Substrate bias dependence of Raman spectra for TiN films deposited by filtered cathodic vacuum arc

Abstract

Raman spectroscopy was used to characterize TiN films deposited by using an off-plane double bend filtered cathodic vacuum arc technique. The influence of substrate bias on the Raman spectra was systematically studied. Four peaks at 235, 320, 440, and 570 cm−1, related to transverse acoustic (TA), longitudinal acoustic (LA), second-order acoustic (2A), and transverse optical (TO) modes of TiN, respectively, were observed in the Raman spectra of TiN films. The intensity of all four peaks and the area fraction as well as the full width at half maximum (FWHM) of the TO peak increase drastically with increasing substrate bias, reaching a maximum at −100 V, and then decrease greatly. However, the area fraction of TA, LA, and 2A peaks, the FWHM of TA and 2A peaks, as well as the frequency of all four peaks decrease rapidly with increasing substrate bias to −100 V, and then increase greatly. At a bias above −200 V, only a slight change in the Raman spectra of TiN films were observed. The change in the N/Ti ratio is the main reason for the evolution in the Raman spectra of TiN films with increasing substrate bias. The internal stress and the crystal size play only a minor role in the Raman spectra of TiN films in the present study.