International Business Machines Corporation

Advanced Vision Technologies, Inc.

Michael David Potter

John Edward Cronin

Gorden Seth Starkey

A lateral-emitter field emission device has a thin-film emitter cathode 50 which has thickness of not more than several hundred angstroms and has an edge or tip 110 having a small radius of curvature. To form a novel display cell structure, a cathodoluminescent phosphor anode 60 is positioned below the plane of the thin-film lateral-emitter cathode 50, allowing a large portion of the phosphor anode's top surface to emit light in the desired direction. An anode contact layer contacts the phosphor anode 60 from below to form a buried anode contact 90 which does not interfere with light emission. The anode phosphor is precisely spaced apart from the cathode edge or tip and receives electrons emitted by field emission from the edge or tip of the lateral-emitter cathode, when a small bias voltage is applied. The device may be configured as a diode, triode, or tetrode, etc. having one or more control electrodes 140 and/or 170 positioned to allow control of current from the emitter to the phosphor anode by an electrical signal applied to the control electrode. In a particularly simple embodiment, a single control electrode 140 is positioned in a plane below the emitter edge or tip 110 and automatically aligned to that edge. The display cell structure may be repeated many times in an array, and the display cell structure of the invention lends itself to novel array structures which are also disclosed. A fabrication process is disclosed using subprocess steps S1-S19 similar to those of semiconductor integrated circuit fabrication to produce the novel display cell structures and their arrays. Various embodiments of the fabrication process allow the use of conductive or insulating substrates 20 and allow fabrication of devices having various functions and complexity.

Field emission display cell structure

A method of etching vias without directional etching damage to the substrate. A pattern image is formed on an insulating layer of known thickness over a substrate. A conformal layer is formed on the pattern image. A vertical contact hole through the conformal layer and into the insulating layer is produced by directional etching. The directional etch also leaves conformal sidewall spacers of a defined width. The depth of the vertical contact hole is equal to the thickness of the insulating layer minus the width of the conformal spacer. The insulating layer is then removed by an isotropic wet etch to achieve a near vertical edge contact hole without directional etching damage to the substrate. The sidewall spacers may also be removed by etching prior to removal of the insulating layer.

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Grand Isle County, VT, United States of America

Michael David Potter