Laser Ablation Mechanism Of Silicon Nitride Layers In A Nanosecond UV Regime

Selective laser ablation of silicon nitride (SiNx) layers is a crucial technological step to achieve alternative front side metallization like electrochemical contact. In this work, we discuss the mechanism of laser ablation with a nanosecond UV laser source. A model with two thresholds corresponding to the melting threshold of silicon and the ablation threshold of silicon nitride is proposed. A finite element method is used to solve the heat transfer equation and describe the ablated SiNx surface for a single laser pulse. Numerical results are compared to optical microscopy measurements of the ablated zone.