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WO1993005530A1 - Production de pointes precises sur un substrat - Google Patents

Production de pointes precises sur un substrat Download PDF

Info

Publication number
WO1993005530A1
WO1993005530A1 PCT/GB1992/001596 GB9201596W WO9305530A1 WO 1993005530 A1 WO1993005530 A1 WO 1993005530A1 GB 9201596 W GB9201596 W GB 9201596W WO 9305530 A1 WO9305530 A1 WO 9305530A1
Authority
WO
WIPO (PCT)
Prior art keywords
substrate
point
electron beam
species
points
Prior art date
Application number
PCT/GB1992/001596
Other languages
English (en)
Inventor
Pippa Howard
Original Assignee
Era Patents Ltd.
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 Era Patents Ltd. filed Critical Era Patents Ltd.
Publication of WO1993005530A1 publication Critical patent/WO1993005530A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/317—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation
    • H01J37/3178—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation for applying thin layers on objects
    • 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

Definitions

  • This invention relates to a method for producing a fine point or sharp spike on a substrate.
  • Such points or spikes are usually arranged in an array on a substrate and can be used as a field-emitter cathode surface in vacuum electronics.
  • Such points or spikes also have applications in lamps, displays, regulators and switching devices.
  • arrays of fine points are produced by etching methods such as wet-etching, ion-beam etching or selective etching of metal oxide-metal or metal carbide- metal composites.
  • Wet-etching and ion-beam etching require the preliminary steps of mask production and are therefore relatively expensive.
  • Wet-etching also has inherent problems with undercutting where material is etched away from under the protective mask, thereby reducing the potential packing density of the points.
  • Selective etching methods are complex because they require the substrate to be made from special materials leading to increased cost.
  • a method of producing a fine point or spike on a substrate comprises placing the substrate in a chamber containing an atmosphere at low pressure including a precursor of a species to be deposited to form the point or spike, irradiating a sharply focused electron beam on a predetermined location on the substrate to cause the deposition of the species from the atmosphere in the chamber onto the surface of the substrate, and
  • the method of the present invention makes it possible to produce spikes in a process involving fewer steps and offering far greater flexibility by comparison wit conventional techniques. It is possible with the method o the present invention to produce structures typically 1 t 3 ⁇ m tall with tips of radius 20 to 60 nm. Such structures are particularly suitable for use as field-emission (FE) needles.
  • FE field-emission
  • the process is repeated with relative movement between the electron beam and the surface to produce an array of points or spikes, the centres of which may be separated by as little as 0.3 ⁇ m.
  • the electron beam is blanked out whilst the relative movement occurs between the production of each point or spike. This ensures that the species is only deposited at the location where the points or spikes are required.
  • a plurality of electron beams may be used simultaneously to produce a plurality of points or spikes.
  • the method of the present invention is particularly suitable for producing an array of points.
  • the method of production means that the configuration of the array is not limited to that of a predetermined mask, as with the prior art techniques. At the same time, it is found that the method produces spikes with a particularly uniform tip radius.
  • the precursor of the species to be deposited is either a hydrocarbon or an organo-metallic gas
  • the substrate is either a metal or semiconductor. More preferably the substrate is a metal of relatively low conductivity such as Mo or Cr.
  • the height of the points or spikes may be increased by increasing the period of time of the irradiation of the electron beam at the predetermined location on the substrate.
  • the focus point of the electron beam may be moved away from the surface as the point or spike is built-up so that the electron beam is always in sharp focus on the surface on which the species is being deposited.
