EP0697710B1 - Procédé de fabrication d'une source d'électrons à micropointes - Google Patents
Procédé de fabrication d'une source d'électrons à micropointes Download PDFInfo
- Publication number
- EP0697710B1 EP0697710B1 EP95401863A EP95401863A EP0697710B1 EP 0697710 B1 EP0697710 B1 EP 0697710B1 EP 95401863 A EP95401863 A EP 95401863A EP 95401863 A EP95401863 A EP 95401863A EP 0697710 B1 EP0697710 B1 EP 0697710B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- layer
- metallic material
- process according
- microtips
- electrically insulating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/02—Manufacture of electrodes or electrode systems
- H01J9/022—Manufacture of electrodes or electrode systems of cold cathodes
- H01J9/025—Manufacture of electrodes or electrode systems of cold cathodes of field emission cathodes
Definitions
- the present invention relates to a method for manufacturing a microtip electron source ("microtips").
- Such a principle is used to realize cold sources of electrons, capable of replacing the electron-emitting heating filaments, because that such cold springs have a more response fast, lower power consumption and are susceptible to greater miniaturization than these heating filaments.
- microtip sources One of the most important applications of these cold sources of electrons, also called “microtip sources” is the manufacture of tubes television dishes.
- Figure 1 is a sectional view schematic and partial of such a flat screen and the Figure 2 is a schematic perspective view and partial view of this flat screen.
- the flat screen in Figures 1 and 2 includes a source of microtip electrons 2 and a substrate glass 4 which is separated from the source 2 by a space thin in which a vacuum has been created.
- the substrate 4 carries, facing the source 2, a transparent, electrically conductive layer 6, for example in indium tin oxide, this layer 6 itself carrying elements cathodoluminescent 8, also called “luminophores”.
- the microtip source 2 includes, on an electrically insulating substrate 10, for example in glass, a set of cathode conductors parallels 12 which constitute the columns of the screen.
- cathode conductors are covered by a layer 14 of an electrically insulating material such as silica.
- a set of other drivers parallel electric 15 is placed above the insulating layer 14 and these other conductors 15, or grids, are perpendicular to the conductors cathodic 12 to form the lines of the screen.
- holes 18, 19 are formed through the insulating layer 14 and these grids 15 and microtips 20 made of a material electron emitter are formed in these holes and are based on the cathode conductors 12.
- the phosphors 8 are formed on the transparent conductive layer 6, opposite these intersections, as seen in Figure 2.
- Electrons are extracted by application appropriate electrical voltages between the grids and the microtips then these electrons are accelerated thanks to appropriate electrical voltages applied between the grids and the conductive layer 6 constituting the anode of the screen.
- Each phosphor 8 excited by electrons 22 emits light 24.
- microtips located at the intersection of a row and a fed column in tension emit electrons to form a picture element or pixel.
- Each pixel is actually "excited" by several hundred microtips whose dimensions are of the order of 1 ⁇ m, generally 1.5 ⁇ m, and which are spaced from each other by a distance of the order of a few micrometers, typically 5 ⁇ m.
- a flat screen typically uses around 10,000 microtips per square millimeter over areas of several square decimetres.
- the flat screens currently manufactured have surfaces of the order of 5 dm 2 and it is envisaged to manufacture flat screens whose surfaces would go up to approximately 1 m 2 .
- FIG. 3 illustrates schematically this process, a structure comprising the insulating substrate 10 on which the cathode conductors 12, and the insulating layer 14 which is formed on these cathode conductors and which carries a grid layer 16 electrically conductive.
- the grids themselves are obtained from this grid layer 16, after having formed the microtips as we will see.
- a nickel layer 16a is deposited on the grid layer 16 by vacuum evaporation and grazing incidence.
- the microtips 20 are obtained by evaporation of an electron emitting material 26.
- a layer 28 of this material then forms on the surface of the gate layer 16a.
- the holes 19 formed in these layers 16 and 16a gradually decrease as as the thickness of layer 28 increases.
- the diameter of the material deposits 26 in the holes 18 of the insulating layer 14 varies as the diameter of the holes layer 16a and grid layer 16, which leads to the point shape of the deposits in the holes 18, that is to say at the microtips 20.
- layer 28 is removed by selective dissolution of the nickel layer 16a, this which brings up these microtips.
- disks 32 are formed from the layer of silica which results from this oxidation.
- Reactive ion etching of the substrate silicon 30 then allows the formation of pedestals 34 made of silicon, the discs 32 serving as masks.
- a layer 40 of silica is then formed. on each disk 32.
- the pedestals 34 are then oxidized thermally, which leads to the formation of microtips 42 from these pedestals.
- a layer 46 of this material also forms on layer 40 silica associated with each disc 32.
- the angle of incidence ⁇ of a beam of evaporation F varies according to the position of the holes 19 of the grid layer 16, which leads to the phenomenon illustrated in FIG. 5, that is to say at microtips with less Y axes perpendicular to the surface of the substrate 10 that the angle of incidence ⁇ is large.
- the object of the present invention is to remedy these drawbacks.
- the layer of grid as a cathode for the electrolytic attack of the metallic material.
- the electrolyte being located around the metallic material so as to avoid an overconcentration of ions which could slow dissolution and cause a significant redeposition of this material on the grid around microdots in formation.
- the protective layer can be formed by depositing, under grazing incidence, a layer of electrically insulating material on the layer of wire rack.
- this protective layer is preferably formed by anodic oxidation of the grid layer.
- the grid layer can be made of a material chosen from the group comprising niobium, tantalum and aluminum.
