Multilayer film deposition of TiN/AlN on a rotating substrate holder from reactive sputtering of elemental targets of titanium and aluminum

Abstract

(Ti,Al)N x coatings have previously been deposited by reactive sputtering from (TiAl) targets. This article will report on a multilayer approach, where a substrate is rotating successively through sputter zones with targets of elemental Ti and Al. In reactive sputtering of these elements the well-known hysteresis curves of total pressure versus reactive gas flow for constant Ar flow were observed. It was then possible to select certain flow values of nitrogen and to maintain a constant sputtering pressure by using a PC process control. By variation of the substrate holder velocity a multilayer TiNx/AlNx system, with bilayer thicknesses from 1 to 8 nm, was studied. The multilayer film was characterized by the acoustic-emission scratch technique used in adhesion studies. Consistency between the various critical load values were achieved, and adhesion values between 40 and 80 N were measured; wear was also found to depend on the number of multilayers.