Wafer bonding process for zero level vacuum packaging of MEMS

It is well known that the packaging of electronic devices is of paramount importance, none more so than in MEMS were fragile mechanical elements are realized. Among the different approaches, wafer to wafer bonding guarantees the advantages of the wafer scaling and provides protection of the devices during the final phase of fabrication. Direct bonding, also known as fusion bonding, is seldom implemented in MEMS fabrication due to the high surface quality required, the high temperature involved and the compulsory wet activation process. In this paper a direct bonding process for MEMS inertial sensor without the need of any wet activation step is presented.