POLISHING OF CVD DIAMOND BY DIFFUSIONAL REACTION WITH MANGANESE POWDER

Because of their extraordinary mechanical hardness, polishing of CVD diamond films is often time consuming and costly. In this work, substantial polishing of diamond films has been accomplished by simple diffusional reaction at 900-degrees-C with manganese powder. The rough growth facets (typically about 20-60 mum variation in height) on the top surface of the films have been essentially removed. The observed polishing effect is attributed to the diffusional transfer of carbon atoms from diamond to manganese which has a large solid solubility for carbon (approximately 12 at.% at about 900-degrees-C). The reaction of manganese with diamond appears to be much faster than that of iron. In addition, much of the manganese reaction product left on the diamond surface is easily etched away in acid, which is not the case with iron. Patterning of diamond films by selective deposition of manganese thin films and reaction with diamond is also described. The polishing techniques utilizing manganese may conveniently be used to remove undesirable parts of the film, such as the top growth facets or the fine-grained bottom layer with inferior physical properties, and for simultaneous processing of a large number of films.