Phase and thickness dependence of thermal diffusivity in a-SiC_xN_y and a-BC_xN_y

Thermal diffusivity (α) and bonding configuration of amorphous silicon carbon nitride (a-SiC_xN_y) and boron carbon nitride (a-BC_xN_y) films on silicon substrates were studied. Measurement of α by the traveling wave technique and bonding characterisation through X-ray photoelectron spectroscopy in a-SiC_xN_y and a-BC_xN_y films having different carbon concentrations revealed that lower coordinated bonds were detrimental to the thermal diffusivity of these films. Furthermore, α was found to depend on the thickness of these films deposited on silicon. This was attributed to the interface thermal resistance between two thermally different materials, the film and the substrate, although other factors such as film microstructure could also play a role. An empirical relation for the variation of thermal diffusivity with thickness is proposed.