Title
Gas ratio effects on the Si etch rate and profile uniformity in an inductively coupled <tex>$Ar/CF_{4}$</tex> plasmaGas ratio effects on the Si etch rate and profile uniformity in an inductively coupled <tex>$Ar/CF_{4}$</tex> plasma
Author
Faculty/Department
Faculty of Sciences. Chemistry
Research group
Plasma, laser ablation and surface modeling - Antwerp (PLASMANT)
Publication type
article
Publication
Bristol :Institute of Physics,
Subject
Physics
Chemistry
Source (journal)
Plasma sources science and technology / Institute of Physics. - Bristol, 1992, currens
Volume/pages
22(2013):1, p. 1-18
ISSN
0963-0252
Article Reference
015017
Carrier
E-only publicatie
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
In this work, a hybrid model is used to investigate the effect of different gas ratios on the Si etching and polymer film deposition characteristics in an Ar/CF4 inductively coupled plasma. The influence of the surface processes on the bulk plasma properties is studied, and also the spatial characteristics of important gas phase and etched species. The densities of F and CF2 decrease when the surface module is included in the simulations, due to the species consumption caused by etching and polymer deposition. The influence of the surface processes on the bulk plasma depends on the Ar/CF4 gas ratio. The deposited polymer becomes thicker at high CF4 content because of more abundant CFx radicals. As a result of the competition between the polymer thickness and the F flux, the etch rate first increases and then decreases upon increasing the CF4 content. The electron properties, more specifically the electron density profile, affect the Si etch characteristics substantially by determining the radical density and flux profiles. In fact, the radial profile of the etch rate is more uniform at low CF4 content since the electron density has a smooth distribution. At high CF4 content, the etch rate is less uniform with a minimum halfway along the wafer radius, because the electron density distribution is more localized. Therefore, our calculations predict that it is better to work at relatively high Ar/CF4 gas ratios, in order to obtain high etch rate and good profile uniformity for etch applications. This, in fact, corresponds to the typical experimental etch conditions in Ar/CF4 gas mixtures as found in the literature, where Ar is typically present at a much higher concentration than CF4.
E-info
https://repository.uantwerpen.be/docman/iruaauth/c7ac49/269ff84982c.pdf
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