EP0578512B1 - Dispositif à émission de champ monocristallin - Google Patents

Dispositif à émission de champ monocristallin Download PDF

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Publication number
EP0578512B1
EP0578512B1 EP93305424A EP93305424A EP0578512B1 EP 0578512 B1 EP0578512 B1 EP 0578512B1 EP 93305424 A EP93305424 A EP 93305424A EP 93305424 A EP93305424 A EP 93305424A EP 0578512 B1 EP0578512 B1 EP 0578512B1
Authority
EP
European Patent Office
Prior art keywords
electrode
single crystal
emitter
thin film
insulator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93305424A
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German (de)
English (en)
Other versions
EP0578512A1 (fr
Inventor
Steve G. Bandy
Christopher Webb
Clifford K. Nishimoto
Ross A. Larue
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Varian Medical Systems Inc
Original Assignee
Varian Associates Inc
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Filing date
Publication date
Application filed by Varian Associates Inc filed Critical Varian Associates Inc
Publication of EP0578512A1 publication Critical patent/EP0578512A1/fr
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/30—Cold cathodes, e.g. field-emissive cathode
    • H01J1/304—Field-emissive cathodes
    • H01J1/3042—Field-emissive cathodes microengineered, e.g. Spindt-type

Definitions

  • This invention pertains to the field of field emission devices, and particularly relates to a device in which some or all of the electrodes are formed from single crystal material.
  • Field emission devices are microscopic electrical components which selectively emit electrons.
  • Such devices 100 as shown in Figures 1a and 1b, generally comprise two electrodes: an emitter electrode 103 for emitting electrons and a gate electrode 104 for controlling the flow of electrons from the emitter electrode 103 depending on the electrical charge present at the gate 104.
  • the electrodes are typically mounted on some kind of substrate 101 or 105 to provide support for the device, with a gap between the electrodes.
  • a third electrode, the anode (not shown in Figures 1a and 1b), may also be present to receive the emitted electrons, although in some devices the gate electrode 104 serves as the anode.
  • Field emission devices have been known for several years to have many potential applications in commercial and military industry, such as: high-definition television; flat-panel video displays; radiation-hard thermally insensitive integrated circuits; microsensors; fast electron sources for vacuum tubes; and electron microscopes.
  • high-definition television flat-panel video displays
  • radiation-hard thermally insensitive integrated circuits microsensors
  • fast electron sources for vacuum tubes and electron microscopes.
  • Three such problems are 1) their extreme sensitivity to damage, 2) their instability evidenced by a tendency towards microstructure changes with use, and 3) the difficulty of manufacturing such devices with sufficient uniformity and reproducibility.
  • the following references detail these problems, and describe the state of the prior art in the manufacture of emission devices.
  • U.S. patent 3,947,716 discloses a field emission tip and process wherein a metal adsorbate is selectively deposited on the tip to create a selectively faceted tip with the emitting planar surface having a reduced work function and the non-emitting planar surfaces having an increased work function, thus yielding improved performance.
  • the patent disdoses the use of a single crystal to fabricate emission tips, but the reason for single crystal use in emission tips has traditionally been to facilitate fabrication of a cone-shaped emitter.
  • the patent does not mention the use of single crystals for the other electrodes of the device, nor does it suggest the use of single crystals in conjunction with thin film emitters or for stability and arc damage resistance.
  • J.E. Wolfe "Operational Experience with Zirconiated T-F Emitters", L Vac., Sci. Technology v. 16, p. 1704 (1979), discusses the characteristics of an electron gun which uses a cathode-filament structure with a needle-shaped cathode. It discusses some techniques for improving performance and extending device lifetime, but does not mention grain boundaries or single-crystal structures.
  • Figure 1a shows a well-known cone emitter structure, in which a cone-shaped emitter electrode 103 is mounted on a conducting substrate 101 (as stated in "Thin Film Emitter Development", “virtually all structures reported in the literature use conducting substrates.”).
  • Figure lb shows the newer “edge emitter” structure discussed in “Thin Film Emitter Development", in which an edge of the emitter 103 protrudes from between an insulator 102 and a metal overlay 106.
  • This structure usually employs an insulating substrate 105.
  • Edge emitters offer several potential advantages over cone-shaped emitters, including improved reproducibility and uniformity, high current densities, and high frequency performance. Even with these advantages, however, the three problems mentioned above persist.
  • WO-A-92/04732 discloses a field emission device comprising an emitter electrode for emitting electrons and a gate electrode for controlling the electron emission formed from a single crystal wherein there is a gap between the emitter electrode and the gate electrode.
  • the present invention is set out in claim 1.
  • FIG. 2 there is shown a sectional diagram of a preferred embodiment of a field emission device 100 according to the present invention.
  • Two insulators 102 made from, e.g. , aluminum gallium arsenide are deposited on an insulating substrate 105 made from, e.g. , gallium arsenide.
  • the insulators 102 are shown spaced apart, but they need not be.
  • the emitter and gate electrodes, 103 and 104 respectively, are formed from a single thin film of e.g. , heavily doped gallium arsenide and rest on the insulators 102, so that a gap 203 is formed between the two electrodes.
  • Ohmic contacts 204 are fastened to the emitter and gate electrodes to facilitate electrical contact with the device.
  • An anode electrode 205 separated from the other components of the device and also formed from a single crystal, may also be present to collect the emitted electrons, or, alternatively, the gate electrode 104 may function as an anode.
  • FIG. 3a the starting material for the process is shown.
  • an insulating substrate 105 of gallium arsenide Deposited on the substrate is a buffer layer 301 of aluminum gallium arsenide, approximately 5 microns thick.
  • a single crystal thin film (approximately 1000 angstroms thick) of conducting material 302, preferably heavily doped gallium arsenide. Other materials and thicknesses may be used.
  • a layer of photoresist 303 is applied on top of the conducting layer 302, according to well-known device manufacturing techniques.
  • the photoresist is applied in a pattern which will eventually define the placement of the electrodes 103 and 104 on the final device, by leaving gaps where the conducting material 302 is to be removed.
  • the conducting layer 302 is etched according to well-known device manufacturing techniques. Wherever photoresist 303 is present, the conducting layer 302 remains intact, but where there is a gap in the photoresist 303, the conducting layer 302 is etched away. In this way, two electrodes 103 and 104 are formed, with a gap 203 between them. Electrode 103 will eventually become the emitter and electrode 104 will become the gate.
  • the buffer layer 301 is etched out under the gap 203, so that there is some overhang of the electrodes 103 and 104.
  • the buffer layer 301 thus becomes two aluminum gallium arsenide insulators 102.
  • the buffer layer may not be etched out, or may only be partially etched out, so that insulators 102 are touching.
  • ohmic contacts 204 are attached to the electrodes 103 and 104 so that electrical connections can be made to the device 100.
  • An anode electrode 205 is also shown, although this is optional; if no anode 205 is present, the gate electrode 104 acts as an anode.
  • the anode 205 if present, may be made of heavily doped gallium arsenide, or gold, or any other conducting material. It may be formed from a single crystal, although this is not necessary. It may or may not be formed from a thin film, and may even be formed from the same film as the other two electrodes (for example, in a coplanar arrangement).
  • the emitter and gate electrodes, 103 and 104 respectively may be formed from two separate single crystal thin films, rather than from one piece 302.

