Abstract
Hermetic sealing, giving a controlled and stable cavity environment, is a key issue for microsensors with high performance and long lifetime. Due to the small cavity volumes of micro electromechanical systems (MEMS), leak rates in the range of 10-14 – 10-16 mbarls-1 are often required for device lifetimes of 5 – 15 years. Hermetic sealing is vital for ensuring high performance of e.g. uncooled infrared microbolometers, as their thermal response time is directly influenced by the pressure surrounding the pixels (the gas contributes to the heat transfer away from the pixels through convection and the pressure inside the cavity is therefore minimized). When selecting a wafer bonding technology to seal a specific device, the technology must be integrated into the process sequence, and it must fulfil the requirements of the device in question. Hermetic wafer level bonding and how to integrate such a process for the fabrication of a microbolometer device will be presented in this talk. The reasoning for the selection of a specific wafer bonding process will be given and results from reliability studies performed to verify the selection will be presented.