EP0188938B1 - Layer acting as a barrier at the ion bombardment in vacuum tubes - Google Patents

Layer acting as a barrier at the ion bombardment in vacuum tubes Download PDF

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Publication number
EP0188938B1
EP0188938B1 EP85402478A EP85402478A EP0188938B1 EP 0188938 B1 EP0188938 B1 EP 0188938B1 EP 85402478 A EP85402478 A EP 85402478A EP 85402478 A EP85402478 A EP 85402478A EP 0188938 B1 EP0188938 B1 EP 0188938B1
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Prior art keywords
barrier layer
layer
barrier
micro
microchannel
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EP85402478A
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German (de)
French (fr)
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EP0188938A1 (en
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Daniel Gally
Pierre-Paul Jobert
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers
    • H01J43/06—Electrode arrangements
    • H01J43/18—Electrode arrangements using essentially more than one dynode
    • H01J43/24—Dynodes having potential gradient along their surfaces
    • H01J43/246—Microchannel plates [MCP]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/18—Luminescent screens
    • H01J29/28—Luminescent screens with protective, conductive or reflective layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/84—Traps for removing or diverting unwanted particles, e.g. negative ions, fringing electrons; Arrangements for velocity or mass selection

Definitions

  • the present invention relates to an ion bombardment barrier layer for a vacuum tube according to the preamble of claim 1.
  • British patent GB-A 1,368,882 thus relates to an intensifier tube i ficitor of light images or IIL with a wafer of microchannels surmounted on the side of the photo-cathode of the tube by a barrier layer to the ion bombardment.
  • IIL intensifier tube i ficitor of light images or IIL with a wafer of microchannels surmounted on the side of the photo-cathode of the tube by a barrier layer to the ion bombardment.
  • FIG. 1 Such a tube is shown diagrammatically in FIG. 1.
  • the reference 1 designates the glass slab which receives the light radiation symbolized by a wavy arrow.
  • the residual pressure in a vacuum tube is never zero regardless of the quality of cleaning and degassing of its constituent parts.
  • the electron bombardment ionizes the residual gases and the ions thus created, positively charged, go up the channels of the wafer towards the lowest potential and bombard the extraction layer 3 located on the surface of the photo-cathode.
  • This extraction layer which is very fragile and very thin, is very quickly destroyed by ion bombardment.
  • an ion bombardment barrier layer 4 is used, placed on the micro-channel plate 5, on the side of the photo-cathode. This layer stops the ions but lets through the photoelectrons suitably accelerated by a sufficient potential difference.
  • the adhesion of the barrier layer to the microchannel wafer and the stress state of the barrier layer after annealing are not very satisfactory.
  • aluminum is a material easy to deposit and which does not present degassing when it is bombarded.
  • alumina AI2 0 3 a silicon oxide Si 0 2 or Si O, or zinc sulfide ZnS. None of these materials is fully satisfactory because the alumina exhibits a state of stress after annealing which is unsatisfactory, the silicon oxide Si 0 2 or Si O degassed when bombarded and the zinc sulfide has a mass. atomic mean too high for photoelectrons to easily pass through.
  • the present invention makes it possible to obtain an image intensifier tube whose lifespan is improved.
  • the present invention relates to an ion bombardment barrier layer, for a light image intensifier tube, deposited between a multiplying micro-channel plate and an extraction layer situated on the surface of the photocathode of the tube for the extraction of photo- electrons, this barrier layer being intended to stop the ions likely to go up in the micro-channels, characterized in that this layer consists of silicon nitride, Si 3 N 4 .
  • the vacuum tube in which the barrier layer against ion bombardment according to the invention is used can be, as explained above, a light image intensifier tube or IIL
  • This layer can also be used in other types of vacuum tubes, such as, for example, penetration screens.
  • this type of tubes which is described for example in French patent application No. 7,619,420 in the name of THOMSON-CSF, the barrier layer according to the invention is used to separate two layers of phosphors, This barrier layer has in this use the advantage of having a minimum degassing when it is bombarded.
  • the improvement of the properties of the barrier layer made up of a stable silicon nitride compound is due to several factors. We know that when subjected to ion bombardment a body like silica degassed by desorption of water molecules and decomposition of hydroxyl radicals. The use of a non-oxygenated material makes it possible to reduce the extent of degassing. It is observed with a scanning electron microscope that when the annealing is carried out the barrier layer has a "pleated" appearance and has a state of minimum stress. Thus any impurity in the form of micro-dust or any other surface irregularity due to the preceding stages of the process does not create any tear in the film stretched over the orifices of the micro-channel pad.
  • a process of deposition by chemical reaction in vapor phase activated by plasma at low temperature is used which makes it possible to leave the microchannel wafers immobile and to reduce handling during the steps of depositing the protective material on the organic film and annealed.
  • the annealing can be done in situ while handling was required for passage through an oven in the case of sputtering or evaporation deposition.
  • FIG. 1 which schematically shows a light image intensifier tube or IIL has been described in the introduction to the description.
  • the ion bombardment barrier layer 4 consists of a stable compound of formula Sis N 4 .
  • This compound has a refractive index between 1.8 and 1.9.
  • the silicon nitride Sis N 4 has characteristics far superior to those of silica Si 0 2 with regard to compactness.
  • Compactness is defined as the ratio of specific mass to average atomic mass.
  • the compactness of the silicon nitride is 0.17 mol average of atom per cubic centimeter and that of the silica is 0.11.
  • the average atomic mass of these two materials is identical. These two materials therefore have a permeability comparable to electrons with the same incident energy.
  • the barrier layer according to the invention When used in an IIL, it must have a thickness of from 3 to 30 nm approximately, and preferably from 5 to 8 nm. For other applications, it is possible to use a layer of greater thickness, of the order of a few micrometers for example.
  • the barrier layer according to the invention is produced at a temperature between 70 and 200 ° C, and preferably between 120 and 150 ° C. A compromise must be found between the state of intrinsic stress in the material at a given temperature and the characteristics organic thin film thermoplastics, placed on the micro-channel pad.
  • barrier layers are used, such as for example sputtering or evaporation by Joule effect.
  • a deposition method which is also known from the prior art, and which is carried out by chemical reaction in the vapor phase activated by plasma at low temperature.
  • the deposit is made in a cylindrical chamber, having two horizontal electrodes separated by a few centimeters.
  • the micro-channel wafers are placed on the lower electrode which is heated to a temperature such as those previously envisaged.
  • Plasma is created in a mixture of gases with chemical formulas Si H 4 , NHs and N 2 .
  • silane Si H 4 can be diluted in nitrogen N 2 .
  • micro-channel patties remain fixed during deposition.
  • annealing which makes it possible to remove the organic layer can be done in situ, either in air or in any suitable gas mixture.

