FIELD EMISSION CATHODE STRUCTURES, DEVICES UTILIZING SUCH STRUCTURES, AND METHODS OF PRODUCING SUCH STRUCTURES

• US 3,789,471 A
• Filed: 01/03/1972
• Issued: 02/05/1974
• Est. Priority Date: 02/06/1970
• Status: Expired due to Term

• Current Assignee: Charles A. Spindt, Kenneth R. Shoulders, Louis N. Heynick
• Original Assignee: Charles A. Spindt, Kenneth R. Shoulders, Louis N. Heynick
• Inventors: Spindt, Charles A., Shoulders, Kenneth R., Heynick, Louis N.
• Primary Examiner(s): Lake, Roy
• Assistant Examiner(s): Davie, J. W.
• Application Number:
  US05/215,068
• Time in Patent Office: 764 Days
• Field of Search: 29/25.17,25.18 313/309,351 117/210,212
• US Class Current: 445/52
• CPC Class Codes: H01J 1/3042 microengineered, e.g. Spindt-type
• CPC Class Codes: H01J 2201/319 Circuit elements associated with the emitters by direct integration
• CPC Class Codes: H01J 9/025 of field emission cathodes

Abstract

Vacuum devices incorporate electron or field forming sources formed by a cellular array of emission sites. The sources comprise a metal/insulator/metal film sandwich on a substrate with a cellular array of holes through the upper metal and insulator, leaving the edges of the upper metal electrode effectively exposed to the upper surface of the lower metal electrode. Sharp protuberances directed toward the upper electrode and constituting emitter tips of controlled configurations are formed on the exposed area of the lower electrode. A method of forming the structure includes starting with the metal/insulator/metal film sandwich having the cellular array of holes already formed and directing permanent electrode material into the cellular array of holes and masking or subsequently removable material onto the surface surrounding the holes whereby an individual sharp cone-like emitter is formed within each of the holes in the cellular array. Vacuum devices are formed from such structures. For example, a diode is formed either by making the masking material over each emission site an electrode or by removing the masking material and applying a conductive electrode material over each emission site.

Claims

1. The method of manufacturing an electric field producing structure, starting with a structure which includes a pair of parallel metal electrodes insulatingly separated by a dielectric film, one of said pair of electrodes and said dielectric film both having a plurality of apertures therethrough whereby edges of said one electrode around said apertures is effectively exposed to a surface of the other of said pair of electrodes, said method comprising the steps of:

a. first, depositing a masking material at a shallow grazing angle on said one of said pair of electrodes thereby to provide a release layer on the said one electrode and build up a lip or mask of controlled diameter around the rim of each cavity therein;

b. second, depositing a conductive metallic emitting material substantially perpendicular to the plane of said pair of electrodes whereby said conductive material is deposited on said second electrode within said apertures, thereby forming cylindrical pedestal-like protuberances within said apertures;

c. third, simultaneously depositing masking material at a shallow grazing angle on said one of said pair of electrodes and depositing conductive metallic emitting material substantially perpendicular to the plane of said pair of electrodes whereby a conical emitting protuberance is formed on said pedestal-like protuberance; and

d. four, subsequently removing all masking and said deposited conductive material from said one of said pair of electrodes.

2. The method of manufacturing an electric field producing structure starting with a structure which includes a pair of metal electrodes insulatingly separated by a dielectric film one of said pair of electrodes and said dielectric film both having a plurality of apertures therethrough whereby edges of said one electrode around said apertures is effectively exposed to a surface of the other of said pair of electrodes, said method comprising the steps of:

a. heat-treating the composite substrate in vacuum at 1,000* C, thereby rendering the the said dielectric film non-etchable with 95* C orthophosphoric acid;

b. simultaneously rotating said composite substrate about an axis perpendicular to its surface and depositing a film at a grazing angle from a source of masking material including alumina whereby a lip is thereby built up around the rim of each cavity;

c. depositing molybdenum from a source perpendicular to the substrate surface, thereby to build a pedestal on the exposed surface of said other one of said pair of electrodes;

d. simultaneously rotating said composite substrate, depositing molybdenum from said second source and the masking material including alumina from said first source, thereby to close the cavity as the pedestal grows, the forming A cone-shaped emitting tip on said pedestal;

e. etching the composite structure with 95* ortho-phosphoric acid, thereby etching away the masking material, thus leaving individual cone-shaped spikes on each of the exposed surfaces of the other one of said pair of electrodes protruding toward the edges of said one electrode within the apertures.