EP0712146A1 - Field effect electron source and method for producing same application in display devices working by cathodoluminescence - Google Patents

Field effect electron source and method for producing same application in display devices working by cathodoluminescence Download PDF

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Publication number
EP0712146A1
EP0712146A1 EP95402450A EP95402450A EP0712146A1 EP 0712146 A1 EP0712146 A1 EP 0712146A1 EP 95402450 A EP95402450 A EP 95402450A EP 95402450 A EP95402450 A EP 95402450A EP 0712146 A1 EP0712146 A1 EP 0712146A1
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EP
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Prior art keywords
diamond
source
micro
electrically insulating
clusters
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EP95402450A
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German (de)
French (fr)
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EP0712146B1 (en
Inventor
Joel Danroc
Danh Van Tran
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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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
    • H01J3/00—Details of electron-optical or ion-optical arrangements or of ion traps common to two or more basic types of discharge tubes or lamps
    • H01J3/02—Electron guns
    • H01J3/021—Electron guns using a field emission, photo emission, or secondary emission electron source
    • H01J3/022—Electron guns using a field emission, photo emission, or secondary emission electron source with microengineered cathode, e.g. Spindt-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/30—Cold cathodes
    • H01J2201/304—Field emission cathodes
    • H01J2201/30403—Field emission cathodes characterised by the emitter shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/30—Cold cathodes
    • H01J2201/304—Field emission cathodes
    • H01J2201/30446—Field emission cathodes characterised by the emitter material
    • H01J2201/30453—Carbon types
    • H01J2201/30457—Diamond
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2329/00—Electron emission display panels, e.g. field emission display panels

Definitions

  • the present invention relates to a field effect electron source.
  • the invention has the same fields of application as electron sources with microtips ("microtips").
  • the present invention applies to the field of flat display devices also called “flat screens”, as well as to the manufacture of pressure measurement gauges.
  • a microtip electron source comprises at least one cathode conductor on an electrically insulating substrate, an electrically insulating layer which covers this cathode conductor and at least one grid formed on this electrically insulating layer.
  • Holes are formed through the grid and the insulating layer above the cathode conductor.
  • micro-tips are formed in these holes and carried by the cathode conductor.
  • each micro-tip is located substantially in the plane of the grid, this grid being used to extract electrons from the micro-tips.
  • the holes have very small dimensions (they have a diameter of less than 2 ⁇ m).
  • These other known display devices comprise a cathodoluminescent anode placed facing an electron source comprising layers of diamond or diamond-like carbon intended to emit electrons.
  • These layers are obtained by laser ablation or by chemical vapor deposition.
  • Diamond or diamond carbon emits electrons much more easily than the materials conventionally used for the manufacture of microtips.
  • the minimum electric field from which an electron emission can be obtained can be twenty times weaker than the minimum electric field corresponding to metals such as molybdenum, for example.
  • the deposits obtained are continuous layers and not micro-tips.
  • the resulting display devices are, as seen above, of the "diode" type, which poses a problem as regards their addressing.
  • the object of the present invention is to remedy the above drawbacks.
  • micro-cluster is meant a micro-heap composed of grains of diamond carbon powder or of diamond type which are in direct contact with their closest neighbors and / or bonded together by a metal.
  • the source object of the present invention emits more electrons than a microtip source, due to the use, in the present invention, of diamond or diamond-like carbon particles which have a higher emissivity than conventional electron-emitting materials such as molybdenum.
  • this device has a greater brightness than a microtip device, for the same control voltage.
  • this device using a source according to the invention requires a control voltage lower than that which is necessary for a microtip device.
  • the micro-clusters can be made of diamond or diamond-like carbon particles or can be made of such particles dispersed in a metal.
  • the micro-clusters can be linked by a deposit of a metal intended to consolidate these micro-clusters, diamond or diamond-like carbon particles emerging from this deposit on the surface of the micro- heap.
  • the process which is the subject of the invention can be implemented with large surface substrates and thus makes it possible to obtain electron sources (and therefore display screens) of large surface area (several tens of inches diagonally).
  • the temperature at which the micro-clusters are formed is close to the ambient temperature (of the order of 20 ° C.).
  • baths which are necessary for the implementation of the process which is the subject of the invention have a long service life (several months).
  • the micro-clusters formed by electrophoresis are then linked using a metal by electrochemical deposition, in order to consolidate these micro-clusters.
  • the diamond or diamond-like carbon particles have a size of the order of 1 ⁇ m or less than 1 ⁇ m.
  • nanometric powders are used.
  • These particles can be obtained from natural or artificial diamond or by a method chosen from laser synthesis, deposition chemical vapor phase and physical vapor deposition.
  • the holes formed through the grid layer and the electrically insulating layer may have a circular or rectangular shape.
  • the size of these holes can be chosen in a range ranging from approximately 1 ⁇ m to several tens of micrometers.
  • micro-clusters are formed in accordance with the process which is the subject of the invention is comparable to the structure in which the micro-tips are formed to manufacture a source with micro-tips.
  • the size of the holes that are formed in the structure to implement the process which is the subject of the invention can be significantly greater than that which is necessary for the implementation of a process for manufacturing a source. with micro-tips.
  • Holes 10 are formed through these grids 8 and the insulating layer 6 above the cathode conductors 4.
  • Micro-clusters 12 containing diamond or diamond-like carbon particles are formed in the holes 10 and carried by the cathode conductors 4.
  • cathode conductors 4 are parallel and that the grids 8 are parallel to each other and perpendicular to the cathode conductors 4.
  • the holes 10 and therefore the micro-clusters 12 are located in the areas where these grids cross the cathode conductors.
  • micro-clusters of such a zone which emit electrons when an appropriate electric voltage is applied, by means not shown, between the cathode conductor 4 and the grid 8 which correspond to this zone.
  • a cathodoluminescence display device is schematically represented in section in FIG. 2.
  • This device comprises the electron source 14 of FIG. 1.
  • the device of FIG. 2 also comprises a cathodoluminescent anode 16 placed opposite the source 14 and separated from the latter by a space 18 in which a vacuum has been created.
  • the cathodoluminescent anode 16 comprises an electrically insulating and transparent substrate 20 which is provided with an electrically conductive and transparent layer 22 forming an anode.
  • this layer 24 emits light which a user of the display device observes through the transparent substrate 20.
  • FIG. 3 schematically illustrates this method.
  • the diameter D1 of the holes (substantially circular) formed in the grid 8 and in the electrically insulating layer 6 can be advantageously greater than the diameter of the holes contained in the electron sources with microtips described in documents (1) to (4).
  • this diameter D1 can take values of the order of 1 ⁇ m up to 20 ⁇ m.
  • FIG. 4 schematically illustrates the fact that the holes 10, instead of having a circular shape, can have a rectangular shape.
  • the width D2 of these holes 10 in FIG. 4, of rectangular shape can be taken equal to the diameter D1 mentioned above and can therefore also be significantly greater than the diameter of the holes of the microtip sources.
  • a diamond or diamond type carbon powder is used.
  • This powder can be obtained by chemical vapor deposition from a mixture of hydrogen and light hydrocarbons.
  • This chemical vapor deposition can be assisted by an electron beam or be assisted by a plasma generated by microwaves.
  • This powder can also be synthesized by means of a laser, that is to say, more precisely, by chemical vapor deposition as previously but assisted by laser.
  • physical vapor deposition from carbon targets (graphite for example) and a plasma gas such as argon alone or mixed with hydrogen , hydrocarbons without dopant or with a dopant such as for example diborane.
  • This powder can also be obtained by laser ablation.
  • artificial diamonds can be prepared by compacting carbon, at high pressure and high temperature, and then making the powder from these artificial diamonds.
  • these diamond carbon powders and these diamond type carbon powders are chosen so as to have a micron or submicron particle size, preferably nanometric.
  • these diamond or diamond carbon powders can be doped or undoped.
  • Boron can for example be used as a dopant.
  • the deposition of the powder (diamond or diamond-like carbon particles) leading to the formation of micro-clusters 12 in the holes 10, on the cathode conductors 4, can be carried out by electrophoresis (cataphoresis or anaphoresis), possibly supplemented by a electrochemical metallic deposition of consolidation, or by electrochemical co-deposition of metal and carbon diamond or of diamond type.
  • the structure provided with holes 10 is placed in an appropriate solution 26 and the bottom of each hole 10 is brought to a positive potential during this deposition phase.
  • the cathode conductors 4 are brought to this positive potential thanks to to a suitable voltage source 28, the positive terminal of which is connected to these cathode conductors 4 while the negative terminal of this source is connected to a counter-electrode 32 of platinum or of stainless steel situated in the bath at a distance from the substrate d '' about 1 to 5 cm.
  • the fine powder of diamond or diamond-like carbon particles is suspended in solution 26 (before placing the structure in this solution).
  • the voltage supplied by the source 28 can range up to around 200 V.
  • the negative terminal of the source 28 which is connected to the cathode conductors 4 while the positive terminal of the source 28 is connected to a counter-electrode 32 of platinum or stainless steel located in the bath at a distance from the substrate of about 1 to 5 cm.
  • a voltage of up to approximately 200 V is then used.
  • a metal for example chosen from Ni, Co, Ag, Au, Rh or Pt or, more generally, from the transition metals, alloys thereof and precious metals.
  • a suitable electrical voltage is then applied between the cathode conductors 4 and an electrode 33 placed in this solution, by means of a voltage source 34.
  • This electrode 33 is for example made of nickel and the solution 30 contains for example 300 g / l of nickel sulphate, 30 g / l of nickel chloride, 30 g / l of boric acid and 0.6 g / l of lauryl sodium sulfate.
  • an electric current of 4 A / dm is used.
  • FIG. 5 shows the metallic deposit 36 which is formed on each micro-cluster 12 after this electrochemical deposition operation, revealing emerging parts of the particles of the micro-cluster.
  • micro-clusters can also be formed by electrochemical co-deposition of metal and of diamond or diamond-like carbon.
  • An appropriate current source is used, for example of the order of 4 A / dm, and the negative terminal of this source is applied to the cathode conductors and the positive terminal of this source to a nickel electrode placed in the bath .
  • the nickel is deposited in the holes, carrying with it the diamond particles, hence the formation of micro-clusters of nickel and diamond in these holes.
  • a powder of particles of silicon carbide or titanium carbide, of micron or submicron size can be used for the implementation of a process according to the invention, and use the same methods as above (electrophoresis, possibly supplemented by an electrochemical metallic deposition of consolidation, or electrochemical co-deposition of metal and such particles), to form the micro-clusters.
  • the tops of the micro-clusters are located substantially in the plane of the grids and these micro-clusters are in contact with these grids.

