Wetting and Adhesion Behavior of Undulated a-C:H Film Deposited on Nano-Scale Copper Dot
This paper investigated the wetting and adhesion property of undulated a-C:H surfaces with surface morphology controlled for a reduced real area of contact. 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, AFM analysis showed that the after repeat deposition and plasma induced damage with Ar ions, the surface was nanoscale undulated. This phenomenon changed the surface morphology of a-C:H surface. Raman spectra of film with changed morphology revealed that the plasma induced damage with Ar ions significantly suppressed the graphitization of a-C:H structure. Also, it was observed that while the untreated flat a-C:H surfaces had wetting angle starting ranged from 72° and adhesion force of 332.79 nN. Had wetting angle the undulated a-C:H surfaces, which resemble the surface morphology of a cylindrical shape, increased up to 103.6° and adhesion force decreased down to 11 nN. The measurements agree with Hertz and JKR models. The surface undulation was affected mainly by several factors: the surface morphology affinity to cylindrical shape, reduction of the real area of contact and air pockets trapped in cylindrical double asperities of the surface.
Alan K.T. Lau, J. Lu, Vijay K. Varadan, F.K. Chang, J.P. Tu and P.M. Lam
Y. J. Jang et al., "Wetting and Adhesion Behavior of Undulated a-C:H Film Deposited on Nano-Scale Copper Dot ", Advanced Materials Research, Vols. 47-50, pp. 948-951, 2008