Polysilicon / SiO2 Interface Microtexture and Dielectric Breakdown

Abstract

An analysis has been made of interfacial texture created during the wet oxidation of polycrystalline silicon (polysilicon) over the temperature range 950°–1100°C, and the effect of this texture on oxide breakdown. Four types of interfacial textural features are described: interface roughness due to initial polysilicon surface texture, "bumps" caused by anomalous polysilicon nucleation at local sites of contamination, "protuberances" that occur during oxidation, and inclusions of unoxidized silicon within the oxide. Models for the generation of the last two defects are presented, and the role of interfacial texture in dielectric breakdown is discussed.