EP0578512A1 - Einkristalline Feldemissionsvorrichtung - Google Patents

Einkristalline Feldemissionsvorrichtung Download PDF

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Publication number
EP0578512A1
EP0578512A1 EP93305424A EP93305424A EP0578512A1 EP 0578512 A1 EP0578512 A1 EP 0578512A1 EP 93305424 A EP93305424 A EP 93305424A EP 93305424 A EP93305424 A EP 93305424A EP 0578512 A1 EP0578512 A1 EP 0578512A1
Authority
EP
European Patent Office
Prior art keywords
single crystal
thin film
emitter electrode
electrode
substrate
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.)
Granted
Application number
EP93305424A
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English (en)
French (fr)
Other versions
EP0578512B1 (de
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/de
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Publication of EP0578512B1 publication Critical patent/EP0578512B1/de
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    • 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 disdoses 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", J. 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.
  • the present invention describes a field emission device (100) and manufacturing method which minimize the problems of sensitivity to damage, instability, and lack of uniformity, by forming some or all of the electrodes of the device out of single crystals having no grain boundaries.
  • the emitter and gate electrodes (103 and 104 respectively) are formed from the same single crystal thin film, by a method which etches a gap (203) in the crystal to define the two electrodes (103 and 104).
  • the emitter and gate electrodes (103 and 104 respectively) can be formed from two independent single crystal thin films, or the electrodes (103 and 104) can be configured using any other emission device structure, including, for example, traditional cone emitter structures.
  • the gate electrode (104), the emitter electrode (103), or both may be single crystal.
  • a single crystal anode electrode (205) may also be used to further reduce the aforementioned problems.
  • Figure 1a is a sectional diagram of a field emission device 100 having a cone-shaped emitter 103 according to the prior art.
  • Figure 1b is a sectional diagram of a thin film field emission device 100 having an edge emitter structure 103.
  • Figure 2 is a sectional diagram of a single crystal thin film emission device 100 in accordance with a preferred embodiment of the present invention.
  • Figures 3a through 3f illustrate a preferred method of manufacturing the single crystal thin film emission device 100 according to the present invention. These Figures are sectional diagrams of the device 100 at six stages of the preferred manufacturing process.
  • 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.
  • the invention may be practised with other device structures wherein differently shaped electrodes, such as the traditional cone-emitter structure of Figure 1a, are employed in place of thin film electrodes.
  • the invention may be practised using single crystals for some but not all of the electrodes.
  • the gate electrode is formed from a single crystal.
  • the emitter electrode can also be formed from a single crystal, either the same as that of the gate electrode or another single crystal. The same applies to the anode electrode.
  • the crystal or any of the crystals as appropriate can be thin films, preferably of gallium arsenide.
  • the emitter is preferably cone shaped.

Landscapes

  • Cold Cathode And The Manufacture (AREA)
  • Junction Field-Effect Transistors (AREA)
EP93305424A 1992-07-09 1993-07-09 Einkristalline Feldemissionsvorrichtung Expired - Lifetime EP0578512B1 (de)

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 true EP0578512A1 (de) 1994-01-12
EP0578512B1 EP0578512B1 (de) 1998-11-11

Family

ID=25429563

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93305424A Expired - Lifetime EP0578512B1 (de) 1992-07-09 1993-07-09 Einkristalline Feldemissionsvorrichtung

Country Status (3)

Country Link
EP (1) EP0578512B1 (de)
JP (1) JPH0697458A (de)
DE (1) DE69322005T2 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0739022A2 (de) * 1995-04-21 1996-10-23 Hewlett-Packard Company Feldemissionsanordnung für eine flache Anzeigevorrichtung

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0444670A2 (de) * 1990-03-01 1991-09-04 Matsushita Electric Industrial Co., Ltd. Flachgestaltete Kaltkathode mit spitzen Enden und Herstellungsverfahren derselben
WO1992004732A1 (en) * 1990-09-07 1992-03-19 Motorola, Inc. A field emission device employing a layer of single-crystal silicon
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

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1331762C (zh) * 2002-06-19 2007-08-15 荷兰联合利华有限公司 水净化系统

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0444670A2 (de) * 1990-03-01 1991-09-04 Matsushita Electric Industrial Co., Ltd. Flachgestaltete Kaltkathode mit spitzen Enden und Herstellungsverfahren derselben
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 (en) * 1990-09-07 1992-03-19 Motorola, Inc. A field emission device employing a layer of single-crystal silicon

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0739022A2 (de) * 1995-04-21 1996-10-23 Hewlett-Packard Company Feldemissionsanordnung für eine flache Anzeigevorrichtung
EP0739022A3 (de) * 1995-04-21 1997-01-22 Hewlett Packard Co Feldemissionsanordnung für eine flache Anzeigevorrichtung

Also Published As

Publication number Publication date
DE69322005D1 (de) 1998-12-17
DE69322005T2 (de) 1999-04-01
JPH0697458A (ja) 1994-04-08
EP0578512B1 (de) 1998-11-11

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