Wafer level packaging for chambers of two different pressures

This study introduces a special process design to fabricate two different pressure chambers (sealed and unsealed chambers) simultaneously by a single wafer bonding process. The pressure in unsealed-chamber is ambient-pressure and sealed-chamber is a specific pressure defined during bonding processes. Two types of sensors were characterized to verify the process scheme. One is a 32 kHz resonator and the other is a Pirani gauge. Characterizations on these two sensors prove that the sensors are functional in different pressure conditions in both unsealed chambers and 10mbar sealed chambers. Therefore the proposed process design is capable of fabricating two different pressure chambers at the same time.