Selective induction heating of metallic microstructures for wafer-level MEMS packaging

Considering the demand for low temperature bonding processes in packaging of micro-electro-mechanical systems (MEMS), such as accelerometers or micro mirrors, in this paper a method for selective and energy-efficient heating of metallic intermediate bonding layers by applying high-frequency electromagnetic fields with frequencies in the range of 1. 0 < f < 2.0 MHz is presented. Therefore, the induction heating process was modeled and analyzed by means of numerical simulation. Additionally, heating experiments were carried out by using IR thermography in order to verify the simulation results. The developed inductor shape allows almost homogeneous heating of all metallic layers with heating rates of more than DT∕Dt = 150 K∕s.