Patterning of diamond microstructures on Si substrate by bulk and surface micromachining

Diamond microstructures were patterned over silicon/silicon dioxide substrate using the processes combined with bulk or surface micromachining, selective growth of diamond and plasma etching technique. Polycrystalline diamond films were prepared using microwave plasma enhanced chemical vapor deposition and a gas mixture of hydrogen and methane. (111)- and (100)-oriented diamond films were synthesized and smooth (100)-textured thin films were successfully deposited on silicon structures, such as trenches, corners, edges, forming a good heat-diffusing and insulating layer as well as a protective wear-resistant surface. Two types of techniques for precise patterning of diamond microstructures were investigated in this paper. The first one was to selectively grow diamond films in the desired region by pre- depositing a Pt interlayer on silicon dioxide layer. The second one was to selectively etch the deposited diamond film by oxygen/argon plasma under an Al mask. Different microstructures, for example, diamond membrane, microgear, microrotor, comb drive structure, etc. were successfully fabricated.