The mechanical properties of the SiOC(H) composite thin films with a low dielectric constant

SiOC(H) composite films with a low dielectric constant are deposited by an inductively coupled plasma chemical vapor deposition system with bis-trimethylsilymethane (BTMSM: H9C3SiCH2SiC3H9) precursor and oxygen gases. Mechanical properties such as hardness, elastic modulus and the atomic density of the film, which are very important for the application of thin films, are investigated by nano-indentation and elastic recoil detection methods. Fourier transform infrared spectroscopy is used to determine SiO and SiCH3 bonding configurations in the films. The formation of the SiOC ring-link mode by attaching CH3 groups to the SiOSi ring-link mode is responsible for the formation of nano-size voids in the film, and porosity depends on the carbon concentration in the film. The hardness and elastic modulus of the annealed SiOC(H) films are measured as 0.38∼0.43 and 4.0∼7.4 (GPa), respectively. A density of as-deposited film is reduced from 1.83 to 1.16 g cm−3 by annealing. The lowest dielectric constant of the annealed film is 2.1, in which the porosity and carbon concentration are 62 and 11%, respectively. The porosity increase within SiOC(H) film tends to decrease the hardness and elastic modulus of film.