Abstract

The electron source has an isolating substrate (2) with a cathode conductor (4) formed on its upper surface. An isolating layer (6) with an upper grid surface (8) is formed above the cathode conductor. Holes (10) are formed in the upper grid and isolating layer, and diamond like powder grain heaps (12) are formed on the cathode surface in the gaps.

Description

DOMAINE TECHNIQUETECHNICAL AREA

La présente invention concerne une source d'électrons à effet de champ.The present invention relates to a field effect electron source.

L'invention a les mêmes domaines d'application que les sources d'électrons à micro-pointes ("microtips").The invention has the same fields of application as electron sources with microtips ("microtips").

En particulier, la présente invention s'applique au domaine des dispositifs de visualisation plats encore appelés "écrans plats", ainsi qu'à la fabrication de jauges de mesure de pression.In particular, the present invention applies to the field of flat display devices also called "flat screens", as well as to the manufacture of pressure measurement gauges.

ETAT DE LA TECHNIQUE ANTERIEURESTATE OF THE PRIOR ART

On connaît déjà des sources d'électrons à effet de champ.Sources of field effect electrons are already known.

Ce sont les sources d'électrons à micro-pointes mentionnées plus haut.These are the sources of microtip electrons mentioned above.

Une source d'électrons à micro-pointes comprend au moins un conducteur cathodique sur un substrat électriquement isolant, une couche électriquement isolante qui recouvre ce conducteur cathodique et au moins une grille formée sur cette couche électriquement isolante.A microtip electron source comprises at least one cathode conductor on an electrically insulating substrate, an electrically insulating layer which covers this cathode conductor and at least one grid formed on this electrically insulating layer.

Des trous sont formés à travers la grille et la couche isolante au-dessus du conducteur cathodique.Holes are formed through the grid and the insulating layer above the cathode conductor.

Les micro-pointes sont formées dans ces trous et portées par le conducteur cathodique.The micro-tips are formed in these holes and carried by the cathode conductor.

Le sommet de chaque micro-pointe se trouve sensiblement dans le plan de la grille, cette grille servant à extraire des électrons des micro-pointes.The apex of each micro-tip is located substantially in the plane of the grid, this grid being used to extract electrons from the micro-tips.

Les trous ont de très petites dimensions (ils ont un diamètre inférieur à 2 µm).The holes have very small dimensions (they have a diameter of less than 2 µm).

Pour réaliser un dispositif de visualisation utilisant une telle source d'électrons à micro-pointes, on réalise un système de type "triode".To produce a display device using such a source of microtip electrons, a "triode" type system is produced.

Plus précisément, on dispose, en face de la source, une anode cathodoluminescente.More precisely, there is, opposite the source, a cathodoluminescent anode.

Les électrons issus de la source viennent bombarder cette anode cathodoluminescente.The electrons from the source bombard this cathodoluminescent anode.

On connaît également d'autres dispositifs de visualisation ayant une structure de type "diode".Other display devices are also known which have a "diode" type structure.

