Field induced emission devices and method of forming same

Abstract

In a method of forming a field-induced emission device, a cathode is provided on a substrate, for example by etching away the substrate to leave a pointed projection. The projection may be covered with a metallic layer to enhance the field-induced cathode emission. A first insulating layer is formed over the substrate, with an aperture therein corresponding to the cathode position. An apertured control grid layer is formed over the first insulating layer and an apertured second insulating layer is formed thereon. A tunnel formed by the apertures in the insulating and conductive layers is filled with a plug of soluble material. An anode strip is formed on the second insulating layer and over the plug, and the plug is then dissolved through gaps at the edges of the anode strip, thereby leaving an unsupported area of anode strip over the cathode. The tunnel may then be evacuated or may be filled with gas and the gaps at the edges of the anode strip will then be sealed to retain the vacuum or gas. If a diode structure is required, the control grid layer and the second insulating layer will be omitted. A switching device may be constructed by associating a number of the cathodes on the substrate with a common control grid and a common anode. The anode, grid and cathode structures may be so dimensioned as to form a transmission line.