Direct Observation of Crystal-Originated Particles on Czochralski-Grown Silicon Wafer Surface and Effect on Gate Oxide Reliability

Abstract

We found that crystal-originated particles (COP) on a Czochralski-grown Si wafer surface consist of single pits and pair pits, using a pattern-defect inspection machine and SEM. The influence of these pits on the gate oxide reliability was studied by means of a time dependent dielectric breakdown (TDDB) test under constant voltage stress (8 MV/cm). It was clearly demonstrated that when the gate oxide thickness was around 10 nm, in the active region pair pits caused gate oxide failure, while single pits did not. It was also found that broad pair pits, formed by preferential oxidation/etching treatment, did not degrade the gate oxide reliability even when situated in the active region.