Two-Step Reactive Ion Etching Process for Diamond-Based Nanophotonics Structure Formation

摘要

Diamond surface modification is one of the most important technologicalchallenges in the creation of diamond quantum photonics devices. It is necessaryto fabricate different 3D structures on the crystal surface with both vertical andV-shaped etching grooves for waveguides, grating couplers, and mesastructures.Herein, the applicability of SF_6-based plasma for diamond processing is studied.SF_6 plasma etches diamond five times faster than commonly used Ar/O_2 3:1 atthe same pressure and bias, but it cannot provide vertical diamond structuresdue to the ion scattering. Herein, the two-step plasma processing method isdeveloped with Molybdenum protective masks that provide steep diamond 3Dstructures with sidewall roughness less than 40 nm and is, therefore, suitable fornanophotonics and other diamond applications. Mo can be chemically patternedby low-power SF6 plasma and then used as a hardmask for anisotropic etching ofdiamond in Ar/O_2 plasma with a selectivity of 27. Unlike common methods ofdiamond processing, the proposed two-step method does not require chlorine.