Reactive Ion Etching of CVD diamond films for MEMS applications

Reactive Ion Etching is an effective method for etching of diamond films, in this paper, the influences of maskant, system pressure and the composition of reactive gas on the etch rate and etched surface of diamond were studied. A gas mixture of O-2 and Ar was used as the reactive agent, the concentration of Ar in this mixture is in the range of 0 to 100%. (V/V), and the etching result reveals that argon is not necessary. The system pressure plays the dominant effect on the etched surface and etched contours of diamond structures. The highest etch rate appears in the range of 60-100Torr, very low and very high pressure both result in etch rate decreasing. The maskant plays an important role in etching process. it can be sputtered and re-deposited on the etched surface of diamond and act as a micro mask, results in rougher etched surface in some conditions. The optimum processing parameters were achieved, and combined this patterning process with conventional photolithography and sacrificial wet etching process, we have formed a new type of surface micromachining technique for fabrication of diamond MEMS structures. Typical MEMS structures such as cantilever beams, diamond micro hinge and diamond tips array have been fabricated successfully.