Effect of bias in patterning diamond by a dual electron cyclotron resonance-radio-frequency oxygen plasma

摘要

Arrays of microhole patterns are fabricated on the surfaces of diamond films through a physical mask in a dual microwave electron cyclotron resonance/radio-frequency oxygen plasma. It is found that nanotips with high aspect ratio form in the microholes, and then through-holes are fabricated with a further increase of etching time. Optical emission spectroscopy was employed to calculate oxygen atom density and evaluate the variation of the plasma excitation temperature. The plasma excitation temperature and the O atom density present significant dependences on the voltage of rf bias V_b at a high frequency of 13.56 MHz, suggesting that the application of the rf bias not only strengthens ion bombardment on the material surface, but also induces the variations of the bulk plasmas including the increase of O atom density. Whereas, both the plasma excitation temperature and the O atom density remain nearly unchanged with V_b under the bias frequency of 400 kHz. The etching process depends on the rf-bias frequency and voltages, which are correlated with the measured plasma characteristics.