UV laser dicing without failure caused by contamination and heat for thick anodically bonded silicon/glass MEMS wafers

UV laser dicing has many advantages such as mechanical stress-free and dicing shape-free, but it is seldom used to dice multi-layer MEMS wafers because of the deposition of a lot of debris and heat affected zones around the dicing lines. A novel UV laser dicing process based on ablation for thick anodically bonded silicon/glass wafers is presented in this paper. The contamination of the microstructures on the silicon is avoided by dicing the bonded wafer from the glass side. The heat caused split of the bonded silicon and glass around the dicing line is prevented by fabricating recesses on either the glass wafer or the silicon wafer. Samples are fabricated for dicing experiments. The thicknesses of the glass and silicon wafers are 500μm and 250μm respectively. The anodically bonding temperature is 360°C, and the boding voltage is 400V. Dicing experiments show that the huge thermal stress caused by the laser can split the originally bonded silicon from glass around the dicing line. After recesses are fabricated along the dicing line, no heat caused split happens. This research can provide a more flexible and cheaper laser dicing process for thick anodically bonded silicon/glass MEMS wafers.