Wetting and Adhesion Behaviors of a-C:H Film Deposited on Nano-Scale Copper Doted Surfaces

Abstract

The wetting and adhesion properties of undulated a-C:H surfaces were investigated. The nano-undulated a-C:H films were prepared by radio frequency plasma enhanced chemical vapor deposition (r.f. PECVD) using nanoscale Cu dots surface on a Si (100) substrate. FE-SEM and AFM analysis showed that the surface had nanoscale undulations. Raman spectra of film showed that the plasma induced damage with Ar ions significantly suppressed the graphitization of a-C:H structure. Also, it was observed that the untreated flat a-C:H surfaces had a water wetting angle of 72° and adhesion force of 333 nN. After the treatment for the undulated a-C:H surfaces whose surface morphologies change to an array of pillar asperities, its wetting angle of water increased up to 104° and adhesion force decreased down to 11 nN. These results agree with the estimation of real area of contact on the basis of Hertz and JKR adhesion models. The effect of the surface undulation treatment was discussed with the following factors: the surface morphology affinity to pillar shape, a reduction of the real area of contact and air pockets trapped in pillar double asperities of the surface.

Keywords

• a-c:h
• surface undulation
• wetting angle
• adhesion force
• real area of contact