Impact of Twofold Coordinated Nitrogen on the Generation of Deep-Level Hole Traps under Negative-Bias Temperature Stressing

Abstract

In this paper, we discuss the generation of deep-level hole traps (DLHTs) during negative-bias temperature stressing. Because of their ability to trap positive charges for a long time, it is imperative to gain a sound understanding on the nature of the DLHT, especially in relation to nitrogen, which has been incorporated in increasing dose into the SiO2 gate oxide to solve boron penetration and gate tunneling leakage issues. Experimental evidence showing a correlation between the generation of DLHTs and nitrogen is first presented. This is followed by a discussion on the role nitrogen plays in influencing the generation of DLHT via first-principles simulation. We focus on the impact of a neighboring nitrogen atom on the structural and electronic properties of the oxygen-vacancy defect (VO), which is a major precursor for hole traps in the SiO2. Finally the charge transition levels (CTL) are discussed, which give us a more comprehensive understanding of DLHT.