Sputter Deposition with Conducting Targets

As mentioned above, Hackenberger et al. [41] concluded that stoichiometric or nearly stoichiometric BN films contained the highest amount of the cubic phase. In sputter deposited films both from the hBN target and the B4C target, atomic ratios B N 1 in the films were achieved [21,24,54]. 

The process data for the sputter deposition of cBN films by RF (13.56 MHz) diode sputtering with hBN and B4C targets as well as by d.c. magnetron sputtering with B4C targets have been reported in detail elsewhere [21,24,54]. In both configurations the ionization was enhanced by additional magnetic coils positioned around the substrate holder. The substrate electrodes were operated either with a d.c. potential, with pulsed d.c. [57] or with RF power. 

Some important parameters of the deposition experiments with conducting targets will be summarized as follows. 

Cross-section TEM investigations of these sputter deposited films revealed the typical phase evolution well known for cBN films. Electron diffraction patterns indicated that in our films the c-axis ([0002]) of turbostratic BN is parallel to (111) direction of cBN and both are perpendicular to the substrate normal [58]. 

The maximum thicknesses reached so far with the both sputter techniques were about 500 nm on Si and about 200 nm on steel substrates. 

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Recently, interesting results have been obtained in this field by combining the plasma polymerization and sputtering methods. For instance, the synthesis of composite thin films made of platinum nanoclusters (3-7 nm) embedded in a porous hydrocarbon matrix was carried out by simultaneous PECVD of pp-ethylene and sputtering of a platinum target. The metal content in the films could be controlled over a wide range of atomic percentages (5-80%) (Dilonardo et al., 2011). Aniline mixed with functionalized platinum nanoparticles as a precursor of PECVD was, in turn, used to prepare a typical 3D-catalyst. The plasma deposition was performed under atmospheric pressure conditions. Plasma polymerized aniline (pp-aniline), which is characterized by both electronic and ionic conductivity, associated with the Pt catalyst in a 3D porous network, without doubt lead to the development of the three-phase boundary (Michel et al., 2010). 

Today SiC thin films (< 1 pm thickness) can also be produced by physical vapor deposition (PVD), for example by sputtering, which method allows lower substrate temperatures, but works more slowly. Electrically conductive B/N-doped sintered aSiC with up to 9weight-% free carbon has been developed as target material, [133]. Novel applications for PVDSiC include films for computer storage media, protective coating for lenses, and microwaveable packaging for food. 

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