Investigation on the Processing Quality of Nanosecond Laser Stealth Dicing for 4H-SiC Wafer

Abstract

Silicon carbide (SiC), due to its characteristic materials performance, gets more attention in Radio Frequecy (RC) and High-power device fabrication. However, SiC wafer dicing has been a tricky task because of the high hardness and brittleness. The blade dicing suffers from poor efficiency and debris contaminants. Furthermore, the laser ablation dicing and Thermal Laser Separation (TSL) can have thermal damage and irregular crack propagation. In this study, Stealth Dicing (SD) with nanosecond pulse laser method was applied to 4H-SiC wafer. A series of experiments were conducted to analyze the influences of different parameters on cross section and surface. An edge defect less than 3 μm and cross section with roughness of about 0.8 μm was achieved. And the three-point stress test was applied to obtain the die strength. Besides, a novel method of double pulse inducing cracks growth was proposed for the first time to optimize the surface edge. Finite Element Analysis (FEA) verifed the feasibility. Through experiments, the edge defect decreased to less than 2 μm. This work contributes to the wafer Stealth Dicing application for SiC and advance semiconductor materials.