CN107217306B - Chemical composition of polycrystalline silicon wafer acid texturing optimizing agent and application thereof - Google Patents

Abstract

The invention provides a chemical composition of a polycrystalline silicon wafer acid texturing optimizing agent, which is an aqueous solution, and the solute is: (1) a polymer having thiodiazoxide structural units; (2) a polyol or derivative thereof. The invention also provides application of the chemical composition of the polycrystalline silicon wafer acid texturing optimizing agent in the acid texturing of the polycrystalline silicon wafer cut by a mortar line or a diamond line. The chemical composition has the advantages of simple preparation and use method, easy implementation and good repeatability, when the chemical composition is used for preparing the texture of the polycrystalline silicon by using a mortar wire or a diamond wire cutting, the texture preparing effect is obviously improved, the prepared silicon wafer has uniform surface appearance, low reflectivity and uniform appearance color after being coated, and compared with the texture surface without adding the auxiliary chemical composition, the uniformity of the silicon wafer is obviously improved.

Description

Chemical Composition and Application of Polycrystalline Silicon Sheet Acid Texturing Optimizing Agent

technical field

The invention belongs to the field of new energy, and in particular relates to a chemical composition used as an acid texturizing optimizer on the surface of polycrystalline silicon wafers, and also relates to the use of the chemical composition of the optimizer in preparing acidic texturing agents for mortar line or diamond wire cutting polycrystalline silicon wafers. Application in texturing liquid.

Background technique

The reflection of incident light on the surface of the silicon wafer greatly reduces the efficiency (current flow) of silicon solar cells. If there is no anti-reflection treatment on the surface of the silicon cell, about 40% of the sunlight will be lost. This antireflection effect must be effective across the entire solar spectrum and at a wide variety of incident light angles.

Currently, antireflection on crystalline silicon photovoltaic cells is achieved through several different techniques. For single crystal silicon, the reflectance of anisotropic (pyramidal) textured etched silicon single crystals is reduced to about 5-15% above facing 100 single crystal silicon, but mainly at incident light angles close to 90° rather than at low angles of incidence Reflectivity. This technique also consumes a large amount of silicon material, making it impractical for thin-film silicon solar cells. For polysilicon, use the acidic isotropic etching method to obtain pit-like suede, which reduces the surface reflectance to 15-20%. With the development of silicon wafer cutting technology, diamond wire cutting silicon wafer technology will replace mortar wire and become the mainstream of silicon wafer production process due to its cost and environmental protection advantages. However, texturing of diamond-wire-cut polysilicon wafers has become the main factor that constrains the promotion of diamond-wire-cut polysilicon in cell manufacturing.

Diamond wire cut polysilicon wafers cannot obtain a uniform suede surface by conventional methods. There have been different attempts to texture diamond wire cut silicon wafers.

Patent CN104328503A discloses a diamond-wire-cut polysilicon texturing method, which is mainly characterized in that a mixed acid solution is used to treat the surface of the silicon wafer to form a porous structure on the surface of the silicon wafer.

Patent CN 104962998 A provides a method for pretreatment of texturing silicon wafers based on diamond wire cutting, which includes the following steps: a) mixing concentrated hydrofluoric acid solution, hydrogen peroxide solution, metal salt and water to obtain a pretreatment solution; b) placing the diamond wire-cut silicon wafer in the pretreatment solution to perform pretreatment a until the cutting lines on the silicon wafer are basically removed.

Patent CN104576830 provides a kind of texturing pretreatment liquid for diamond wire cutting polycrystalline silicon wafers, the texturing treatment liquid includes the first treatment liquid and the second treatment liquid A or B, the first treatment liquid is concentrated hydrofluoric acid, hydrogen peroxide, The mixed solution of metal salt and water, described treatment solution A comprises nitric acid and strong alkali, and described treatment solution B is the mixed solution of nitric acid, concentrated hydrofluoric acid and water; A great improvement is produced, but the obtained silicon wafer cells still have significant differences in surface uniformity and reflectance reduction compared with mortar wire-cut polysilicon.

