A clean wafer-scale chip-release process without dicing based on vapor phase etching

A new method to release MEMS chips from a wafer without dicing is presented. It can be applied whenever SOI wafers are used that are structured from both the device and the handle side using DRIE. This method enables the release of extremely fragile structures without any mechanical impact on the chips. No more dicing residues or debris are created and deposited onto the wafer. The basic idea consists of etching deep surrounding trenches on the device and the handle layer that are displaced by about 20 μm and thus create overlapping areas. For release, the buried silicon dioxide between the overlapping areas is etched away using hydrofluoric acid vapor phase etching.