Technology Outline (Process Description)

“Tunnel Oxide Passivated Contact” solar cell, known as TOPCon solar cell, is touted as the next generation of solar cell technology after PERC. Compared to the other potential new technologies, such as HJT and IBC, TOPCon can be upgraded from the current PERC line with lower capital investment for a significant gain in solar cell efficiency. p-type CZ wafers (180 μm) was taken and processed through saw damage removal, alkaline texturing, and RCA cleaning and homogeneous emitter is diffused in diffusion furnace through liquid POCl3. The PSG layer is removed in 5% HF solution. SiNx was deposited on the front side as ARC layer through PECVD method. RIE have been used to polish the rear side of the wafer followed by KOH treatment.

1.5 nm SiOx layer has been grown through thermal oxidation. 100 nm of p-polysilicon has been deposited by PECVD process followed by high temperature (850¡C) annealing. Front metallization has been done by screen printing technology and back metallization was carried out through low temperature thermal evaporation technique.