Ces autres dispositifs de visualisation connus comprennent une anode cathodoluminescente placée en regard d'une source d'électrons comprenant des couches de carbone diamant ou de type diamant destinées à émettre des électrons.These other known display devices comprise a cathodoluminescent anode placed facing an electron source comprising layers of diamond or diamond-like carbon intended to emit electrons.

Ces couches sont obtenues par ablation laser ou par dépôt chimique en phase vapeur ("chemical vapour deposition").These layers are obtained by laser ablation or by chemical vapor deposition.

Le carbone diamant ou de type diamant émet beaucoup plus facilement des électrons que les matériaux classiquement utilisés pour la fabrication des micro-pointes.Diamond or diamond carbon emits electrons much more easily than the materials conventionally used for the manufacture of microtips.

Avec le carbone diamant ou de type diamant, le champ électrique minimal à partir duquel on peut obtenir une émission d'électrons peut être vingt fois plus faible que le champ électrique minimal correspondant à des métaux comme par exemple le molybdène.With diamond or diamond carbon, the minimum electric field from which an electron emission can be obtained can be twenty times weaker than the minimum electric field corresponding to metals such as molybdenum, for example.

Malheureusement, le dépôt des couches de carbone diamant ou de type diamant, avec les méthodes mentionnées plus haut, a lieu à haute température (de l'ordre de 700°C).Unfortunately, the deposition of diamond or diamond-like carbon layers, with the methods mentioned above, takes place at high temperature (of the order of 700 ° C.).

De plus, il est impossible d'obtenir directement des micro-pointes par ces méthodes.In addition, it is impossible to obtain micro-tips directly by these methods.

Les dépôts obtenus sont des couches continues et non pas des micro-pointes.The deposits obtained are continuous layers and not micro-tips.

Les dispositifs de visualisation qui en résultent sont, comme on l'a vu plus haut, de type "diode", ce qui pose un problème en ce qui concerne leur adressage.The resulting display devices are, as seen above, of the "diode" type, which poses a problem as regards their addressing.

Il faut en effet réaliser des systèmes électroniques d'adressage permettant d'appliquer des tensions de l'ordre de plusieurs centaines de volts à ces dispositifs.Electronic addressing systems must in fact be used to apply voltages of the order of several hundred volts to these devices.

De plus, la température élevée à laquelle sont formées les couches de carbone diamant ou de type diamant interdit l'utilisation de verre standard en tant que substrat destiné à porter ces couches.In addition, the high temperature at which the diamond or diamond-like carbon layers are formed prohibits the use of standard glass as a substrate intended to carry these layers.

EXPOSE DE L'INVENTIONSTATEMENT OF THE INVENTION

La présente invention a pour but de remédier aux inconvénients précédents.The object of the present invention is to remedy the above drawbacks.

Elle a pour objet une source d'électrons à effet de champ, cette source comprenant :

  • sur un substrat électriquement isolant, au moins une première électrode jouant le rôle de conducteur cathodique,
  • une couche électriquement isolante qui recouvre ce conducteur cathodique,
  • au moins une deuxième électrode jouant le rôle de grille, formée sur la couche électriquement isolante, des trous étant formés à travers cette grille et la couche électriquement isolante au-dessus du conducteur cathodique, et
  • des éléments qui sont susceptibles d'émettre des électrons et qui sont formés dans ces trous et portés par le conducteur cathodique,
cette source étant caractérisée en ce que ces éléments sont des micro-amas contenant des particules de carbone diamant ou de type diamant ("diamond like carbon" ou DLC dans les articles en langue anglaise).Its subject is a source of field effect electrons, this source comprising:
  • on an electrically insulating substrate, at least a first electrode playing the role of cathode conductor,
  • an electrically insulating layer which covers this cathode conductor,
  • at least one second electrode acting as a grid, formed on the electrically insulating layer, holes being formed through this grid and the electrically insulating layer above the cathode conductor, and
  • elements which are capable of emitting electrons and which are formed in these holes and carried by the cathode conductor,
this source being characterized in that these elements are micro-clusters containing particles of diamond carbon or of the diamond type ("diamond like carbon" or DLC in articles in English).

Par "micro-amas", on entend un micro-tas composé de grains de poudre de carbone diamant ou de type diamant qui sont en contact direct avec leurs plus proches voisins et/ou liés entre eux par un métal.By "micro-cluster" is meant a micro-heap composed of grains of diamond carbon powder or of diamond type which are in direct contact with their closest neighbors and / or bonded together by a metal.

Pour une même tension électrique de commande, la source objet de la présente invention émet plus d'électrons qu'une source à micro-pointes, du fait de l'utilisation, dans la présente invention, des particules de carbone diamant ou de type diamant qui ont un pouvoir émissif plus élevé que des matériaux émetteurs d'électrons classiques comme par exemple le molybdène.For the same electrical control voltage, the source object of the present invention emits more electrons than a microtip source, due to the use, in the present invention, of diamond or diamond-like carbon particles which have a higher emissivity than conventional electron-emitting materials such as molybdenum.

Ainsi, dans le cas de l'utilisation d'une source conforme à l'invention pour fabriquer par exemple un dispositif de visualisation, ce dispositif a une plus grande luminosité qu'un dispositif à micro-pointes, pour même tension de commande.Thus, in the case of the use of a source according to the invention for manufacturing, for example, a display device, this device has a greater brightness than a microtip device, for the same control voltage.

A luminosités égales, ce dispositif utilisant une source conforme à l'invention nécessite une tension de commande inférieure à celle qui est nécessaire à un dispositif à micro-pointes.At equal luminosities, this device using a source according to the invention requires a control voltage lower than that which is necessary for a microtip device.

De plus, l'utilisation d'une source conforme à l'invention conduit à un système de type "triode" qui nécessite des tensions de commande inférieures à celles qui sont nécessaires aux dispositifs de type "diode" mentionnés plus haut, qui utilisent des couches de carbone diamant ou de type diamant.In addition, the use of a source according to the invention leads to a “triode” type system which requires control voltages lower than those which are necessary for the “diode” type devices mentioned above, which use layers of diamond carbon or diamond type.

Dans la présente invention, les micro-amas peuvent être faits de particules de carbone diamant ou de type diamant ou peuvent être faits de telles particules dispersées dans un métal.In the present invention, the micro-clusters can be made of diamond or diamond-like carbon particles or can be made of such particles dispersed in a metal.

Dans la source objet de l'invention, les micro-amas peuvent être liés par un dépôt d'un métal destiné à consolider ces micro-amas, les particules de carbone diamant ou de type diamant émergeant de ce dépôt à la surface des micro-amas.In the source object of the invention, the micro-clusters can be linked by a deposit of a metal intended to consolidate these micro-clusters, diamond or diamond-like carbon particles emerging from this deposit on the surface of the micro- heap.

