Controlling the concentration and position of nitrogen in ultrathin oxynitride films formed by using oxygen and nitrogen radicals

The formation of oxynitride films less than 2.0 nm by using oxygen and nitrogen radicals produced by an electron cyclotron resonance plasma in an ultrahigh-vacuum system has been studied. We found that the N concentration can be controlled at values up to 15% and that, although the interface roughness tends to increase with increasing N concentration, supplying oxygen and nitrogen radicals simultaneously decreases the roughness of the film and increases its nitrogen concentration (N: 12.1%, root mean square: 0.12 nm). We also could easily control the nitrogen profile in the oxynitride less than 2.0-nm-thick by using different processing sequences.