CN110707163A - Method for texturing on surface of single crystal silicon by using tetramethylguanidine organic alkali - Google Patents

Method for texturing on surface of single crystal silicon by using tetramethylguanidine organic alkali Download PDF

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CN110707163A
CN110707163A CN201910893517.0A CN201910893517A CN110707163A CN 110707163 A CN110707163 A CN 110707163A CN 201910893517 A CN201910893517 A CN 201910893517A CN 110707163 A CN110707163 A CN 110707163A
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silicon wafer
texturing
tetramethylguanidine
deionized water
solution
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黄仕华
张嘉华
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Zhejiang Normal University CJNU
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Zhejiang Normal University CJNU
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02Details
    • H01L31/0236Special surface textures
    • H01L31/02363Special surface textures of the semiconductor body itself, e.g. textured active layers
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

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  • Condensed Matter Physics & Semiconductors (AREA)
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Abstract

The invention discloses a method for preparing texture on a monocrystalline silicon wafer by using tetramethylguanidine organic alkali, which comprises the steps of firstly cleaning the silicon wafer, then preparing a mixed solution of tetramethylguanidine and isopropanol by using a deionized water solvent, wherein the volume ratio of tetramethylguanidine is 10 percent, the volume ratio of isopropanol is 7 percent, and preheating the mixed solution for later use in a water bath kettle at the temperature of 80 ℃; and (3) putting the silicon wafer into the texturing solution, heating the silicon wafer in water bath at 80 ℃ for 35min, washing the silicon wafer with deionized water for two to three times, and then carrying out ultrasonic treatment on the silicon wafer with the deionized water for 5min to remove the solution residues. The optical reflectivity of the tetramethyl guanidine organic alkali monocrystalline silicon after texturing is greatly reduced, the pollution of metal ions in the texturing solution to a silicon wafer is eliminated, and the subsequent treatment cost of the texturing waste liquid is reduced.

