Impacts of strained SiO/sub 2/ on TDDB lifetime projection

We clarify the effects of the strained-SiO/sub 2/ on the time dependent dielectric breakdown (TDDB) characteristics, the activation energy of the oxide breakdown and Weibull slope (/spl beta/) for the ultra-thin gate oxide. Considerations based on the extended-Stillinger-Weber potential model show that the built-in compressive strain in SiO/sub 2/ changes the statistical distribution of the Si-O-Si angle, leading to a decrease of T/sub pd/ and a spread of the distribution. The oxide breakdown tends to occur at the Si-O-Si network with a lower bond angle (/spl sim/115/spl deg/) for the 2 nm-thick SiO/sub 2//Si system.