V. Cholet et al., CHARACTERIZATION OF BORON-NITRIDE FILMS DEPOSITED FROM BCL3-NH3-H-2 MIXTURES IN CHEMICAL-VAPOR INFILTRATION CONDITIONS, Journal of Materials Science, 29(6), 1994, pp. 1417-1435
Boron nitride (BN) thin films deposited by isopressure and isothermal
chemical vapour infiltration (ICVI) from BCl3-NH3-N-2 mixtures have be
en characterized from a physicochemical point of view as functions of
both the deposition conditions and the destabilizing action of moistur
e. As-deposited (deposited at 773 K and post-treated at 1273 K), the B
N films are turbostractic (d(002)=0.36 nm, L(c)=1.5 nm), have a low de
nsity (1.4 g cm(-3)) and contain oxygen (about 20 at %). A first oxyge
n content (191.5 eV by XPS) is inserted in the films during the CVI st
ep in relation to the hygroscopy of intermediate solid products and th
e quasi-equilibrium between the formation of BN and B2O3. A second oxy
gen content (192.5 eV) is due to the hydrolysis of BN by moisture whic
h induces a very drastic transformation of BN. This destabilization af
fects both boron and nitrogen atoms and leads to the formation of ammo
nium berate hydrates. Different post-treatments have been investigated
to stabilize the BN films and it appears that nitriding under ammonia
is the most efficient.