Generation of Hole Traps in Silicon Dioxide Under Fowler-Nordheim Stress

Abstract

AbstractHigh field electron injection in silicon oxide layers in metal-oxide-semiconductor system is widely known to degrade thin silicon oxide layers and the silicon-oxide interface, eventually leading to catastrophic oxide breakdown. In this work we report generation of hole traps under high-field stressing of thermal silicon dioxide layers on silicon. Excess hole trapping on newly generated hole traps is observed by substrate hot-hole injection in 9 nm oxide PMOS transistors after high-field Fowler-Nordheim stress followed by standard post-metallization annealing in nitrogen. The concentration of generated traps is stress-polarity dependent and increases with electron fluence during degrading stress. Relaxation behavior under switching oxide fields indicates that the nature of hole trapping sites is different from anomalous positive charge centers. A correlation of density of generated hole traps with the amount of generated electron traps shows that both types of traps are effectively generated in the oxide layer under Fowler-Nordheim tunneling electron injection.