Low-k Si–O–C–H composite films prepared by plasma-enhanced chemical vapor deposition using bis-trimethylsilylmethane precursor

Low-k Si–O–C–H composite films were prepared using bis-trimethylsilylmethane as a precursor and oxygen in a rf plasma reactor. The growth rate of the Si–O–C–H composite film followed a second-order exponential decay function. This behavior could be explained by the formation of nanosized voids due to ${\mathrm{Si–CH}}_3$ and OH-related bonds included in the film. OH-related bonds were detected in films deposited at 30 °C, but could not be observed for the films deposited above 60 °C. In contrast, ${\mathrm{Si–CH}}_3$ bonds were also detected at 30 °C, but decreased monotonically up to 210 °C and were absent of higher temperatures. After postannealing the film deposited at 30 °C, the ${\mathrm{Si–CH}}_3$ bonds were unchanged, but the OH-related bonds were easily removed. This film showed a low dielectric constant of 2.44 and leakage current density of ${\text{4.4×10}}^{\text{−7}}$ ${\mathrm{A/cm}}^2$ at 1 MV/cm.