EP0569671A1 - Cathode froide à émission de champ et sa procédé de fabrication - Google Patents

Cathode froide à émission de champ et sa procédé de fabrication Download PDF

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Publication number
EP0569671A1
EP0569671A1 EP93103085A EP93103085A EP0569671A1 EP 0569671 A1 EP0569671 A1 EP 0569671A1 EP 93103085 A EP93103085 A EP 93103085A EP 93103085 A EP93103085 A EP 93103085A EP 0569671 A1 EP0569671 A1 EP 0569671A1
Authority
EP
European Patent Office
Prior art keywords
cold cathode
layer
field emission
emission cold
emitter
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.)
Withdrawn
Application number
EP93103085A
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German (de)
English (en)
Inventor
Hideo Makishima
Hironori Imura
Keizo Yamada
Toshihide Kuriyama
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.)
NEC Corp
Original Assignee
NEC Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by NEC Corp filed Critical NEC Corp
Publication of EP0569671A1 publication Critical patent/EP0569671A1/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/022—Manufacture of electrodes or electrode systems of cold cathodes
    • H01J9/025—Manufacture of electrodes or electrode systems of cold cathodes of field emission cathodes
    • 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

  • the present invention relates to a field emission cold cathode and a method for manufacturing the same in which a fine process technology is used for fabrication.
  • Fig. 2 shows a cross-section of a combination of an anode and a conventional cold cathode constituting a display unit.
  • the cathode shown in Fig. 2 is called a cold cathode of a Spindt type among conventional cold cathodes fabricated by a fine process technology.
  • An insulating layer 33 forming recesses therein, a gate 34 of a thin metal film having holes 39 each aligned with the recess, and emitters 32 each having a pointed tip and disposed at the recess are formed on a semiconductor substrate 31.
  • the gate 34 serving as a control electrode for an emission current is applied with a positive voltage relative to both the emitters 32 and the semiconductor substrate 31 maintained at a common potential.
  • the semiconductor substrate 31, the emitters 32, the insulating layers 33 and the gate 34 constitute the cold cathode 35, and the anode 36 is disposed opposite to the cathode 35.
  • Each of the emitters 32 has an extremely pointed tip, so that a very high electric field is generated around the tips, hence electrons are emitted from the emitters 32 in an amount corresponding to the voltage applied to the gate 34.
  • the space between the cathode 35 and the anode 36 is kept at a vacuum, and the electrons emitted from the cathode 35 reach and hit the anode 36 applied with the positive voltage and coated with a fluorescent material.
  • the current of the electron beam emitted from one of the emitters 32 is of a small amount in an order of 10 - 50 ⁇ A at most, so that a number of emitters are arranged on the surface of the substrate 31 for obtaining a desired electron beam current.
  • Fig. 3 shows a cross-section of another combination of an anode and a cold cathode of a laid-down type among the conventional cold cathodes fabricated by the fine process technology.
  • an emitter 32, a gate 34 and a laid-down anode 37 constituting a cold cathode 35 are formed on an insulating substrate 38 and an opposite anode 36 is disposed opposite to the cold cathode 35.
  • a sheet-figured electron beam is emitted from the line-figured tip of the emitter 32 and reaches at the laid-down anode 37 or the opposite anode 36 applied with a positive voltage relative to the cathode 35 and coated with a fluorescent material.
  • the emitters 32 of about a 1 ⁇ m height are fabricated in such a way that a metal is deposited by a vapor deposition through the holes 39 of the gate 34 so as to form an extremely pointed tip figure of the emitter 32 during the deposition process.
  • a metal is deposited by a vapor deposition through the holes 39 of the gate 34 so as to form an extremely pointed tip figure of the emitter 32 during the deposition process.
  • Such a process is different from a conventional process in the semiconductor fabrication technology, so that special designs for a manufacturing apparatus and a fabrication procedure are required.
  • the amount of the current should be designed in part by the radius of the curvature of the emitter tips, it is difficult to fabricate the radius of the curvature of each tip with a good reproducibility and a uniformity.
  • the electron beam emitted in a horizontal direction from the emitter 32 must be deflected by a right-angle with an accuracy to reach and hit a certain position of the anode 36.
  • the position hit by the electron beam changes due to only a slight change in the conditions such as the voltage change between the electrodes, so that it is difficult to realize a stable display unit utilizing the cold cathode of a laid-down type.
  • an object of the present invention is to provide a field emission cold cathode and a method for manufacturing the same in which a tip figure of the emitter of the cold cathode is reproducible and uniform.
  • Another object of the present invention is to provide a field emission cold cathode and a method for manufacturing the same in which a change rate in an emitter current relative to the change of the gate voltage is considerably large.
  • a field emission cold cathode comprising: a substrate; an insulating layer carried by said substrate and having a recess therein; a control electrode layer formed on said insulating layer and having a cut-out at least partially overlapping said recess; and an emitter layer having an edge portion at said recess.
  • a method for manufacturing a field emission cold cathode including steps of: forming a structure having a perpendicular surface substantially perpendicular to a substrate; forming at least one emitter layer at least on said perpendicular surface; forming a filling layer on said emitter layer; removing partially said structure, said emitter layer and said filling layer substantially parallel to said substrate for exposing a cross-section of said emitter layer.
