Mp. Johansson et al., MICROSTRUCTURE OF BN-C FILMS DEPOSITED ON SI SUBSTRATES BY REACTIVE SPUTTERING FROM A B4C TARGET, Thin solid films, 287(1-2), 1996, pp. 193-201
The microstructure and composition of boron nitride:carbon (BN:C) thin
films prepared by reactive r.f. diode sputtering of a B4C target in m
ixed Ar and N-2 discharges were determined by high-resolution electron
microscopy, electron diffraction, infrared spectroscopy, electron pro
be microanalysis, and X-ray photoelectron spectroscopy. Films were pre
pared with three characteristic phase compositions; cubic BN:C (c-BN),
turbostratic BN:C (t-BN), and phase mixture of c-BN and t-BN on Si(00
1) substrates. While keeping the B/N ratio close to unity, phase struc
tures were mainly correlated to the energy and flux of impinging (Ar+ N-2(+)) ions towards the negatively d.c. biased substrate. At a cons
tant ion flux, substrate biases of 500 V yielded c-BN films while bias
es lower than 300 V resulted in t-BN. Films prepared with the same ion
flux and with biases between 300 and 500 V consisted of c-BN and t-BN
phase mixtures. The film phase evolution in c-BN films was from an in
itial amorphous BN:C (a-BN) layer, over a highly oriented t-BN layer w
ith the c axis parallel to the film surface, to a c-BN layer exhibitin
g (110) preferred orientation. Films consisting of c-BN and t-BN phase
mixtures were non-textured nano- to sub-microcrystalline. The c-BN la
yers/grains showed twinning on the c-BN(111) lattice planes. As-deposi
ted films contained as much as 5-15 at.% of C with mainly C-C and B-C
bonds. The film C content decreased with increasing volume fraction of
c-BN.