La présente invention concerne également un dispositif de visualisation par cathodoluminescence comprenant :

  • une source d'électrons à effet de champ, et
  • une anode cathodoluminescente comprenant une couche d'un matériau cathodoluminescent,
dispositif caractérisé en ce que la source est celle qui fait l'objet de l'invention.The present invention also relates to a cathodoluminescence display device comprising:
  • a source of field effect electrons, and
  • a cathodoluminescent anode comprising a layer of a cathodoluminescent material,
device characterized in that the source is that which is the subject of the invention.

On a vu plus haut les avantages d'un tel dispositif par rapport aux dispositifs connus utilisant des micro-pointes et aux dispositifs comprenant des couches de carbone diamant ou de type diamant.We have seen above the advantages of such a device compared to known devices using microtips and to devices comprising layers of diamond carbon or of diamond type.

La présente invention concerne aussi un procédé de fabrication d'une source d'électrons à effet de champ, procédé selon lequel :

  • on fabrique une structure comprenant un substrat électriquement isolant, au moins un conducteur cathodique sur ce substrat, une couche électriquement isolante qui recouvre chaque conducteur cathodique et une couche de grille électriquement conductrice qui recouvre cette couche électriquement isolante,
  • on forme des trous à travers la couche de grille et la couche électriquement isolante, au niveau de chaque conducteur cathodique, et
  • on forme, dans chaque trou, un élément susceptible d'émettre des électrons,
ce procédé étant caractérisé en ce que les éléments sont des micro-amas qui contiennent des particules de carbone diamant ou de type diamant et sont formés par électrophorèse ou par co-dépôt électrochimique de métal et de carbone diamant ou de type diamant.The present invention also relates to a method for manufacturing a field effect electron source, method according to which:
  • a structure is made up comprising an electrically insulating substrate, at least one cathode conductor on this substrate, an electrically insulating layer which covers each cathode conductor and an electrically conductive grid layer which covers this electrically insulating layer,
  • holes are formed through the grid layer and the electrically insulating layer, at the level of each cathode conductor, and
  • an element capable of emitting electrons is formed in each hole,
this process being characterized in that the elements are micro-clusters which contain diamond or diamond-like carbon particles and are formed by electrophoresis or by electrochemical co-deposition of diamond and diamond-like metal and carbon.

Le procédé objet de l'invention peut être mis en oeuvre avec des substrats de grande surface et permet ainsi l'obtention de sources d'électrons (et donc d'écrans de visualisation) de grande surface (plusieurs dizaines de pouces de diagonale).The process which is the subject of the invention can be implemented with large surface substrates and thus makes it possible to obtain electron sources (and therefore display screens) of large surface area (several tens of inches diagonally).

De plus, dans le procédé objet de l'invention, la température à laquelle on forme les micro-amas est voisine de la température ambiante (de l'ordre de 20°C).In addition, in the process which is the subject of the invention, the temperature at which the micro-clusters are formed is close to the ambient temperature (of the order of 20 ° C.).

Il est ainsi possible d'utiliser, pour fabriquer une source conforme à l'invention, un substrat en verre ordinaire (sodocalcique), sans précautions particulières.It is thus possible to use, for manufacturing a source according to the invention, an ordinary glass substrate (soda-lime), without special precautions.

On notera aussi que le procédé objet de l'invention est plus simple que le procédé de fabrication des sources à micro-pointes car, contrairement à ce dernier, il n'utilise ni couche sacrificielle ("lift off layer") ni dépôt sous vide.It will also be noted that the process which is the subject of the invention is simpler than the process for manufacturing micro-tip sources because, unlike the latter, it uses neither a sacrificial layer ("lift off layer") nor deposition under vacuum. .

En outre, les bains qui sont nécessaires pour la mise en oeuvre du procédé objet de l'invention ont une durée de vie importante (plusieurs mois).In addition, the baths which are necessary for the implementation of the process which is the subject of the invention have a long service life (several months).

Selon un mode de mise en oeuvre particulier du procédé objet de l'invention, les micro-amas formés par électrophorèse sont ensuite liés à l'aide d'un métal par dépôt électrochimique, afin de consolider ces micro-amas.According to a particular embodiment of the process which is the subject of the invention, the micro-clusters formed by electrophoresis are then linked using a metal by electrochemical deposition, in order to consolidate these micro-clusters.

De préférence, les particules de carbone diamant ou de type diamant ont une taille de l'ordre de 1 µm ou de moins de 1 µm.Preferably, the diamond or diamond-like carbon particles have a size of the order of 1 μm or less than 1 μm.

Préférentiellement on utilise des poudres nanométriques.Preferably, nanometric powders are used.

Ces particules peuvent être obtenues à partir de diamant naturel ou artificiel ou par une méthode choisie parmi la synthèse par laser, le dépôt chimique en phase vapeur et le dépôt physique en phase vapeur.These particles can be obtained from natural or artificial diamond or by a method chosen from laser synthesis, deposition chemical vapor phase and physical vapor deposition.

Les trous formés à travers la couche de grille et la couche électriquement isolante peuvent avoir une forme circulaire ou rectangulaire.The holes formed through the grid layer and the electrically insulating layer may have a circular or rectangular shape.

La taille de ces trous peut être choisie dans un intervalle allant d'environ 1 µm jusqu'à plusieurs dizaines de micromètres.The size of these holes can be chosen in a range ranging from approximately 1 μm to several tens of micrometers.

La structure dans laquelle on forme les micro-amas conformément au procédé objet de l'invention est comparable à la structure dans laquelle on forme les micro-pointes pour fabriquer une source à micro-pointes.The structure in which the micro-clusters are formed in accordance with the process which is the subject of the invention is comparable to the structure in which the micro-tips are formed to manufacture a source with micro-tips.

En revanche, la taille des trous que l'on forme dans la structure pour mettre en oeuvre le procédé objet de l'invention peut être nettement supérieure à celle qui est nécessaire à la mise en oeuvre d'un procédé de fabrication d'une source à micro-pointes.On the other hand, the size of the holes that are formed in the structure to implement the process which is the subject of the invention can be significantly greater than that which is necessary for the implementation of a process for manufacturing a source. with micro-tips.

Ceci est très avantageux compte tenu des difficultés liées à l'obtention de trous calibrés de petite taille (inférieure à 2 µm) sur de grandes surfaces.This is very advantageous given the difficulties associated with obtaining calibrated holes of small size (less than 2 μm) on large surfaces.