Abstract

1. A barrier layer (4) providing protection against ion bombardement, for use in a light picture intensifier tube and deposited between a multiplier micro-channel disk and an extraction layer (3) provided on the surface of the photocathode of the tube for the purpose of extracting photoelectrons, the barrier layer (4) being intended to retain the ions susceptible of ascending into the microchannels, characterized in that said layer is consituted of a stable compound consisting of silicon nitride Si3 N4 .

Description

La présente invention concerne une couche barrière au bombardement ionique pour tube à vide selon le préambule de la revendication 1.The present invention relates to an ion bombardment barrier layer for a vacuum tube according to the preamble of claim 1.

Il est connu d'utiliser de telles couches, notamment dans les tubes intensificateurs d'images lumineuses.It is known to use such layers, in particular in light image intensifier tubes.

Ainsi le brevet anglais GB-A 1.368.882 concerne un tube intensificateur d'images lumineuses ou IIL avec une galette de microcanaux surmontée du côté de la photo-cathode du tube par une couche barrière au bombardement ionique. Un tel tube est représenté schématiquement sur la figure 1.British patent GB-A 1,368,882 thus relates to an intensifier tube i ficitor of light images or IIL with a wafer of microchannels surmounted on the side of the photo-cathode of the tube by a barrier layer to the ion bombardment. Such a tube is shown diagrammatically in FIG. 1.

