Observation of critical gate oxide thickness for substrate-defect related oxide failure

Abstract

The presence of crystal originated particles in silicon substrates leads to gate oxide failures in metal–oxide–semiconductor devices. A nonlinear relationship is known to exist between the oxide defect density and the oxide thickness, but the mechanism behind this remains unclear. In this work, we evaluate the gate oxide integrity for oxide thicknesses ranging from 2.5 to 26.5 nm. The results show no appreciable oxide degradation below an oxide thickness of approximately 5 nm; above this threshold value, the defect density depends strongly on the presence of crystal originated particles. Oxide thinning is unlikely to be responsible for this behavior.