BREVE DESCRIPTION DES DESSINSBRIEF DESCRIPTION OF THE DRAWINGS

La présente invention sera mieux comprise à la lecture de la description d'exemples de réalisation donnés ci-après, à titre purement indicatif et nullement limitatif, en faisant référence aux dessins annexés sur lesquels :

  • la figure 1 est une vue en coupe schématique d'une source d'électrons conforme à la présente invention,
  • la figure 2 est une vue en coupe schématique d'un dispositif de visualisation utilisant la source de la figure 1,
  • la figure 3 illustre schématiquement un procédé de fabrication d'une source d'électrons conforme à l'invention,
  • la figure 4 illustre schématiquement la possibilité d'utiliser des trous rectangulaires pour fabriquer une source conforme à l'invention, et
  • la figure 5 illustre schématiquement un autre procédé de fabrication d'une source d'électrons conforme à l'invention.
The present invention will be better understood on reading the description of exemplary embodiments given below, by way of purely indicative and in no way limiting, with reference to the appended drawings in which:
  • FIG. 1 is a schematic sectional view of an electron source according to the present invention,
  • FIG. 2 is a schematic sectional view of a display device using the source of FIG. 1,
  • FIG. 3 schematically illustrates a process for manufacturing an electron source according to the invention,
  • FIG. 4 schematically illustrates the possibility of using rectangular holes to manufacture a source according to the invention, and
  • Figure 5 schematically illustrates another method of manufacturing an electron source according to the invention.

EXPOSE DETAILLE DE MODES DE REALISATION PARTICULIERSDETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

La source conforme à l'invention, qui est schématiquement représentée en coupe sur la figure 1, comprend :

  • sur un substrat électriquement isolant 2, des électrodes 4 jouant le rôle de conducteurs cathodiques (un seul conducteur cathodique est visible sur la figure 1),
  • une couche électriquement isolante 6 qui recouvre chaque conducteur cathodique, et
  • des électrodes 8 jouant le rôle de grilles et formées sur la couche électriquement isolante 6 (une seule grille est visible sur la figure 1).
The source according to the invention, which is schematically represented in section in FIG. 1, comprises:
  • on an electrically insulating substrate 2, electrodes 4 acting as cathode conductors (a single cathode conductor is visible in FIG. 1),
  • an electrically insulating layer 6 which covers each cathode conductor, and
  • electrodes 8 playing the role of grids and formed on the electrically insulating layer 6 (a single grid is visible in FIG. 1).

Des trous 10 sont formés à travers ces grilles 8 et la couche isolante 6 au-dessus des conducteurs cathodiques 4.Holes 10 are formed through these grids 8 and the insulating layer 6 above the cathode conductors 4.

Des micro-amas 12 contenant des particules de carbone diamant ou de type diamant, sont formés dans les trous 10 et portés par les conducteurs cathodiques 4.Micro-clusters 12 containing diamond or diamond-like carbon particles are formed in the holes 10 and carried by the cathode conductors 4.

On précise que les conducteurs cathodiques 4 sont parallèles et que les grilles 8 sont parallèles les unes aux autres et perpendiculaires aux conducteurs cathodiques 4.It is specified that the cathode conductors 4 are parallel and that the grids 8 are parallel to each other and perpendicular to the cathode conductors 4.

Les trous 10 et donc les micro-amas 12 se trouvent dans les zones où ces grilles croisent les conducteurs cathodiques.The holes 10 and therefore the micro-clusters 12 are located in the areas where these grids cross the cathode conductors.

Ce sont les micro-amas d'une telle zone qui émettent des électrons lorsqu'une tension électrique appropriée est appliquée, par des moyens non représentés, entre le conducteur cathodique 4 et la grille 8 qui correspondent à cette zone.It is the micro-clusters of such a zone which emit electrons when an appropriate electric voltage is applied, by means not shown, between the cathode conductor 4 and the grid 8 which correspond to this zone.

Un dispositif de visualisation par cathodoluminescence est schématiquement représenté en coupe sur la figure 2.A cathodoluminescence display device is schematically represented in section in FIG. 2.

Ce dispositif comprend la source d'électrons 14 de la figure 1.This device comprises the electron source 14 of FIG. 1.

Le dispositif de la figure 2 comprend aussi une anode cathodoluminescente 16 placée en regard de la source 14 et séparée de celle-ci par un espace 18 dans lequel on a fait le vide.The device of FIG. 2 also comprises a cathodoluminescent anode 16 placed opposite the source 14 and separated from the latter by a space 18 in which a vacuum has been created.

L'anode cathodoluminescente 16 comprend un substrat électriquement isolant et transparent 20 qui est pourvu d'une couche électriquement conductrice et transparente 22 formant une anode.The cathodoluminescent anode 16 comprises an electrically insulating and transparent substrate 20 which is provided with an electrically conductive and transparent layer 22 forming an anode.

Celle-ci est disposée en regard de la source d'électrons 14 et revêtue, en face de cette source, d'une couche 24 d'un matériau cathodoluminescent ou "luminophore" ("phosphor" dans les publications en langue anglaise).This is placed opposite the electron source 14 and coated, opposite this source, with a layer 24 of a cathodoluminescent material or "phosphor" ("phosphor" in publications in English).

Sous l'impact des électrons émis par les micro-amas 12 de la source, cette couche 24 émet une lumière qu'un utilisateur du dispositif de visualisation observe à travers le substrat transparent 20.Under the impact of the electrons emitted by the micro-clusters 12 from the source, this layer 24 emits light which a user of the display device observes through the transparent substrate 20.

Il s'agit d'un dispositif que l'on peut comparer aux dispositifs de visualisation décrits dans les documents (1) à (4) mentionnés ci-après mais qui présente des avantages par rapport à ces dispositifs, comme on l'a vu plus haut :

  • (1) FR-A-2 593 953 correspondant à EP-A-0 234 989 et à US-A-4 857 161
  • (2) FR-A-2 623 013 correspondant à EP-A-0 316 214 et à US-A-4 940 916
  • (3) FR-A-2 663 462 correspondant à EP-A-0 461 990 et à US-A-5 194 780
  • (4) FR-A-2 687 839 correspondant à EP-A-0 558 393 et à la demande de brevet américain du 26 février 1993, numéro de série 08/022,935 (Leroux et al.).
It is a device that can be compared to the display devices described in documents (1) to (4) mentioned below but which presents advantages compared to these devices, as we saw above:
  • (1) FR-A-2 593 953 corresponding to EP-A-0 234 989 and US-A-4 857 161
  • (2) FR-A-2 623 013 corresponding to EP-A-0 316 214 and to US-A-4 940 916
  • (3) FR-A-2 663 462 corresponding to EP-A-0 461 990 and US-A-5 194 780
  • (4) FR-A-2 687 839 corresponding to EP-A-0 558 393 and to the American patent application of February 26, 1993, serial number 08 / 022,935 (Leroux et al.).

On explique ci-après un procédé de fabrication de la source d'électrons de la figure 1 en se référant à la figure 3 qui illustre schématiquement ce procédé.A method of manufacturing the electron source of FIG. 1 is explained below with reference to FIG. 3 which schematically illustrates this method.

