EFFECTS OF HIGH-FIELD INJECTION ON THE HOT-CARRIER-INDUCED DEGRADATION OF SUBMICROMETER PMOSFETS

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