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Gas‐phase chemistry and reactive‐ion etching kinetics for silicon‐based materials in C 4 F 8 + O 2 + Ar plasma
Author(s) -
Lee Byung Jun,
Efremov Alexander,
Kwon KwangHo
Publication year - 2021
Publication title -
plasma processes and polymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 74
eISSN - 1612-8869
pISSN - 1612-8850
DOI - 10.1002/ppap.202000249
Subject(s) - analytical chemistry (journal) , chemistry , etching (microfabrication) , kinetics , plasma , ion , langmuir probe , plasma modeling , reactive ion etching , inductively coupled plasma , phase (matter) , plasma diagnostics , layer (electronics) , physics , organic chemistry , chromatography , quantum mechanics
In this study, we investigated the effects of C 4 F 8 /O 2 and Ar/O 2 component ratios in C 4 F 8 + O 2 + Ar gas system on plasma parameters, gas‐phase chemistry, and etching kinetics for Si, SiO 2 , and Si 3 N 4 under the condition of inductively coupled radiofrequency (13.56 MHz) plasma. The use of plasma diagnostics by Langmuir probes, together with the zero‐dimensional plasma modeling, allowed one to compare two different gas mixing regimes in respect to (a) electrons‐ and ions‐related plasma parameters; (b) steady‐state densities of plasma active species; and (c) formation and decay kinetics for F atoms and polymerizing radicals. It was shown that variations in both C 4 F 8 /O 2 and Ar/O 2 mixing ratios result in nonmonotonic (with maximums at ∼10% to 15% O 2 ) Si, SiO 2 , and Si 3 N 4 etching rates as well as in opposite changes in corresponding effective reaction probabilities. The model‐based analysis of etching mechanisms allowed one to suggest that the net effect from all heterogeneous (i.e., appeared on the etched surface) interaction pathways may be controlled either by the fluorocarbon radical flux (in the case of Ar/O 2 mixing ratios at constant fraction of C 4 F 8 ) through the polymer film thickness or by the O atom flux (in the case of C 4 F 8 /O 2 mixing ratios at constant fraction of Ar) through the balance of adsorption sites.