Micromachined field emission cathode with an integrated heater

We report on the fabrication and operation of integrated micromachined and suspended field emission cathode tips. The emitter tips are suspended at the center of a silicon beam using multiple patterning methods of high aspect ratio silicon structures using a single layer silicon dioxide etch mask. The integrated, suspended silicide microheater is used to clean and to activate the cathodes. The silicon tips are subsequently modified to improve their emission properties. The modified cathodes exhibit a significantly lower turn on voltage of about 50 V (similar to 100 V for silicon cathodes), and need no chemical tip cleaning prior to emission. A much larger emission current with reduced emission noise has been observed when a single tip is cycled through the tip forming process. (C) 1995 American Vacuum Society.