Simulation of a Polymer-Free Drie Process Using SF₆/O₂ Plasma Etching

Abstract

We present a feature-scale simulation of the cyclic polymer-free deep-reactive ion etching (DRIE) process titled CORE which was experimentally demonstrated in [1]. The CORE process consists of four steps: Clear, Oxidize, Remove, Etch, and is based on the Bosch etching principle, whereby polymer deposition is replaced with minimal surface oxidation. Our simulation approach combines a Langmuir-type SF<inf>6</inf> / O<inf>2</inf> etching model with Monte Carlo ray tracing for ballistic flux calculation and is implemented in the level-set-based topography simulator ViennaPS. Essential for the CORE process is the surface oxidation step, which we model by tracking an oxide thickness surface property in the context of the Langmuir-type surface model. We demonstrate the model's capabilities by reproducing experimental etch profiles over multiple CORE cycles.