Sur cette figure, on désigne par la référence 1 la dalle de verre qui reçoit le rayonnement lumineux symbolisé par une flèche ondulée.In this figure, the reference 1 designates the glass slab which receives the light radiation symbolized by a wavy arrow.

A la suite de cette dalle de verre, on trouve une photocathode 2 qui est recouverte d'une couche 3 permettant l'extraction de photo-électrons. On trouve ensuite la couche barrière au bombardement ionique 4 qui est portée par la galette de micro-canaux 5, puis une couche métallique 6, une couche de luminophore 7 et une dalle de verre 8.Following this glass slab, there is a photocathode 2 which is covered with a layer 3 allowing the extraction of photoelectrons. Next, there is the ion bombardment barrier layer 4 which is carried by the micro-channel plate 5, then a metal layer 6, a phosphor layer 7 and a glass slab 8.

Le pression résiduelle dans un tube à vide n'est jamais nulle quelle que soit la qualité du nettoyage et du dégazage de ses pièces constitutives. Le bombardement électronique ionise les gaz résiduels et les ions ainsi créés, chargés positivement, remontent les canaux de la galette vers le potentiel le plus bas et bombardent la couche d'extraction 3 située à la surface de la photo-cathode. Cette couche d'extraction, qui est très fragile et très mince, est très rapidement détruite par le bombardement ionique.The residual pressure in a vacuum tube is never zero regardless of the quality of cleaning and degassing of its constituent parts. The electron bombardment ionizes the residual gases and the ions thus created, positively charged, go up the channels of the wafer towards the lowest potential and bombard the extraction layer 3 located on the surface of the photo-cathode. This extraction layer, which is very fragile and very thin, is very quickly destroyed by ion bombardment.

Pour éviter cette destruction, on utilise une couche barrière au bombardement ionique 4, posée sur la galette de micro-canaux 5, du côté de la photo-cathode. Cette couche arrête les ions mais laisse passer les photo-électrons convenablement accélérés par une différence de potentiels suffisante.To avoid this destruction, an ion bombardment barrier layer 4 is used, placed on the micro-channel plate 5, on the side of the photo-cathode. This layer stops the ions but lets through the photoelectrons suitably accelerated by a sufficient potential difference.

Dans le brevet anglais cité, le procédé utilisé pour déposer la couche barrière est le suivant :

  • - on réalise un film mince organique, à base de nitro-cellulose par exemple, en utilisant l'un des procédés de fabrication des écrans de tubes à rayons cathodiques ;
  • - on dépose ce film sur la galette de micro-canaux;
  • - on dépose une couche de matériau protecteur, de préférence une couche d'aluminium, sur le film organique posé sur la galette de micro-canaux ;
  • - on effectue un recuit à l'air pour assurer la combustion du film organique et la mise en contact de la couche de matériau protecteur avec la galette de micro-canaux.
In the cited English patent, the process used to deposit the barrier layer is as follows:
  • - An organic thin film is produced, based on nitro-cellulose for example, using one of the methods for manufacturing screens of cathode ray tubes;
  • - this film is deposited on the micro-channel cake;
  • - A layer of protective material, preferably an aluminum layer, is deposited on the organic film placed on the micro-channel pad;
  • - An air annealing is carried out to ensure the combustion of the organic film and the contacting of the layer of protective material with the micro-channel wafer.

Lorsqu'on utilise une couche barrière en aluminium, l'adhérence de la couche barrière sur la galette de micro-canaux et l'état de contrainte de la couche barrière après le recuit ne sont pas très satisfaisants.When using an aluminum barrier layer, the adhesion of the barrier layer to the microchannel wafer and the stress state of the barrier layer after annealing are not very satisfactory.

Par contre l'aluminium est un matériau facile à déposer et qui ne présente pas de dégazage lorsqu'il est bombardé.On the other hand aluminum is a material easy to deposit and which does not present degassing when it is bombarded.