Patent CN105304734 provides a polycrystalline silicon chip texturing auxiliary agent and its application method. The auxiliary agent is composed of a silver inducer, an oxidant, a buffer, a dispersant and deionized water. Add this auxiliary agent into the traditional isotropic texturing solution composed of concentrated hydrofluoric acid and nitric acid mixture, and then immerse the polycrystalline silicon wafer in the texturing solution, and the surface of the silicon wafer will undergo isotropic corrosion and anisotropy. Corrosion, so as to obtain the silicon surface with the coexistence of corrosion pits with reflectivity lower than 10% and inverted pyramid morphology with different directions.

CN104393114 discloses a method for preparing polycrystalline black silicon with a micro-nano composite textured structure. First, the polycrystalline silicon wafer is placed in an etching solution to prepare a polycrystalline silicon wafer with a micron textured structure; then it is placed in a metal ion compound solution Deposit metal nanoparticles on the micro-textured surface, and then place it in an etching solution for etching to obtain a polycrystalline silicon wafer with a micro-nano composite textured structure; after cleaning and removing the residual metal particles on the surface, it is finally placed in an alkaline solution for micro-nano composite textured texture modification etching.

However, in addition to the high cost of use of the above methods, and the introduction of metal ions, there are limitations in uniformity and electrical properties. industrialization.

The acidic etching solution widely used in the acidic isotropic texturing process is formed by mixing hydrofluoric acid (HF), nitric acid (HN03) and pure water in a certain proportion. The function of nitric acid in this method is to oxidize the silicon surface, while the function of hydrofluoric acid is to continuously remove the oxide layer on the silicon surface. The biggest feature of this process is that it is very simple, but it cannot be directly applied to diamond wire cut silicon wafers. The main problems are the high reflectivity after texture, the poor uniformity of the texture, the large color difference (especially the color difference between different interfaces) of the texture, and the low conversion efficiency of silicon cells, etc.

Contents of the invention

Purpose of the invention: The first purpose of the present invention is to provide a chemical composition of an optimization agent for acidic texturing of polycrystalline silicon wafers, which can be used for surface texturing of acidic polycrystalline silicon wafers, thereby obtaining a uniform textured surface.

The second object of the present invention is to provide the application of the chemical composition of the above-mentioned optimizer in the preparation of acidic texturing liquid for mortar wire or diamond wire cutting polycrystalline silicon wafers.

Technical solution: the chemical composition of polycrystalline silicon sheet acid texturing optimizer provided by the present invention, the composition is an aqueous solution, and the solute is: (1) a polymer having a thiadiazolium salt structural unit; (2) polyhydric alcohol or its derivative.

As a preference, the weight percent of the polymer having the thiadiazolium salt structural unit is 0.05-5%, preferably 0.1-3.0%; the structural form of the polymer having the thiadiazolinium salt structural unit is As shown in (I):

Wherein, R is selected from an alkoxy group with 2-8 carbon atoms, an alkyl group or a substituted alkyl group with 1-10 carbon atoms; n is an integer of 2 or more.

As another preference, R is selected from alkyl groups with 1-5 carbon atoms; R is selected from hydroxyl-containing alkyl groups with 1-4 carbon atoms.

As another preference, the weight percentage of the polyol or its derivatives is 0.0001-15%, preferably 0.01-5%.

As another preference, the polyol or its derivative is polyethylene glycol with a molecular weight of 400-20000.

As another preference, the solvent of the aqueous solution is deionized water.

The present invention also provides the application of the chemical composition of the above polycrystalline silicon chip acid texturizing optimizer in mortar line or diamond wire cut polycrystalline silicon chip acid texturing.

The application comprises the following steps: adding the chemical composition of the polycrystalline silicon chip acid texturing optimizer into the hydrofluoric acid-nitric acid mixed solution to obtain an acidic texturing solution; immersing the polycrystalline silicon chip cut by a mortar wire or a diamond wire into Texture is made in the acidic texturing solution.

