阅读说明：本技术 金刚线多晶硅片表面织构化加工方法 (Surface texturing processing method for diamond wire polycrystalline silicon wafer ) 是由 王懿喆 易武雄 潘鼎鼎 张卫 于 2018-06-26 设计创作，主要内容包括：本发明公开了一种金刚线多晶硅片表面织构化加工方法,包括如下步骤：S1:对金刚线多晶硅片的一侧表面进行均匀喷砂处理,在该侧面形成太阳光的入射面；S2：将步骤S1处理后的金刚线多晶硅片放入腐蚀液内进行腐蚀处理,所述腐蚀液包括4-10%的氢氟酸,30-50%的硝酸,0.01-0.05%的表面活性剂,0.01-0.5%的缓蚀剂,和0.01-0.5%的稳定剂,其余为去离子水。本发明能够将金刚线切割应用于多晶硅片的表面织构化加工中,具有减反射效果显著、外观形貌均匀、成本低廉、清洁环保的特点。(The invention discloses a method for texturing the surface of a diamond wire polycrystalline silicon wafer, which comprises the following steps: s1, uniformly performing sand blasting treatment on one side surface of the diamond wire polycrystalline silicon wafer to form a sunlight incidence surface on the side surface; s2: and (4) putting the diamond wire polycrystalline silicon wafer processed in the step (S1) into an etching solution for etching, wherein the etching solution comprises 4-10% of hydrofluoric acid, 30-50% of nitric acid, 0.01-0.05% of surfactant, 0.01-0.5% of corrosion inhibitor, 0.01-0.5% of stabilizer and the balance of deionized water. The diamond wire cutting method can be used for applying diamond wire cutting to surface texturing processing of polycrystalline silicon wafers, and has the characteristics of remarkable antireflection effect, uniform appearance, low cost, cleanness and environmental protection.)

1. A surface texturing processing method of a diamond wire polycrystalline silicon wafer is characterized by comprising the following steps:

s1, performing sand blasting treatment on one side surface of the diamond wire polycrystalline silicon wafer to form a sunlight incidence surface on the side surface;

s2: and (4) putting the diamond wire polycrystalline silicon wafer treated in the step (S1) into an etching solution for wet treatment, wherein the etching solution comprises 4-10% of hydrofluoric acid, 30-50% of nitric acid, 0.01-0.05% of surfactant, 0.01-0.5% of corrosion inhibitor, 0.01-0.5% of stabilizer and the balance of deionized water.

2. The surface texturing processing method of the diamond wire polycrystalline silicon wafer according to claim 1, characterized by comprising the following steps: the sand blasting treatment refers to the uniform spraying treatment of one side surface of the polycrystalline silicon wafer by carrying solid powdery grinding materials through high-pressure gas.

3. The surface texturing processing method of the diamond wire polycrystalline silicon wafer according to claim 2, characterized by comprising the following steps: the abrasive is any one or combination of any several of silicon nitride, quartz sand and silicon carbide.

4. The surface texturing processing method of the diamond wire polycrystalline silicon wafer according to claim 2, characterized by comprising the following steps: the grinding material is micron-sized grinding material with the purity of more than 99.9 percent and the particle size of 1-6 um.

5. The surface texturing processing method of the diamond wire polycrystalline silicon wafer according to claim 2, characterized by comprising the following steps: the pressure value of the high-pressure gas is in the range of 0.05-0.3kgf/cm² 。

6. The surface texturing processing method of the diamond wire polycrystalline silicon wafer according to claim 2, characterized by comprising the following steps: the material removal thickness of the diamond wire polycrystalline silicon wafer by the sand blasting treatment is 0.5-5 um.

7. The surface texturing processing method of the diamond wire polycrystalline silicon wafer according to claim 1, characterized by comprising the following steps: the surfactant adopts gemini cationic surfactants, quaternary ammonium salt cationic surfactants and compound.

8. The surface texturing processing method of the diamond wire polycrystalline silicon wafer according to claim 1, characterized by comprising the following steps: the temperature of the corrosive liquid is a certain constant temperature value within 3-10 ℃, and the corrosion time is 30-240 seconds.

Technical Field

The invention belongs to the technical field of solar cells, and particularly relates to a surface texturing processing method for a diamond wire polycrystalline silicon wafer.

