Processing and evaluation of DLC deposited by FIB-CVD

Abstract

Diamond-like carbon (DLC) is of great interest due to superior properties as a coating material, e.g., high hardness, high wear resistance and chemical stability. Recently, a focused ion-beam assisted chemical vapor deposition (FIB-CVD) method is proposed as a new technique for fabricating three dimensional micro- and/or nano- structures of DLC. Processing conditions, microstructures and mechanical properties of this material are, however, not clear sufficiently so far. In this study, therefore, processing conditions of DLC using the FIB-CVD method were examined. Microstructures of the DLC were also analyzed. Mechanical properties were investigated in consideration of applying for structural material of MEMS and/or NEMS. DLC samples were deposited by the FIB system with Ga + ion-beam. Source gas was supplied by heating of phenanthrene powder. The deposition condition was varied by controlling ion-beam irradiation. The surface topology of deposited DLC was measured by atomic force microscopy in order to obtain the deposited volume and the deposition rate of the samples. Microstructure of the DLC was characterized by using a high-resolution transmission electron microscopy (HRTEM). Mechanical properties of the DLC were examined using a nano-hardness tester. Various deposition experiments indicated that the fabricating of DLC structure required suitable conditions of ion-beam irradiation. HRTEM images and diffraction images, which showed halo patterns, showed that the DLC had amorphous structures. Energy dipersive spectroscopy analysis indicated that Ga was included 3-5 at.% and distributed homogeneously in all over the samples. Vickers hardness and Young's modulus were in the range of 1100-1300HV and 130-140GPa, respectively. These properties were obtaind similarly even though the deposition conditions were changed in our study.