Laser Polishing for Enhanced Micro-grooving of Silicon Wafers

Abstract

In semiconductor packaging, wafers are separated into individual chips through a process known as dicing, which can be performed using a mechanical blade or laser-based methods. In laser dicing, one common approach is laser grooving, where the laser forms shallow channels along the dicing lanes to guide the final mechanical separation of dies. While this method offers high precision and minimal mechanical stress, it can also create surface defects such as microcracks, recast layers, and debris that reduce die strength and yield. This study introduces a two-step laser-based process aimed at improving the surface quality of grooves formed during laser dicing. In the first step, a nanosecond ultraviolet (UV) laser ablates microchannels with controlled geometry at a pulse fluence of approximately 19.9 J/cm². In the second step, the same laser re-scans the grooves at lower laser pulse fluence (∼10.6 J/cm²) to induce localized melting and re-solidification, smoothing the sidewalls and reducing surface roughness without additional ablation. Surface analyses using laser profilometry and scanning electron microscopy (SEM) showed that this approach significantly improves surface uniformity and minimizes residual defects. The proposed method can be readily integrated into existing dicing workflows that combine laser grooving with mechanical separation, providing a cleaner and more reliable route for high-yield semiconductor packaging.