1/f noise and aging effects on MOS transistors

Abstract

The 1/f noise magnitude of n-channel metal-oxide-semiconductor field effect transistors is found to decrease by up a factor of ~3 after 18 years of room-temperature aging. This decrease is largest in devices with high-temperature post-gate-oxidation nitrogen annealing, which increases the densities of O vacancies and strained Si-Si bonds near the silicon/silicon dioxide interface. Approximately 100 mV positive threshold voltage shifts are observed for all device types during aging; these are attributed to reactions with hydrogenous species (e.g., water vapor). The aging related changes in 1/f noise may well be caused by the relaxation of strained Si-Si bonds associated with O vacancies in the near-interfacial silicon dioxide layer.