PLANAR-PROCESSED TUNGSTEN AND POLYSILICON VACUUM MICROELECTRONIC DEVICES WITH INTEGRAL CAVITY SEALING

Solid-state micromachining and planar lithography have been applied in the formation of vacuum microdiode devices. These devices are fabrica ted with an on-chip vacuum cavity through directional material sealing techniques initiated at vacuum pressure of approximately 2 x 10(-6) T . Both tungsten and polycrystalline silicon have been used as cold-cat hode emitter materials. The resulting current-voltage characteristics are stable and show good Fowler-Nordheim characteristics to operating currents in excess of 50 muA for wedge-shaped emitter tips. Electrical noise measurements carried out indicate a dominance of flicker noise at low frequencies for both tungsten and polycrystalline silicon micro diodes with the tungsten devices exhibiting excellent characteristics.