Plasma etching of high aspect ratio features in SiO2 using Ar/C4F8/O2 mixtures: A computational investigation

Plasma etching of high aspect ratio (HAR) features, typically vias, is a critical step in the fabrication of high capacity memory. With aspect ratios (ARs) exceeding 50 (and approaching 100), maintaining critical dimensions (CDs) while eliminating or diminishing twisting, contact-edge-roughening, an...

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Bibliographic Details
Published in:Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2019-05, Vol.37 (3)
Main Authors: Huang, Shuo, Huard, Chad, Shim, Seungbo, Nam, Sang Ki, Song, In-Cheol, Lu, Siqing, Kushner, Mark J.
Format: Article
Language:English
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Summary:Plasma etching of high aspect ratio (HAR) features, typically vias, is a critical step in the fabrication of high capacity memory. With aspect ratios (ARs) exceeding 50 (and approaching 100), maintaining critical dimensions (CDs) while eliminating or diminishing twisting, contact-edge-roughening, and aspect ratio dependent etching (ARDE) becomes challenging. Integrated reactor and feature scale modeling was used to investigate the etching of HAR features in SiO2 with ARs up to 80 using tri-frequency capacitively coupled plasmas sustained in Ar/C4F8/O2 mixtures. In these systems, the fluxes of neutral radicals to the wafer exceed the fluxes of ions by 1–2 orders of magnitude due to lower threshold energies for dissociation compared with ionization. At low ARs (
ISSN:0734-2101
1520-8559
DOI:10.1116/1.5090606