Nitridation for HfO₂ high-k films on Si by an NH₃ annealing treatment

The characteristics of nitrided Hf O2 films suggest that the diffusion of Si from the Si substrate to the film surface is induced by annealing in an N H3 ambient and that the incorporation of N is closely related to the diffusion of Si. Changes in the core-level energy state of the N 1s peaks of nitrided Hf O2 films indicate that the quantity of N incorporated into the film drastically increases with increasing annealing temperature, especially at temperatures over 900 °C. The incorporated N is mostly bonded to Si that diffused from the Si substrate into the film, while some N is incorporated to Hf O2 at high annealing temperature. Some molecular N2 is generated in the film, which is easily diffused out after additional annealing. Moreover, the chemisorbed N in the film is not completely stable, compared to that at the interfacial region: i.e., the N in the film predominantly out diffuses from the film after additional annealing in a N2 ambient.