PROCESS AND PROPERTY RELATIONSHIPS IN HARD COATINGS MADE BY PLASMA-ASSISTED AND ION-ASSISTED METHODS

The relationship between the process parameters and the properties of the resultant hard coatings is discussed. Two approaches are considered: plasma-assisted chemical vapor deposition (PACVD) and ion-assisted physical vapor deposition (IAPVD). In PACVD the plasma is used to activate the gaseous precursors and the film is formed during ion-molecule and radical-molecule reactions in the plasma bulk and at the plasma-surface boundary. In IAPVD, partially ionized metal vapor is injected into an argon-supported plasma together with a reactive gas; these precursors react at the substrate surface to form the film under intense ion bombardment and at a reduced pressure. The correlation between experimental variables and properties of the deposits is illustrated with hard nitride films, namely Si3N4 made by PACVD and TiN made by IAPVD. Two picostructural examples are illustrated: argon entrapment in TiN made by IAPVD, and lattice strain effects on the Raman spectrum of diamond films made by (microwave) PACVD.