Thermal catalytic etching of diamond by double-metal layers

We introduce a novel technique for thermal catalytic etching of single-crystal diamond under hydrogen atmosphere using a double-metal layer consisting of two different metallic thin films. Surface phenomena, catalytic activity, hydrogen pressure dependence and etch rates in several double-metal layer configurations were investigated. We observe that etching with an optimized thickness ratio of Ni/Pd films increases the etch rate by a factor up to 11 compared to etching with a single-metal layer Ni film. The proposed double-metal layer technique enhances hydrogen absorption, which contributes to an increased etch rate of the process, as compared to conventional single-metal layer thermal catalytic etching. Moreover, the etched pattern shows smooth (111) plane sidewalls and flat (100) step-terrace bottom features.