Oxide or metal interface damage improvement of deep silicon etch process by low power RF of low frequency

This study investigates the damage of the heterogeneous interface either dielectric oxide or metal materials induced by through silicon deep reactive ion etching (DRIE) process at the predefined bottom cavity area first time and establishes the failure model of the interface damage as well as metal re-deposition introduced by the silicon DRIE process. Thus, the DRIE process of low power and low frequency bias-RF is proposed to resolve the aforementioned problems by electrical testing verification. In applications, the Si-above-CMOS (TSMC 0.18μm generic CMOS process) process platform has been employed to demonstrate the present process approach. The fabrication results demonstrate that the problems of metal (or oxide) interface-layer damage and current leakage of CMOS-to-MEMS (or MEMS-to-MEMS) are prevented. Thus, the yield and performances of the capacitive motion sensors implemented using the Si-above-CMOS platform are significantly improved.