Paper AS-TuP12
Atmospheric Plasma Surface Modification Analysis by Energy Resolved Molecular Beam Mass Spectrometry and SIMS

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

Electrical plasmas can be readily produced at atmospheric pressure and have relatively low running costs. They are ideal for a variety of industrial process applications for many materials. Processing using non-thermal atmospheric plasma currently extends to areas such as surface cleaning and functionalisation, plasma activation, tissue engineering and sterilisation. To aid in understanding the mechanisms involved in plasma/surface interaction we present results of both plasma measurements and surface composition studies for a range of materials treated using an atmospheric dielectric surface barrier discharge (DSBD). The plasma properties were determined using an energy-resolved molecular beam mass spectrometer (ERMBMS). The surface compositions of the materials before and after treatment were compared using a static SIMS instrument. The dielectric surface barrier discharges were operated using helium gas and applied to molybdenum, silicon wafers and printed circuits. Silicon test pieces were treated using hydrofluoric acid to produce a strongly hydrophobic, hydrogen-terminated surface. The hydrophobicity of the surfaces could be significantly reduced by short exposure to certain plasma conditions. Static SIMS analyses of these surfaces showed a significant reduction in the observed SiH+ signal and an accompanying increase in the Si and the reactive silanol groups [Si-OH]. ERMBMS consists of an energy mass spectrometer (QMS) with a differentially pumped three-stage inlet system [1]. Mass spectra of the ions generated in the DBSD source show a high concentration of monoatomic and diatomic oxygen. Analysis of the ion energy reveals that the ions are fully thermalized, with energies close to 0.03 eV. ERMBMS analyses of the plasmas provided information on the relative contributions of ionic and radical species to the changes in the surface structure and the combination of data from the two diagnostic techniques contributes to our general understanding of such plasma/surface processing.

Reference [1] Y.Aranda Gonzalvo, T.D. Whitmore, J.A. Rees, D.L.Seymour, E. Stoffels, 2006 J.Vac.Sci. Technol., A 24 550. Keywords: energy mass spectrometer, dielectric surface barrier discharge, atmospheric plasmas, SIMS.