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Method for gettering phosphorus in N-type polysilicon slice by metallurgical method

A technology of polycrystalline silicon wafers and metallurgical methods, applied in chemical instruments and methods, silicon compounds, non-metallic elements, etc., can solve the problems of long diffusion time, high diffusion temperature, small phosphorus diffusion coefficient, etc., and achieve high surface concentration, doping High concentration and good repeatability

Inactive Publication Date: 2012-06-27
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the diffusion coefficient of phosphorus in silicon is very small, and a higher diffusion temperature and a longer diffusion time are required to achieve the gettering effect.

Method used

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  • Method for gettering phosphorus in N-type polysilicon slice by metallurgical method
  • Method for gettering phosphorus in N-type polysilicon slice by metallurgical method
  • Method for gettering phosphorus in N-type polysilicon slice by metallurgical method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] (1) Clean metallurgical N-type polysilicon wafers with RCA liquid, and dry; RCA liquid cleaning includes: No. III liquid H 2 SO 4 :H 2 o 2 =4:1; No. I liquid NH 4 OH:H 2 o 2 :H 2 O=1:2:5; II solution HCl:H 2 o 2 :H 2 O=1:2:8. h 2 SO 4 、H 2 o 2 , NH 4 Both OH and HCl are of superior grade, and the mass fractions are 95-98%, 30%, 25-28%, and 36-38% respectively, and the three solution formulas adopt volume ratio.

[0032] (2) Pass the silicon wafer obtained in step (1) into phosphorus oxychloride POCl at a temperature of 900°C in a four-tube microcomputer diffusion furnace 3 Perform phosphorus gettering treatment for 3 hours, the gas flow rates used are: large N 2 1.5L / min; small N 2 0.05L / min; O 2 0.3L / min, the silicon wafer is naturally cooled in the air.

[0033] (3) Soak the silicon chip obtained in step (2) in dilute HF (HF: H 2 (O=1:10) solution for 10min, then HF:HNO 3(1:3) Soak in acid corrosion solution for 45s, and wash with deionized water ...

Embodiment 2

[0036] Same as embodiment 1, its difference is that phosphorus gettering heat treatment temperature and time are different, and step (2) is:

[0037] (2) Pass the silicon wafer obtained in step (1) into POCl at a temperature of 1200°C in a four-tube microcomputer diffusion furnace 3 For 2h phosphorus gettering treatment, the gas used is the flow rate: large N 2 1.5L / min; small N 2 0.05L / min; O 2 0.3L / min, the silicon wafer is naturally cooled in the air.

[0038] The resistivity of the silicon wafer obtained in step (3) is tested; PECVD double-sided deposition of silicon nitride 80nm measures the minority carrier lifetime of the silicon wafer. The test method is the same as in Example 1, and the results show that the average minority carrier lifetime is increased from 1.2 μs to 12.0 μs, and the minority carrier lifetime distribution diagram is as follows figure 2 As shown, the resistivity increased from 0.2Ω·cm to 1.0Ω·cm.

[0039] Minority carrier lifetime distribution ...

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Abstract

The invention provides a method for gettering phosphorus in an N-type polysilicon slice by a metallurgical method, and relates to polysilicon. The method is good in gettering effect, low in cost and simple in operation, and is suitable for industrial production. The method for gettering phosphorus in the N-type polysilicon slice by the metallurgical method comprises the following steps of: washing and drying the N-type polysilicon slice; feeding a gas into the obtained polysilicon slice at the temperature of 700 to 1,200 DEG C, performing phosphorous diffusion gettering thermal treatment, andcooling the polysilicon slice; immersing the obtained polysilicon slice into hydrogen fluoride (HF) solution; and corroding a gettering layer on the polysilicon slice by using acid corrosive liquid, washing and drying, and baking so as to obtain the phosphorous-gettered polysilicon slice.

Description

technical field [0001] The invention relates to a polysilicon, in particular to a method for absorbing phosphorous on an N-type polysilicon sheet by a metallurgical method. Background technique [0002] High efficiency and low cost are the main trends in the development of solar cells. Polycrystalline silicon solar cells are low in price and high in conversion efficiency, and have become a research hotspot in the international photovoltaic field. At present, the modified Siemens method is generally used in the production of solar-grade polysilicon, but the cost is high, and the technology is monopolized by foreign countries, resulting in a shortage of this material and high prices. At present, more and more researchers and manufacturers are focusing on polysilicon purified by metallurgical methods. Metallurgical silicon purification technology (Wu Hongjun, Chen Xiuhua, Ma Wenhui, etc. Research status of polysilicon for solar cells and its gettering [J]. Materials Herald, 2...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/037
Inventor 陈朝郑兰花潘淼李艳华杨倩徐进
Owner XIAMEN UNIV
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