Multi-layer carbon nitride thin films prepared by repeated process of carbon sputter-deposition and nitrogen ion implantation

Multi-layer carbon nitride (CNx) films have been deposited onto Si (100) substrates by repeated process of DC magnetron sputter-deposition and nitrogen ion beam (N⁺/N2⁺) implantation. The composition, bonding structure and mechanical properties of multi-layer CNx films prepared by the repeated process were investigated. Depth profile studies by X-ray photoelectron spectroscopy (XPS) showed that it is possible to control the layer structure by regulating sputter deposition time and ion beam energy in the repeated process. Two different films were fabricated and compared. The one is a multi-layer film of carbon and carbon nitride and the other is a homogeneous layer film of carbon nitride. Measurements of internal stress of the films showed compression. Variation in the morphology of multi-layer CNx films and non-irradiated CNx film deposited by pure N2 gas sputtering was examined by scanning electron microscopy (SEM). Nanoindentation studies revealed that the hardness of multi-layer CNx films was higher than that of non-irradiated CNx film.