CNx coatings deposited by pulsed RF supersonic plasma jet: hardness, nitrogenation and optical properties

A low pressure pulsed RF supersonic plasma jet system (RPJ) has been used f or deposition of CNx thin films. The aim of the CNx thin films deposition w as an application for tribological coatings. Chemical composition, mechanic al and optical properties of deposited CNx films have been measured. The ob tained parameters were found to be similar to those of CNx films prepared b y DC magnetron sputtering. The deposition rate for the CNx films prepared i n RPJ reactor was of approximately 2 mum/h. During the deposition process, the substrate temperature did not exceed 250 degreesC, as required for cert ain kinds of machine tribological coatings. A strong correlation between DC bias magnitude, nitrogen concentration and mechanical properties was found . The value of the substrate bias V-DC = -100 V was found to be optimal for deposition of hard CNx films with maximum microhardness H = 22 GPa. The fi lms with the highest microhardness had the lowest atomic concentration of n itrogen. Analogous correlation has been found in 'Diamond Relat. Mater. 7 ( 1998) 417', although the deposition method and conditions were quite differ ent. The chemically active plasma has been investigated in the RF supersoni c plasma jet channel during the deposition process by means of 'in situ' em ission spectroscopy. The mechanism of CN., formation has been studied as we ll. (C) 2001 Elsevier Science B.V. All rights reserved.