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High-uniformity shallow junction diffusion process in low-pressure environment

A low-pressure environment, diffusion process technology, applied in the field of solar cells, can solve the problems of single-chip and whole tube non-uniformity control range, inability to real-time diffusion depth, small square resistance control range, etc., to reduce local poor sintering and facilitate sintering. process, the effect of reducing unit energy consumption

Active Publication Date: 2019-08-16
ZHEJIANG BEYONDSUN PV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In actual production, because the diffusion depth cannot be real-time, the square resistance of each area on the surface of the cell is monitored. The existing technology in the industry is to control the square resistance at 100-110, and the unevenness of the single-chip square resistance is controlled within 8%. The resistance unevenness is controlled within 6%, the uniformity is not enough, the control range of the square resistance is small, and the control range of the unevenness of the single chip and the whole tube is small, and the cell efficiency is low

Method used

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  • High-uniformity shallow junction diffusion process in low-pressure environment
  • High-uniformity shallow junction diffusion process in low-pressure environment
  • High-uniformity shallow junction diffusion process in low-pressure environment

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Cell diffusion is carried out according to the following process:

[0021] Unified collection of silicon wafers after traditional acid texturing;

[0022] Lead the silicon wafer into the special quartz boat for low-pressure process;

[0023] Purify the furnace tube, the time is 20s, the temperature is 780°C, the pressure of the furnace body is normal pressure, the gas medium is nitrogen, and the maximum nitrogen mass flow rate is 3000SCCM;

[0024] Entering the boat, the time is 1000s, the temperature is 780°C, the pressure of the furnace body is normal pressure, the gas medium is nitrogen, and the maximum nitrogen mass flow rate is 3000SCCM;

[0025] Constant temperature diffusion, time 400s, temperature 780°C, furnace body pressure is normal pressure, gas medium is oxygen and nitrogen, mass flow rate of oxygen is 500SCCM, large nitrogen is 500SCCM, open the source pipeline, source bottle pressure is 500mba, small nitrogen is 800SCCM.

[0026] Constant temperature de...

Embodiment 2

[0037] Cell diffusion is carried out according to the following process:

[0038] Unified collection of silicon wafers after traditional acid texturing;

[0039] Lead the silicon wafer into the special quartz boat for low-pressure process;

[0040] Purify the furnace tube, the time is 20s, the temperature is 780°C, the pressure of the furnace body is normal pressure, the gas medium is nitrogen, and the maximum nitrogen mass flow rate is 3000SCCM;

[0041] Entering the boat, the time is 1000s, the temperature is 780°C, the pressure of the furnace body is normal pressure, the gas medium is nitrogen, and the maximum nitrogen mass flow rate is 3000SCCM;

[0042] The main vacuuming time is 240s, the temperature is 780°C, and the furnace body pressure is 50mbar;

[0043] Leak detection, time 60s, temperature 780°C, furnace pressure 50mbar;

[0044] Vacuuming, time 40s, temperature 780°C, furnace pressure 50mbar;

[0045] Constant temperature diffusion, time 400s, temperature 780...

Embodiment 3

[0066] Cell diffusion is carried out according to the following process:

[0067] Unified collection of silicon wafers after traditional acid texturing;

[0068] Lead the silicon wafer into the special quartz boat for low-pressure process;

[0069] Purify the furnace tube, the time is 20s, the temperature is 780°C, the pressure of the furnace body is normal pressure, the gas medium is nitrogen, and the maximum nitrogen mass flow rate is 3000SCCM;

[0070] Entering the boat, the time is 1000s, the temperature is 780°C, the pressure of the furnace body is normal pressure, the gas medium is nitrogen, and the maximum nitrogen mass flow rate is 3000SCCM;

[0071] The main vacuuming time is 240s, the temperature is 780°C, and the furnace body pressure is 100mbar;

[0072] Leak detection, time 60s, temperature 780°C, furnace pressure 100mbar;

[0073] Vacuuming, time 40s, temperature 780°C, furnace pressure 100mbar;

[0074] Constant temperature diffusion, time 400s, temperature ...

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Abstract

The invention discloses a high-uniformity shallow junction diffusion process in low-pressure environment, which comprises the following steps: (1) introducing a silicon wafer into a quartz boat, and introducing the quartz boat into a purified furnace tube at constant temperature and at atmospheric pressure; (2) carrying out vacuum pumping until the pressure of the furnace body is 50-100mbar, and carrying out segmented diffusion heating, constant-temperature deposition and constant-temperature segmented advance heating on the furnace body; (3) cooling and annealing the furnace body at 50-100mbar; and (4) restoring the pressure to the atmospheric pressure by nitrogen charging, and taking the quartz boat out. Compared with the prior art, the surface diffusion concentration can be reduced by adjusting the uniformity of cell PN junctions, and a junction with better uniformity can better match sintering, so that the ohmic contact quality of the surface can be improved, the minority carrier life can be prolonged by the annealing process, the electrical performance parameters of cells can be improved, and the conversion efficiency can be improved ultimately.

Description

technical field [0001] The invention relates to the technical field of solar cells, in particular to a high-uniform shallow junction diffusion process under a low-voltage environment. Background technique [0002] P-type polysilicon wafers need to deposit phosphorus on the surface during the diffusion process to form a layer of N-type silicon layer to form a PN junction structure. The depth and uniformity of the surface junction will directly affect the quality of the cell during the production process. The N-type layer will greatly reduce the appearance of dead layers on the surface, reduce the impact of doping on bulk materials, improve the minority carrier life, and thus improve the conversion efficiency of the cell; a more uniform PN junction will help match the back-end sintering and reduce Local poor sintering caused by poor square resistance uniformity. [0003] In actual production, because the diffusion depth cannot be real-time, the square resistance of each area ...

Claims

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Application Information

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IPC IPC(8): H01L31/18H01L31/068H01L21/223
CPCH01L21/2233H01L31/068H01L31/182Y02E10/547Y02P70/50
Inventor 何一峰赵庆国吕文辉姚春梅汪燕萍张宇辉
Owner ZHEJIANG BEYONDSUN PV
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