High-efficiency selective emitter solar cell diffusion process

Abstract

The invention relates to a high-efficiency selective emitter solar cell diffusion process. The high-efficiency selective emitter solar cell diffusion process comprises the steps of: boat feeding, temperature rise, constant temperature, oxidization, deposition 1, propulsion 1, deposition 2, propulsion 2, oxidation, deposition 3, temperature rise, temperature reduction, deposition 4, temperature reduction and boat taking. According to the invention, high-temperature post-oxidation is added in the process, after the deposition step at the low temperature is finished, the temperature rises continuously and is kept at a certain high-temperature condition, on this basis, a phosphorus source is activated, and then the temperature reduction, oxidization and deposition are performed to perform richphosphorus gettering, the improved steps can effectively enable the phosphorus source in the formed PSG to be continuously distributed into a silicon substrate, and in addition, the PSG is enriched with a large amount of effective phosphorus sources. The improvement of the process ensures that the non-laser region keeps a low surface concentration after diffusion, and the laser heavily doped region has a high surface concentration, thereby effectively solving the problem of compatibility of the low surface concentration of the non-laser region and the high surface concentration of the laser heavily doped region; the homogeneity of sheet resistance is obviously improved after diffusion through the improvement of the process; and the sheet resistance of the laser heavily doped region is lower, and the metallization contact is better.

Description

technical field [0001] The invention relates to the technical field of solar cells, in particular to a high-efficiency selective emitter solar cell diffusion process. Background technique [0002] At present, the preparation route of mass-produced selective emitter PERC solar cells is basically the following path: ① Texturing; ② Diffusion; ③ Laser doping; ④ Backside acid polishing; ⑤ Secondary annealing; PE; ⑧Laser slotting on the back; ⑨Silk screen printing; ⑩Injection test; Among them, the more critical steps ③ and ④ basically adopt the high-resistance diffusion process, and the basic structure of the high-resistance diffusion process is: heating-oxidation --deposit POCI3--push the junction--cool down--out of the boat; the high square resistance (between 120-130) obtained by this method can basically meet the requirements of the selective emitter PERC battery. [0003] However, the batteries prepared by the current diffusion process of this method have the following probl...

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Problems solved by technology

[0004] 1. The surface concentration of shallow laser doping (non-laser area) and laser heavily doped laser area is relatively high, and high surface concentration is more serious for surface recombination, resulting in a relatively low Uoc of the battery

[0005] 2. The uniformity of diffusion resistance prepared by this method is relatively poor, which will lead to a decrease in Isc

[0006] 3. The current low surface concentration diffusion process is not compatible with the laser doping process. The low surface concentration after diffusion will directly lead to a low phosphorus source content in the phosphosilicate glass, thereby reducing the surface concentration of the laser heavily doped area. Shallow doping Low dopant surface concentration is beneficial to reduce the recombination of the surface and improve the opening voltage of the battery, but the heavily doped region needs to be in contact with the metal electrode, and the low surface concentration will lead to poor contact of the battery and reduce the efficiency of the battery

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