ENHANCED OXIDATION ETCHING OF DIAMOND FILMS IN PRESENCE OF MOLYBDENUMBY ANNEALING IN AN AMBIENT ATMOSPHERE

We report an apparently new phenomenon observed when diamond films of 40-50 mu m thick deposited on Mo substrates are annealed in an ambient atmosphere at 700 degrees C. It is found that, after annealing for 3 h, diamond films are etched off, and large MoO3 crystals are formed. T hese two reactions apparently occur concurrently in an enhanced oxidat ion etching reaction. A systematic investigation has been carried out and it shows that the presence of a molybdenum substrate or powders sp eeds up the oxidation etching effect on diamond thin films, regardless of whether these films were made by microwave plasma CVD techniques o r by an oxyacetylene combustion flame method. We present our experimen tal results and propose a possible mechanism for this enhanced oxidati on etching reaction.