Fabrication of Slanted Grating Utilizing Reaction Ion Beam Etching: The Role of CHF3 and O2 Etching Atmosphere

The etching of silicon-based slanted grating based on CHF 3 /O 2 /Ar reactive ion beam (RIBE) etching is investigated. Impacts of the CHF 3 /O 2 /Ar gases flow rate on the roughness, tilt angle and etching rate are studied in detail. It is found that when the Cr is adopted as the metal mask, the etching rate, sidewall roughness, and inclination angle of the mesa are changed significantly with the flow rate variation of the CHF 3 /O 2 gases. When the etching gases of the CHF 3 /O 2 /Ar =5/3/2, a controllable grating etching rate of 32.8 nm/min, an inclination of 120°, and a smooth mesa side-wall are finally obtained, which can improve the sidewall inclination and ensuring the smoothness of the grating sidewall. The stable grating etching processes delivered in this work are of benefit to preparing the grating, which has a very important influence on the development of AR/VR.