A thermodynamic estimation of the chemical vapor deposition of some borides

The temperature dependencies of the change in Gibbs energy for a series of probable reactions of chemical vapor deposition (CVD) of TiB2, ZrB2, NbB2, TaB2, and LaB6 using BCl3, BBr3, B2H6, B5H9, and B10H14 as boron sources have been plotted on the basis of thermodynamic data from the literature. It has been shown that from a thermodynamic point of view the deposition of these borides should proceed in all cases under milder conditions when boron hydrides are the boron sources. Is has been established that of the two boron halides BBr3 is the more suitable boron precursor in the CVD of the borides under consideration. Due to its properties this boron halide would probably prove especially appropriate for technological processes of transition metal diboride deposition. (C) 2000 Academic Press.