Chun-Wen Cheng

Bulk-Si with poly bump process scheme for MEMS sensors

A MEMS process scheme designed for multi- sensors is presented. This new process scheme includes a poly bump not only provides stiction prevention and gap control function, and also electrical connection between MEMS structure and routing lines. Another advantage for this scheme is a better vacuum level because all material can be high temperature annealed before final encapsulation. This study also demonstrated some MEMS devices using this new scheme, including resonators, accelerometers and magnetometers.

12 inch MEMS process for sensors implementation and integration

This study presents the development of a foundry available process scheme to implement and integrate MEMS devices on 12 inch wafer for the first time. After overcome various process challenges such as wafer warpage, bonding quality, etc., this study has successfully accomplished the bulk Si process scheme on 12 inch wafer. Accelerometer, resonators and Pirani gauges were fabricated and characterized to demonstrate the feasibility of the proposed process scheme. The vacuum condition of the sealed chambers was then monitored using the quality factor (detected by resonators) and the pressure (measured by Pirani gauges). This 12 inch MEMS process could facilitate the monolithic integration of devices with different vacuum requirements, a monolithically integrated silicon-based Pirani vacuum gauge to provide in situ pressure monitor is also demonstrated.