  • the electrical conductivity of the points or sharp spikes may be improved by depositing a thin film of metal such as platinum or zinc aluminium onto them once formed, and they may be made more durable by depositing a thin film of a durable material. Ion-beam or wet-etching can be used to improve the sharpness of the points after they have been formed in accordance with the present invention.
  • a suitable device for forming a point or sharp spike in accordance with the present invention is a scanning electron microscope, which has the advantages of being able to monitor the degree of focus and the beam current and can also image the final array of points or sharp spikes.
  • Figure 1 shows an apparatus for producing a point or spike
  • Figure 2 shows a plan view of an array of points or spikes
  • Figure 3 shows the profiles of points grown on different substrates
  • Figures 4a and 4b are TEM micrographs; and Figure 5 shows a profile of a needle grown for a field emission device.
  • Figure 1 shows an apparatus which is used for producing points or sharp spikes on a substrate.
  • the substrate which is a metal or semi-conductor mounted on a stage in a chamber containing a precursor of a species to be deposited in a low pressure atmosphere.
  • the precursor is a residual gas left after evacuation of the chamber.
  • the precursor may be for example an organo-metallic or hydrocarbon gas.
  • An electron beam 6 is emitted from an electron source 1 towards the substrate 5.
  • the beam is focused by a lens focusing system 2a, 2b positioned by a deflecting means 3 to pass through an aperture 4 and onto the substrate 5. By focusing a beam for a predetermined period on a stationary position on the substrate a point or sharp spike is produced.
  • the height of the point or spike may be increased by increasing the time that the beam is incident upon the substrate.
  • the precise operating conditions of the apparatus will determine the aspect ratio (diameter of base/height) of the tip.
  • a computer control system which is also able to blank the beam to prevent the whole surface of the substrate from being irradiated, either by a deflection means or a blocking means, when the beam is being repositioned.
  • a scanning electron microscope to irradiate the substrate, the array of points or sharp spikes produced can be inspected by scanning the substrate with the microscope in the secondary electron or imaging mode.
  • the substrate is first degreased in acetone and placed on a stage in a scanning electron microscope.
  • the scanning electron microscope is set to have an electron beam voltage of 20 kv, the chamber is evacuated to 10 -4 to 10-6 Torr, the final aperture has a diameter of 50 ⁇ m and the working distance is 27 mm.
  • a point is formed having a diameter of about 400 nm.
  • Optimum results have been found to be obtained using such a 20 kv electron beam with a 3 picoamp probe current (that is the current flow to the substrate) , a spot diameter of 200 A and a beam divergence having a semi-angle of 3 milliradians. Acceptable results are obtained with probe currents of 1 to 30 pA, beam diameters of 100 to 400 k and a beam divergence of 2.7 - 4 milliradians.
  • the time taken to grow a point is varied according to the size required, but is typically in the range 20 to 100 seconds. Prolonging this up to, say, 400 seconds results in further growth of the point.
  • the present inventor has found that cleaning of the substrate surface prior to deposition has a marked effect on the quality of the structure produced.
  • acetone cleaning was used but still better results are to be obtained if the substrate is plasma-cleaned prior to the deposition of the spike. It is found, for example, that after cleaning in an argon glow discharge, copper is a better substrate than aluminium.
  • Figures 4a and 4b are TEM micrographs showing spikes deposited on the edge of an Aluminium TEM grid.
  • Figure 4b shows the structures in profile. Examination of the needles under a field-emission SEM show that the needle is not entirely homogenous but has a fine structure of the order of 3-5 nm.
  • the present invention is well suited to the production of field emission devices.
  • an insulating layer 10 typically 1 to 2 ⁇ m thick, is provided on a substrate, and a thin metal layer 11 is provided on the insulator.
  • a window typically of 2 ⁇ m diameter, is provided through the insulator, preferably undercutting the thin metal layer 11.
  • a needle is grown by the method of the present invention on the substrate within the window.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Cold Cathode And The Manufacture (AREA)

