First-Principles Study on the Evolution and Annealing of Hydrogen Bridge Defects at the a-SiO2/Si(100) Interface

Interface defects at the a-SiO₂/Si(100) interface, particularly hydrogen-related defects, critically impact fixed positive charge and device reliability in bipolar transistors. This work employs first-principles density functional theory to investigate the evolution and annealing of hydrogen-bridge defects. The Climbing Image Nudged Elastic Band method reveals the transformation of symmetric and asymmetric hydrogen bridges into puckered structures (Si-H···O(3)⁺) with low energy barriers of 0.22 eV and 0.15 eV, respectively. Annealing reactions with protons generate Si dimers and H₂ molecules. Furthermore, electron capture by the puckered structure causes its collapse, forming a deep-level defect within the silicon band gap. This study provides atomic-scale insight into the origin of fixed positive charge, offering important theoretical guidance for enhancing device reliability.