UV and IR laser induced ablation of Al2O3/SiN:H and a-Si:H/SiN:H

Abstract

Experimental work on laser induced ablation of thin Al2O3(20 nm)/SiN:H (70 nm) and a-Si:H (20 nm)/SiN:H (70 nm) stacks acting, respectively, as p-type and n-type silicon surface passivation layers is reported. Results obtained using two different laser sources are compared. The stacks are efficiently removed using a femtosecond infra-red laser (1030 nm wavelength, 300 fs pulse duration) but the underlying silicon surface is highly damaged in a ripple-like pattern. This collateral effect is almost completely avoided using a nanosecond ultra-violet laser (248 nm wavelength, 50 ns pulse duration), however a-Si:H flakes and Al2O3 lace remain after ablation process.