Pour réaliser cette couche barrière, il est connu d'utiliser d'autres matériaux tels que l'alumine AI2 03, un oxyde de silicium Si 02 ou Si O, ou le sulfure de zinc ZnS. Aucun de ces matériaux ne donne pleinement satisfaction car l'alumine présente un état de contrainte après le recuit qui est peu satisfaisant, l'oxyde de silicium Si 02 ou Si O dégaze lorsqu'il est bombardé et le sulfure de zinc a une masse atomique moyenne trop élevée pour que les photo-électrons puissent le traverser aisément.To make this barrier layer, it is known to use other materials such as alumina AI2 0 3 , a silicon oxide Si 0 2 or Si O, or zinc sulfide ZnS. None of these materials is fully satisfactory because the alumina exhibits a state of stress after annealing which is unsatisfactory, the silicon oxide Si 0 2 or Si O degassed when bombarded and the zinc sulfide has a mass. atomic mean too high for photoelectrons to easily pass through.

Dans l'art antérieur, les couches barrières au bombardement ionique sont déposées par les techniques bien connues de pulvérisation cathodique ou d'évaporation par effet Joule. Ces techniques présentent notamment les inconvénients suivants :

  • - le film organique peut être détérioré;
  • - il faut nécessairement des pièces en rotation et une régulation sophistiquée pour réaliser de façon reproductible des films très minces;
  • - enfin le chauffage lors des différents dépôts est difficile à réaliser.
In the prior art, the barrier layers to ion bombardment are deposited by the well known techniques of sputtering or evaporation by Joule effect. These techniques have the following disadvantages in particular:
  • - the organic film can be damaged;
  • - rotating parts and sophisticated regulation are necessarily required to reproduce very thin films in a reproducible manner;
  • - Finally, heating during various deposits is difficult to achieve.

La présente invention concerne une couche barrière qui présente des propriétés plus satisfaisantes que les couches barrières de l'art antérieur notamment sur les points suivants:

  • - l'adhérence sur la galette de micro-canaux car le film organique n'est pas détérioré lors de la formation de la couche barrière;
  • - la masse atomique moyenne minimum pour que les photo-électrons la traversent aisément, mais une compacité élevée;
  • - l'absence de défauts tels que des trous ou des déchirures provenant d'une part du recuit et de l'état de contrainte qu'il crée, et d'autre part des manipulations nécessaires par exemple pour implanter la galette de micro-canaux dans l'IIL.
The present invention relates to a barrier layer which has more satisfactory properties than the barrier layers of the prior art, in particular on the following points:
  • - the adhesion to the micro-channel wafer because the organic film is not deteriorated during the formation of the barrier layer;
  • - the minimum average atomic mass for photoelectrons to pass through easily, but with a high compactness;
  • - the absence of faults such as holes or tears originating on the one hand from the annealing and from the stress state which it creates, and on the other hand from the manipulations necessary for example to implant the micro-channel wafer in the IIL.

Du fait de l'amélioration des propriétés de la couche barrière, la présente invention permet d'obtenir un tube intensificateur d'images dont la durée de vie est améliorée.Due to the improvement of the properties of the barrier layer, the present invention makes it possible to obtain an image intensifier tube whose lifespan is improved.

La présente invention concerne une couche barrière au bombardement ionique, pour tube intensificateur d'images lumineuses, déposée entre une galette de micro-canaux multiplicatrice et une couche d'extraction située à la surface de la photocathode du tube pour l'extraction de photo-électrons, cette couche barrière étant destinée à arrêter les ions susceptibles de remonter dans les micro-canaux, caractérisée en ce que cette couche est constituée de nitrure de silicium, Si3N4. Le tube à vide dans lequel est utilisée la couche barrière au bombardement ionique selon l'invention peut être, comme cela a été exposé précédemment, un tube intensificateur d'images lumineuses ou I.I.L.The present invention relates to an ion bombardment barrier layer, for a light image intensifier tube, deposited between a multiplying micro-channel plate and an extraction layer situated on the surface of the photocathode of the tube for the extraction of photo- electrons, this barrier layer being intended to stop the ions likely to go up in the micro-channels, characterized in that this layer consists of silicon nitride, Si 3 N 4 . The vacuum tube in which the barrier layer against ion bombardment according to the invention is used can be, as explained above, a light image intensifier tube or IIL

