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Abstract
Planar surface micromachining techniques have been applied in the fabrication of two types of vacuum microelectronic devices. The lateral vacuum microtriode device consists of a cold cathode, anode, and control electrode (grid) formed of heavily doped n-type polysilicon. The entire active area is sealed in a vacuum cavity which is built on the surface of a silicon wafer. Polysilicon micromembranes are deposited over a 1.0 $\mu$m-thick phosphosilicate glass (PSG) sacrificial layer (spacing layer) which is laterally etched away forming a spacing between active electrodes and top membrane. The side-walls of the membrane are then sealed by the directional sputtering of silicon dioxide at a low pressure to complete the formation of the vacuum cavity.
Field emission characteristics for both cold-cathode diodes and triodes has been studied. The typical value of the emission current measured from the cathode emitter is 0.5 $\mu$A when the anode-to-cathode voltage is 60 volts. The function of gate electrodes in the performance of fabricated cold cathode devices has been investigated. The experimental results and analysis provides suggestions for the improvement of the triode design and its fabrication.
