Failure modes of Wafer Level Thin Film MEMS packages during wafer thinning

An increasing number of semiconductor companies have research programs related to MEMS resonators. This can be explained by the possible wide range of application areas. Many resonators operate in vacuum and sealing of the cavity can be obtained by using a Wafer Level Thin Film Package (WLTFP). To fit the MEMS-die into a small package it needs to be thinned. In this paper the effect of wafer thinning on the WLTFP is investigated by means of simulation and experiments. The effects of tape removal on WLTFP's are simulated in 2 and 3 dimensions using the cohesive zones technique. Necessary adhesive properties of the grinding foil are measured by a grinding tape peeling experiment. In 2D FE simulations damage is included to predict the most likely cracking path.