Cette couche peut aussi être utilisée dans d'autres types de tubes à vide, comme par exemple les écrans à pénétration. Dans ce type de tubes, qui est décrit par exemple dans la demande de brevet français no 7 619 420 au nom de THOMSON-CSF, la couche barrière selon l'invention est utilisée pour séparer deux couches de luminophores, Cette couche barrière présente dans cette utilisation l'avantage d'avoir un dégazage minimum lorsqu'elle est bombardée.This layer can also be used in other types of vacuum tubes, such as, for example, penetration screens. In this type of tubes, which is described for example in French patent application No. 7,619,420 in the name of THOMSON-CSF, the barrier layer according to the invention is used to separate two layers of phosphors, This barrier layer has in this use the advantage of having a minimum degassing when it is bombarded.

L'amélioration des propriétés de la couche barrière constituée d'un composé stable de nitrure de silicium (SisN4) tient à plusieurs facteurs. On sait que lorsqu'il est soumis au bombardement ionique un corps comme la silice dégaze par désorption de molécules d'eau et décomposition des radicaux hydroxyles. L'utilisation d'un matériau non oxygéné permet de réduire l'ampleur de dégazage. On observe au microscope électronique à balayage que lorsqu'on effectue le recuit la couche barrière a un aspect "plissé" et présente un état de contrainte minimum. Ainsi toute impureté sous forme de micro- poussière ou toute autre irrégularité de surface due aux étapes précédentes du procédé ne crée aucune déchirure dans le film tendu au-dessus des orifices de la galette de micro-canaux.The improvement of the properties of the barrier layer made up of a stable silicon nitride compound (Si s N 4 ) is due to several factors. We know that when subjected to ion bombardment a body like silica degassed by desorption of water molecules and decomposition of hydroxyl radicals. The use of a non-oxygenated material makes it possible to reduce the extent of degassing. It is observed with a scanning electron microscope that when the annealing is carried out the barrier layer has a "pleated" appearance and has a state of minimum stress. Thus any impurity in the form of micro-dust or any other surface irregularity due to the preceding stages of the process does not create any tear in the film stretched over the orifices of the micro-channel pad.

Au contraire, lorsqu'une couche barrière en silice Si 02 est utilisée, on observe qu'on obtient un film tendu après le recuit ce qui entraîne un état de contrainte important.On the contrary, when a silica barrier layer Si 0 2 is used, it is observed that a stretched film is obtained after annealing, which results in a significant state of stress.

Enfin, on utilise un procédé de dépôt par réaction chimique en phase vapeur activée par plasma à basse température qui permet de laisser immobiles les galettes de micro-canaux et de réduire les manipulations lors des étapes de dépôt du matériau protecteur sur le film organique et de recuit. Ainsi le recuit peut se faire in situ alors qu'il fallait une manipulation pour le passage en étuve dans le cas de dépôt par pulvérisation cathodique ou par évaporation.Finally, a process of deposition by chemical reaction in vapor phase activated by plasma at low temperature is used which makes it possible to leave the microchannel wafers immobile and to reduce handling during the steps of depositing the protective material on the organic film and annealed. Thus the annealing can be done in situ while handling was required for passage through an oven in the case of sputtering or evaporation deposition.

D'autres objets, caractéristiques et résultats de l'invention ressortiront de la description suivante donnée à titre d'exemple non limitatif et illustrée par la figure annexée qui représente le schéma d'un tube intensificateur d'images lumineuses.Other objects, characteristics and results of the invention will emerge from the following description given by way of nonlimiting example and illustrated by the appended figure which represents the diagram of a light image intensifier tube.

Sur la figure annexée, pour des raisons de clarté, les cotes et proportions des divers éléments ne sont pas respectées.In the attached figure, for reasons of clarity, the dimensions and proportions of the various elements are not observed.

La figure 1 qui représente de façon schématique un tube intensificateur d'image lumineuse ou IIL a été décrite dans l'introduction à la description.Figure 1 which schematically shows a light image intensifier tube or IIL has been described in the introduction to the description.

Selon l'invention, la couche barrière au bombardement ionique 4 est constituée d'un composé stable de formule Sis N4.According to the invention, the ion bombardment barrier layer 4 consists of a stable compound of formula Sis N 4 .

