Studies on the discharge characteristics and atomic layer etching of high aspect ratio patterned-wafer in radio frequency biased inductively coupled plasma with Ar/C₄F₆ gas mixture

Recently, as the critical dimension decreases and the aspect ratio of the pattern increases in semiconductor manufacturing industry, precise control of the plasma etching process is urgently required. This can be achieved through process design based on understanding of the discharge characteristics, which depends on the chamber configuration, plasma source, and type of processing gas. Among them, C₄F₆ (Hexafluoro-1,3-butadiene) is a next-generation etching gas with a low global warming potential and excellent etch selectivity. A radio-frequency (RF) biased inductively coupled plasma (ICP) has been actively used in the etching process because it can control ion energy with high plasma density. In this study, we comprehensively investigated the discharge characteristics and atomic layer etching of high aspect ratio patterned-wafer in RF biased ICP with Ar/C₄F₆ mixture¹. Our investigation includes discharge mode transition, instability, and electron density characteristics by C₄F₆. Considering these discharge characteristics, the etching thickness was controlled at the atomic-level in the high aspect ratio pattern etching.