Landscapes

  • Cold Cathode And The Manufacture (AREA)
  • Junction Field-Effect Transistors (AREA)

Claims (7)

  1. Dispositif à émission de champ (100) comprenant une électrode émettrice (103) pour émettre des électrons et une électrode de grille (104) pour commander l'émission d'électrons formée d'un monocristal, dans lequel il y un intervalle (203) entre l'électrode émettrice et l'électrode de grille, caractérisé en ce que l'électrode émettrice est un monocristal en couche mince, le monocristal de l'électrode de grille est une couche mince, chaque électrode étant formée d'une couche mince cristalline n'ayant pas de limites de grains, ce qui a pour effet d'améliorer la stabilité et la résistance à la formation d'arc dans ledit dispositif.
  2. Dispositif selon la revendication 1, dans lequel la couche mince est formée à partir d'arséniure de gallium.
  3. Dispositif selon la revendication 1 ou 2, comprenant par ailleurs une électrode anodique monocristalline (205) espacée de l'électrode émettrice pour recevoir les électrons de l'électrode émettrice.
  4. Dispositif selon la revendication 3, dans lequel l'électrode 3, dans lequel l'électrode anodique est formée en relation coplanaire avec le monocristal mentionné en premier lieu.
  5. Dispositif selon la revendication 4, dans lequel ladite anode monocristalline est une électrode séparée disposée à proximité distale de l'alignement émetteur-grille.
  6. Dispositif selon l'une quelconque des revendications précédentes, dans lequel l'électrode émettrice est formée du même monocristal que celui de l'électrode de grille.
  7. Dispositif à émission de champ selon la revendication 2 ou l'une quelconque des revendications qui en dépendent, comprenant par ailleurs un substrat isolant (105), un premier isolant (102) monté sur le substrat, un second isolant (102) monté sur le substrat au voisinage du premier isolant, et une couche de recouvrement métallique montée sur l'électrode émettrice, qui est montée sur le premier isolant de telle sorte que l'électrode émettrice fasse saillie au-delà du bord du revêtement métallique, ladite électrode de grille étant montée sur le second isolant.
EP93305424A 1992-07-09 1993-07-09 Dispositif à émission de champ monocristallin Expired - Lifetime EP0578512B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US91095792A 1992-07-09 1992-07-09
US910957 1992-07-09

Publications (2)

Publication Number Publication Date
EP0578512A1 EP0578512A1 (fr) 1994-01-12
EP0578512B1 true EP0578512B1 (fr) 1998-11-11

Family

ID=25429563

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93305424A Expired - Lifetime EP0578512B1 (fr) 1992-07-09 1993-07-09 Dispositif à émission de champ monocristallin

Country Status (3)

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EP (1) EP0578512B1 (fr)
JP (1) JPH0697458A (fr)
DE (1) DE69322005T2 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5587628A (en) * 1995-04-21 1996-12-24 Kuo; Huei-Pei Field emitter with a tapered gate for flat panel display

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004000732A1 (fr) * 2002-06-19 2003-12-31 Unilever Plc Systeme de purification d'eau

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2574500B2 (ja) * 1990-03-01 1997-01-22 松下電器産業株式会社 プレーナ型冷陰極の製造方法
US5214347A (en) * 1990-06-08 1993-05-25 The United States Of America As Represented By The Secretary Of The Navy Layered thin-edged field-emitter device
WO1992004732A1 (fr) * 1990-09-07 1992-03-19 Motorola, Inc. Dispositif d'emission de champ utilisant une couche de silicium monocristal

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004000732A1 (fr) * 2002-06-19 2003-12-31 Unilever Plc Systeme de purification d'eau

Also Published As

Publication number Publication date
JPH0697458A (ja) 1994-04-08
DE69322005D1 (de) 1998-12-17
EP0578512A1 (fr) 1994-01-12
DE69322005T2 (de) 1999-04-01

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