Semi-isotropic surface etching of diamond using a Faraday cage

Etching of diamond is one of themost important process steps to realize diamond based devices. Isotropic etching in diamond yielding a high etch rate is challenging owing to its material properties. In the current study, singlecrystalline diamond is etched using a Faraday cage that acts as the mask to attain semi-isotropic etching. An oxygen/chlorine plasma dischargewith a pressure of 10 mTorr is used. The etching process is optimized by varying the applied plasma power, and the substrate bias together with varying parameters such as the thickness of the mask, the mask-to-diamond surface distance and the diameter of the holes in the mask. After optimization, semiisotropic etched surface profiles up to a depth of 5 μmwith an etch rate of 80nm/min and surface roughness close to that of the unetched surface are achieved.