Fabrication of submicron scale vertically aligned diamond rods by mask-free oxygen plasma etching

A mask-free plasma etching process is described to fabricate 6 μm long submicron diamond rods (SDRs) in long conical shape. Polished polycrystalline diamond is etched in oxygen plasma ignited at a pressure of 10 mTorr by radio-frequency power of 100 W at 13.56 MHz. Each SDR is a bi-crystal, consisting of two diamond crystallites of micron size. The SDR is coated with a Fe2O3 layer, as characterized by Auger electron spectroscopy, X-ray photoemission microscopy, and transmission electron microscopy. We propose that a “self-forming” mask of Fe2O3 is generated during the etching process in which iron atoms sputtered from the substrate holder are deposited and oxidized on the diamond surface forming “micromask” that protects the underlying diamond and promotes the formation of SDRs.

Research highlights
► A mask-free plasma etching process has been developed for the fabrication of very long submicron diamond rods.
► The mask-free etching process is able to extract single- or bi-crystal diamond rods from a polycrystalline diamond film.
► Each submicron diamond rod is coated with Fe2O3, ensuring survival during oxygen plasma etching.
► The extracted diamond rods of several microns in length may be used to fabricate one-dimensional diamond devices.