Effects of high field injection on the hot carrier induced degradation of submicrometer pMOSFET´s

The interaction between the hot carrier (HC) induced pMOSFET´s degradation and the Fowler-Nordheim (FN) injection is investigated. It has been found that the FN injection is an efficient method to recover pMOSFET´s from the HC induced degradation. This is achieved by removing some of the trapped electrons from the oxide and forming positive charges along the channel. The relative importance of these two factors is determined. The contribution of the interface states created by FN injection is negligible, since they are acceptor-like and not charged during pMOSFET´s operation. The positive charges increase the lifetime of a recovered pMOSFET by requiring more electron trapping to compensate their effects on the threshold voltage. They also enhance the magnitude of punchthrough voltage. The effects of FN injection on the HC trapping kinetics are discussed. Under our experimental conditions, the new trapping sites created by FN injection are negligible, compared with the as-grown traps. When a recovered pMOSFET is stressed again, its degradation rate is not higher than that of a fresh pMOSFET. This allows FN injection to be used repeatedly and we can therefore control the pMOSFET´s degradation within a given range