Improved adhesion of amorphous carbon thin films on glass by plasma treatment

We investigated the effects of plasma treatment on adhesion of sputter deposited amorphous carbon thin films to glass. Prior to the deposition, the glass surface was exposed under argon (Ar), oxygen (O2), or hydrogen (H2) plasma, and subsequently the films were deposited onto the glass by direct current magnetron sputtering. The adhesion strength of the film was considerably improved by the plasma treatment. X-ray photoelectron spectroscopy analysis revealed that silicon-carbon bonds were formed at the interface between the films and plasma-treated glass, which were not observed for the film deposited onto the glass without plasma treatment, and that the number of silicon-carbon bonds was larger for the film having higher adhesion strength. These results indicate that the silicon-carbon bonds at the interface are a major factor governing the adhesion strength of the films to glass. Furthermore, it was also found that Ar and H2 plasma were more effective to create the silicon-carbon bonds at the interface than O2 plasma. This difference can be understood in terms of the difference in interactions between the introduced gas and dangling bonds associated with silicon formed by plasma treatment