Background

At present, in the solar photovoltaic power generation technology, a polycrystalline silicon battery occupies the mainstream position of photovoltaic power generation due to low cost and stable process. Currently, the main ways to slice silicon include mortar wire saw cutting and diamond wire cutting. Among them, diamond wire cutting is becoming the mainstream technology of silicon wafer production gradually due to the characteristics of high cutting efficiency and less silicon material waste. Those skilled in the art generally refer to a single crystal silicon wafer produced by diamond wire sawing as a diamond wire single crystal silicon wafer, and a polycrystalline silicon wafer produced by diamond wire sawing as a diamond wire polycrystalline silicon wafer. As is known, the diamond wire has been successfully applied to the production of diamond wire monocrystalline silicon wafers at present, but the cell conversion efficiency of the diamond wire polycrystalline silicon wafers is not fully exerted due to the texturing process. The single crystal silicon wafer texturing process utilizes the characteristic that the crystal structure of silicon is corroded by alkali solution with specific concentration in different crystal directions with different rates, and obtains an inverted pyramid structure on the surface of the whole silicon wafer by controlling the conditions of concentration, reaction temperature and the like of the alkali corrosion solution, thereby obtaining a very good antireflection effect. When the polysilicon is cast, the crystal orientation distribution of crystal grains is disordered, and the alkali solution corrosion cannot obtain the completely consistent inverted pyramid structure on the surface of the silicon wafer, so that an ideal antireflection effect cannot be obtained. Specifically, the texturing treatment by acid etching on the surface of diamond wire-cut polycrystalline silicon wafers is not satisfactory: since acid etching always preferentially proceeds along the already present microcracks on the wafer surface, these microcracks are high energy states, providing pit-forming "primers" and ultimately a light-trapping texture. When the polycrystalline silicon wafer is cut by the sand wire, the cutting wire does not carry out cutting processing, the main function of the cutting wire is to bring grinding slurry into a cutting area at a high speed and apply load to the grinding material, and finally, the silicon material is ground and cut by the grinding material, so microcracks with very high distribution density are formed on the surface of the silicon wafer. However, in the process of cutting silicon wafers by diamond wires, the diamond wire saw runs at a high speed, and hard diamond grains fixed on the diamond wires directly grind and cut silicon materials at a certain pressure. The diamond wire cutting has certain grinding property, so that the density of micro-cracks formed on the silicon surface is low, and 'primers' required by acid corrosion are not formed, so that the light trapping effect is not obvious, and the improvement of the cell efficiency is influenced.

For the texturing technology of diamond wire cutting polycrystalline silicon wafer, foreign countries already existVarious companies have proposed different solutions to the results. The black silicon technology is developed and applied initially. The first of these is the so-called dry black silicon technique: placing the polycrystalline silicon wafer with the damaged layer removed in a plasma dry etching cavity, and carrying out CF (CF) etching₄And continuously etching the surface of the silicon wafer by reactive ions formed after the reaction gas is subjected to plasma treatment, and finally forming micropores with the size of tens to hundreds of nanometers, wherein the micropores have a good antireflection effect. The dry etching has the characteristics of best antireflection effect, but expensive equipment, multiple matched processes and high cost, and has no sign of popularization in the whole industry except for tests carried out by a few first-line large factories. The second is a wet black silicon technique: and carrying out catalytic etching reaction on the silicon wafer with the damaged layer removed on the surface in a hydrofluoric acid/nitric acid/silver nitrate system (or other similar formula systems). After reaction, a micro porous structure is formed on the surface of the silicon, and then the silicon is further expanded to form a proper surface light trapping structure. Compared with dry black silicon, wet black silicon has slightly poorer antireflection effect, but the used equipment is relatively simple and cheap, so the method has the potential of large-scale application, but various heavy metal elements such as Ag and Au are used in the process, so the method is not environment-friendly and easily pollutes a silicon wafer, so the control requirement of the process is high. The common characteristics of the two black silicon schemes are that the change of the texturing equipment of the existing production line is large, so that the equipment cost is very high, and common enterprises are difficult to bear. Therefore, how to develop a new method for texturing the surface of a diamond wire polycrystalline silicon wafer, which can achieve the purpose of texturing the surface of the diamond wire polycrystalline silicon wafer without greatly changing the texturing equipment of the existing production line and reducing the cost, is the research direction of the technicians in the field.

Disclosure of Invention

The invention provides a method for texturing the surface of a diamond wire polycrystalline silicon wafer, which can achieve the purpose of texturing the surface of the diamond wire polycrystalline silicon wafer and reducing the cost. The adopted specific technical scheme is as follows:

a surface texturing processing method of a diamond wire polycrystalline silicon wafer comprises the following steps: s1, performing sand blasting treatment on one side surface of the diamond wire polycrystalline silicon wafer to form a sunlight incidence surface on the side surface; s2: and (4) placing the diamond wire polycrystalline silicon wafer treated in the step (S1) into an etching solution for wet texturing, wherein the etching solution comprises 4-10% of hydrofluoric acid, 30-50% of nitric acid, 0.01-0.05% of surfactant, 0.01-0.5% of corrosion inhibitor, 0.01-0.5% of stabilizer and the balance of deionized water.

By adopting the technical scheme, the textured surface with good antireflection effect is obtained by carrying out sand blasting pretreatment on the diamond wire silicon wafer and then carrying out wet etching treatment. The technical scheme can utilize the existing texturing equipment on the conventional polycrystalline production line to the maximum extent so as to achieve the effect of being compatible with the production line, thereby saving the production cost. While also avoiding the environmentally unfriendly CF produced in black silicon schemes₄Such as gases, and heavy metals such as Ag, Au, etc.

