Titanium containing DLC coatings from a PACVD process using titanium (IV) isopropylate as a precursor

Abstract

We report here the plasma activated deposition of Ti-DLC films using titanium (IV) isopropylate as a precursor. Gas phase processes during film deposition were analyzed using a differentially pumped quadrupole mass spectrometer (QMS). The film composition and the chemical nature of the film elements Ti, C and O were obtained using X-ray induced photoelectron spectroscopy (XPS). These measurements were complemented by the determination of the film growth rate. With decreasing U(SB) (increasing rf power) the QMS measurements demonstrated a change in the fragmentation pattern of the precursor, especially in the range of U(SB) between -100 and -300 V. These gas phase changes correlate with changes in the film composition, film hardness and adhesion behavior. With XPS we determined for U(SB) = -900 V the film composition of Ti-O-C:H coatings to be: 48 at% C, 29 at% O and 23 at% Ti. We note that the Ti content of the film is significantly higher than that of the precursor (5.9 at% Ti). With decreasing self-bias voltage (-100 to -400 V) the C/Ti ratio in the film decreases from 2.5 to below 2. Further, we note also a slight decrease of the O/Ti ratio with decreasing U(SB). Analyzing the Ti 2p doublet with XPS we find that for U(SB) = -100 to -200 V, TiO2 is the predominant Ti species. For U(SB) ≤ -200 V a second Ti doublet evolves at lower binding energy which is related to the presence of TiC. The development of Ti-C bonding is also detected in the C 1s spectra. (C) 2000 Published by Elsevier Science S.A. All rights reserved.