Dielectric breakdown mechanism of Hf -silicate high-k gate dielectrics.

Abstract

Dielectric breakdown mechanism of Hafnium (Hf) silicate film has been discussed, on the basis of the temperature dependence of the charge-to-breakdown (Qbd). It has been found that the activation energy of Qbd as a function of reciprocal temperature was around 0.1 eV, irrespective of the injection direction of electrons. The activation energy of Qbd for Hf-slicate gate dielectrics is almost same as that for silicon-dioxide (SiO2). Furthermore, it was found that Qbd for Hf-silicate was remarkably small, compared with that for SiO2. On the basis of the experimental results, the dielectric breakdown model for Hf-slicate dielectrics is proposed in this paper. It is inferred that, in high temperatures, the dominant mechanism for the dielectric breakdown is the hydrogen-related process, irrespective of the material of the gate dielectrics. We consider that a large amount of the defects in Hf-silicate films brings about the relative small life-time, compared with that with SiO2.