Preferably, in the method for texturing the surface of a diamond wire polycrystalline silicon wafer: the sand blasting treatment refers to the uniform spraying treatment of one side surface of the polycrystalline silicon wafer by carrying solid powdery grinding materials through high-pressure gas.

More preferably, in the method for texturing the surface of a diamond wire polycrystalline silicon wafer: the abrasive is any one or the combination of any several of materials such as silicon nitride, quartz sand, silicon carbide and the like.

More preferably, in the method for texturing the surface of a diamond wire polycrystalline silicon wafer: the grinding material is micron-sized grinding material with the purity of more than 99.9 percent and the particle size of 1-6 um.

More preferably, in the method for texturing the surface of a diamond wire polycrystalline silicon wafer: the pressure value of the high-pressure gas is in the range of 0.05-0.3kgf/cm 2.

More preferably, in the method for texturing the surface of a diamond wire polycrystalline silicon wafer: the material removal thickness of the polycrystalline silicon wafer by the sand blasting treatment is 0.5-5 um.

More preferably, in the method for texturing the surface of a diamond wire polycrystalline silicon wafer: the surfactant adopts gemini cationic surfactants, quaternary ammonium salt cationic surfactants and compound.

More preferably, in the method for texturing the surface of a diamond wire polycrystalline silicon wafer: the temperature of the corrosive liquid is a certain constant temperature value within 3-10 ℃, and the corrosion time is 30-240 seconds.

Compared with the prior art, the diamond wire cutting method can be used for applying diamond wire cutting to surface texturing processing of polycrystalline silicon wafers, and has the characteristics of good antireflection effect, uniform appearance, low cost, cleanness and environmental protection.

Drawings

The invention will be described in further detail with reference to the following detailed description and accompanying drawings:

FIG. 1 is a schematic flow chart of the present invention;

FIG. 2 is a graph showing the comparison of reflectivity measurements, wherein the dotted line is the reflectivity curve of a conventional diamond wire polycrystalline silicon wafer, and the solid line is the reflectivity curve of a product obtained by performing surface texturing on the diamond wire polycrystalline silicon wafer according to the present invention;

FIG. 3 is a textured SEM image of a conventional diamond wire polycrystalline silicon wafer;

FIG. 4 is a textured SEM image of a product obtained by texturing a diamond wire polycrystalline silicon wafer according to the present invention.

Detailed Description

In order to more clearly illustrate the technical solution of the present invention, the following will be further described with reference to the embodiments.

FIG. 1 shows an example:

firstly, a diamond wire polycrystalline silicon wafer prepared by diamond wire cutting is provided, and the thickness of the diamond wire polycrystalline silicon wafer is controlled to be 150-250 um. The polycrystalline silicon wafer is input into a sand blasting machine in chain transmission for single-side sand blasting pretreatment, a nozzle of the sand blasting machine is in a swing type reciprocating motion mode, the sand blasting is ensured to be uniform, and the pressure of sand blasting gas is 0.08kgf/cm 2. The silicon chip runs through the conveyor belt from the lower part of the spray head along a straight line in a direction vertical to the swinging direction of the spray head, and the conveying speed is 2.0 m/s. The sand blasting material is high-purity quartz sand with the granularity of 3000 meshes, and the size is 2-6 um.

Secondly, carrying out further wet texturing treatment on the polycrystalline silicon wafer subjected to sand blasting treatment through a chain type texturing device: the equipment is a RENA corporation 5-way or 8-way equipment. In the used corrosive liquid, the proportion of each component is as follows: 70 liters of 49% hydrofluoric acid, 300 liters of 68% nitric acid and 150 liters of deionized water. The additive GY-DAD series for texturing the diamond wire silicon wafer is prepared from surfactant, corrosion inhibitor and stabilizer, and the additive accounts for 1% of the total volume of the corrosive liquid. The corrosive liquid is circularly cooled and updated by a circulating pump, and the cooling temperature is kept at 6-9 ℃. And (3) conveying the silicon wafer subjected to the sand blasting process through a roller, and passing the silicon wafer 1-2cm below the liquid level. And adjusting the speed and the temperature of the silicon wafer conveying belt, ensuring that the etching thinning amount of the silicon wafer is 0.25g, and finishing the texturing process.

FIGS. 2-4 are the comparison of reflectivity test and appearance of SEM pictures of the product obtained by the above process with that of a common diamond wire silicon wafer. As can be seen from fig. 2 to 4, the method disclosed by the present invention can greatly improve the roughness of the silicon wafer surface, and reduce the reflectivity, thereby contributing to the improvement of the cell conversion efficiency.

The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. The protection scope of the present invention is subject to the protection scope of the claims.