Analytical and Bioanalytical Chemistry

, Volume 403, Issue 8, pp 2437–2448

Pulsed rf-GD-TOFMS for depth profile analysis of ultrathin layers using the analyte prepeak region

Original Paper

DOI: 10.1007/s00216-011-5601-3

Cite this article as:
Pisonero, J., Valledor, R., Licciardello, A. et al. Anal Bioanal Chem (2012) 403: 2437. doi:10.1007/s00216-011-5601-3

Abstract

Direct solid analysis of ultrathin layers is investigated using pulsed radiofrequency (rf) glow discharge (GD) time-of-flight mass spectrometry (TOFMS). In particular, previous studies have always integrated the detected ion signals in the afterglow region of the rf-GD pulse, which is known to be the most sensitive one. Nevertheless, the analytical capabilities of other pulse time regions have not been evaluated in detail. Therefore, in this work, we investigate the analyte prepeak region, which is the pulse region where the analyte ions peak after the initial sputtering process of each GD pulse, aiming at obtaining improved depth profile analysis with high depth resolution and with minimum polyatomic spectral interferences. To perform these studies, challenging ultrathin Si–Co bilayers deposited on a Si substrate were investigated. The thickness of the external Si layer was 30 nm for all the samples, whilst the internal Co layer thicknesses were 30, 10, 5, 2 and 1 nm, respectively. It should be remarked that the top layer and the substrate have the same matrix composition (Si > 99.99%). Therefore, the selected samples are suitable to evaluate the response of the Si ion signal in the presence of an ultrathin Co layer as well as the possible oxygen contaminations or its reactions. Additionally, these samples have been evaluated using time-of-flight secondary ion mass spectrometry, and the results compare well to those obtained by our pulsed rf-GD time-of-flight mass spectrometry results.

Keywords

Glow dischargeMass spectrometryDepth profile analysisNanometer layersAnalyte prepeakAfterglowSIMS

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • J. Pisonero
    • 1
  • R. Valledor
    • 1
  • A. Licciardello
    • 2
  • C. Quirós
    • 3
    • 4
  • J. I. Martín
    • 3
    • 4
  • A. Sanz-Medel
    • 5
  • N. Bordel
    • 1
  1. 1.Department of PhysicsUniversity of OviedoMieresSpain
  2. 2.Dipartimento di Scienze ChimichedUniversita` degli Studi di CataniaCataniaItaly
  3. 3.Department of PhysicsUniversity of OviedoOviedoSpain
  4. 4.Centro de Investigación en Nanomateriales y Nanotecnología (CINN)CSIC—Universidad de Oviedo-Principado de AsturiasLlaneraSpain
  5. 5.Department of Physical and Analytical ChemistryUniversity of OviedoOviedoSpain