Ce composé a un indice de réfraction compris entre 1,8 et 1,9.This compound has a refractive index between 1.8 and 1.9.

Le nitrure de silicium Sis N4 présente des caractéristiques bien supérieures à celles de la silice Si 02 en ce qui concerne la compacité. La compacité est définie comme le rapport de la masse spécifique à la masse atomique moyenne. La'compacité du nitrure de silicium est de 0,17 moles moyennes d'atome par centimètre cube et celle de la silice est de 0,11.The silicon nitride Sis N 4 has characteristics far superior to those of silica Si 0 2 with regard to compactness. Compactness is defined as the ratio of specific mass to average atomic mass. The compactness of the silicon nitride is 0.17 mol average of atom per cubic centimeter and that of the silica is 0.11.

La masse atomique moyenne de ces deux matériaux est identique. Ces deux matériaux présentent donc une perméabilité comparable aux électrons de même énergie incidente.The average atomic mass of these two materials is identical. These two materials therefore have a permeability comparable to electrons with the same incident energy.

Lorsque la couche barrière selon l'invention est utilisée dans un IIL, elle doit présenter une épaisseur de 3 à 30 nm environ, et préférentiellement de 5 à 8 nm. Pour d'autres applications, on peut utiliser une couche de plus grande épaisseur, de l'ordre de quelques micromètres par exemple.When the barrier layer according to the invention is used in an IIL, it must have a thickness of from 3 to 30 nm approximately, and preferably from 5 to 8 nm. For other applications, it is possible to use a layer of greater thickness, of the order of a few micrometers for example.

La couche barrière selon l'invention est réalisée à une température comprise entre 70 et 200°C, et de préférence entre 120 et 150°C. Il faut trouver un compromis entre l'état de contrainte intrinsèque au matériau à température donnée et les caractéristiques thermoplastiques de film mince organique, posé sur la galette de micro-canaux.The barrier layer according to the invention is produced at a temperature between 70 and 200 ° C, and preferably between 120 and 150 ° C. A compromise must be found between the state of intrinsic stress in the material at a given temperature and the characteristics organic thin film thermoplastics, placed on the micro-channel pad.

On a vu précédemment que dans l'art antérieur, on utilise des méthodes du dépôt des couches barrières, telles que par exemple la pulvérisation cathodique ou l'évaporation par effet Joule.We have seen above that in the prior art, methods of depositing barrier layers are used, such as for example sputtering or evaporation by Joule effect.

Ces méthodes concement uniquement le dépôt de la couche barrière. Elles sont mises en oeuvre pour déposer la couche barrière sur le film mince organique déposé sur la galette de micro-canaux et elles sont suivies par le recuit à l'air, comme cela a été exposé précédemment.These methods relate only to the deposition of the barrier layer. They are used to deposit the barrier layer on the organic thin film deposited on the microchannel wafer and they are followed by air annealing, as has been explained above.

Selon l'invention, on utilise de préférence une méthode de dépôt qui est également connue de l'art antérieur, et qui est réalisée par réaction chimique en phase vapeur activée par plasma à basse température.According to the invention, use is preferably made of a deposition method which is also known from the prior art, and which is carried out by chemical reaction in the vapor phase activated by plasma at low temperature.

Le dépôt se fait dans une chambre cylindrique, présentant deux électrodes horizontales séparées de quelques centimètres. On pose les galettes de micro-canaux sur l'électrode inférieure qui est chauffée à une température telle que celles envisagées précédemment. La plasma est créé dans un mélange de gaz de formules chimiques Si H4, NHs et N2. Pour diminuer la vitesse de dépôt, on peut diluer du silane Si H4 dans de l'azote N2.The deposit is made in a cylindrical chamber, having two horizontal electrodes separated by a few centimeters. The micro-channel wafers are placed on the lower electrode which is heated to a temperature such as those previously envisaged. Plasma is created in a mixture of gases with chemical formulas Si H 4 , NHs and N 2 . To decrease the deposition rate, silane Si H 4 can be diluted in nitrogen N 2 .

