X-ray diffraction stress analysis of interrupted titanium nitride films: Combining the sin2ψ and crystallite group methods

Abstract

Interruptions during film growth have been discussed by researchers to assist in understanding the evolution of stress in physical vapour deposition films. A change in intrinsic stress is directly related to microstructure, hence careful analysis of stress in films can provide valuable structure–stress correlated information. In this study we discuss the use of combining two X-ray diffraction (XRD) stress analysis methods to elucidate the effect of interruptions during growth on the residual stress of TiN films. The sin2ψ and crystallite group method (CGM), scanning the (220) peaks from all grains in the film and only (111) oriented crystallites respectively, were used to analyse residual stress in standard and interrupted cathodic arc TiN films 1.5, 3.5 and 6.5μm thick, grown on high-speed steel substrates. The sin2ψ method does not reveal any changes in stress with interruptions, however, measurements using the CGM show increased compressive stress and increased a0 in the resultant TiN films. A comparison of results from both XRD methods indicates that an increased compressive stress from interruptions could be due to an increased number of defects in (111) oriented grains during the interruptions which would also affect a0 as evident. In both methods, compressive stresses are found to decrease with increased thickness of films.