AVS 45th International Symposium
    Vacuum Technology Division Wednesday Sessions
       Session VT-WeM

Paper VT-WeM10
Diamond Coated Silicon Field Emitter Array

Wednesday, November 4, 1998, 11:20 am, Room 329

Session: Vacuum Microelectronics
Presenter: W. Fu, Old Dominion University
Authors: S. Albin, Old Dominion University
W. Fu, Old Dominion University
G.R. Myneni, Thomas Jefferson National Accelerator Facility
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Diamond coated silicon tip arrays, with and without a self-aligned gate, were fabricated and their I-V characteristics were measured. Sharp silicon tips were prepared by a wet etching technique. For samples without the gate, the silicon array was selectively nucleated at the tip region using ultrasonic agitation in a 10-nm diamond suspension. CVD diamond films were grown uniformly on the tips with a negative bias on the substrate to enhance the diamond growth. The arrays were tested for current emission under a vacuum of 10@super -6@ torr. A piece of polished silicon was used as anode with a 2-@micron@ thermal oxide spacer. An emission current of 50 @mu@A was obtained at 5 V from an array of 400 tips. The I-V curve of the diamond coated silicon arrays showed typical diode characteristic under forward and reverse bias. To fabricate the self-aligned gate structure, 1-@micron@ thermal oxide was grown on the etched samples followed by deposition of 0.2 @micron@ tungsten as a gate metal using RF sputtering. After planarization by etch back, the exposed gate metal and oxide were removed from the tips. Diamond films were grown selectively on the silicon tips. A copper anode was placed 200 @micron@ away from the array surface with an applied voltage of 400 V. The turn-on gate voltage was found to be 40 V for the gate aperture of about 1.5 @micron@. An emission current of 3 @mu@A was obtained from an array of 400 tips at a gate voltage of 80 V. Our technique shows the potential for development of diamond based low voltage vacuum electronic devices and field emission based micro sensors.