FIELD-EMITTER ARRAYS FOR VACUUM MICROELECTRONICS

The evolution of a new class of miniature vacuum field-effect devices-vacuum microelectronics-depends critically on the availability of a miniature, cold, intense electron source (cathode). An ongoing SRI program on microfabricated field-emitter arrays has produced a gated field-emitter tip structure with submicrometer dimensions, and techniques for fabricating emitter arrays with tip packing densities of up to 1.5 x 10(7) tips/cm2. Arrays have been fabricated over areas varying from a few micrometers up to 13 cm in diameter. Very small overall emitter size, materials selection, and rigorous emitter-tip processing procedures have all contributed to reducing the potential required for field emission to tens of volts. Emission current densities of up to 1000 A/cm2 have been achieved with small arrays of tips, and 100-mA total emission is commonly produced with arrays 1 mm in diameter containing 10 000 tips. Transconductances of 5.0-mu-S per tip have been demonstrated, indicating that 50 S/cm2 should be achievable with tip densities of 10(7) tips/cm2. Details of the cathode arrays and a variety of performance characteristics are discussed.