Stress-induced diffusion suppression and defect-related B-mode breakdown in thermal SiO2 on Czochralski silicon

We present an analytical model describing the degradation of the dielectric breakdown field in thermal SiO2 films grown on Czochralski (CZ) silicon substrates containing void-type defects, such as crystal-originated particles. The model quantitatively reproduces the experimentally observed inverse square-root dependence of the breakdown field on oxide thickness, as well as the distinct breakdown characteristics between dry and wet oxidation. Within the framework of the classical Deal–Grove oxidation theory, we incorporate the effect of locally enhanced stress at concave defect regions. The stress is assumed to suppress the oxidant diffusion coefficient, leading to a reduction of the parabolic oxidation rate constant and consequently to localized oxide thinning. This geometrical thinning enhances the local electric field and induces defect-related B-mode breakdown. The present formulation provides a physically consistent explanation of oxide-thickness-dependent breakdown behavior in defect-containing CZ silicon and offers a unified interpretation of stress-induced degradation mechanisms in thermal oxides.