3D Assembly Using Au-Si Eutectic and Au-Au Thermocompression Wafer Level Bonding for M(O)EMS Device Fabrication

Abstract

The purpose of this study was to determine solutions of 3D wafer level assembly for M(O)EMS structures. Validation of the concept will be done by realizing the assembly of a micro mirrors array which is at the present time assembled at chip level with silver glue (assembly and electrical interconnection). The actual bonding surface is around 5x8 μm2 and the release of mirrors is done before assembly. In this study we will first identify a wafer bonding solution that is compatible with the release process and later applying it to the mirror bonding design in order to verify the compatibility. Two bonding processes were identified as good candidate for this application: Au/Si eutectic and Au/Au thermocompression bonding. For the two processes, a preliminary study was realized to determine bonding parameters, design possibility (minimum bonding surface, density, pitch size) and compatibility with release process (SiO2 etching).