Cycle of two-step etching process using ICP for diamond MEMS applications

Inductively coupled plasma (ICP) etching was performed to etch diamonds, and a new diamond etching technique was established in order to obtain the high selective etching rate of diamond with respect to the silicon oxide etching mask and the smooth etched surface. Scanning electron microscope (SEM) observations and energy dispersive X-ray (EDX) characterizations of the etched diamond surfaces show that the silicon oxide etching mask particles were re-deposited on the fresh etched diamond surface. This results in un-intentional whisker formation. In order to obtain both the high selectivity and the smooth etched surface, a sequential cycle of ICP etching was, for the first time, applied for diamond. Diamond is etched with O2 plasma during the first step and, in the second step, silicon oxide was removed using (CF4 + O2) plasma. Both the selective etching rate of diamond to silicon oxide was improved and the smooth surface was obtained. By applying the two-step etching process, diamond gene-surgery tips for atomic force microscopy (AFM) have been fabricated.