Micro/nanomechanical behavior of magnetron sputtered Si-C-N coatings through nanoindentation and scratch tests

Si-C-N/Si based MEMs are advantageous to conventional MEMS because of their ease of fabrication and high temperature sustainability. The failure mechanism of such systems has to be known for their efficient performance. Nanoindentation and scratch behavior were performed on Si-C-N coatings deposited on silicon substrates by RF magnetron sputtering. Crack growth and propagation were studied using optical and SEM views of the deformed region. Different failure mechanisms were observed and analyzed. The crack deflection was due to nanocrystalline phases in the Si-C-N nanocomposite film, as no such deflection was observed in the amorphous CNx film. A different failure mechanism in the form of tensile and conformal cracking was observed. The films' failure mechanism changes from cohesive failure at lower loads to adhesive failure at higher loads during nanoscratching.