The effect of multiple film-forming species on the film quality during chemical vapor deposition (CVD) of SiC from CH3SiCl3/H2 was examined by separating each species using high aspect-ratio (AR) parallel-plate microchannels. Profiles of the chemical and physical properties of the grown SiC films, including the composition, crystallinity and surface roughness, were characterized along the microchannel depth. The exceptionally high AR, which was typically more than 1;000 : 1, allowed film growth with a variety of film-forming species that significantly changed with depth. We were thus able to examine the effect of each film-forming species on film growth. The exceptionally large depth, which was typically centimeterscale, allowed depth profile analysis using various kinds of film characterization techniques having large detection areas. For CVD SiC from CH3SiCl3/H2, multiple film-forming species with different sticking probabilities of 8 X 10-7, 1X10-4, and 2X10-2 provided almost the same film quality.