Study of temperature dependence of breakdown voltage and AC TDDB reliability for thick insulator film deposited by plasma process

Abstract

In this paper, temperature dependence of breakdown electrical field (Ebd) and time-to-failure (TTF) in AC TDDB for thick insulator film (300 nm) deposited by plasma process are discussed. In SiO2 film deposited using TEOS and O2 gases, increase of both Ebd and TTF beyond 100 °C is observed. On the other hand, in the SiO2 film and SiN film involving nitrogen, both Ebd and TTF decrease with increasing temperature. In order to explain this difference, we focused on the type of conductivity and introduced de-trapped effect by thermal energy. And we proposed a simple model to explain the temperature dependence of those AC TDDB results. In the SiO2 film deposited using TEOS and O2, the temperature dependence of number of trapped carrier is smaller because the conductivity type is the FN tunnelling, while the number of de-trapped carrier significantly increases with temperature and the TTF beyond 100 °C becomes longer. In these films involving nitrogen, the de-trapped effect is negligible because the number of trapped carrier exponentially increases with temperature because of Poole-Frenkel conductivity.