(Invited) Trench-Gated MOSFET Instability Caused by High Temperature Reverse-Bias Stress

Abstract

We discuss the instability of trench-gated MOSFET under high temperature reverse-bias stress (HTRB) and highly accelerated temperature & humidity stress test (HAST). We have observed that gate oxide interface trap density has been increased at both HTRB stress and HAST stress. However humid HAST stress is observed to further introduce mobile positive charge in the gate oxide of the trench-gated MOSFET. This positive charge is argued to be proton (H+). The HTRB stress or HAST stress is a negative bias temperature instability (NBTI) in a parasitic p-channel MOSFET structure occurring in the trench-gate n-channel MOSFET. The NBTI is enhanced by the presence of moisture in the oxide.