ION-BEAM-ASSISTED ETCHING OF DIAMOND

The high thermal conductivity, low rf loss, and inertness of diamond make it useful in traveling wave tubes operating in excess of 500 GHz. Such use requires the controlled etching of type IIA diamond to produce grating like structures tens of micrometers deep. Previous work on reactive ion etching with O//2 gave etching rates on the order of 20 nm/min and poor etch selectivity between the masking material (Ni or Cr) and the diamond. The authors report on an alternative approach which uses a Xe** plus beam and a reactive gas flux of NO//2 in an ion-beam-assisted etching system. An etching rate of 200 nm/min was obtained with an etching rate ratio of 20 between the diamond and an aluminum mask.