The Anode Hydrogen Release (AHR) mechanism at interfaces is responsible for the generation of defects, that traps charge carriers and can induce dielectric breakdown in Metal-Oxide-Semiconductor Field Effect Transistors. The AHR has been extensively studied at Si/SiO2 interfaces but its characteristics at metal-silica interfaces remain unclear. In this study, we performed Density Functional Theory (DFT) calculations to study the hydrogen release mechanism at the typical Al/SiO2 metal-oxide interface. We found that interstitial hydrogen atoms can break interfacial Al-Si bonds, passivating a Si sp3 orbital. Interstitial hydrogen atoms can also break interfacial Al-O bonds, or be adsorbed at the interface on aluminum, forming stable Al-H-Al bridges. We showed that hydrogenated O-H, Si-H and Al-H bonds at the Al/SiO2 interfaces are polarized. The resulting bond dipole weakens the O-H and Si-H bonds, but strengthens the Al-H bond under the application of a positive bias at the metal gate. Our calculations indicate that Al-H bonds and O-H bonds are more important than Si-H bonds for the hydrogen release process.
@article{arxiv.1610.08365,
title = {Hydrogen release at metal-oxide interfaces: A first principle study of hydrogenated Al/SiO$_2$ interfaces},
author = {Jianqiu Huang and Eric Tea and Guanchen Li and Céline Hin},
journal= {arXiv preprint arXiv:1610.08365},
year = {2017}
}