A strong demand exists for improved low-k intermetal dielectric materials, such as organosilicons, to enhance the performance of ultralarge scale integrated circuits. Pulsed-plasma enhanced chemical vapor deposition was used to deposit organosilicon thin films, from diethylsilane and oxygen. Fourier-transform infrared (FTIR) analysis showed significant organic content as well as hydroxyl and silanol moieties in the as-deposited materials. FTIR showed a complete removal of hydroxyl groups after annealing at 400 ° C for 1 h. This removal indicates a condensation reaction between proximal hydroxyl groups leading to the formation of additional Si-O-Si linkages, which would increase both the hardness and modulus of the film. Mechanical property measurements were in accordance with this hypothesis, as both the hardness and modulus increased by over 50% after annealing. Film structure and properties were strongly dependent on the precursor feed ratio. © 2005 American Vacuum Society.