Quantum Chemistry Treatment of Silicon-Hydrogen Bond Rupture by Nonequilibrium Carriers in Semiconductor Devices

Abstract

The interaction of charge carriers with hydrogen-related defects plays a key role in modern semiconductor applications. Particularly in the field of micro- and nanoelectronics, where silicon together with amorphous gate oxides is still the technology of choice, Si-H bonds participate in a rich variety of phenomena. For example, the passivating nature of H and its influence on surface reconstruction are fundamentally useful features for modern technologies and emerging research fields alike. However, the dissociation of Si-H bonds results in electrically active defects and is associated with a number of device reliability issues. In this work we develop a general quantum kinetic formulation to describe the dynamics of bond excitation and breaking. The wealth of experimental and theoretical studies on Si-H bond breaking induced by energetic carriers enables us to extract the most useful excitation pathways. Based on the open-system density-matrix theory we develop a model that accounts for all relevant system-bath interactions: vibrational relaxation and dipole scattering as well as resonance-induced excitation. In contrast to existing theoretical studies, our model is coupled to a Boltzmann transport equation solver, which is required for the correct consideration of nonequilibrium carrier energy distribution functions occuring in an electronic device. Finally, we apply our framework to model Si-H bond breakage at the Si/SiO2 interface and validate our approach against different experimental data sets. The results provide a fundamental understanding of Si-H dissociation mechanisms and allow for an accurate microscopic description of hot-carrier-induced damage at the device level. Due to the model formulation being free of empirical parameters, the approach can be easily applied to future technologies and materials systems.