Pour fabriquer cette source, on commence par fabriquer une structure comprenant :

  • le substrat 2,
  • les conducteurs cathodiques 4,
  • la couche électriquement isolante 6,
  • une couche de grille 25, qui recouvre cette couche électriquement isolante 6, et
  • les trous 10 formés dans cette couche de grille 25 et la couche électriquement isolante 6.
To make this source, we start by making a structure comprising:
  • the substrate 2,
  • cathode conductors 4,
  • the electrically insulating layer 6,
  • a grid layer 25, which covers this electrically insulating layer 6, and
  • the holes 10 formed in this grid layer 25 and the electrically insulating layer 6.

La fabrication d'une telle structure est connue et, à ce sujet, on se reportera aux documents (1) à (4) mentionnés plus haut.The manufacture of such a structure is known and, on this subject, reference will be made to documents (1) to (4) mentioned above.

On précise cependant que le diamètre D1 des trous (sensiblement circulaires) formés dans la grille 8 et dans la couche électriquement isolante 6 peut être avantageusement supérieur au diamètre des trous que comportent les sources d'électrons à micro-pointes décrites dans les documents (1) à (4).However, it should be noted that the diameter D1 of the holes (substantially circular) formed in the grid 8 and in the electrically insulating layer 6 can be advantageously greater than the diameter of the holes contained in the electron sources with microtips described in documents (1) to (4).

Par exemple, ce diamètre D1 peut prendre des valeurs de l'ordre de 1 µm jusqu'à 20 µm.For example, this diameter D1 can take values of the order of 1 μm up to 20 μm.

La figure 4 illustre schématiquement le fait que les trous 10, au lieu d'avoir une forme circulaire, peuvent avoir une forme rectangulaire.FIG. 4 schematically illustrates the fact that the holes 10, instead of having a circular shape, can have a rectangular shape.

La largeur D2 de ces trous 10 de la figure 4, de forme rectangulaire, peut être prise égale au diamètre D1 mentionné plus haut et peut donc être également nettement supérieure au diamètre des trous des sources à micro-pointes.The width D2 of these holes 10 in FIG. 4, of rectangular shape, can be taken equal to the diameter D1 mentioned above and can therefore also be significantly greater than the diameter of the holes of the microtip sources.

Il s'agit ensuite de former dans les trous 10 les micro-amas 12 de carbone diamant ou de type diamant (après quoi on formera les grilles, perpendiculairement aux conducteurs cathodiques, par gravure de la couche de grille 25).It is then a question of forming in the holes 10 the micro-clusters 12 of diamond carbon or of diamond type (after which the grids will be formed, perpendicular to the cathode conductors, by etching of the grid layer 25).

Pour former les micro-amas 12, on utilise une poudre de carbone diamant ou de type diamant.To form the micro-clusters 12, a diamond or diamond type carbon powder is used.

Cette poudre peut être obtenue par dépôt chimique en phase vapeur, à partir d'un mélange d'hydrogène et d'hydrocarbures légers.This powder can be obtained by chemical vapor deposition from a mixture of hydrogen and light hydrocarbons.

Ce dépôt chimique en phase vapeur peut être assisté par un faisceau d'électrons ou être assisté par un plasma engendré par des micro-ondes.This chemical vapor deposition can be assisted by an electron beam or be assisted by a plasma generated by microwaves.

On peut également synthétiser cette poudre au moyen d'un laser, c'est-à-dire, plus précisément, par dépôt chimique en phase vapeur comme précédemment mais assisté par laser.This powder can also be synthesized by means of a laser, that is to say, more precisely, by chemical vapor deposition as previously but assisted by laser.

On peut également synthétiser la poudre par dépôt physique en phase vapeur ("physical vapour deposition"), à partir de cibles de carbone (graphite par exemple) et d'un gaz plasmagène tel que l'argon seul ou mélangé avec de l'hydrogène, des hydrocarbures sans dopant ou avec un dopant comme par exemple le diborane.One can also synthesize the powder by physical vapor deposition ("physical vapor deposition"), from carbon targets (graphite for example) and a plasma gas such as argon alone or mixed with hydrogen , hydrocarbons without dopant or with a dopant such as for example diborane.

On peut également obtenir cette poudre par ablation laser.This powder can also be obtained by laser ablation.

On peut également utiliser une poudre de diamant naturel.You can also use a natural diamond powder.

En variante, on peut préparer des diamants artificiels par compactage de carbone, à haute pression et haute température, puis fabriquer la poudre à partir de ces diamants artificiels.Alternatively, artificial diamonds can be prepared by compacting carbon, at high pressure and high temperature, and then making the powder from these artificial diamonds.

De préférence, ces poudres de carbone diamant et ces poudres de carbone de type diamant sont choisies de façon à avoir une granulométrie micronique ou submicronique, de préférence nanométrique.Preferably, these diamond carbon powders and these diamond type carbon powders are chosen so as to have a micron or submicron particle size, preferably nanometric.

On précise que ces poudres de carbone diamant ou de type diamant peuvent être dopées ou non dopées.It is specified that these diamond or diamond carbon powders can be doped or undoped.

On peut par exemple utiliser le bore en tant que dopant.Boron can for example be used as a dopant.

Le dépôt de la poudre (particules de carbone diamant ou de type diamant) conduisant à la formation des micro-amas 12 dans les trous 10, sur les conducteurs cathodiques 4, peut être réalisé par électrophorèse (cataphorèse ou anaphorèse), éventuellement complétée par un dépôt métallique électrochimique de consolidation, ou par co-dépôt électrochimique de métal et de carbone diamant ou de type diamant.The deposition of the powder (diamond or diamond-like carbon particles) leading to the formation of micro-clusters 12 in the holes 10, on the cathode conductors 4, can be carried out by electrophoresis (cataphoresis or anaphoresis), possibly supplemented by a electrochemical metallic deposition of consolidation, or by electrochemical co-deposition of metal and carbon diamond or of diamond type.

Dans le cas du dépôt par anaphorèse, la structure pourvue des trous 10 est placée dans une solution appropriée 26 et le fond de chaque trou 10 est porté à un potentiel positif pendant cette phase de dépôt.In the case of deposition by anaphoresis, the structure provided with holes 10 is placed in an appropriate solution 26 and the bottom of each hole 10 is brought to a positive potential during this deposition phase.

Plus précisément, les conducteurs cathodiques 4 sont portés à ce potentiel positif grâce à une source de tension appropriée 28 dont la borne positive est reliée à ces conducteurs cathodiques 4 tandis que la borne négative de cette source est reliée à une contre-électrode 32 en platine ou en acier inoxydable située dans le bain à une distance du substrat d'environ 1 à 5 cm.More precisely, the cathode conductors 4 are brought to this positive potential thanks to to a suitable voltage source 28, the positive terminal of which is connected to these cathode conductors 4 while the negative terminal of this source is connected to a counter-electrode 32 of platinum or of stainless steel situated in the bath at a distance from the substrate d '' about 1 to 5 cm.

