Precise removal of ultra-thin SiNx layer deposited on silicon substrate using nanosecond green laser for PERC solar cell fabrication

Creating narrow openings on a silicon substrate containing a SiNx nanofilm (80–85 nm) is essential in fabricating PERC solar cells. This research shows that nanosecond laser ablation can selectively remove only the SiNx layer with high precision. Four ablation regimes were identified based on experimental measurements of the ablated surface and temperature evaluations from computational modeling. In one regime, only the SiNx layer is ablated via film breakage due to the subsurface silicon's thermal expansion. In contrast, the other regimes demonstrated much deeper ablation depths with severe thermal damage in the ablated region.