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Proceedings Paper

Techniques for improving material fidelity and contrast consistency in secondary electron mode helium ion microscope (HIM) imaging
Author(s): William Thompson; Lewis Stern; Dave Ferranti; Chuong Huynh; Larry Scipioni; John Notte; Colin Sanford
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Paper Abstract

Recent helium ion microscope (HIM) imaging studies have shown the strong sensitivity of HIM induced secondary electron (SE) yields [1] to the sample physical and chemical properties and to its surface topography. This SE yield sensitivity is due to the low recoil energy of the HIM initiated electrons and their resulting short mean free path. Additionally, a material's SE escape probability is modulated by changes in the material's work function and surface potential. Due to the escape electrons' roughly 2eV mean energy and their nanometer range mean free path, HIM SE mode image contrast has significant material and surface sensitivity. The latest generation of HIM has a 0.35 nanometer resolution specification and is equipped with a plasma cleaning process to mitigate the effects of hydrocarbon contamination. However, for surfaces that may have native oxide chemistries influencing the secondary electron yield, a new process of low energy, shallow angle argon sputtering, was evaluated. The intent of this work was to study the effect of removing pre-existing native oxides and any in-situ deposited surface contaminants. We will introduce the sputter yield predictions of two established computer models and the sputter yield and sample modification forecasts of the molecular dynamics program, Kalypso. We will review the experimental technique applied to copper samples and show the copper grain contrast improvement that resulted when argon cleaned samples were imaged in HIM SE mode.

Paper Details

Date Published: 3 June 2010
PDF: 9 pages
Proc. SPIE 7729, Scanning Microscopy 2010, 77290J (3 June 2010); doi: 10.1117/12.861488
Show Author Affiliations
William Thompson, Carl Zeiss SMT Inc. (United States)
Lewis Stern, Carl Zeiss SMT Inc. (United States)
Dave Ferranti, Carl Zeiss SMT Inc. (United States)
Chuong Huynh, Carl Zeiss SMT Inc. (United States)
Larry Scipioni, Carl Zeiss SMT Inc. (United States)
John Notte, Carl Zeiss SMT Inc. (United States)
Colin Sanford, Carl Zeiss SMT Inc. (United States)

Published in SPIE Proceedings Vol. 7729:
Scanning Microscopy 2010
Michael T. Postek; Dale E. Newbury; S. Frank Platek; David C. Joy, Editor(s)

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