La poudre fine de particules de carbone diamant ou de type diamant est mise en suspension dans la solution 26 (avant de placer la structure dans cette solution).The fine powder of diamond or diamond-like carbon particles is suspended in solution 26 (before placing the structure in this solution).

La solution 26 comporte par exemple :

  • de l'acétone,
  • un acide qui peut être de l'acide sulfurique à 8 µl par litre de solution, et
  • de la nitrocellulose qui joue le rôle de liant et de dispersant.
Solution 26 includes for example:
  • acetone,
  • an acid which may be sulfuric acid at 8 μl per liter of solution, and
  • nitrocellulose which acts as a binder and dispersant.

L'immersion de la structure dans cette solution et l'application du potentiel positif au fond des trous conduit à l'obtention des micro-amas 12.The immersion of the structure in this solution and the application of the positive potential to the bottom of the holes leads to the production of micro-clusters 12.

La tension fournie par la source 28 peut aller jusqu'à environ 200 V.The voltage supplied by the source 28 can range up to around 200 V.

Dans le cas de la cataphorèse, un potentiel négatif est appliqué au fond des trous.In the case of cataphoresis, a negative potential is applied to the bottom of the holes.

Plus précisément, dans ce cas, c'est la borne négative de la source 28 qui est reliée aux conducteurs cathodiques 4 tandis que la borne positive de la source 28 est reliée à une contre-électrode 32 en platine ou en acier inoxydable située dans le bain à une distance du substrat d'environ 1 à 5 cm.More specifically, in this case, it is the negative terminal of the source 28 which is connected to the cathode conductors 4 while the positive terminal of the source 28 is connected to a counter-electrode 32 of platinum or stainless steel located in the bath at a distance from the substrate of about 1 to 5 cm.

La solution 26 comporte alors par exemple :

  • de l'alcool isopropylique,
  • un liant minéral comme exemple Mg(NO₃)₂, 6H₂O (de concentration 10⁻⁵ mole par litre), et
  • un dispersant tel que le glycérol (dont la concentration est de l'ordre de 1% en volume).
The solution 26 then comprises for example:
  • isopropyl alcohol,
  • a mineral binder, for example Mg (NO₃) ₂, 6H₂O (with a concentration of 10⁻⁵ mole per liter), and
  • a dispersant such as glycerol (the concentration of which is around 1% by volume).

On utilise alors une tension pouvant aller jusqu'à 200 V environ.A voltage of up to approximately 200 V is then used.

On obtient le même type de dépôt que dans le cas de l'anaphorèse.The same type of deposit is obtained as in the case of anaphoresis.

Dans l'intention de consolider le dépôt obtenu par électrophorèse, on peut, après celui-ci, réaliser un dépôt électrochimique d'un métal par exemple choisi parmi Ni, Co, Ag, Au, Rh ou Pt ou, plus généralement, parmi les métaux de transition, les alliages de ceux-ci et les métaux précieux.With the intention of consolidating the deposit obtained by electrophoresis, it is possible, after this, to carry out an electrochemical deposit of a metal, for example chosen from Ni, Co, Ag, Au, Rh or Pt or, more generally, from the transition metals, alloys thereof and precious metals.

Ceci est schématiquement illustré par la figure 5 où l'on voit la structure pourvue des micro-amas 12 et plongée dans une solution 30 permettant un tel dépôt électrochimique.This is schematically illustrated in Figure 5 where we see the structure provided with micro-clusters 12 and immersed in a solution 30 allowing such electrochemical deposition.

Une tension électrique appropriée est alors appliquée entre les conducteurs cathodiques 4 et une électrode 33 placée dans cette solution, au moyen d'une source de tension 34.A suitable electrical voltage is then applied between the cathode conductors 4 and an electrode 33 placed in this solution, by means of a voltage source 34.

Cette électrode 33 est par exemple en nickel et la solution 30 contient par exemple 300 g/l de sulfate de nickel, 30 g/l de chlorure de nickel, 30 g/l d'acide borique et 0,6 g/l de lauryl sulfate de sodium.This electrode 33 is for example made of nickel and the solution 30 contains for example 300 g / l of nickel sulphate, 30 g / l of nickel chloride, 30 g / l of boric acid and 0.6 g / l of lauryl sodium sulfate.

On utilise par exemple un courant électrique de 4 A/dm.For example, an electric current of 4 A / dm is used.

On voit sur la figure 5 le dépôt métallique 36 qui est formé sur chaque micro-amas 12 après cette opération de dépôt électrochimique, laissant apparaître des parties émergeantes des particules du micro-amas.FIG. 5 shows the metallic deposit 36 which is formed on each micro-cluster 12 after this electrochemical deposition operation, revealing emerging parts of the particles of the micro-cluster.

On peut également former les micro-amas par co-dépôt électrochimique de métal et de carbone diamant ou de type diamant.The micro-clusters can also be formed by electrochemical co-deposition of metal and of diamond or diamond-like carbon.

Pour ce faire, on utilise par exemple un bain contenant des ions de nickel et de la poudre de diamant en suspension dans ce bain.To do this, use is made, for example, of a bath containing nickel ions and diamond powder suspended in this bath.

On peut utiliser jusqu'à 60% en poids de diamant en suspension dans le bain.Up to 60% by weight of diamond suspended in the bath can be used.

On utilise une source de courant appropriée, par exemple de l'ordre de 4 A/dm, et l'on applique la borne négative de cette source aux conducteurs cathodiques et la borne positive de cette source à une électrode de nickel placée dans le bain.An appropriate current source is used, for example of the order of 4 A / dm, and the negative terminal of this source is applied to the cathode conductors and the positive terminal of this source to a nickel electrode placed in the bath .

Le nickel se dépose dans les trous en entraînant avec lui les particules de diamant, d'où la formation de micro-amas de nickel et de diamant dans ces trous.The nickel is deposited in the holes, carrying with it the diamond particles, hence the formation of micro-clusters of nickel and diamond in these holes.

Au lieu de carbone diamant ou de type diamant, on peut utiliser, pour la mise en oeuvre d'un procédé conforme à l'invention, une poudre de particules de carbure de silicium ou de carbure de titane, de taille micronique ou submicronique, et utiliser les mêmes méthodes que précédemment (électrophorèse, éventuellement complétée par un dépôt métallique électrochimique de consolidation, ou co-dépôt électrochimique de métal et de telles particules), pour former les micro-amas.Instead of diamond or diamond-type carbon, a powder of particles of silicon carbide or titanium carbide, of micron or submicron size, can be used for the implementation of a process according to the invention, and use the same methods as above (electrophoresis, possibly supplemented by an electrochemical metallic deposition of consolidation, or electrochemical co-deposition of metal and such particles), to form the micro-clusters.

