Field emission cold cathode element having exposed substrate

Abstract

A field emission cold cathode element having a conducting substrate, a dielectric layer which is on the substrate and has holes, emitter electrodes each of which have a sharp-pointed tip and stand on the substrate in the respective holes in the dielectric layer, and a gate electrode layer which is on the dielectric layer and has apertures right above the respective holes in the dielectric layer. The tip of each emitter electrode is near or in the aperture in the gate electrode layer, and the emission current depends on the position of the emitter tip relative to the gate electrode. The dielectric layer and the gate electrode layer are largely removed so as to remain only in limited first regions which are around the holes for the respective emitter electrodes and limited second regions each of which connects one of the first regions to another. The partial removal of the dielectric and gate electrode layers is for reducing interlayer stresses induced by temperature changes. In the first regions the gate electrode layer is made thicker than in the second regions to compensate for inevitable variations in the emitter electrode heights without augmenting the interlayer stresses.