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. In this paper, a novel UV laser dicing method for anodically bonded wafers is presented. 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. The Finite Element Method (FEM) in the ANSYSTM software was utilized to analyze the temperature and thermal stress distributions during the dicing process. The thermal stress is minimized sharply due to the fabrication of the recesses beneath the dicing line. The thicknesses of the glass and silicon wafers are 500μm and 250μm, respectively. The anodically bonding temperature is 360oC, and the bonding 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. The experiment results are in a good agreement with the FEM simulation. Compared with other methods, this research can provide a more reliable, flexible and cheaper laser dicing process for thick anodically bonded silicon/glass MEMS wafers, especially for multi-layer wafers with free shape.
THERMAL STRESS TESTING OF SM-2 FUEL ELEMENTS. Final Report for January 1, 1959 to July 1, 1960
