Effect of SiNx interlayer thickness on adhesion and friction properties of diamond-like carbon films

A suitable interlayer thickness is critical to reduce film mismatch and roughness. In this text, diamond-like carbon (DLC) films with different SiNx interlayer thicknesses were successfully synthesized on Si (100) substrates by radio frequency (RF) and direct current (DC) magnetron sputtering method. The effect of SiNx interlayer thickness on surface morphology, adhesion, tribological and mechanical properties of DLC films was investigated. The results show that, due to the use of SiNx interlayer in the DLC films, the adhesion is significantly enhanced, the surface roughness is increased, and the spa content and modulus are lowered. When the SiNx interlayer is introduced, the intemal stress and the roughness decrease first decrease and then increase. The reason may be related to the accumulation of nitrogen vacancy centers (NVC). A sample of about 10 nm SiNx interlayer was found to have the best combination of tribology, mechanical properties, and surface roughness.