An atomic force microscopy study of the effects of surface treatments of diamond films produced by chemical vapor deposition

Diamond films produced by chemical vapor deposition (CVD) technique must be polished and machined in order to be used for many applications (windows, heat spreaders, surface acoustic wave devices, etc). We present an Atomic Force Microscopy study of the effects of mechanical polishing, hydrogen plasma etching, and ion implantation followed by annealing and chemical etching, on the morphology of Microwave Plasma CVD polycrystalline diamond films. Both growth and nucleation sides of 0.3-0.5 mm thick free-standing films were characterized. We found that grain boundaries and anisotropy of mechanical properties (hardness and wear rate) mostly contribute to the overall roughness of Microwave Plasma CVD diamond films, which is below 0.2 nm at the single-grain scale. The further deposition of a diamond overlayer, even of small thickness, on highly polished polycrystalline diamond, results in a variety of growth modes and different growth rates depending on the grain orientation, leading to the roughness increase. Hydrogen plasma etching proved to be effective for inducing morphological and chemical changes on the surface, while an ion implantation/annealing/etching can be used for precise removal of thin diamond layers. The latter approach is promising for diamond lithography.