Mechanisms of reactive sputtering of titanium nitride and titanium carbide III: Influence of substrate bias on composition and structure

• Published in: Thin solid films 1983-07, Vol.105 (4), p.385-393
• Main Authors: Sundgren, J.-E., Johansson, B.-O., Hentzell, H.T.G., Karlsson, S.-E.
• Format: Article
• Language: English
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/0040-6090(83)90320-6

Films of TiN and TiC were grown by reactive r.f. sputtering of titanium in mixed ArN 2 and ArCH 4 discharges on negatively biased substrates. The compositions of the films were measured using Auger electron spectroscopy and their structure and morphology studied using X-ray diffraction and scanning electron microscopy respectively. The composition was found to be strongly affected by the bias voltage. An increase in bias both the carbon and the nitrogen contents in substoichiometric films. However, when stoichiometric TiN is formed no further change in the composition occurs. For TiC films an increase in the carbon- to-titanium ratio above 1.0 is possible. The structure is also affected by the bias voltage. For example the grain size of TiN has a maximum at a bias of 200 V. A possible explanation is a double influence of the ion bombardment. At low voltages, the adatom mobility is enhanced and the grain size increases but as the bias increases resputtering of species from the growing film surface becomes increasingly important and the grain size decreases.