Sidewall profiles and etching mechanisms in an inductively coupled plasma for silicon, silicon dioxide and lithium niobate.

摘要

Current work on deep-RIE etching has been primarily focused on creating vertical sidewalls for MEMS and electronics applications. For micro-optical and MOEM structures, control of the sidewall angles other than vertical is as important as the ultimate depth. In this dissertation, we investigate the mechanisms of sidewall profile control using an inductively coupled plasma (ICP) reactor. The material systems being investigated are silicon, silicon dioxide and Lithium Niobate. Test structures are created by photolithography and different chemistries such as CF4, CF4/Ar, CF4/O2, CHF3, SF6 and SF 6/O2 have been explored to achieve a wide range of etch rates, etch profiles, sidewall angles, and surface roughness. The FDTD method is developed for the simulation and the analysis of V-grooved micro-optic designs. This research also includes the statistical experimental fractional factorial design for controlling the sidewall profiles by adjusting processing gas composition, the ICP power, processing pressure, bias power and etching time. The etch profiles are characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and white light interferometer (WLI).