TABLE OF CONTENTS M.Chiao and L.Lin
This chapter will give an overview of wafer-level sealing processes for MEMS packaging technology. The integrated sealing process using thin film materials will be described and wafer bonding processes with and without intermediate layers will be reviewed. Wafer-level vacuum packaging and accelerated testing in a harsh environment will also be covered.
Sealing or encapsulation is an important step in either IC (integrated circuits) or MEMS packaging to protect working devices. In the traditional IC packaging procedures, the overall packaging steps often involve: (1) wafer dicing, (2) pick-and-place, (3) electrical connections, such as wire bonding and (4) plastic moulding or housing for the sealing process [1,2]. Unlike regular ICs, the diversity of MEMS products complicates the sealing issues. MEMS packaging processes cannot directly follow the procedures set by the IC packaging industry due to possible free-standing physical microstructures or chemical substances which cannot survive the dicing or pick-and-place steps before the sealing process. It has been suggested that MEMS packaging processes, including the sealing process, should be considered right from the beginning in the device development plan and packaging schemes should be designed and incorporated into the device fabrication process. Moreover, each MEMS device may have its own specially designed packaging and sealing methods that are best fitted to its functions. On the other hand, a versatile approach for MEMS packaging and sealing is attractive, especially as many devices are now fabricated by integrating MEMS and microelectronics on the same chip. There is...
