Optical emission spectroscopy of a PCVD process used for the deposition of TiN on cemented carbides

Abstract

In CVD processes enhanced by plasma excitation of the gaseous species the analysis of the optical emission spectra enables the direct observation of reactive species in the close vicinity of the growing film. In this paper we report on a new OES study of the PCVD process for the deposition of titanium nitride from pulsed DC TiCl 4–H 2–N 2–Ar discharges. From the results we expect a better understanding of the plasma processes used in the coating production. Using optimized conditions of spectra recording, we selected reliable signals (lines/bands) of 12 species (Ti, Ti +, Cl, Cl +, H 2, H, N 2, N 2 +, N, N +, Ar and Ar +) involved in the TiN deposition process. The OES measurements were made with successively modified process parameters. An analysis of the waveforms of both the discharge current and the OES signals gave insights into the dynamics of the pulsed discharge. The characteristic temporal evaluation of the discharge was attributed to the slow movement of the ionization front from the cathode to the anode.