EFFECT OF SUBSTRATE BIAS ON SPUTTER-DEPOSITED TICX, TINY AND TICXNY THIN-FILMS

Carbides and nitrides of transition metals such as Ti attract signific ant interest since they find a wide field of applications ranging from high-temperature structural materials to contact layers in solar cell s. In the present study we report on the influence of the bias voltage on the development of TiCx, TiN, and TiC(x)Ny films (600-3000 Angstro m thick) developed by magnetron sputtering. The TiCx films were deposi ted by rf. magnetron sputtering from TiC targets, while the TiNy and T iCxNy films were deposited by d.c. and r.f. reactive sputtering from T i and TIC targets, respectively The bias voltage was varied from 0 to 200 V for all three types of film. In-situ spectroscopic ellipsometry (SE) was used in the energy region 1.5-5.5 eV to monitor film characte ristics. Auger electron spectroscopy (AES), X-ray photoelectron spectr oscopy (XPS), X-ray diffraction (XRD) and microhardness measurements w ere taken to characterize the composition, stoichiometry, structure, q uality and integrity of the films as a function of the bias voltage. F or the present deposition conditions, the substrate bias voltage was f ound to have a significant effect on the stoichiometry and structure o f all three types of films. The results show that for TiNy films the s ubstrate bias can promote stoichiometry and structure refinement throu gh resputtering effects. For TiCx and TiCxNy films, substrate bias can influence stoichiometry and structure by increasing reaction probabil ities (of carbon and nitrogen, respectively) in the plasma through ion ization and plasma activation effects. Mechanistic aspects of the film development process are discussed in view of the in-situ SE results a nd the post deposition AES, XPS, XRD and microhardness evaluation.