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Title: Penetration of plasma into the wafer-focus ring gap in capacitively coupled plasmas

Abstract

In plasma etching equipment for microelectronics fabrication, there is an engineered gap between the edge of the wafer and wafer terminating structures, such as focus rings. The intended purpose of these structures is to make the reactant fluxes uniform to the edge of the wafer and so prevent a larger than desired edge exclusion where useful products cannot be obtained. The wafer-focus ring gap (typically<1 mm) is a mechanical requirement to allow for the motion of the wafer onto and off of the substrate. Plasma generated species can penetrate into this gap and under the beveled edge of the wafer, depositing films and possibly creating particles which produce defects. In this paper, we report on a computational investigation of capacitively coupled plasma reactors with a wafer-focus ring gap. The penetration of plasma generated species (i.e., ions and radicals) into the wafer-focus ring gap is discussed. We found that the penetration of plasma into the gap and under the wafer bevel increases as the size of the gap approaches and exceeds the Debye length in the vicinity of the gap. Deposition of, for example, polymer by neutral species inside the gap and under the wafer is less sensitive to the sizemore » of the gap due the inability of ions, which might otherwise sputter the film, to penetrate into the gap.« less

Authors:
;  [1]
  1. Iowa State University, Department of Electrical and Computer Engineering, 104 Marston Hall, Ames, Iowa 50011 (United States)
Publication Date:
OSTI Identifier:
20979407
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 11; Other Information: DOI: 10.1063/1.2736333; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DEBYE LENGTH; DEPOSITION; ETCHING; IONS; MICROELECTRONICS; PARTICLES; PLASMA; POLYMERS; RADICALS; SUBSTRATES; WALL EFFECTS

Citation Formats

Babaeva, Natalia Y., and Kushner, Mark J. Penetration of plasma into the wafer-focus ring gap in capacitively coupled plasmas. United States: N. p., 2007. Web. doi:10.1063/1.2736333.
Babaeva, Natalia Y., & Kushner, Mark J. Penetration of plasma into the wafer-focus ring gap in capacitively coupled plasmas. United States. doi:10.1063/1.2736333.
Babaeva, Natalia Y., and Kushner, Mark J. Fri . "Penetration of plasma into the wafer-focus ring gap in capacitively coupled plasmas". United States. doi:10.1063/1.2736333.
@article{osti_20979407,
title = {Penetration of plasma into the wafer-focus ring gap in capacitively coupled plasmas},
author = {Babaeva, Natalia Y. and Kushner, Mark J.},
abstractNote = {In plasma etching equipment for microelectronics fabrication, there is an engineered gap between the edge of the wafer and wafer terminating structures, such as focus rings. The intended purpose of these structures is to make the reactant fluxes uniform to the edge of the wafer and so prevent a larger than desired edge exclusion where useful products cannot be obtained. The wafer-focus ring gap (typically<1 mm) is a mechanical requirement to allow for the motion of the wafer onto and off of the substrate. Plasma generated species can penetrate into this gap and under the beveled edge of the wafer, depositing films and possibly creating particles which produce defects. In this paper, we report on a computational investigation of capacitively coupled plasma reactors with a wafer-focus ring gap. The penetration of plasma generated species (i.e., ions and radicals) into the wafer-focus ring gap is discussed. We found that the penetration of plasma into the gap and under the wafer bevel increases as the size of the gap approaches and exceeds the Debye length in the vicinity of the gap. Deposition of, for example, polymer by neutral species inside the gap and under the wafer is less sensitive to the size of the gap due the inability of ions, which might otherwise sputter the film, to penetrate into the gap.},
doi = {10.1063/1.2736333},
journal = {Journal of Applied Physics},
number = 11,
volume = 101,
place = {United States},
year = {Fri Jun 01 00:00:00 EDT 2007},
month = {Fri Jun 01 00:00:00 EDT 2007}
}