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Method for direct growth of monocrystalline silicon through CVD (chemical vapor deposition) reaction

A direct technology for growing single crystal 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., to shorten steps and cycles, reduce production costs, cost reduction effect

Inactive Publication Date: 2012-06-06
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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  • Method for direct growth of monocrystalline silicon through CVD (chemical vapor deposition) reaction

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] A 10-micron-thick gold thin layer is deposited on the surface of the silicon substrate by magnetic air sputtering, and the silicon substrate is placed in a CVD reaction chamber, and the temperature is raised to 363°C, which is higher than the temperature between the silicon substrate and the silicon substrate. The temperature of the eutectic point of the metal forms a liquid eutectic layer; then silane is introduced into the CVD reaction chamber, and at the same time the chamber is heated to 500°C to reduce and decompose the silane; 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 silicon substrate below; during preparation, the silicon substrate is made of semiconductor-grade polished silicon wafers, the crystal orientation of which is preferably (111), and the size is 6-8 inches suitable for photovoltaic-grade silicon wafers Smaller size is be...

Embodiment 2

[0026] A thin layer of aluminum with a thickness of 5 microns is plated on the surface of the silicon substrate by thermal evaporation deposition method, the silicon substrate is placed in the CVD reaction chamber, the temperature is raised to 527°C to form a liquid eutectic layer, and then trichloro Hydrogen-silicon (TCS) is introduced 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, and 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 continue to precipitate silicon crystals on the crystal plane of the silicon substrate below. The silicon substrate in Embodiment 1 can also be selected to grow silicon ingots directly used for slicing.

[0027] The silicon crystal grown by the above method can reach a height of 10-20 cm after sufficient growth time, and the crystal o...

Embodiment 3

[0030] The thickness of the thin metal layer was screened, other things being equal:

[0031]

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

[0033] To sum up, using the method of the present invention can directly grow silicon ingots that meet the slicing standards, eliminating the need for high-purity polysilicon raw material crushing, ingot casting and other processes, and can directly cut the grown silic...

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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 monocrystalline silicon crystals. Specifically, it is a method for directly growing monocrystalline silicon by CVD reaction, which belongs to the field of photovoltaic materials. technical background [0002] With the increasing energy crisis and environmental degradation, solar cells, as a clean and renewable energy source, have gradually become the focus of attention. At present, silicon wafers of solar cells are mainly made of polycrystalline silicon and monocrystalline silicon. The common method of manufacturing monocrystalline silicon is mainly to use high-purity polycrystalline silicon as a raw material, re-cast ingots, and obtain slices. At present, the commonly used production technologies of polysilicon raw materials mainly include silane method, fluidized bed method, metallurgical method, Siemens method and improved Siemens method. Compared with other methods, the modified Siemens method realiz...

Claims

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Application Information

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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