FABRICATION OF GATED SILICON FIELD-EMISSION CATHODES FOR VACUUM MICROELECTRONICS AND ELECTRON-BEAM APPLICATIONS

Two types of silicon gated field-emission cathodes have been fabricated. The first is fabricated using a phosphosilicate glass insulation layer and a non-self-aligned etched polysilicon gate. The second type is formed by evaporating silicon dioxide and chrome onto a field-emission point capped by its etch mask. The self-aligned gate is then patterned by lifting-off the cap. Cathode current of the etched-gate structure was not measured until 150 V, at which value the device also failed. Current was measured, however, between the gate and the anode of this structure. This gate-anode current is attributed to a nonplanar gate structure and a gate-anode spacing of approximately 0.5 mum. Gate-anode currents follow a Fowler-Nordheim characteristic, emitting 0.16 muA/gate at 4 V. Current from the lift-off structure was measured between the cathode and the gate. Currents averaging to 0.2 muA/tip at 23 V on the gate have been measured. These devices are intended for application to vacuum microelectronics, flat-panel displays, and cold-cathode electron-beam instruments.