SiC coatings grown by liquid injection chemical vapor deposition using single source metal-organic precursors

Abstract

SiC coatings have been grown by direct liquid injection of organosilanes in a hot-wall chemical vapor deposition reactor (DLICVD). 1,3-disilabutane (DSB) and polysilaethylene (PSE) were used as single-source precursors. Amorphous and stoichiometric SiC coatings were deposited under low pressure on various substrates in the temperature range of 923–1073K. Thickness gradients due to the temperature profiles and the precursor depletion were observed along the reactor axis but the thickness uniformity could be improved as a function of the deposition conditions. Growth rates as high as 90μm·h−1 were obtained using pure precursors. The injection of PSE solutions in toluene significantly reduces the deposition rate due to the decrease of the PSE mole fraction but allows a better control of the growth rates and the microstructure of coatings. They exhibit a smooth surface morphology and a very dense structure. The films grown using pure precursors exhibit an Si:C atomic ratio equal to 1:1 while those using toluene solutions are slightly C-rich (54at.% C). The presence of solvent vapor in the CVD reactor becomes a source of carbon contamination at deposition temperatures equal to or higher than 1073K. The influence of the growth conditions is discussed, in particular the presence of toluene vapor.