Surface engineering has enabled dramatic improvement in the lifetime of machining tools as a direct result of the development of hard nitride coatings such as titanium nitride (TiN), chromium nitride (CrN) and titanium aluminium nitride (TiAlN). More recently, TiAlN coatings have attracted a great deal of interest owing to their extremely high hardness, durability at higher temperatures, improved wear and corrosion resistance.
The current project is a preliminary investigation in the deposition of TixNbyNz thin films with the aim being to establish the basic relationships between the films material properties, such as structure, morphology, microstructure, and the various deposition parameters available during reactive DC co-sputtering.
The TiNbN films investigated in this study were produced by reactive DC magnetron co-sputtering (AJA Int, Orion 5 system) with individual Titanium (99.9%) and Niobium (99.9%) targets that were varied in discharge power from 0-150 W to yield a range of Ti:Nb compositions. The substrates were p-Si (100) wafers and the typical deposition pressure was 3 mTorr argon with p(N2) fixed at 0.6 mTorr. Alternative deposition parameters were also investigated to reveal their influence on the structure of the TixNbyNz films.
The composition, deposition rate and grain size all show a clear relationship with the applied Nb/Ti discharge power. It is also clear that the deposition of Nb is less affected by the presence of nitrogen than that of the Ti. Upon increasing the nitrogen partial pressure, the deposition rate is observed to decrease markedly from 8.8 nm/min to 5.6 nm/min, and is significantly higher when the p(N2) is reduced.
TixNbyNz has been deposited under a range of deposition conditions, such as deposition pressure, p(N2) and applied bias. It is apparent that the selection of p(N2) is vital is determining not only the deposition rate of the TixNbyNz films, but also the structure and microstructure.