Description

Method for texturing on surface of single crystal silicon by using tetramethylguanidine organic alkali
Technical Field
The invention belongs to the technical field of photovoltaics, and particularly relates to a method for texture surface making of a monocrystalline silicon wafer by using tetramethylguanidine organic alkali.
Background
The texture characteristic of the monocrystalline silicon solar cell is one of important factors influencing the conversion efficiency of the monocrystalline silicon solar cell. The existing texturing methods include: chemical etching, reactive ion etching, photolithography, mechanical grooving, and the like. Among the above methods, mechanical grooving is to simultaneously form V-grooves on the surface of polysilicon by using a plurality of blades to reduce optical reflection. Although the method has the advantages of simple process and high grooving speed, the mechanical grooving is deep, requires a thicker silicon wafer and is not suitable for manufacturing a thin-substrate solar cell. Meanwhile, in the etching process, the surface of the silicon wafer can be damaged, and impurities can be introduced. The reactive ion etching method is also called plasma etching, and is a dry etching process which adopts low-pressure gas to generate plasma and utilizes a physical mechanism to assist chemical etching or generates reactive ions to participate in chemical etching. The reflectivity of the formed texture is particularly low, the reflectivity in the spectral range of 450 to 1000nm can be less than 2%, but the silicon surface is seriously damaged, the open-circuit voltage and the filling factor of the battery can be reduced, and in addition, the defects of low yield and high manufacturing cost are realized. The chemical etching method generally uses a mixed solution of alkali (NaOH or KOH) alcohol (isopropanol or ethanol) as an etching system. Wherein, the alkali is a corrosive agent used for corroding the silicon chip, and the alcohol is a defoaming agent used for removing hydrogen bubbles generated by the reaction.
The formation of "pyramids" is due to the anisotropic reaction of the base with silicon. In a certain concentration of alkali solution, OH-The reaction speed of the ions and the (100) surface of the silicon is several times or even dozens of times faster than that of the (111) surface, the corrosion reaction starts from the (100) surface, and finally, staggered (111) crystal surfaces are exposed, so that a plurality of tetrahedral pyramids, commonly called pyramid structures, are formed on the surface of the silicon wafer.
At present, the most persuasive model for texturing monocrystalline silicon is an electrochemical model. The main principle of the model is that the anisotropic etching of silicon by alkali is mainly caused by the difference of dangling bond density and back bond structure and energy level of the silicon surface. During the whole etching process, the first 4 OH groups-Ions react with silicon on one surface while OH-The ions combine with unpaired electrons on the surface of the silicon wafer to form Si-O bonds. Since the energy level of electrons on the dangling bond is relatively high, the reaction proceeds further as the reaction proceeds by thermally exciting the electrons into the conduction band. And the electrons entering the conduction band neutralize H in solution2O reacts to form new OH-And H2. The entire reaction can be simply written as:
Si+2OH-+2H2O→SiO2(OH)2 2-+2H2
the pyramid structure is mainly increased by two refractions of light rays in the pyramid structureThe times of light absorption are increased, so that the light absorption rate of the silicon chip is increased, and the reflectivity of the surface of the silicon chip is reduced. Has extremely wide application in the field of solar cells. Most of the existing texturing methods use inorganic alkali to provide OH-Ionic. The commonly used inorganic alkali mainly comprises KOH, NaOH and the like, so that a large amount of metal ions exist in the texturing solution, the existence of the metal ions has certain influence on the minority carrier lifetime of the silicon wafer, and the influence of the metal ions is particularly important in the manufacturing process of a high-efficiency solar cell. Therefore, in recent years, organic alkali texturing solutions have come into widespread use. Another major reason organic bases begin to dominate the market for texturing solutions is the treatment of waste streams. Along with the increasing importance of our country on environmental protection in recent years, the treatment of waste liquid in the process of making herbs into wool also becomes another important principle for people to select the making herbs into wool.
Disclosure of Invention
The invention aims to provide a method for texturing a monocrystalline silicon wafer by using tetramethylguanidine organic alkali.
The technical scheme of the invention is as follows:
a method for texture etching of a monocrystalline silicon wafer by using tetramethylguanidine organic alkali comprises the following steps:
1) cleaning a silicon wafer;
2) preparing a mixed solution of tetramethylguanidine and isopropanol by using a deionized water solvent, wherein the volume ratio of the tetramethylguanidine is 10 percent, the volume ratio of the isopropanol is 7 percent, and preheating the mixed solution for later use in a water bath kettle at the temperature of 80 ℃;
3) putting the silicon wafer obtained in the step 1) into the texturing solution obtained in the step 2), heating the silicon wafer in water bath at 80 ℃ for 35min, washing the silicon wafer with deionized water for two to three times, and then carrying out ultrasonic treatment on the silicon wafer with deionized water for 5min to remove solution residues.
According to the invention, organic alkali-tetramethylguanidine is used for replacing the traditional sodium hydroxide or potassium hydroxide to be used as a corrosion solution for monocrystalline silicon texturing, the pyramid distribution on the surface of the textured monocrystalline silicon is dense and uniform in size, and the average optical reflectivity of the silicon wafer is 3.14% within the wavelength range of 400-1000 nm. Compared with the traditional inorganic alkali monocrystalline silicon texturing, the optical reflectivity of the tetramethylguanidine organic alkali monocrystalline silicon provided by the invention after texturing is greatly reduced, the pollution of metal ions in the texturing solution to silicon wafers is eliminated, and the subsequent treatment cost of the texturing waste liquid is also reduced.
Drawings
The following detailed description is made with reference to the accompanying drawings and embodiments of the present invention
FIG. 1 is a metallographic microscope photograph of a sample of this example;
FIG. 2 is a reflectance chart of the sample of this example.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
1.1 Main raw materials
P-type monocrystalline silicon piece: 2 inches in diameter.
Chemical reagents: acetone, absolute ethyl alcohol, sodium hydroxide, isopropanol, hydrofluoric acid, tetramethylguanidine, ammonia water, hydrochloric acid and hydrogen peroxide.
1.2 Main test Instrument
Metallographic microscope, ultraviolet visible spectrophotometer.
1.3 preparation Process
(1) Silicon wafer cleaning
a. Putting a silicon wafer into a clean polytetrafluoroethylene beaker, adding a proper amount of acetone, performing ultrasonic treatment for 10min, washing with deionized water for two to three times, and adding deionized water, performing ultrasonic treatment for 5min to remove solution residues;
b. adding a proper amount of absolute ethyl alcohol into a beaker, carrying out ultrasonic treatment for 10min, washing with deionized water for two to three times, and carrying out ultrasonic treatment with deionized water for 5min to remove solution residues;
c. putting the silicon wafer into 25% NaOH solution, heating the silicon wafer in water bath at 80 ℃ for 20min to remove mechanical damage on the surface of the silicon wafer, then washing the silicon wafer with deionized water for two to three times, and then carrying out ultrasonic treatment on the silicon wafer with deionized water for 5min to remove solution residues;
d. adding into a beaker at a ratio of 1:1:5Addition of NH4OH、H2O2、H2Heating O in water bath at 80 deg.C for 15min, washing with deionized water for two to three times, and ultrasonic treating with deionized water for 5min to remove solution residue;
e. adding the mixture into a beaker according to the proportion of 1:1:5 adding HCl and H2O2、H2Heating O in water bath at 80 deg.C for 15min, washing with deionized water for two to three times, and ultrasonic treating with deionized water for 5min to remove solution residue;
f. soaking for 3min with 1% hydrofluoric acid, washing with deionized water for two to three times, and ultrasonically treating with deionized water for 5min to remove the solution residue;
g. with N2And drying for later use.
(2) Texturing process
a. Preparing a mixed solution of 10 percent (vl) of tetramethylguanidine and 7 percent (vl) of isopropanol, and preheating for 10min in a water bath kettle at the temperature of 80 ℃.
b. And (3) putting the cleaned silicon wafer into a preheated texturing solution, heating the silicon wafer in water bath at 80 ℃ for 35min, washing the silicon wafer with deionized water for two to three times, and performing ultrasonic treatment on the silicon wafer with the deionized water for 5min to remove solution residues.
(3) Sample characterization
a. Preliminarily observing the surface appearance of the sample by using a metallographic microscope;
b. the reflectance of the sample was measured using an ultraviolet-visible-near infrared spectrophotometer.
1.4 results and analysis
The metallographic microscope image in fig. 1 can preliminarily observe that the pyramid-shaped texture surface is successfully prepared on the surface of the silicon wafer, and the pyramids are densely distributed and uniform in size. However, due to the problems of depth of field and resolution of the metallographic microscope, the specific morphological characteristics of the pyramid cannot be accurately and finely observed.
From the reflectance graph of fig. 2, it can be seen that the overall reflectance of the sample is less than 7% in the wavelength range of 200nm to 1000nm, indicating that the sample has a good antireflection effect.

