Change in phase separation and electronic structure of nitrided Hf-silicate films as a function of composition and post-nitridation anneal

The thermal stability and electronic structure of nitrided xHf O2 (100-x) Si O2 (HfSiO) (x=25%, 50%, and 75%), prepared using an N H3 annealing treatment, were investigated. The quantity of N incorporated into the Hf-silicate film was dependent on the mole fraction of Si O2 in the film: i.e., a silicate film containing a high mole fraction of Si O2 contained a higher quantity of N, resulting in the suppression of phase separation. In particular, the incorporated N easily diffuses out through a silicate film that contains a small quantity of Si O2 during the post-nitridation anneal, while in a film with a high quantity of Si O2, it is relatively stable. The phase separation effect in the nitrided film with a low Si O2 mole fraction was significantly influenced by the stability of N in the film and interface.