Developments in the deposition of hard coatings by plasma-based techniques

Abstract

Titanium nitride (TiN), the most widely used hard material for coatings, offers an excellent example of developments in plasma-based techniques for the deposition of hard coatings. Chemical vapour deposition (CVD), which is widely used today, requires a deposition temperature of about 1000°C. The deposition of TiN at moderate temperature (⩽ 500°C) can be performed by plasma-based techniques. Reactive ion plating (RIP) was the first plasma-based technique for the deposition of high quality TiN and is now well established. To achieve good film uniformity it is necessary to rotate the work-pieces during the deposition procedure. Reactive high rate sputtering, which was developed later, faces the same problems of film uniformity if only one target is used. But this technique offers the possibility of using a double target arrangement, where the targets are situated on both sides of the work-pieces. With the superposed material flows from the targets achieved by this setup, a fairly good film uniformity can be obtained. Recent developments in plasma CVD show that high quality TiN coatings with good uniformity can also be obtained at moderate temperature by this technique, but special attention must be given to the design of the gas inlet and gas distribution system.