Ultra-short pulsed laser ablation of silicon nitride layers: Investigation near threshold fluence

In this work, silicon nitride (SiNx) layers, deposited on a planar silicon wafer are locally irradiated by ultra short laser pulses with fluences near the threshold fluence. The irradiated areas are investigated by SEM and TEM in order to analyze the laser influence to silicon and to the SiNx layer. Thereby, a lift-off process is observed for this SiNx layer. The silicon absorbs the laser pulse energy. For low fluences, crystalline silicon is disordered below the SiNx layer. For high fluences, silicon evaporates below the SiNx layer and bulge the SiNx layer. If the pressure within the bulge is high enough, the SiNx layer will break down due to high mechanical stress.