Abstract

Procédé de production d'une pointe ou d'un alignement de pointes précises sur un substrat (5), selon lequel un faisceau électronique (6) est concentré sur le substrat (5) à chaque endroit où une pointe est requise. Le substrat (5) est placé en atmosphère de basse pression, cette atmosphère contenant un précurseur du matériau, tel qu'un gaz d'hydrocarbure ou organo-métallique, qui doit former la pointe ou le point précis. Le faisceau électronique concentré (6) provoque le dépôt du matériau sur le substrat (5) de façon qu'il forme la pointe précise. Un alignement de ces pointes peut être utilisé comme surface cathodique à émission de champ dans des systèmes électroniques à vide.
PCT/GB1992/001596 1991-09-02 1992-09-01 Production de pointes precises sur un substrat WO1993005530A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB919118721A GB9118721D0 (en) 1991-09-02 1991-09-02 Production of fine points
GB9118721.1 1991-09-02

Publications (1)

Publication Number Publication Date
WO1993005530A1 true WO1993005530A1 (fr) 1993-03-18

Family

ID=10700775

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1992/001596 WO1993005530A1 (fr) 1991-09-02 1992-09-01 Production de pointes precises sur un substrat

Country Status (2)

Country Link
GB (1) GB9118721D0 (fr)
WO (1) WO1993005530A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0632480A1 (fr) * 1993-05-19 1995-01-04 Kabushiki Kaisha Toshiba Procédé et dispositif pour la fabrication de matériaux aciculairs et procédé de fabrication de micro-émetteurs
EP0660359A3 (fr) * 1993-12-22 1995-07-26 Canon Kabushiki Kaisha Procédé de fabrication d'un dispositif émetteur d'électrons et appareil de formation d'images
FR2721751A1 (fr) * 1994-06-27 1995-12-29 Commissariat Energie Atomique Procédé d'élaboration de micropointes à composition contrôlée sur de grandes surfaces.

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0350539A1 (fr) * 1988-07-15 1990-01-17 Koninklijke Philips Electronics N.V. Formation de microstructures par faisceau d'électrons
EP0443920A1 (fr) * 1990-02-23 1991-08-28 Thomson-Csf Procédé de croissance controlée de cristaux aciculaires, et application à la réalisation de microcathodes à pointes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0350539A1 (fr) * 1988-07-15 1990-01-17 Koninklijke Philips Electronics N.V. Formation de microstructures par faisceau d'électrons
EP0443920A1 (fr) * 1990-02-23 1991-08-28 Thomson-Csf Procédé de croissance controlée de cristaux aciculaires, et application à la réalisation de microcathodes à pointes

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY: PART B vol. 6, no. 1, 1988, NEW YORK US pages 477 - 481 H W P KOOPS ETAL. 'High-resolution electron-beam induced deposition' *
OPTIK vol. 78, no. 4, 1988, STUTTGART, DE pages 158 - 164 P KREUZER 'Formation and examination of self-supporting contamination filaments' *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0632480A1 (fr) * 1993-05-19 1995-01-04 Kabushiki Kaisha Toshiba Procédé et dispositif pour la fabrication de matériaux aciculairs et procédé de fabrication de micro-émetteurs
US5509843A (en) * 1993-05-19 1996-04-23 Kabushiki Kaisha Toshiba Method and apparatus for manufacturing needle shaped materials and method for manufacturing a microemitter
EP0660359A3 (fr) * 1993-12-22 1995-07-26 Canon Kabushiki Kaisha Procédé de fabrication d'un dispositif émetteur d'électrons et appareil de formation d'images
US6063453A (en) * 1993-12-22 2000-05-16 Canon Kabushiki Kaisha Method of manufacturing electron-emitting device and image-forming apparatus comprising such devices
FR2721751A1 (fr) * 1994-06-27 1995-12-29 Commissariat Energie Atomique Procédé d'élaboration de micropointes à composition contrôlée sur de grandes surfaces.
WO1996000450A1 (fr) * 1994-06-27 1996-01-04 Commissariat A L'energie Atomique Procede d'elaboration de micropointes a composition controlee sur de grandes surfaces

Also Published As

Publication number Publication date
GB9118721D0 (en) 1991-10-16

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