Complete extraction of defect bands responsible for instabilities in n and pFinFETs

Abstract

Bias temperature instabilities (BTI) are serious reliability issues in high-k technologies and occur for positive and negative stress voltages in both n and pMOSFETs. The cases with the strongest degradation, namely negative BTI (NBTI) in pMOS and positive BTI (PBTI) in nMOSFETs, are typically studied and modeled separately, which led to considerable inconsistencies regarding the distributions of the responsible defects. Here we present the first study which successfully describes all four combinations of BTI in n/pMOSFETs within a single model. This was achieved by determining the physical properties of the defects in HfO2 and in SiO2. Using our extraction method, any ambiguity regarding the location of the defect bands is completely eliminated, allowing for correct physics-based extrapolation of degradation data to use conditions.