IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Thin Films Monday Sessions
       Session TF+MM-MoM

Paper TF+MM-MoM3
MEMS Device Platforms as Research Tools for Developing Improved Sensing Films

Monday, October 29, 2001, 10:20 am, Room 123

Session: Thin Film Sensors
Presenter: C.J. Taylor, National Institute of Standards and Technology
Authors: C.J. Taylor, National Institute of Standards and Technology
S. Semancik, National Institute of Standards and Technology
R.E. Cavicchi, National Institute of Standards and Technology
Correspondent: Click to Email
Gas sensing characteristics of metal oxide films are dependent on the preparation method used in their fabrication. To optimize sensing film performance, one must understand how processing parameters influence composition and microstructure, and then correlate these changes with changes in the selectivity, sensitivity and stability of a sensor. We have been using arrays of microhotplates, MEMS devices fabricated with individually addressable heaters and sensing contacts, for both combinatorial studies and gas sensing. The short thermal time constant of the microhotplates makes them excellent microsubstrates for materials research where rapid heating and cooling during deposition are desired (heating rates of 10@super 5@ - 10@super 6@ °C /s are possible). Experiments have been performed using 4- and 16-element arrays as microsubstrates for CVD processing of titanium oxide and tin oxide using the single source precursors titanium(IV) nitrate, titanium(IV) isopropoxide and tin(IV) nitrate. Sensing films have been deposited both isothermally in the temperature range 100 to 450 °C, and using variable temperature deposition. Variable temperature deposition was achieved by applying triangle or square waves of varying frequency and amplitude to the heater. Film microstructure was examined by FESEM and its composition measured by EDS. We report on correlations between processing method, film microstructure and temperature dependent sensing performance for toluene, methanol, isopropanol, carbon monoxide, acetone, and other compounds.