Synthesis of nanocrystalline diamond films using microwave plasma CVD

Diamond is one of the most valuable materials for the industrial applicatio ns because of its excellent properties including high hardness, with good e lectrical insulation and thermal conductivity. Mechanical polishing process es of diamond are difficult and very costly. To limit those costs, it is re asonable to think that the surface roughness of the as-grown diamond film s hould be as small as possible. In this study, a nanocrystalline diamond fil m was synthesized on a 4-inch Si wafer at 923 K and rn thane concentration of 10 vol.%, (H-2/CH4 = 100/10 Seem) using a microwave plasma CVD system. I n order to increase the nucleation density, the substrate was pretreated by dry scratch method with diamond powder of two sizes (250 rim and 5 nm). Th e nucleation density was approximately 1 X 10(11) cm(-2). The grown diamond films were analyzed by Raman spectroscopy and X-ray diffraction (XRD). The grain size was observed to be approximately 10 nm by FE-SEM observation. S urface roughness was measured as Rms = 8.4 nm by atomic force microscope (A FM). The as-grown properties of those nanocrystalline diamond films were al most efficient for tribological and the optical applications. (C) 2001 Else vier Science B.V. All rights reserved.