A low-voltage diffusion process for high square resistance crystalline silicon cells

Abstract

The invention discloses a high-sheet resistance crystalline silicon cell low-voltage diffusion process. In order to effectively improve productivity of a diffusion tube to reduce diffusion cost of a single sheet and improve performance uniformity of mass-production batteries to improve the entire cost performance of the mass-production batteries, a voltage reduction diffusion process is adopted, and great reform is carried out on the original normal voltage diffusion process. Compared with the normal voltage diffusion process, the total nitrogen flow and the total time can be effectively reduced, longitudinal distribution of the diffusion doping concentration can be well controlled, and uniformity of diffusion sheet resistance inside the sheet and between sheets can be effectively improved. The diffusion process of the invention can be applied to a voltage reduction diffusion furnace, the process is strongly matched with the voltage reduction diffusion furnace, the process is applied to industrialized production, productivity can be greatly improved, and the process can then be applied to the crystalline silicon cell production line in a large scale.

Description

technical field [0001] The invention belongs to the field of diffusion processing in the preparation process of crystalline silicon batteries, and specifically relates to a diffusion process capable of increasing the production capacity of a diffusion furnace, and improving the resistance value of a diffusion square and the uniformity between chips. Background technique [0002] The PN junction is the core of crystalline silicon cells. The preparation of a uniform high-resistance emitter is an important way to improve the conversion efficiency of crystalline silicon cells. It can not only reduce the front surface recombination to increase the open circuit voltage, but also greatly improve the short-wave spectral response to enhance the short circuit current. Continuous breakthroughs have been made in the development of high square resistance silver paste, which has solved the problems of excessive series resistance and emitter burn-through due to high square resistance. Impr...

AI Technical Summary

Problems solved by technology

Atmospheric pressure and high temperature diffusion tubes are usually selected at the nozzle or the end of the tube, and the gas is taken to the other end through a large nitrogen flow, which is easy to cause the phenomenon of high concentration at one end and low concentration at the other end, and the free path of gas molecules is small under normal pressure. There is a large difference in the probability of silicon wafers being exposed to phosphorus sources in different regions, and the sheet resistance can only be controlled by adjusting the temperature, but the uniformity within and between wafers cannot be guaranteed.

Atmospheric pressure diffusion will reduce the consistency of the doping concentration in the vertical direction of the diffused PN junction, thereby affecting the consistency of the depth of the PN junction and electrical properties. Preparation of electrodes under the same screen printing and sintering conditions will increase the number of defective chips due to large leakage currents. Ratio, while reducing the consistency of battery performance, increasing the proportion of low-grade (B-piece) cells, greatly affecting the reduction of battery manufacturing costs

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