Gate Oxide Instability and Lifetime in SiC MOSFETs under a Wide Range of Positive Electric Field Stress

Abstract

We investigated the positive bias temperature instability (PBTI) in 4H-SiC MOSFETs under a wide range of high oxide electric field (E <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ox</inf> ) stress. The purpose of this study is to deepen the understanding of this phenomenon and experimentally evaluate the lifetime prediction model. For the first time, we analyzed the process of electron capture in SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> under high E <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ox</inf> stress by focusing on the region where electron capture is dominant and found systematical behavior of threshold voltage drift (ΔV <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> ). Additionally, the amount of charges injected into the gate oxide (Q <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">stress</inf> ) was found to be a criterion for ΔV <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> in a high E <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ox</inf> region. Finally, it was presented that lifetime under PBTI testing exhibits a power-law relationship with E <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ox</inf> , resulting in longer lifetime than that predicted by the widely used E-model. Insights from the presented analyses must be beneficial for PBTI modeling and testing of SiC MOSFETs.