Surface preparation and eutectic wafer bonding

Bond surface preparation is an integral part of all eutectic wafer bond processes currently used in high volume production. It is not unusual to have a requirement conflict between the bond surfaces and the device itself, especially in case of MEMS inertial sensors. A typical example of the issue at hand is the need of an anti-stiction coating material for the device and the interference of the material with the eutectic bond process. This paper reports on the novel usage of localized plasma in conjunction with an improved permanent wafer bonder to reconcile the conflicting needs in case of eutectic Aluminum-Germanium wafer bonding.