for producing a solar cell according to the second embodiment of the present invention, the metal ion-containing mixed solution used for forming the porous layer on the tantalum substrate is used by using a metal concentration of (ie_4)m. • The mixed solution of the above and less than (8E-4) M is effective in producing a solar cell with high efficiency and reducing the cost of the chemical solution. [Industrial Applicability] As described above, the method for producing a solar cell according to the present invention is useful for a method for producing a solar cell, and is particularly suitable for forming minute irregularities (texture) on the surface of a tantalum substrate. Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art to which the present invention pertains may be made without departing from the spirit and scope of the invention. Change

211M0310-PF 17 201031009

And retouched, as defined. BRIEF DESCRIPTION OF THE DRAWINGS The first and first drawings for explaining the present invention are a flow chart for explaining a method of manufacturing a solar cell related to a silver-containing ion. Fig. 2 is a photograph of a porous layer obtained by carrying out a mixture of oxygen water (t hydrogen peroxide water; valley liquid) and hydrofluoric acid. Fig. 3 is an electron micrograph showing the texture formed on the surface of the crucible substrate. 'This is an embodiment of the present invention! In the method for producing a solar cell, a mixed acid mainly composed of hydrofluoric acid and nitric acid is used to etch a porous oxide layer to form a texture on the surface of the tantalum substrate. 4 is a graph which shows the reflectance of the texture and the alkali etching texture produced by the method for producing a solar cell according to Embodiment i of the present invention. Fig. 5 is a photograph obtained by photographing the appearance of a wafer which has been subjected to etching with a mixed solution of hydrogen peroxide-containing hydrogen peroxide and hydrofluoric acid according to the embodiment of Patent Document 3. Fig. 6 is a graph showing the results of measurement of the reflectance of the wafer on which the porous layer is formed according to the embodiment of Patent Document 3 and the wafer subjected to the texture processing. Fig. 7 is a flow chart' showing the flow of fabricating a solar cell unit from a wafer. 2111-10310-PF =18 201031009 Fig. 8 is a graph of a wafer manufactured by using the wafer of the embodiment of Patent Document 3 and the wafer processed by the application inspection. The internal quantum efficiency of solar cells. Fig. 9 is a photograph obtained by photographing the appearance of a wafer which is a mixture of hydrogen peroxide and hydrofluoric acid having a silver ion containing αΕ_4).

Figure 10 is a photograph of the appearance of the wafer, which has been shown in Figure 9 with HF (509〇:HN(M69%):H2〇=1:4:15). The porous layer was etched for three minutes. Figure 11 is a photograph of the appearance of the wafer, which has been subjected to HF (50%): HN〇3 (69%): H2〇=1:5 The mixed acid of 15 was etched for three minutes in the porous layer shown in Fig. 9. Fig. U is a photograph obtained by photographing a stain film formed at the end of the wafer shown in Fig. u. Fig. 13 is a photograph of the appearance of the wafer. It has been (4) (10)): _3: repair 1:6: mixed = 9 shown in the porous layer for three minutes (four). The acid on the 14th picture shows the appearance of the wafer + is already HF (5〇9〇, ......, the film 'the above wafer [5〇%): delete 3 (69%): Η 2〇 =1:9:15, the pattern of the porous scorpion acid shown in the early 9th figure on the first pore layer for three minutes. Figure 15 is a graph showing the comparison of the hydrogen peroxide-containing hydrogen peroxide solution. The internal quantum effect of the silver ion concentration in the liquid. * - Figure 16 is a graph. Green wish

2111-10310-PF 圏, which is plotted against the change in silver ion concentration. 19 201031009 Normalized short-circuit photocurrent density is plotted. Is dissolved. Figure 17 is a photograph of the appearance of the wafer, the wafer

Three minutes of etching with a mixture of hydrogen peroxide and hydrofluoric acid containing (4E-4)M of silver ions has been carried out. Fig. 18 is a photograph obtained by photographing the appearance of a wafer which has been subjected to a three-minute etching with a mixed solution of hydrogen peroxide containing (8E-4)M of silver ions;

Fig. 19 is an explanatory view for comparing the short-circuit photocurrent density of the solar cell unit and the alkali-etched textured battery cell fabricated by the characterization of the embodiment of the patent document 3. FIG. 20 is a diagram for explaining a short circuit of a battery unit which is formed by comparing a texture produced by using the manufacturing method according to the first embodiment of the present invention, and an alkali-etched textured battery unit. Photocurrent density.

Fig. 21 is an explanatory diagram for comparing a solar cell monolayer formed by using a porous layer formed by a mixed solution of hydrogen peroxide containing different concentrations of silver ions, and short-circuiting with the etch-treated cell unit. Photocurrent density. [Main component symbol description] S1~S18, S1 Bu S14~Step

2111-10310-PF 20

Claims (1)

201031009 VII. Patent application scope: 1. A method for manufacturing a solar cell, which is a method for producing a solar cell having a texture on a surface of a ruthenium substrate, which comprises the following steps: a substrate is immersed in a mixed surface solution of an oxidizing agent and a hydrofluoric acid containing a gold eyebrow ion, and is on the surface of the substrate; 117 is a porous layer; and: The second step! 'The surface of the ruthenium substrate which has passed through the first step is immersed in a mixed acid mainly composed of hydrofluoric acid and nitric acid to form a texture 0 2 · The solar energy as described in claim 1 A method of manufacturing a battery, characterized in that: the mixing element used in the second chapter is: a capacity of 50% of hydrofluoric acid is 1 and a capacity of 60% of nitric acid is 6 The mixed acid mixed in the above manner. 3. The method of manufacturing a solar cell according to claim 1, wherein the method further comprises: the third step of: wherein the substrate is pasted by the first step. 4. The method of manufacturing a solar cell according to claim 2, wherein the second step is: circulating the mixed acid or stirring the mixed acid while performing the step of The etching of the germanium substrate. 5. The method for manufacturing a solar cell according to claim 1, wherein: 2111-10310-PF 21 201031009 in the first step and/or the second step, the substrate is horizontally When it is set or horizontally conveyed and immersed, it becomes the surface of the above table (4) and is used as the light receiving surface of the solar cell. 6. The method according to the scope of the patent application is characterized in that: the metal ion concentration of the metal in the mixed aqueous solution of the metal ion-containing oxidizing agent and the ammonia-like aqueous solution used in the (m) is (1E-4) M or more. , really not Φ full (8E-4) M 〇2111-10310-PF Θ 22