Control of Nitrogen Depth Profile and Chemical Bonding State in Silicon Oxynitride Films Formed by Radical Nitridation

• Published in: Japanese Journal of Applied Physics 2005-10, Vol.44 (10R), p.7395
• Main Authors: Kawase, Kazumasa, Umeda, Hiroshi, Inoue, Masao, Tsujikawa, Shimpei, Akamatsu, Yasuhiko, Suwa, Tomoyuki, Higuchi, Masaaki, Komura, Masanori, Teramoto, Akinobu, Ohmi, Tadahiro
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.44.7395

Chemical bonding states and depth profiles of nitrogen in radical nitrided silicon oxide film formed in Ar/N 2 plasma excited by microwave has been investigated using X-ray photoelectron spectroscopy with HF step etching. The main chemical bonding state of nitrogen atom is Si 3 ≡N configuration, and the other unknown bonding state (termed N high ) is observed, whose peak energy shift is about +4.8 eV. The nitrogen atoms forming Si 3 ≡N configuration accumulate only at the film surface and those forming N high configuration are distributed deeper in the films. The N high bond is very weak because it is desorbed completely at low temperature (300–500°C). Although the nitrogen atoms forming N high configuration are removed by post O 2 -annealing, those forming Si 3 ≡N configuration migrate toward the film/substrate interface and they increase negative bias temperature instability. In the case of ultra thin film, nitriding species forming N high bond reach the film/substrate interface and form Si 3 ≡N bond at the interface. Suppression of the generation of nitriding species forming N high bond in the plasma is very important. It is clear that N high bond is reduced using Ar/NH 3 plasma.