Blister formation mechanism during high dose implanted photoresist stripping
Résumé
Dry strip processes performed after implantation steps have to remove efficiently the photoresist mask protecting the non-implanted area without leaving any defects on the substrate. In this study bubble-like defects called blisters are observed on implanted areas after several N2H2 dry strip processes. Analyses have been performed to study the blistering phenomenon. The formation of these defects is due to hydrogen diffusion and accumulation in the amorphized silicon layer formed by the implantation step. The effects of implantation parameters (dopant species, dose and energy) on blister formation have been demonstrated. The experimental results have been compared to simulations (using SRIM software) highlighting the main influence of amorphization rate against amorphized layer thickness. Optimization of the stripping process and integration modification are then proposed to delay the appearance of the blisters.
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