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Research Paper

Applied Science and Convergence Technology 2021; 30(4): 102-106

Published online July 30, 2021

https://doi.org/10.5757/ASCT.2021.30.4.102

Copyright © The Korean Vacuum Society.

Characteristics of SiO2 Etching by Capacitively Coupled Plasma with Different Fluorocarbon Liquids (C7F14, C7F8) and Fluorocarbon Gas (C4F8)

Seung-Wan Yooa , Chulhee Chob , d , Kyungtae Kimb , Hyochang Leec , and Shinjae Youb , d , *

aMemory Division, SAMSUNG Electronics, Hwasung 18448, Republic of Korea
bDepartment of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
cAdvanced Instrumentation, Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea
dInstitute of Quantum System (IQS), Chungnam National University, Daejeon 34134, Republic of Korea

Correspondence to:E-mail: sjyou@cnu.ac.kr

Received: June 25, 2021; Revised: July 27, 2021; Accepted: July 29, 2021

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Fluorocarbon (C7F14, C7F8) plasmas are investigated to verify their etching characteristics as an alternative etchant of SiO2 etch process because C7F8 and C7F14 precursors are expected to have low Global warming potentials. Comparing the etch results of C4F8, C7F14, and C7F8 plasmas, C7F8 provides the highest selectivity for etching SiO2 at a moderate etching rate of the three fluorocarbons. C4F8 and C7F14 plasmas show similar magnitudes of selectivity at the same O2 injection. O2 addition is used to control densities of carbon species and optimize etching conditions. From comparison of the species existing in the C4F8, C7F14, and C7F8 plasmas by the electron-emitting source, CF radicals and carbon atoms are important in determining the remarkable selectivity of C7F8 plasma. This understanding is verified using X-ray photoelectron spectroscopy analysis.

Keywords: Silicon oxide etching, Liquid fluorocarbon precursor, Global warming potential, Etch selectivity, Capacitively coupled plasma

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