Bien entendu, dans la présente invention, les sommets des micro-amas (éventuellement recouverts d'un dépôt métallique de consolidation) se trouvent sensiblement dans le plan des grilles et ces micro-amas sont sans contact avec ces grilles.Of course, in the present invention, the tops of the micro-clusters (possibly covered with a metallic consolidation deposit) are located substantially in the plane of the grids and these micro-clusters are in contact with these grids.

Claims (10)

Source d'électrons à effet de champ, cette source comprenant : - sur un substrat électriquement isolant (2), au moins une première électrode (4) jouant le rôle de conducteur cathodique, - une couche électriquement isolante (6) qui recouvre ce conducteur cathodique, - au moins une deuxième électrode (8) jouant le rôle de grille, formée sur la couche électriquement isolante, des trous (10) étant formés à travers cette grille et la couche électriquement isolante au-dessus du conducteur cathodique, et - des éléments (12) qui sont susceptibles d'émettre des électrons et qui sont formés dans ces trous et portés par le conducteur cathodique, cette source étant caractérisée en ce que ces éléments sont des micro-amas (12) contenant des particules de carbone diamant ou de type diamant.Source of field effect electrons, this source comprising: - on an electrically insulating substrate (2), at least a first electrode (4) playing the role of cathode conductor, - an electrically insulating layer (6) which covers this cathode conductor, - at least one second electrode (8) acting as a grid, formed on the electrically insulating layer, holes (10) being formed through this grid and the electrically insulating layer above the cathode conductor, and - elements (12) which are capable of emitting electrons and which are formed in these holes and carried by the cathode conductor, this source being characterized in that these elements are micro-clusters (12) containing diamond or diamond-like carbon particles. Source selon la revendication 1, caractérisée en ce que les micro-amas (12) sont faits de particules de carbone diamant ou de type diamant ou sont faits de telles particules dispersées dans un métal.Source according to claim 1, characterized in that the micro-clusters (12) are made of diamond or diamond-like carbon particles or are made of such particles dispersed in a metal. Source selon la revendication 2, caractérisée en ce que ces micro-amas (12) sont liés par un dépôt d'un métal, les particules de carbone diamant ou de type diamant émergeant de ce dépôt à la surface des micro-amas.Source according to claim 2, characterized in that these micro-clusters (12) are linked by a deposit of a metal, diamond or diamond-like carbon particles emerging from this deposit on the surface of the micro-clusters. Dispositif de visualisation par cathodoluminescence comprenant : - une source d'électrons (14) à effet de champ, et - une anode cathodoluminescente (16) comprenant une couche d'un matériau cathodoluminescent (24), dispositif caractérisé en ce que la source (14) est conforme à l'une quelconque des revendications 1 à 3.Cathodoluminescence display device comprising: - a field effect electron source (14), and - a cathodoluminescent anode (16) comprising a layer of a cathodoluminescent material (24), device characterized in that the source (14) conforms to any one of claims 1 to 3. Procédé de fabrication d'une source d'électrons à effet de champ, procédé selon lequel : - on fabrique une structure comprenant un substrat électriquement isolant (2), au moins un conducteur cathodique (4) sur ce substrat, une couche électriquement isolante (6) qui recouvre chaque conducteur cathodique et une couche de grille électriquement conductrice (25) qui recouvre cette couche électriquement isolante, - on forme des trous (10) à travers la couche de grille et la couche électriquement isolante, au niveau de chaque conducteur cathodique, et - on forme, dans chaque trou, un élément (12) susceptible d'émettre des électrons, ce procédé étant caractérisé en ce que les éléments sont des micro-amas (12) qui contiennent des particules de carbone diamant ou de type diamant et sont formés par électrophorèse ou par co-dépôt électrochimique de métal et de carbone diamant ou de type diamant.Method for manufacturing a field effect electron source, method according to which: - a structure is produced comprising an electrically insulating substrate (2), at least one cathode conductor (4) on this substrate, an electrically insulating layer (6) which covers each cathode conductor and an electrically conductive grid layer (25) which covers this electrically insulating layer, - holes (10) are formed through the grid layer and the electrically insulating layer, at the level of each cathode conductor, and - an element (12) capable of emitting electrons is formed in each hole, this process being characterized in that the elements are micro-clusters (12) which contain particles of diamond or diamond-like carbon and are formed by electrophoresis or by electrochemical co-deposition of metal and diamond or diamond-like carbon. Procédé selon la revendication 5, caractérisé en ce que les micro-amas (12) formés par électrophorèse sont ensuite liés à l'aide d'un métal par dépôt électrochimique.Method according to claim 5, characterized in that the micro-clusters (12) formed by electrophoresis are then bonded using a metal by electrochemical deposition. Procédé selon l'une quelconque des revendications 5 et 6, caractérisé en ce que les particules de carbone diamant ou de type diamant ont une taille de l'ordre de 1 µm ou de moins de 1 µm.Process according to either of Claims 5 and 6, characterized in that the diamond or diamond-like carbon particles have a size of the order of 1 µm or less than 1 µm. Procédé selon la revendication 7, caractérisé en ce que les particules sont obtenues à partir de diamant naturel ou artificiel ou par une méthode choisie parmi la synthèse par laser, le dépôt chimique en phase vapeur et le dépôt physique en phase vapeur.Process according to claim 7, characterized in that the particles are obtained from natural or artificial diamond or by a method chosen from laser synthesis, chemical vapor deposition and physical vapor deposition. Procédé selon l'une quelconque des revendications 5 à 8, caractérisé en ce que les trous (10) ont une forme circulaire ou rectangulaire.Method according to any one of claims 5 to 8, characterized in that the holes (10) have a circular or rectangular shape. Procédé selon l'une quelconque des revendications 5 à 9, caractérisé en ce que la taille des trous (10) est choisie dans un intervalle allant d'environ 1 µm à plusieurs dizaines de micromètres.Method according to any one of Claims 5 to 9, characterized in that the size of the holes (10) is chosen in a range ranging from approximately 1 µm to several tens of micrometers.
EP95402450A 1994-11-08 1995-11-03 Field effect electron source and method for producing same application in display devices working by cathodoluminescence Expired - Lifetime EP0712146B1 (en)

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FR9413371A FR2726688B1 (en) 1994-11-08 1994-11-08 FIELD-EFFECT ELECTRON SOURCE AND MANUFACTURING METHOD THEREOF, APPLICATION TO CATHODOLUMINESCENCE VISUALIZATION DEVICES
FR9413371 1994-11-08

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FR2726688B1 (en) 1996-12-06
US5828162A (en) 1998-10-27
EP0712146B1 (en) 1999-06-30
JPH08241664A (en) 1996-09-17
FR2726688A1 (en) 1996-05-10
DE69510521D1 (en) 1999-08-05
DE69510521T2 (en) 2000-03-16

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