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A method of directly growing monocrystalline silicon by CVD reaction

A direct technology for growing monocrystalline silicon, applied in the direction of crystal growth, single crystal growth, single crystal growth, etc., can solve the problems of high energy consumption, high pollution, secondary pollution, etc., shorten steps and cycles, reduce production costs, cost reduction effect

Inactive Publication Date: 2014-10-15
TIANWEI NEW ENERGY HLDG +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The growth of silicon ingots refers to the directional solidification of polycrystals and the pulling of single crystals. First, the high-purity silicon raw materials obtained in the early stage are placed in a crucible to melt, and then the growth of silicon ingots is completed. In this step, the high-purity silicon raw materials obtained in the early stage need to be Pure silicon raw materials are crushed and reloaded, and melted to realize the growth of silicon ingots, causing secondary pollution and increasing production costs
Moreover, the Siemens method / improved Siemens method at the upper end of the industry chain produces silicon raw materials, which is a process of high energy consumption and high pollution, especially in the reduction deposition stage of polysilicon. The reaction temperature needs to be kept above 1000°C, and the reduction power consumption is about 70-80 degrees. / kg, the power consumption in the whole polysilicon production process reaches about 300 degrees / kg
[0004] At present, there is no method to directly grow single crystal silicon during gas phase reduction of silicon raw materials

Method used

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  • A method of directly growing monocrystalline silicon by CVD reaction

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] A 10 micron thick gold layer was deposited on the surface of the silicon substrate by magneto-air sputtering deposition. The silicon substrate was placed in the CVD reaction chamber and the temperature was raised to 363°C, which is higher than that of the silicon substrate. The eutectic point temperature of the metal forms a liquid eutectic layer; then silane is introduced into the CVD reaction chamber while the chamber is heated to 500°C to reduce and decompose the silane; the vapor phase silicon atoms generated are absorbed by the liquid eutectic layer to supersaturation , And continuously precipitate silicon crystals on the crystal surface of the silicon substrate below; during preparation, semiconductor-grade polished silicon wafers are used for the silicon substrate, whose crystal orientation is preferably (111), and the size is 6-8 inches suitable for photovoltaic-grade silicon wafers The size is better.

[0023] The silicon crystal grown by the above method can reac...

Embodiment 2

[0026] A 5 micron thick aluminum layer is plated on the surface of the silicon substrate by thermal evaporation deposition method, the silicon substrate is placed in the CVD reaction chamber, and the temperature is raised to 527°C to form a liquid eutectic layer, and then trichloro Hydrogen silicon (TCS) is fed into the CVD reaction chamber, and hydrogen gas is introduced at the same time. The temperature of the chamber is raised to about 1150°C. The TCS is reduced and decomposed into silicon and other by-products. The gas-phase silicon atoms generated are absorbed by the liquid eutectic layer to supersaturation. And continuously precipitate silicon crystals on the crystal surface of the lower silicon substrate. The silicon substrate in Embodiment 1 can also be used to grow silicon ingots directly used for slicing.

[0027] The silicon crystal grown by the above method, after sufficient growth time, its height can reach 10-20 cm, and the crystal orientation is consistent with the...

Embodiment 3

[0030] Under other conditions unchanged, the thickness of the metal thin layer was screened:

[0031]

[0032] It can be seen from the test results that when the thickness of the metal thin layer is 1-10 microns, the silicon crystal growth rate is normal, and the metal thin layer has no cracks, and the crystal layer is not split; when the thickness is less than 1 micron, good silicon crystals cannot be obtained. ; When the thickness is greater than 10 microns, although the crystal growth is better, the growth rate is significantly slower. Therefore, considering the growth effect of crystals and the production cost, a metal thin layer with a thickness of 1-10 microns is preferred in the present invention.

[0033] In summary, the method of the present invention can be used to directly grow silicon ingots that meet the slicing standards, eliminating the need for the crushing and ingot casting of high-purity polysilicon raw materials, and the grown silicon ingots can be directly cut i...

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Abstract

The invention which discloses a method for the growth of a monocrystalline silicon crystal concretely relates to a method for the direct growth of monocrystalline silicon through a CVD reaction. The method concretely comprises the following steps: 1, plating the surface of a silicon substrate with a thin metal layer with the thickness of 1-100mum; 2, putting the silicon substrate plated with the thin metal layer into the cavity of a CVD reactor, and liquefying aneutectic layer to form a liquid eutectic layer by heating to make the temperature in the cavity be higher than the eutectic temperature which is lower than 1000DEG C; 3, inletting a silicon-containing raw gas to the cavity, and simultaneously heating to make the temperature in the cavity reach the reduction decomposition temperature of the raw gas to generate gaseous silicon atoms; and 4, precipitating the monocrystalline silicon crystal under the silicon substrate through absorbing the generated gaseous silicon atoms by the liquid eutectic layer formed in step 2 to supersaturation. The method of the invention has the advantages of production operation saving, production cost reduction, realization of the selection of a low decomposition temperature silicon source gas, and production energy consumption reduction.

Description

Technical field [0001] The invention relates to a method for growing single crystal silicon crystals. Specifically, it is a method of directly growing monocrystalline silicon by CVD reaction, which belongs to the field of photovoltaic materials. technical background [0002] With the increasingly serious energy crisis and environmental degradation, solar cells as a clean and renewable energy source have gradually become the focus of attention. At present, the silicon wafers of solar cells are mainly made of polycrystalline silicon and monocrystalline silicon. The commonly used method of manufacturing monocrystalline silicon is mainly to use high-purity polycrystalline silicon as a raw material, recast ingots, and slice them. At present, the commonly used production technologies of polysilicon raw materials mainly include silane method, fluidized bed method, metallurgy method, Siemens method and modified Siemens method. Compared with other methods, the improved Siemens method r...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C30B25/00C30B29/06
Inventor 吕铁铮林洪峰兰洵盛雯婷张凤鸣
Owner TIANWEI NEW ENERGY HLDG