Method of electrodepositing silicon

A technology of electrodeposition and pure silicon, which is applied in the field of electrolysis and electrophoresis, can solve the problems of high energy consumption, difficulty in controlling the purity of silicon, flammability and explosion, and achieve good application prospects, low cost, and easy access

Inactive Publication Date: 2007-10-17
NORTH CHINA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Moreover, some of these processes consume high raw materials or energy, some involve safety issues of inflammability and explosion, and the purity of silicon produced by some is not easy to control, etc.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Weigh the dissolved salt medium according to the molar ratio of NaCl, KCl, and NaF at a ratio of 1:1:4.5. 2 Accounting for 10% of the mass percentage of the molten salt medium, weigh powdered SiO with a particle size ≥ 180 mesh 2 , Mix the above four substances evenly, put them into a crucible, put them into an electric furnace and raise the temperature to 900°C, and keep the temperature constant for 10 minutes. Put the Mo electrode in, give electricity at a temperature of 850°C, a pulse current, and an average current density of 400A / m 2 Under the conditions of pre-deposition for 20 minutes to remove impurities. Take out the molybdenum electrode, insert the Pt electrode, and feed it with a pulse current at a temperature of 950°C and an average current density of 500A / m 2 Under the conditions of 3 hours, pure silicon was obtained by electrodeposition. The X-ray energy spectrum analysis of the deposited layer on the Pt electrode shows that the deposited layer is pure ...

Embodiment 2

[0016] Weigh the dissolved salt medium according to the molar ratio of NaCl, KCl, and NaF at a ratio of 1:1:2. 2 Accounting for 10% of the mass percentage of the molten salt medium, weigh powdered SiO with a particle size ≥ 180 mesh 2 , Mix the above four substances evenly, put them into a crucible, put them into an electric furnace and raise the temperature to 900°C, and keep the temperature constant for 10 minutes. Put the Mo electrode in, give electricity at a temperature of 870°C, pulse current, and an average current density of 300A / m 2 Under the conditions of pre-deposition for 20 minutes to remove impurities. Take out the molybdenum electrode, insert the Pt electrode, and feed it with a pulse current at a temperature of 800°C and an average current density of 1000A / m 2 Under the condition of , pure silicon was obtained by electrodeposition for 1 hour. The X-ray energy spectrum analysis of the deposited layer on the Pt electrode shows that the deposited layer is pure ...

Embodiment 3

[0018] Weigh the dissolved salt medium according to the molar ratio of NaCl, KCl, and NaF at a ratio of 1:1:0.5. 2 Accounting for 10% of the mass percentage of the molten salt medium, weigh powdered SiO with a particle size ≥ 180 mesh 2 , Mix the above four substances evenly, put them into a crucible, put them into an electric furnace and raise the temperature to 900°C, and keep the temperature constant for 10 minutes. Put the Mo electrode in, at a temperature of 900°C, pulse current feeding, and an average current density of 200A / m 2 Under the conditions of pre-deposition for 20 minutes to remove impurities. Take out the molybdenum electrode, insert the Pt electrode, and feed it at a temperature of 900°C with a pulse current and an average current density of 700A / m 2 Under the conditions of 0.5 hours of electrodeposition, pure silicon was obtained. The X-ray energy spectrum analysis of the deposited layer on the Pt electrode shows that the deposited layer is pure silicon.

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Abstract

A process for electrodeposition of silicon belongs to the electroanalysis and electrophoresis technology field and used forone-step electrodeposition of silicon from SiO2 by using molten salt as medium and adoping direct current. Said process is characterized as follows: using a 3-constituent element composed of NaCl, KCl and NaF as medium, wherein the mol ratio thereof is 1:1:0.5-1:1:4.5, and adding powdery SiO2 which mass is 10% of the fused-salt medium mass therein; after pre-electrolysis impurities removing, electrodepositing pure silicon with electrodeposition temperature of 800 -950 DEG C, electrodeposit time of 0.5 -3 hours and ampere density of 500-1000 A / m2.The present invention is characterized as follows: 1, the constituent elements forming molten salt are usual and cheap pharma-ceutical products which are easy to obtain, then the cost is low and the consumption is small; 2, the manufacturing technique is simple and the process is easy to control. Said process in accordance with the present invention possesses excellent applications foreground in semi-conductor devices fabricating.

Description

technical field [0001] The invention relates to an electrodeposition method, in particular to a method for electrodepositing silicon in a molten salt system, and belongs to the technical field of electrolysis and electrophoresis. Background technique [0002] Silicon has excellent physical, chemical and semiconductor properties (high melting point, high hardness, good thermal stability, and large band gap), and has been widely used in metallurgy, chemical industry, electronics industry, spacecraft, satellites, etc. Silicon is widely distributed in nature, accounting for 27.6% of the mass of the earth's crust, second only to oxygen. There is no free form of silicon in nature, mostly oxides (SiO 2 ) exists in the form of silicon and is the raw material for the preparation of silicon. At present, whether it is to prepare industrial silicon, single crystal silicon, polycrystalline silicon, or powdery amorphous silicon, the first step is to mix quartz stone or silica (mainly co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25B1/00
Inventor 李运刚梁精龙田薇何小凤
Owner NORTH CHINA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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