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Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received March 10, 2003
Accepted September 16, 2003

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

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Thickness of a Modified Surface Layer Formed in a Silsesquioxane-based Low-k Material During Etching in a Fluorocarbon Plasma

Sung-Wook Hwang Gyeo-Re Lee Jae-Ho Min Sang Heup Moon^†

School of Chemical Engineering and Institute of Chemical Processes, Seoul National University, San 56-1, Shillim-dong, Kwanak-ku, Seoul 151-744, Korea

shmoon@surf.snu.ac.kr

Korean Journal of Chemical Engineering, November 2003, 20(6), 1131-1133(3), 10.1007/BF02706948

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Abstract

This paper explains the origin of our previous observation that, when a silsesquioxane-based low-k film is etched in fluorocarbon plasmas, the thickness of a surface modified layer, in which cage-like Si-O bonds are dissociated to extents greater than a specified level, changes linearly with log[F]²/[CF₂], where [F] and [CF₂] denote concentrations of F and CF₂ radicals in the bulk plasma. During the etching process, the substrate consists of three distinct layers: a fluorocarbon layer, a modified surface layer, and an unmodified layer. F density at the interface between the fluorocarbon and the modified surface layers, denoted as F₀ in this study, is determined in proportional to [F]2/[CF2], and the density decreases exponentially with the film depth. As a result, the thickness of the modified surface layer changes in proportion to a parameter, log[F]²/[CF₂].

Keywords

Low-k Material Silsesquioxane Plasma Etching Fluorocarbon Surface Layer

References

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