Low-k silicon carbonitride (SiC xN y) films with k of 3.6-4.6 were prepared by radio frequency plasma-enhanced chemical vapor deposition at 25 to 400°C under low power density of 0.15 Wcm 3, using a single source precursor, 1, 3, 5-trimethyl-1, 3, 5- trivinylcyclotrisilazane (VSZ), and Ar. At lower deposition temperatures (≤ 200°C), most cyclic VSZ structures were preserved in the SiC xN y films, resulting in a lower density (1.60-1.76 gcm 3), a lower dielectric constant (k∼3.6-3.9) and a fairly good elastic modulus of 22.0-25.0 GPa. When the deposition temperature was raised to 400°C, the cyclic N-Si-N linkages were reformed to a dense Si-N structure, with the desorption of CH x bonds, resulting in higher density (2.0 gcm 3), a dielectric constant of 4.6, and an excellent elastic modulus of 65.2 GPa. The leakage current density of SiC xN y films was reduced from 1.5×10 -6 to 4.0×10 -8 Acm 2 at 1 MVcm, upon increasing the deposition temperature from 25°C to 400°C. The conduction mechanism of the SiC xN y films, except the film deposited at 400°C and tested under higher electric field, exhibited Schottky emission due to few charged defects by using a cyclic VSZ precursor and a lower plasma power density of 0.15 Wcm 3.