Massive thinning of diamond films by a diffusion process

Substantial thinning or polishing of diamond films is a nontrivial problem because of the extraordinary hardness of diamond. In this letter, we report the observation of massive thinning of CVD diamond film (from ∼220 to ∼120 μm thickness) by simple diffusional transfer of carbon from diamond to iron foil at 900 °C. The thinning process also creates relatively smooth surfaces by eliminating much of the roughness from the top faceted surface of the film. A very sharp Raman peak at 1332 cm⁻¹ indicates that the high quality of the diamond bonding is not compromised by the thinning heat treatment. This technique may be useful for conveniently removing the undesirable part of the diamond films, such as the rough growth facets or the fine‐grained bottom layer with inferior thermal properties.