Method for preparing cast polycrystalline silicon through melting silicon and doping nitrogen under nitrogen

A technology of polysilicon and nitrogen, which is applied in the growth of polycrystalline materials, chemical instruments and methods, crystal growth, etc., can solve the problems of low mechanical strength of polysilicon, and achieve the effects of less dislocation density, lower cost and longer life

Active Publication Date: 2009-12-09
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
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Problems solved by technology

[0004] The invention provides a method for preparing cast polysilicon by melting silicon and doping nitrogen under nitrogen, utilizing the characteristic that nitrogen in silicon can improve its mechanical strength, and solvi

Method used

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Examples

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Example Embodiment

[0014] Example 1

[0015] Place 240 kg of polysilicon raw material in a crucible, add 60 g of dopant gallium, and load it into a furnace. Then the furnace chamber was evacuated and 99.999% purity nitrogen was introduced. The nitrogen pressure was 10 Torr and the nitrogen flow rate was 10 L / min. The polysilicon raw materials and gallium were gradually heated to 1420° C. until the silicon melt was completely melted. 5 hours after the nitrogen gas was introduced, the argon gas was changed to nitrogen gas, and then polysilicon was cast. Raise the heat preservation cover in the furnace at a speed of 2mm / min, and at the same time blow cooling helium gas into the bottom of the crucible, so that the heat exchange of the silicon melt mainly occurs at the bottom of the crucible, so that the silicon melt will gradually solidify from the bottom upward to form nitrogen doped Of polysilicon. The gallium concentration in the formed polysilicon is 1×10 16 / cm 3 , And the nitrogen concentration is...

Example Embodiment

[0017] Example 2

[0018] Place 240 kg of polysilicon raw material in a crucible, add 6 g of dopant boron, and load it into a furnace. Then the furnace chamber was evacuated and 99.9999% purity nitrogen was introduced. The nitrogen pressure was 100 Torr and the nitrogen flow rate was 100 L / min. The polysilicon raw material and boron were gradually heated to 1450° C., until the silicon melt was completely melted. 16 hours after the nitrogen gas was introduced, the argon gas was changed to nitrogen gas, and the polysilicon casting started. Lift the heat preservation cover in the furnace at a speed of 4mm / min, and at the same time pass cooling water into the bottom of the crucible, so that the heat exchange of the silicon melt mainly occurs at the bottom of the crucible. In this way, the silicon melt will gradually solidify from the bottom upwards to form nitrogen-doped Polysilicon. The boron concentration in the formed polysilicon is 1×10 15 / cm 3 , And the nitrogen concentration is...

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Abstract

The invention discloses a method for preparing cast polycrystalline silicon through melting silicon and doping nitrogen under nitrogen. The method comprises the following steps: doping the nitrogen in such a manner that the nitrogen is led in during the meting period of raw polycrystalline silicon to be reacted with molten silicon; controlling the nitrogen doping concentration through controlling the silicon melting time; directionally solidifying and casting; and obtaining the nitrogen-doped monocrystalline silicon with controllable nitrogen concentration. The polycrystalline silicon has higher mechanical strength and is used for cutting a thinner silicon chip in a solar battery, thereby reducing the production cost of the solar battery. The method can be further used for producing the nitrogen-doped polycrystalline silicon with different mechanical strength requirements. The invention further discloses the cast polycrystalline silicon prepared by adopting the method, which contains boron, gallium and phosphor with the concentration of 1*10-1*10/cm, and further contains the nitrogen with the concentration of 1*10-5*10/ cm.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a method for preparing cast polysilicon by melting silicon and doping nitrogen under nitrogen. Background technique [0002] Solar energy is an inexhaustible clean energy. Using the photoelectric conversion characteristics of semiconductor materials, it can be prepared into solar cells, which can convert solar energy into electrical energy. [0003] Cast polysilicon is a main material for solar cells, but has the disadvantage of low mechanical strength. If the thickness of the cast polycrystalline silicon wafer is reduced, the silicon wafer will be easily damaged and broken during the process of processing, battery preparation and battery assembly into components, etc., and the breakage rate of the silicon wafer will increase, which will inevitably lead to an increase in cost. However, one of the main obstacles affecting the widespread use of solar cells is the high cost,...

Claims

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Application Information

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IPC IPC(8): C30B28/06C30B29/06
Inventor 杨德仁余学功阙端麟
Owner ZHEJIANG UNIV
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