Laser Dicing of Silicon: Comparison of Ablation Mechanisms with a Novel Technology of Thermally Induced Stress

The major issue for dicing of silicon is the edge quality with corresponding die strength. We compared the influence of pulse duration and cutting speed with the corresponding edge quality by using a three-point bending test. As a result the bending strength of the cut samples directly correlates with edge defects. In contrast to the laser dicing technologies using ablation, we investigated a novel mechanism of thermally induced stress cutting of silicon wafers. This process does not produce any debris or other edge defects and uses continuous wave laser radiation. One-step cutting for wafers is possible up to a thickness of a several hundred microns if laser radiation with photon energy near the indirect band gap of silicon is used. The results of ablation rates and bending strength will be presented from picosecond to continuous wave laser dicing.