Etching behaviour of pure and metal containing amorphous carbon films prepared using filtered cathodic vacuum arc technique

A preliminary study on the etching behaviour of pure and metal containing amorphous carbon (a-C) films has been studied using reactive ion etching (RIE) as well as reactive ion beam etching (RIBE). The RIE etching of a-C films, prepared from pure and 1 at.% Al containing carbon cathodes, displays a significant increase in etching rate with increase in discharge power. The inclusion of even a small percentage of metal causes a drastic reduction in the etching rate. The films that contain higher percentages of metal become more difficult to etch using RIE with oxygen plasma. Therefore, etching of the samples by RIBE technique using a plasma mixture of oxygen and argon has been carried out. A significant reduction in the etching rate with increasing metal content was observed for both Al and Ti containing a-C films. This led us to try etching of Ti containing a-C films by RIE technique using a plasma mixture of CF4 and oxygen. The result shows that the etching rate increases with increasing Ti content. The analysis of the etched surfaces measured by visible Raman indicates that all the surfaces remain almost the same regardless of the processes undergone. However, the morphology measured using Atomic Force Microscopy (AFM) shows that the surface roughness increases significantly after etching, especially for the pure carbon films.