Enhancement of the mechanical properties of the carbon nitride thin films by doping Original Research Article

Silicon doped carbon nitride (CNx) thin films were synthesized by hot-filament plasma enhanced chemical vapor deposition (HF-PECVD) technique. Slightly doped films showed enhanced mechanical behavior in terms of hardness with reference to undoped films as revealed by nanoindentation measurement. A 26 GPa hardness for the doped CNx was found without the film delamination from the substrate in comparison with 15 GPa for undoped CNx film. Substrate temperature influenced the mechanical properties of the deposited film. With the increase of substrate temperature from 50 to 650 °C, the hardness of the films increased about three times. The observed enhancement of the mechanical property was well supported by the optical measurement. With the increase of Si doping concentrations the film hardness decreases. The role of Si for the film hardening was discussed.