Preparation method of selective emitter of N-type battery

Abstract

The invention discloses a preparation method of a selective emitter of an N-type battery. The following steps are carried out in sequence on a silicon wafer in chain type equipment: depositing boron slurry and taking the boron slurry as a doping source of a heavily doped region; performing high-temperature propulsion for the first time to enable the doping source in the heavily doped region to be diffused into the silicon wafer; depositing a liquid boron source, and taking the liquid boron source as a doping source of a lightly doped region; and performing high-temperature propulsion for the second time to enable the doping source of the heavily doped region and the doping source of the lightly doped region to be diffused into the silicon wafer. The boron slurry is used as the doping source of the heavily doped region, the liquid boron source is used as the doping source of the lightly doped region, the preparation of the emitter of the heavily doped region and the lightly doped region is realized through the chain type equipment, the external expansion is controllable, the textured surface is not damaged, the steps are simple, the time is saved, the yield is high, and large-batch production is facilitated. The whole-course chain mode is adopted, the whole preparation process is implemented in the same chain type equipment, the silicon wafer does not need to be turned over among a plurality of pieces of equipment, and the cleanliness of battery pieces is greatly improved. The process window is wide, the junction depth difference is controllable, and the boron source expansion influence is avoided.

Description

technical field [0001] The invention relates to the field of photovoltaics, in particular to a method for preparing a selective emitter of an N-type battery. Background technique [0002] The PERC cell SE process is mature and mass-produced in battery factories, but N-type cells have not yet formed a mass-produced selective emitter process. The main reason is that the boron doping process is more difficult, and the doping The difficulty is mainly determined by the nature of the material itself. [0003] At present, the N-type battery selective emitter preparation process mainly includes: secondary diffusion method, mask method, reverse etching method, laser doping method and doping slurry thermal diffusion method, etc. [0004] The secondary diffusion method needs to go through the steps of depositing mask layer-laser slotting (heavy doping area), first thermal diffusion (preparation of heavy doping area), cleaning mask layer, second thermal diffusion (preparation of light ...

AI Technical Summary

Problems solved by technology

[0004] The secondary diffusion method needs to go through the steps of depositing mask layer-laser slotting (heavy doping area), first thermal diffusion (preparation of heavy doping area), cleaning mask layer, second thermal diffusion (preparation of light doping area) and other steps , needs to enter and exit the tube furnace twice, and needs to use laser equipment, which is easy to damage the suede structure, takes a long time, costs a lot, and the process is cumbersome

[0005] The masking method needs to go through the first thermal diffusion, mask patterning, BSG cleaning in the non-masked area, mask removal, second thermal diffusion and other steps. The whole process also needs to enter and exit the tube furnace twice, which takes a long time. cumbersome operation

[0006] The reverse etching method needs to go through steps such as thermal diffusion, mask patterning, acid etching (non-mask area), and mask layer removal. Although the process steps are simple, the process window is narrow, which is not conducive to process control, and damages the suede surface. Suitable for light-receiving surface structure preparation, and there is environmental protection pressure

[0007] The laser doping method is to perform patterned laser treatment on the surface of the BSG cell after thermal diffusion. There are two difficulties: first, the damage to the suede surface cannot be eliminated by the laser; second, due to the difficulty of boron doping in silicon, the laser Energy control is difficult and the process window is narrow; the contradiction between these two aspects makes the process immature

[0008] In summary, the disadvantages of the existing N-type battery selective emitter preparation process are summarized as follows: ① It takes a long time to enter and exit the tube furnace twice, and the heating and cooling of the tube furnace is time-consuming. The thermal history is too long, which affects the performance of silicon wafers; ②The process is complicated, such as using a mask, it is necessary to deposit a film layer or print a mask, and it is necessary to use a wet method to clean and remove the mask, and the use of chemicals increases the pressure on environmental protection;③ The process is unstable and the window is small, such as laser doping process, the laser energy is too large to damage the front suede structure, the laser energy is too small to do enough boron source, and the expected effect cannot be achieved; ④ damage the suede, and the front of the N-type battery is light-receiving Surface, laser or chemical corrosion will destroy the suede, which has a great impact on the short-circuit current of the battery