  • the emitter layer emitting an electron beam from an edge thereof can be fabricated with a good reproducibility and a uniformity by using a semiconductor fabrication technology. Besides, a change rate in the emission current relative to the change of the gate voltage is considerably large, since the emission edge can be formed extremely sharp. Moreover, since the direction of the emission current can be substantially perpendicular to the control electrode layer, a stable and accurate electron beam reaching and hitting a certain position of a display screen can be obtained when it is applied to a display unit.
  • Figs. 1(a) to 1(i) each shows a cross-section of a field emission cold cathode in a fabrication step for showing a method according to an embodiment of the present invention for manufacturing a field emission cold cathode.
  • a common conductive layer 2 is deposited on an insulating substrate 1.
  • a first oxide layer 3 is formed and subjected to a vertical etching treatment by a reactive ion etching (RIE) process for building a surface 3A of the first oxide layer 3, the surface being substantially perpendicular to the substrate 1.
  • RIE reactive ion etching
  • a set of layers including three conductive layers 4, the vertical portion of which is to be formed as an emitter electrode 4A are deposited in an overlapping configuration as shown in Fig. 1(b).
  • the central conductive layer among the three conductive layers 4 constitutes an emitter layer 5 and the remaining two constitute supporting layers 6. Platinum, tungsten or molybdenum may be utilized as a material for the emitter layer 5. Since the supporting layers 6 are removed selectively from the emitter layer 5 by a later etching process, the supporting layers 6 should be formed of a material having a nature chemically different from the emitter layer 5.
  • the emitter layer 5, which is formed in a tens to hundreds of angstrom thickness, for example, 50 - 500 angstrom, may be preferably grown by molecular beam epitaxy (MBE).
  • a second oxide layer 7 is then deposited and a subsequent leveling treatment is carried out to the second oxide layer 7.
  • unnecessary portions of the three conductive layers 4 extending horizontally on the first oxide layer 3 is removed, for example, by grinding parallel to the substrate 1 to dispose the cross-section 8 of the three conductive layer 4 between the surfaces of the first and second oxide layers 3 and 7 as shown in Fig. 1(d).
  • a mask 9 is formed on the cross-section 8 by patterning a layer deposited at the region on the cross-section 8 of the three conductive layers 4. Since the mask 9 functions only as a sacrificial layer, such a material as resist titanium, gold, aluminium may be used which can be removed without interference with the other materials. Subsequently, as shown in Fig. 1(f), the first and second oxide layers 3 and 7 and the horizontal portion 4B of the three conductive layers 4 are removed by another RIE process selectively from the vertical portions 4A of the three conductive layers 4 using the mask 9 to obtain a vertical structure of the emitter electrode 4A.
  • an oxide material and another conductive material are consecutively deposited for forming a third oxide layer 10 and another conductive layer serving as a control electrode 11.
  • the control electrode layer 11 has a hole or a cut-out at the location where the mask 9 is formed.
  • a metal as tungsten is preferably used as the conductive material for the control electrode layer 11.
  • the oxide and conductive materials are also formed as layers 12 and 13, respectively, above the emitter electrode 4A.
  • the oxide layer 12 and the conductive layer 13 are then removed as shown in Fig. 1(h) by using an etchant which can etch only the material forming the mask 9.
  • the supporting layers 6A among the three vertical conductive layers constituting the emitter electrode 4A are slightly removed at the tip portion by etching for exposing a tip of the central emitter layer 5A.
  • another etching process is carried out for removing the unnecessary oxide layers 14 as remaining portions of the first and second oxide layers 3 and 7 disposed around the emitter electrode 4A.
  • the field emission cold cathode as shown in Fig. 1(i), has an insulating substrate 1, a common conductive layer 2 formed on the substrate 1, an insulating layer 10 formed on the common conductive layer 2 and having a recess 15, a control electrode layer or a gate layer 11 disposed on the insulating layer 10 and having a hole or a cut-out 16 overlapping the recess 15, and an emitter electrode 4A including an emitter layer 5A and supporting layers 6A for supporting the emitter layer 5A and disposed at the recess 15.
  • the emitter layer 5A has a perpendicular portion substantially perpendicular to the control electrode layer 11, and the perpendicular portion of the emitter layer 5A has an edge or a line-figured tip extending from between the supporting layers 6A at the recess 15 and below the cut-out 16.
  • each of the supporting layers may be an insulating layer instead of a conductive layer.
  • a plane-figured cathode such a construction may be employed in which the structure of Fig. 1(i) is formed as having a continuous configuration on a large chip area.
  • an emitter layer extremely sharp and moreover uniform as well as reproducible in the tip figure can be obtained, since a thin layer of a tens or hundreds of angstrom thickness can be easily formed by utilizing a semiconductor process such as a MBE process for growing an emitter layer. Since the emitter layer can be supported at both or one of the sides thereof, the extremely thin layer serving as an emitter can be kept in a vertical position in a good stability.
  • the field emission cold cathode according to the embodiment of the present invention can be produced at a process completely equivalent to the conventional semiconductor process, hence the method is more advantageous when forming the field emission cold cathode on a larger chip area. Besides, since only the emitter layer of the emitter electrode should be a thin layer and the remaining members of the emitter electrode may be thick, heat-resistivity and mechanical strength of the emitter electrode may be large so that an emitter structure of a good stability is obtained.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Cold Cathode And The Manufacture (AREA)
EP93103085A 1992-05-12 1993-02-26 Cathode froide à émission de champ et sa procédé de fabrication Withdrawn EP0569671A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP118637/92 1992-05-12
JP11863792A JPH05314891A (ja) 1992-05-12 1992-05-12 電界放出冷陰極およびその製造方法