The application comprises the following steps: the mass ratio of the chemical composition of the polycrystalline silicon sheet acid texturizing optimizer to the hydrofluoric acid-nitric acid mixed solution is (0.5-5):100; the hydrofluoric acid-nitric acid mixed solution Among them, the mass percentage concentration of hydrofluoric acid is 5-15%, and the mass percentage concentration of nitric acid is 35-75%.

Said application, the texturing temperature is 5-20°C, and the texturing time is 60-300S.

Beneficial effects: the preparation and use method of the chemical composition provided by the present invention is simple, easy to implement, and has good repeatability. When it is used for mortar line or diamond wire cutting polysilicon texturing, the texturing effect is obviously improved, and the prepared silicon wafer has a high capacity. The surface is uniform and the reflectivity is low, the appearance color of the coated silicon chip is uniform, and the uniformity of the suede surface is obviously improved compared with that without adding the auxiliary chemical composition.

Description of drawings

Fig. 1 is a microscope plan view of the surface of a diamond wire-cut polysilicon wafer for solar cells without texture.

Fig. 2 is a microscopic plan view of the textured surface of a diamond wire-cut polycrystalline silicon wafer for solar cells using a mixed acid solution without adding the optimizer chemical composition of the present invention.

Fig. 3 is a microscopic plan view of the surface of a diamond wire-cut polysilicon wafer for solar cells textured by using a mixed acid solution added with texturing liquid ZHW04.

Fig. 4 is a microscopic plan view of a diamond-wire-cut polysilicon wafer for solar cells coated with a coated acid solution obtained by using a mixed acid solution without adding the optimizer chemical composition of the present invention.

Fig. 5 is a microscopic plan view of a diamond-wire-cut polysilicon wafer for solar cells obtained by texturing with a mixed acid solution added with texturing solution ZHW04 after coating.

Fig. 6 shows a microscope plan view of the surface morphology of the mortar wire-cut polysilicon wafer textured by using the mixed acid solution added with the texturing liquid ZHW09.

Literature reference

CN102816297A, Bibenzothiadiazole-based polymer and its preparation method and application

Qian Yanbing, Synthesis, Structure and Properties of Novel Conjugated Polymers Containing Thiazole Rings, Ningbo University, 2012

Detailed ways

The present invention will be further described below in combination with specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms are also applicable to the scope defined by the appended claims of this application.

Example 1

Prepare a batch of chemical compositions of acid texturizing optimizers for polycrystalline silicon wafers, the formulas of which are shown in Table 1.

Table 1

In the above composition, the balance is deionized water.

Example 2

Configure acidic texturing solution:

Example 3

The polycrystalline silicon wafer cut by the mortar wire or the diamond wire is immersed in the acidic texturing solution of Example 2 for texturing, the texturing temperature is 5-20° C., and the texturing time is 60-300 s.

For example:

(1) Take solar cells and use diamond wire to cut polycrystalline silicon wafers, respectively immerse them in acidic texturing liquid for texturing, and the conditions for texturing:

instance number Texturing liquid Texturing temperature ℃ Texturing time S 01 ZRY01 10 180 02 ZRY02 15 180 03 ZRY03 10 180 04 ZRY04 15 180 05 ZRY05 10 180 06 ZRY06 15 180 07 ZRY07 10 180 08 ZRY08 15 180 09 ZRY09 10 180 10 ZRY10 20 60 11 ZRY11 5 300 12 ZRY12 20 120 13 ZRY13 5 240

Figure 1 shows the surface morphology of a diamond wire-cut polysilicon wafer for solar cells without texturing, which presents a very uneven surface morphology.

Figure 2 shows the surface morphology of diamond wire-cut polysilicon wafer textured for solar cells using a mixed acid solution that does not add the optimizer chemical composition of the present invention, and the surface uniformity is very poor.

