In the fabrication of microelectromechanical system (MEMS) devices the encapsulation of sensors and actuators is often required. Moreover, polysilicon has proven to be an indispensable material in various applications in MEMS area. In this study, we have concentrated on the development of polishing processes for polysilicon and then bonding it to quartz, Pyrex, and low-alkali glass. Simultaneously, basic investigation of high-temperature direct bonding of polysilicon is initiated where Si∕Si - and Si∕Ox -bonding is studied. The main emphasis in material selection has been in thick atmospheric-pressure chemical vapor deposited polysilicon. Spontaneous bonding was achieved with all wafer combinations. Plasma-assisted polysilicon-to-glass bonding was found to yield void free interfaces, whereas high-temperature bonded couples showed void formation. Thus, low-temperature bonding for polysilicon has been enabled with an advanced polishing process.
- elemental semiconductors
- bonding processes
- micromechanical devices
- voids (solid)
Luoto, H., Suni, T., Henttinen, K., & Kulawski, M. (2006). Direct bonding of thick film polysilicon to glass substrates. Journal of the Electrochemical Society, 153(11), G981-G985. https://doi.org/10.1149/1.2345578