Etching of polycrystalline diamond and amorphous carbon films by RIE

Abstract

Amorphous carbon films and doped and undoped polycrystalline diamond films were patterned with RIE in an oxygen plasma. Insitu measurement of the etch rate gave different, depth-dependent etch rate values. For the amorphous films, an etch rate of 150 nm/min to 600 nm/min was measured; for the polycrystalline films the etch rate measured was 10 nm/min to 60 nm/min. The etched polycrystalline films exhibit a columnar structure, which can be traced back to the anisotropic etching behaviour. Suitable masking layers include PECVD oxide and nitride with excellent selectivity towards diamond. The etch rate rises with increasing RF power and decreases with increasing oxygen partial pressure.