Comparison of picosecond laser sources for SiNx ablation with subsequent nickel silicide formation by excimer laser annealing (ELA) for high efficiency silicon solar cells

We compare two types of laser ablation for ARC removal on polished and textured surfaces. Selective ablation with limited impact on the underlying substrate is performed with short wavelength picosecond sources working at relatively low repetition rate ( + emitter. The thermal effect induced by the short duration between pulses performs simultaneously SiNx removal and selective emitter structure with with deep dopant profiles and low surface concentration. We investigate the correlation between the post-ablation properties and a nickel silicidation process using Excimer Laser Annealing of a thin layer of Ni. A reference process is first described on pyramid topography without pre-ablation of SiN x . It is demonstrated efficient formation of SixNiy compounds on the silicon substrate depending and laser fluence. The similar silicidation process is transferred on sample after the SiN x ablation step. A continuous nickel silicide layer is observed but its thickness distribution reveals non-uniformity over the pyramids due to post ablation roughness.