Simulation of profile evolution in etching-polymerization alternation in DRIE of silicon with SF6/C4F8

This paper presents a new 2-D simulator, which can simulate etching, deposition and arbitrary sequential combination of them for infinite trench. Having been implemented with a mixed method based on cell structure and string structure, this simulator has the ability to emulate the etching of different materials. Using this simulator, etching-polymerization alternation in silicon DRIE (deep reactive ion etching) with SF₆ and C₄F₈ has been modeled. The simulation results verify that the polymerization in the alternation is a critical step in the DRIE process to achieve high anisotropy. The simulation results also indicate lag effect. Simulated profiles show good match with experiments.