Publications (1)

Publication Number Publication Date
EP0569671A1 true EP0569671A1 (fr) 1993-11-18

Family

ID=14741471

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93103085A Withdrawn EP0569671A1 (fr) 1992-05-12 1993-02-26 Cathode froide à émission de champ et sa procédé de fabrication

Country Status (2)

Country Link
EP (1) EP0569671A1 (fr)
JP (1) JPH05314891A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996010835A1 (fr) * 1994-09-30 1996-04-11 Polaroid Corporation Source de lumiere pour enregistreur de film dotee d'une cathode a emission par effet de champ
WO1997033295A3 (fr) * 1996-03-09 1997-12-04 Deutsche Telekom Ag Systeme de tubes electroniques et son procede de production
FR2758206A1 (fr) * 1997-01-08 1998-07-10 Futaba Denshi Kogyo Kk Procede de fabrication d'une cathode a emission de champ
WO2001093295A1 (fr) * 2000-05-26 2001-12-06 Litton Systems, Inc. Fabrication d'elements a emission de champ pour magnetron

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100302183B1 (ko) * 1997-11-29 2001-11-22 김영남 전계방출표시소자의필드에미터어레이형성방법

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0400406A1 (fr) * 1989-05-19 1990-12-05 Matsushita Electric Industrial Co., Ltd. Dispositif émetteur d'électrons et procédé de fabrication
WO1991007771A1 (fr) * 1989-11-22 1991-05-30 Motorola, Inc. Systeme d'emission de champ de cathode froide ayant une electrode prise dans une couche d'encapsulation

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0400406A1 (fr) * 1989-05-19 1990-12-05 Matsushita Electric Industrial Co., Ltd. Dispositif émetteur d'électrons et procédé de fabrication
WO1991007771A1 (fr) * 1989-11-22 1991-05-30 Motorola, Inc. Systeme d'emission de champ de cathode froide ayant une electrode prise dans une couche d'encapsulation

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996010835A1 (fr) * 1994-09-30 1996-04-11 Polaroid Corporation Source de lumiere pour enregistreur de film dotee d'une cathode a emission par effet de champ
WO1997033295A3 (fr) * 1996-03-09 1997-12-04 Deutsche Telekom Ag Systeme de tubes electroniques et son procede de production
FR2758206A1 (fr) * 1997-01-08 1998-07-10 Futaba Denshi Kogyo Kk Procede de fabrication d'une cathode a emission de champ
WO2001093295A1 (fr) * 2000-05-26 2001-12-06 Litton Systems, Inc. Fabrication d'elements a emission de champ pour magnetron

Also Published As

Publication number Publication date
JPH05314891A (ja) 1993-11-26

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