Stoichiometry determination of reactively sputtered titanium-silicide

• Published in: Vacuum 1982-01, Vol.32 (10), p.665-667
• Main Authors: Blom, H-O, Berg, S, Ostling, M, Petersson, S
• Format: Article
• Language: English
• ISSN: 0042-207X; 1879-2715; 1879-2715
• DOI: 10.1016/0042-207X(82)94045-3

If SiH 4is exposed to a rf-plasma, the molecule will dissociate partly to solid Si. This technique has been successively used to form thin films of silicon e.g. for solar cells. However, if the SiH 4 is mixed with Ar it is possible not only to deposit Si onto exposed surfaces, sputter etching could also be performed. We have investigated the process of simultaneous plasma deposition and sputter etching of Si using a Ti-target in a rf-sputtering equipment. By varying the rf-power applied to the Ti-target it is possible to form thin films with different stoichiometry, TiSi x. Increasing sputtering power gives decreasing Si-content in the TiSi x-film. However, this can be compensated for by applying a small rf-bias to the substrate. This rf-bias is enough to cause plasma deposition of Si onto the substrate. By this technique, excess Si could be added to the growing TiSi x-film on the substrates. If the rf-bias is too large, however, sputter removal of the deposited silicon becomes predominant and no excess Si can be added to the substrate. We will report on the stoichiometry variations depending on rf-power and substrate bias for different mixtures of SiH 4+Ar. The stoichiometry of the TiSi x-films was determined by Rutherford Backscattering Analysis.