Inhomogeneous deposition of TiN by pulsed PACVD caused by a plasma dynamiceffect

In the present work. we investigate the time development of pulsed d.c. pla smas relevant for the production of TiN coatings by PACVD. A videocamera wi th gateable image-intensifier is used for studying the spatial and temporal evolution of the light intensity of the plasma. Additionally, we use a sin gle electrostatic probe to determine a time-resolved charged particle distr ibution of the plasma during the pulses and afterglow. In the presence of e lectronegative 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 di stribution of quality and thickness of the coatings. Langmuir-probe measure ments demonstrate the conversion of electrons into negative ions during the time interval between the pulses. (C) 1999 Elsevier Science S.A. All right s reserved.