Abstract
The issue of specimen contamination becomes more important at a rate proportional to the use of high-brightness electron source Transmission Electron Microscopes (TMM). The trend in the transmission electron microscopy of materials science specimens is to use higher-voltage microscopes incorporating field emission gun technology [1]. These FEG TEMs combine smaller electron probes with increased beam current, allowing high resolution specimen imaging and enhanced analytical data collection. This is of particular importance for semiconductor specimens which demand fine-probe microanalyis.
Small, high current electron probes tend to increase the migration rates of hydrocarbon contamination on the specimen’s surface to the impingement point of the electron probe as shown in Figure 1. This image was generated using a CM200 FEG operating at 200 kV with a 1 rm probe. The carbon mass was formed during a 300 second probe exposure at a β-tilt of −200°. Imaging was conducted at a β-tilt of +400°. These types of carbon deposits often times obstrnct imaging and precludes acceptable analytical results. By plasma cleaning the specimen, contamination is removed and the results obtained by high resolution electron microscopy (HREM), scanning uanmission electron microscopy (STEM) and analytical electron microscopy (AEM) 20pm using EDS or electron energy loss spectroscopy (EELS) are greatly enhanced [2-6].
Recent instrumentation developments have resulted in the application of a high fiequency, low energy, reactive gas plasma that chemically removes hydrocarbon contamination from both the TEM specimen holder and the specimen without altering its properties. Critical aspects of the plasma generation, ion energy, electrode location, process gas, and vacuum technology are discussed. The effect of plasma processing parameters on various materials research specimens will be presented.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
P.M. Mul, B.J.M. Bormans and L. Schaap, Design of a Field Emission Gun for the Philips CM/20 STEM Microscope, Proceedings of the XII International Congress for Electron Microscopy, Volume 2, Pages 100–101, (1990).
R.S. Thomas, Use of Chemically-Reactive Gas Plasmas in Preparing Specimens for Scanning Electron Microscopy and Electron Probe Microanalysis, Proceeding of the 7th Annual Scanning Electron Microscope Symposium, Scanning Electron Microscopy, Pgs. 84–89, (1974).
Nestor J. Zaluzec (private communication).
Nestor J. Zaluzec, U.S. Patent Number 5,510,624, Simultaneous Specimen and Stage Cleaning Device for Analytical Electron Microscopy - Argonne National Laboratory and the University of Chicago (23 April 1996).
H.W. Zandbergen, A.C.A. Delsing, C. Traeholt, A. Van Veen, and J. de Roode, The Use of Plasma-Cleaning for the Preparation of Clean Electron-Transparent Thin Foils, Proceedings of the XII International Congress for Electron Microscopy, Volume 1, Pages 1003–1004, (1994).
Hendrik W. Zandbergen, European Patent 0 651 243 A1, Method of Making Specimens for an Electron Microscope (3 May 1995).
P.B. Hirsch, A. Howie, R-B. Nicholson, D.W. Pashley and M.J. Whelan, Electron Microscopy of Thin Crystals, (The Butterworth Group, 1965).
Michael A. Lieberman, Allan J. Lichtenberg, Principles of Plasma Discharges and Materials Processing (John Wiley & Sons, Inc., 1994).
M. Tuszewski, J.T. Scheuer, J.A. Tobin, Composition of the Oxygen Plasmas from Two Inductively Coupled Sources JVST A 13(4), (1995).
Fischione, Kelly, Dalley, Holzman and Dawson-Elli, Advances in Ultrasonic Disk Cutting and Precision Dimpling edited by K.M. Anderson, B. Tracy, and J.C. Bravman, (Materials Research Society Symposium Proceedings, Volume 254, Pittsburgh, PA, 1992) pp. 79–97.
J.L Farrant and E. Bez, Oil-Free Forepumps for Electron Microscopes, Proceedings of the XII International Congress for Electron Microscopy, Volume 1, Pages 186–187, (1990).
Acknowledgement
The authors would like to thank Dr. Nestor Zaluzec of Argonne National Laboratory for advice and input in determining instrmnen structure and required performance, Mr. John Fahy of Philips Electron Optics for both significant input and encouragement throughout the instrument development process and Dr. Michel Tuszewski of the Los Alamos National Laboratory for contributions toward developing and refining the instrument’s plasma physics properties.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Fischione, P.E., Ringnada, J., Feng, Y. et al. The Use of a Cold Gas Plasma for the Final Processing of Contamination-Free Tem Specimens. MRS Online Proceedings Library 480, 225–234 (1997). https://doi.org/10.1557/PROC-480-225
Published:
Issue Date:
DOI: https://doi.org/10.1557/PROC-480-225