Synthesis of thick DLC film for micromachine components

A diamond-like carbon (DLC) film generally exhibits low adhesion strength, i.e. easiness of peeling off from the surface of a substrate due to the internal compressive stress, as high as 2 GPa, generated in the film, thus resulting in the limitation of the film thickness to as small as 1-3 mum. The purpose of this study is to establish a technology, which can synthesize DLC film thicker than 30 mum, for micromachine components, using the RF plasma chemical vapor deposition (CVD) method. The results showed that the introduction of silicon can reduce the internal stress to approximately 0.8 GPa, and the formation of a multilayered structure in addition to silicon can reduce it further to 0.68 GPa. Thus, these measures succeeded in reducing the stress by as much as 40% compared with that in the film synthesized by conventional techniques. Furthermore, the reduction of the stress allowed the formation of a freestanding thick DLC film that can be used as the material for micromachine components. Microcutting and grooving performance of the film, by the usage of YAG laser and focused ion beam (FIB) techniques, are shown. Finally, we fabricated a DLC rod of 30-mum length and 5-mum diameter. (C) 2003 Elsevier B.V. All rights reserved.