AVS 49th International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThM

Paper AS-ThM4
Surface Analytical Characterization of SiO@sub 2@ Gradient Membrane Coatings on Gas Sensor Microarrays

Thursday, November 7, 2002, 9:20 am, Room C-106

Session: Practical Surface Science I
Presenter: M. Bruns, Forschungszentrum Karlsruhe GmbH, Germany
Authors: M. Bruns, Forschungszentrum Karlsruhe GmbH, Germany
H. Baumann, Universit@um a@t Frankfurt/Main, Germany
M. Frietsch, Forschungszentrum Karlsruhe GmbH, Germany
E. Nold, Forschungszentrum Karlsruhe GmbH, Germany
V. Trouillet, Forschungszentrum Karlsruhe GmbH, Germany
R. White, Thermo V.G. Scientific, England
A. Wright, Thermo V.G. Scientific, England
Correspondent: Click to Email
The growing demand for inexpensive, space-saving and intelligent gas sensor systems led to the development of a gas sensor microarray at the Forschungszentrum Karlsruhe. The microarray currently comprises 38 sensor elements on an area of 4x8mm@super 2@ and is based on an 150 nm thick SnO@sub 2@ layer, the electrical conductivity of which is highly sensitive to the composition of the ambient atmosphere. The basic structure of the microarray is manufactured by R.F. magnetron sputtering, applying a shadow masking technique. Parallel platinum strip electrodes for the conductivity measurement are sputtered on top of the metal oxide, thus subdividing the latter into the initially identical sensor elements. In order to modify the gas response of individual sensor segments, a gas-permeable SiO@sub 2@ membrane with a thickness variation of approximately 2 to 50 nm was deposited across microarray using ion beam assisted deposition.@footnote 1@ Auger electron spectroscopy already has been proven to be a powerful tool in quality control of the fabrication of gas sensor microarrays@footnote 2@ and, therefore, was used for rapid evaluation of the geometrical integrity of the electrode pattern. The chemical state determination of the layer constituents was carried out by X-ray photoelectron spectroscopy. Parallel ARXPS (angle resolved XPS) data collected with the Thermo VG Theta Probe can provide thickness information from the SiO@sub 2@ membrane in a non-destructive manner using a well-controlled analysis area (X-ray spot size 50 µm). In addition, ellipsometry, nuclear resonant reaction analysis, and non-Rutherford backscattering spectrometry were used to achieve a comprehensive characterization. @FootnoteText@ @footnote 1@M. Frietsch, L.T. Dimitrakopoulos T. Schneider, J. Goschnick, Surf. Coat. Technol., 120-121 (1999) 265 @footnote 2@R. Schlesinger, M. Bruns, Thin Solid Films, 366 (2000) 265.