Figure 3 shows the surface morphology of diamond wire-cut polycrystalline silicon wafers for solar cells textured by using the mixed acid solution added to the texturing liquid ZHW04, and the surface uniformity is very good; the same surface morphology was obtained by using the texturing liquid ZRY01-ZRY13 result.

It can be seen from Figures 1 to 3 that the distribution of the corroded textured surface formed by texturing with the texturing solution of the present invention is relatively uniform.

Fig. 4 has shown the follow-up coating process of the diamond wire-cut polysilicon wafer for solar cells obtained by using the mixed acid solution that does not add the optimizer chemical composition of the present invention. Chromatic aberration, will not be put into production use.

Figure 5 shows the subsequent coating process of diamond wire-cut polysilicon wafers for solar cells obtained by adding texturing solution ZHW04 mixed acid solution. Obviously, the surface of the coated solar cells has good uniformity.

Figure 6 shows the surface morphology of the mortar wire-cut polysilicon wafer textured with the mixed acid solution added with the texturing liquid ZHW09, and the surface uniformity is very good; the same results were obtained with the texturing liquid ZRY01-ZRY13.

The specific embodiments of the present invention have been fully described above. It should be pointed out that any changes made by those skilled in the art to the specific embodiments of the present invention will not depart from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited only to the foregoing specific embodiments.

Claims (10)

1. The chemical composition of the polycrystalline silicon wafer acid texturing optimizing agent is characterized in that: the composition is an aqueous solution, and the solute is: (1) a polymer having thiodiazoxide structural units; (2) a polyol;

the weight percentage of the polymer with the thiobiazole structural unit is 0.05-5%; the structural form of the polymer with the thiodiazoxide structural unit is shown as (I):

wherein R is selected from an alkyleneoxy group of 2 to 8 carbon atoms, an alkylene group of 1 to 10 carbon atoms or a substituted alkylene group; n is an integer of 2 or more;

the weight percentage of the polyalcohol is 0.0001-15%, and the polyalcohol is polyethylene glycol with the molecular weight of 400-20000.

2. The chemical composition of a polycrystalline silicon wafer acid texturing optimizing agent according to claim 1, wherein: the weight percentage of the polymer with the thiobiazole structural unit is 0.1-3.0%.

3. The chemical composition of a polycrystalline silicon wafer acid texturing optimizing agent according to claim 1, wherein: r is selected from alkylene groups of 1 to 5 carbon atoms.

4. The chemical composition of a polycrystalline silicon wafer acid texturing optimizing agent according to claim 1, wherein: r is selected from hydroxyl-containing alkylene groups of 1 to 4 carbon atoms.

5. The chemical composition of a polycrystalline silicon wafer acid texturing optimizing agent according to claim 1, wherein: the weight percentage of the polyol is 0.01-5%.

6. The chemical composition of a polycrystalline silicon wafer acid texturing optimizing agent according to claim 1, wherein: the solvent of the aqueous solution is deionized water.

7. The use of the chemical composition of the polycrystalline silicon wafer acid texturing optimizing agent of claim 1 in the acid texturing of a mortar wire or diamond wire cut polycrystalline silicon wafer.

8. The use according to claim 7, wherein: the method comprises the following steps: adding the chemical composition of the polycrystalline silicon wafer acid texturing optimizing agent in the invention to a hydrofluoric acid-nitric acid mixed solution to obtain an acid texturing solution; immersing the mortar wire or the diamond wire cutting polycrystalline silicon wafer into the acidic texturing liquid for texturing.

9. The use according to claim 8, wherein: the method comprises the following steps: the mass ratio of the chemical composition of the polycrystalline silicon wafer acid texturing optimizing agent to the mixed solution of hydrofluoric acid and nitric acid is (0.5-5) 100; in the hydrofluoric acid-nitric acid mixed solution, the mass percentage concentration of hydrofluoric acid is 5-15%, and the mass percentage concentration of nitric acid is 35-75%.

10. The use according to claim 8, wherein: the texturing temperature is 5-20 ℃, and the texturing time is 60-300S.

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