Selective Induction Heating for Microsystem Packaging

Preliminary research on selective induction heating to achieve wafer bonding is presented in this paper. Some effects of bonding layer materials, coil design and impedance matching on induction heating are discussed. By choosing a suitable frequency of high frequency power supply and optimizing the induction coil, selective induction heating for wafer bonding has been achieved. Induction heating patterns in terms of bonding layer should be in closed loop, which is also effective for hermetic packaging, while other open-loop-patterns such as circuits, pads, et al., cannot be effectively heated because no eddy current or little eddy current can be inducted and are kept to be at low temperature, there damages on some temperature-sensitive devices can be avoided. The new technique can be applied to various IC and MEMS packaging such as eutectic bonding, solder bonding, and diffusion bonding