Inhomogeneous deposition of TiN by pulsed PACVD caused by a plasma dynamic effect

In the present work. we investigate the time development of pulsed d.c. plasmas relevant for the production of TiN coatings by PACVD. A videocamera with gateable image-intensifier is used for studying the spatial and temporal evolution of the light intensity of the plasma. Additionally, we use a single electrostatic probe to determine a time-resolved charged particle distribution of the plasma during the pulses and afterglow. In the presence of electronegative species like TiCl4 the ignition of the plasma in each pulse is slow, reaching some parts of the cathode surface only after substantial delays. This phenomenon is most likely responsible for the inhomogeneous distribution of quality and thickness of the coatings. Langmuir-probe measurements demonstrate the conversion of electrons into negative ions during the time interval between the pulses. (C) 1999 Elsevier Science S.A. All rights reserved.