Deep reactive ion etching of thermally co-evaporated Te-Ge films for IR integrated optics components

Due to their remarkable transparency in the infrared region, telluride glasses are very promising materials for the realization of IR integrated optics components for specific applications, such as the detection of pollutant gases in the atmosphere or the detection of exoplanetary systems. In order to prove the feasibility of channel waveguiding structures based on this kind of materials, deep etching of thermally co-evaporated Te-Ge films, one of the most important and critical steps, was investigated. Reactive ion etching was carried out using different mixtures of three gases CHF3, O2 and Ar, and for different chamber pressures and RF powers. The influence of each parameter on the quality of etched Te-Ge films, in term of rib dimensions and surface roughness for example, was studied. Finally optimized parameters i.e. a CHF3/O2/Ar ratio of 59.5/10.5/30, a chamber pressure of 30 mTorr and a RF power of 50 W were used to fabricate a pattern showing the achievement in term of etching resolution.