Local Thinning Induced Less Oxide Breakdown in MOS Structures Due to Lateral Non-Uniformity Effect

Abstract

The reliability of MOSCAPs with ultrathin gate oxide is investigated by constant voltage stress tests. The results show that the degradation behavior in gate oxide can be reduced by introducing lateral non-uniformity in oxide thickness to obtain lower sustaining electric field in oxide layer. The strong oxide field transition region between 2.5 nm and 3.5 nm SiO2 thickness is believed to be the origin for the observed degradation behavior, as confirmed by TCAD simulations.