Claims (1)

1. A method for texture etching of a monocrystalline silicon wafer by using tetramethylguanidine organic alkali is characterized by comprising the following steps: the method comprises the following steps:
1) cleaning a silicon wafer;
2) preparing a mixed solution of tetramethylguanidine and isopropanol by using a deionized water solvent, wherein the volume ratio of the tetramethylguanidine is 10 percent, the volume ratio of the isopropanol is 7 percent, and preheating the mixed solution for later use in a water bath kettle at the temperature of 80 ℃;
3) putting the silicon wafer obtained in the step 1) into the texturing solution obtained in the step 2), heating the silicon wafer in water bath at 80 ℃ for 35min, washing the silicon wafer with deionized water for two to three times, and then carrying out ultrasonic treatment on the silicon wafer with deionized water for 5min to remove solution residues.
CN201910893517.0A 2019-09-20 2019-09-20 Method for texturing on surface of single crystal silicon by using tetramethylguanidine organic alkali Pending CN110707163A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110180132A1 (en) * 2010-01-28 2011-07-28 Curtis Dove Texturing and damage etch of silicon single crystal (100) substrates
CN102169818A (en) * 2009-12-17 2011-08-31 罗门哈斯电子材料有限公司 Improved method of texturing semiconductor substrates
CN102400225A (en) * 2010-09-16 2012-04-04 上海神舟新能源发展有限公司 Texture etching solution of monocrystaline silicon solar cell, preparation method, and application thereof
CN103314448A (en) * 2010-09-03 2013-09-18 肖特太阳能股份公司 Method for the wet-chemical etching of a highly doped semiconductor layer
CN106521635A (en) * 2016-11-17 2017-03-22 上海交通大学 All-solution preparation method of nanoscale pyramid suede on silicon surface

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102169818A (en) * 2009-12-17 2011-08-31 罗门哈斯电子材料有限公司 Improved method of texturing semiconductor substrates
US20110180132A1 (en) * 2010-01-28 2011-07-28 Curtis Dove Texturing and damage etch of silicon single crystal (100) substrates
CN103314448A (en) * 2010-09-03 2013-09-18 肖特太阳能股份公司 Method for the wet-chemical etching of a highly doped semiconductor layer
CN102400225A (en) * 2010-09-16 2012-04-04 上海神舟新能源发展有限公司 Texture etching solution of monocrystaline silicon solar cell, preparation method, and application thereof
CN106521635A (en) * 2016-11-17 2017-03-22 上海交通大学 All-solution preparation method of nanoscale pyramid suede on silicon surface

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