Surface Analysis Studies of Yield Enhancements in Secondary Ion Mass Spectrometry by Polyatomic Projectiles

Published

May 1, 2001

Author(s)

E Fuoco, J Greg Gillen, M Wijesundara, William E. Wallace, L Hanley

Abstract

In this paper examine the mechanism of secondary ion yield enhancements previously observed for polyatomic projectiles by measuring the weight loss, volume loss, and surface composition of poly(methylmethacrylate) (PMMA) films sputtered by keV SF₅⁺ and Ar⁺ projectile ions. The sputter yield the amount of material removed from the surface by 3.0 keV SF₅⁺ projectiles-was found to be 2.2 0.8 higher than for Ar⁺ projectiles, measured by weight loss in the PMMA film with a quartz crystal microbalance. This result is consistent with sputter yield measurements reported here using 5.5 keV ions and stylus profilometry. Thus, the > 10x enhancement in secondary ion yield in secondary ion mass spectrometry observed for polyatomic ion projectiles is not attributable to the modest difference of} 2x enhancements observed in the sputter yields for this molecular solid. Surface chemical measurements by X-ray photoelectron spectroscopy also indicated fundamental differences in atomic versus polyatomic sputtering mechanisms at 3.0 keV, but not at 0.7 keV. These results provide a reasonable explanation for the depth profiling capability demonstrated here on PMMA films for 5.5 keV SF₅⁺ ions that is not possible with isoenergetic Ar⁺ ions.

Citation

Journal of Physical Chemistry B

Volume

No. 105

Issue

No. 18

Pub Type

Journals

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Keywords

cluster bombardment, polyatomic ion bombardment, secondary ion mass spectrometry, sputter yield

Citation

Fuoco, E. , Gillen, J. , Wijesundara, M. , Wallace, W. and Hanley, L. (2001), Surface Analysis Studies of Yield Enhancements in Secondary Ion Mass Spectrometry by Polyatomic Projectiles, Journal of Physical Chemistry B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=831207 (Accessed September 16, 2024)