Les galettes de micro-canaux restent fixes lors du dépôt. De plus, le recuit qui permet d'éliminer la couche organique peut être fait in situ, soit à l'air, soit dans tout mélange de gaz convenable.The micro-channel patties remain fixed during deposition. In addition, the annealing which makes it possible to remove the organic layer can be done in situ, either in air or in any suitable gas mixture.

Claims (5)

1. A barrier layer (4) providing protection against ion bombardement, for use in a light picture intensifier tube and deposited between a multiplier microchannel disk and an extraction layer (3) provided on the surface of the photocathode of the tube for the purpose of extracting photoelectrons, the barrier layer (4) being intended to retain the ions susceptible of ascending into the microchannels, characterized in that said layer is constituted of a stable compound consisting of silicon nitride Si3N4.
2. A barrier layer according to claim 1, characterized in that the compound is chosen such that its refraction index is comprised between 1,8 and 1,9.
3. A barrier layer according to claim 1 or 2, characterized in that its thickness is comprised between 5 and 8 nm.
4. A process for the manufacture of a barrier . layer according to one of claims 1 to 3, characterized in that it comprises the following sequence of operations:
- depositing a thin organic film on the microchannel disk,
- depositing the barrier layer (4) constituted of a stable compound of nitrogen and silicon on the thin organic film by means of a vapour phase chemical reaction activated by a low-temperature plasma,
- annealing in air so as to ensure the combustion of the organic film providing the adherence of the barrier layer on the microchannel disk.
5. A process according to claim 4, characterized in that its deposition is effected at a temperature comprised between 120°C und 150°C.
EP85402478A 1984-12-18 1985-12-12 Layer acting as a barrier at the ion bombardment in vacuum tubes Expired EP0188938B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8419362A FR2580864B1 (en) 1984-12-18 1984-12-18 ION BOMBING BARRIER LAYER FOR VACUUM TUBE
FR8419362 1984-12-18

Publications (2)

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EP0188938A1 EP0188938A1 (en) 1986-07-30
EP0188938B1 true EP0188938B1 (en) 1989-07-12

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EP85402478A Expired EP0188938B1 (en) 1984-12-18 1985-12-12 Layer acting as a barrier at the ion bombardment in vacuum tubes

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EP (1) EP0188938B1 (en)
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FR2683388A1 (en) * 1991-10-31 1993-05-07 Thomson Tubes Electroniques RADIOLOGICAL IMAGE INTENSIFIER TUBE WITH IMPROVED RESOLUTION.
US6373174B1 (en) 1999-12-10 2002-04-16 Motorola, Inc. Field emission device having a surface passivation layer
US6396049B1 (en) * 2000-01-31 2002-05-28 Northrop Grumman Corporation Microchannel plate having an enhanced coating
JP6817160B2 (en) * 2017-06-30 2021-01-20 浜松ホトニクス株式会社 Electronic polyploid
CN112420477B (en) * 2020-10-30 2022-09-06 北方夜视技术股份有限公司 High-gain and low-luminescence ALD-MCP and preparation method and application thereof

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US2303563A (en) * 1941-05-09 1942-12-01 Rca Corp Cathode ray tube and luminescent screen
GB1104935A (en) * 1964-05-08 1968-03-06 Standard Telephones Cables Ltd Improvements in or relating to a method of forming a layer of an inorganic compound
US3742224A (en) * 1972-02-29 1973-06-26 Litton Systems Inc Light amplifier device having an ion and low energy electron trapping means
US4242371A (en) * 1976-06-25 1980-12-30 Thomson-Csf High-luminance color screen for cathode-ray tubes and the method for manufacturing the same
US4395438A (en) * 1980-09-08 1983-07-26 Amdahl Corporation Low pressure chemical vapor deposition of silicon nitride films
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US4618541A (en) * 1984-12-21 1986-10-21 Advanced Micro Devices, Inc. Method of forming a silicon nitride film transparent to ultraviolet radiation and resulting article

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FR2580864B1 (en) 1987-05-22
EP0188938A1 (en) 1986-07-30
US4931693A (en) 1990-06-05
FR2580864A1 (en) 1986-10-24
DE3571530D1 (en) 1989-08-17

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