High-quality phosphorus diffusion method for matching selective etching of HF/HNO3 system

Abstract

The invention relates to a phosphorus diffusion method, in particular to a high-quality phosphorus diffusion method for matching selective etching of an HF / HNO3 system, which belongs to the technicalfield of crystalline silicon solar cells. The method comprises the following steps of: (1) tube entering, (2) temperature rise to a first temperature, (3) oxidation, (4) phosphorus source deposition,(5) temperature rise to a second temperature, wherein the second temperature is higher than the first temperature, (6) knot pushing, (7) second-time phosphorus source deposition after knot pushing toform second phosphorus diffusion on the surface of a silicon wafer, and (8) cooling down and tube existing. According to the high-quality phosphorus diffusion method disclosed in the invention, in a condition of reducing etching weight loss, moderate sheet resistance in an etching area is ensured, the surface phosphorus doping concentration is low, and besides, steps in the etching area and a non-etching area are reduced, and passivation of a subsequent silicon nitride film is facilitated.

Description

technical field [0001] The invention relates to a phosphorus diffusion method, in particular to a matching HF / HNO 3 The invention relates to a high-quality phosphorous diffusion method for systematic selective etching, which belongs to the technical field of crystalline silicon solar cells. Background technique [0002] With the gradual depletion of fossil energy, clean energy has attracted more and more attention. Photovoltaic power generation technology, as a mainstream technology for utilizing solar energy resources, has been market-oriented and commercialized. In order to further promote the utilization and promotion of photovoltaic battery products, it is necessary to gradually improve battery efficiency and reduce the cost of electricity. [0003] Nowadays, the mainstream mass production technologies for preparing selective emitters mainly include: laser selective doping and HF / HNO 3 System selective etching. Among them, the laser selective doping process requires ...

AI Technical Summary

Problems solved by technology

Existing HF / HNO 3 The weight loss of the etching process is large, and the steps formed by the etching area and the non-etching area are relatively high, which has a great impact on the density of the subsequently deposited silicon nitride, which in turn affects the passivation effect of silicon nitride and reduces the open circuit of the battery Voltage

At the same time, a large etching weight loss will make the phosphorus diffusion layer in the etching area thinner, which will affect the lateral transport of carriers in the diffusion layer and reduce the fill factor of the battery.

If under the existing phosphorus diffusion process, directly reduce the etching weight loss, it will cause high square resistance in the etching area, high phosphorus doping concentration on the surface, high recombination in the surface area, and directly reduce the open circuit voltage of the battery

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