Characteristics and high water-repellency of a-C:H films deposited by r.f. PECVD

Hydrogenated amorphous carbon (a-C:H) films have been prepared by r.f. plasma-enhanced chemical vapor deposition at low bias voltage from 0 to −40 V with CH4 and H2 as raw materials. The a-C:H films deposited with no bias applied showed characteristics of polymeric films with a large fluorescence level while the a-C:H films deposited at a bias voltage of r.f. 150 W showed characteristics from diamond-like carbon to graphitic nature with a significantly reduced fluorescence level. High water-repellency of over 140° in a contact angle obtained at a-C:H/trimetylmethoxysilane/Si structures. This high water-repellency is due to CH groups on surfaces and the roughness.