Deposition pressure dependence of internal stress in TiN films deposited by filtered cathodic vacuum arc

Abstract

TiN films were deposited by an off-plane double bend filtered cathodic vacuum arc technique. The composition, structure, and surface morphology of the films were characterized by x-ray photoelectron spectroscopy, x-ray diffraction, and atomic force microscopy, respectively. Internal stress was determined by a substrate bending method. The influence of the deposition pressure on the composition, structure, and internal stress of the films was studied systematically. At a deposition pressure of 1×10−5 Torr, the films are composed of single α-TiN0.30 phase with fairly low internal stress, and the atomic ratio of N to Ti is 0.32. As the deposition pressure increases to 5×10−5 Torr, the N/Ti ratio increases to 0.56, and the films are composed of a mixture of hexagonal α-TiN0.30 and cubic TiN0.90. The formation of TiN0.90 phase and the mismatch of these two kinds of phases contribute to a dramatic increase of internal stress in the films. The increase of deposition pressure to 2×10−4 Torr results in the formation of stoichiometric TiN films with single TiN phase, which corresponds to slightly lower internal stress. However, a further increase of deposition pressure results in a continuous increase in the N/Ti ratio and the formation of overstoichiometric films. The incorporation of excess N atoms in the films accounts for the further increase of internal stress.