- Metallic material can be chosen in the group comprising iron, nickel, chromium, Fe-Ni, gold, silver and copper.
- the protective layer can be removed by chemical attack.
- This protective layer can also be removed by reactive ion etching.
- Figure 6A a structure 49 like the one shown on Figure 3 and which includes the substrate electrically insulator 10 on which the conductors are formed cathodic 12, electrically insulating layer 14 formed on these cathode conductors and the layer of grid 16 formed on this layer electrically insulating 14 (it being understood that, in other modes of specific implementation, the structure may not understand only one cathode conductor).
- the substrate 10 is in glass
- cathode conductors are made of a bilayer of chromium and copper
- layer 14 is in silica
- the gate layer 16 is made of niobium, tantalum or aluminum.
- a anodic oxidation of the gate layer 16 which leads to the formation of a layer 50 of oxide of niobium or tantalum oxide or aluminum oxide in the example considered, which covers the part remaining of the grid layer 16, as seen in Figure 6B.
- An electrolytic deposition is then carried out metallic material at the bottom of holes 18 to that this metallic material overflows from these holes as seen in Figure 6C, part of this material then being above layer 50.
- the electrolytic bath can be used, the composition of which is as follows: NiCl 2 , 6H 2 O 50 gl -1 NiSO 4 , 6H 2 O 21 gl -1 FeSO 4 2 gl -1 H 3 BO 3 25 gl -1 Na saccharinate 0.8 gl -1
- the conductors cathodes 12 serve as cathode and block 56 serves anode.
- the electrically conductive elements 60 which result from the deposition of metallic material at the bottom holes 18 are in contact with the conductors cathodic but are electrically isolated from the grid layer 16 thanks to the protective layer 50 which covers the latter.
- This protective layer is then removed 50 by chemical attack or by ion etching reactive ( Figure 6D).
- the structure where the protective layer 50 has been removed, is placed in an appropriate electrolytic bath 64 (containing for example 10% HCl at 37% and 90% H 2 O for the dissolution of nickel iron) and , by means of a suitable electrical voltage source 66, an electrical voltage is established (for example 1 to 2 V for the dissolution of iron-nickel) between the cathode conductors 12 which, in this case, serve as an anode, and the grid layer 16 which serves as a cathode.
- an appropriate electrolytic bath 64 containing for example 10% HCl at 37% and 90% H 2 O for the dissolution of nickel iron
- an electrical voltage for example 1 to 2 V for the dissolution of iron-nickel
- the material of elements 60 is eliminated substantially symmetrical around the Z axis of the holes 18 and the ions metals produced by the chemical attack on the material elements 60 are partly eliminated thanks to the electrolyte renewal and partly redeposited on the grid layer.
- the fraction redeposited ions is more or less important and can be checked.
- this step of forming microtips is done with the glass substrate above and the electrolytic bath below, so that allow parts 68 to fall into the bath electrolytic.
- the interest of the process object of the present invention is to enable the manufacture of self-aligned microtips over the diaper holes grid 16, using a non-directive technique, in an isotropic liquid medium (electrolytic bath 64).
Description
- 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, une couche de grille électriquement conductrice qui recouvre cette couche électriquement isolante, des trous étant formés à travers cette couche de grille et la couche électriquement isolante, au niveau de chaque conducteur cathodique, et
- on forme, dans chaque trou, une micropointe qui est faite en un matériau métallique émetteur d'électrons et qui repose sur le conducteur cathodique correspondant à ce trou,
- on forme une couche de protection électriquement isolante sur la couche de grille,
- on forme un dépôt chimique, de préférence électrolytique, du matériau métallique émetteur d'électrons au fond des trous jusqu'à ce que ce matériau métallique déborde de ceux-ci,
- on élimine la couche de protection, et
- on réalise une attaque électrolytique du matériau métallique déposé, de manière à obtenir les micropointes à partir de ce matériau métallique.
- la figure 1, déjà décrite, est une vue en coupe schématique et partielle d'un écran plat,
- la figure 2, déjà décrite, est une vue schématique et partielle en perspective de cet écran plat,
- la figure 3, déjà décrite, illustre schématiquement un procédé connu de fabrication des micropointes d'une source d'électrons à micropointes,
- la figure 4, déjà décrite, illustre schématiquement un autre procédé connu de fabrication des micropointes d'une source d'électrons à micropointes,
- la figure 5, déjà décrite, illustre schématiquement des inconvénients de ces procédés connus, et
- les figures 6A à 6E illustrent schématiquement des étapes d'un mode de mise en oeuvre particulier du procédé objet de l'invention.
NiCl2, 6H2O | 50 g.l-1 |
NiSO4, 6H2O | 21 g.l-1 |
FeSO4 | 2 g.l-1 |
H3BO3 | 25 g.l-1 |
Saccharinate de Na | 0,8 g.l-1 |
- d'éléments pointus qui affleurent sensiblement à la surface de la couche de grille 16 et constituent les micropointes 62, et
- de parties 68 qui se détachent de ces micropointes et restent dans le bain électrolytique comme on le voit sur la figure 6E.
Claims (9)
- Procédé de fabrication d'une source d'électrons à micropointes, procédé selon lequel :on fabrique une structure (49) comprenant un substrat électriquement isolant (10), au moins un conducteur cathodique (12) sur ce substrat, une couche électriquement isolante (14) qui recouvre chaque conducteur cathodique, une couche de grille électriquement conductrice (16) qui recouvre cette couche électriquement isolante, des trous (18, 19) étant formés à travers cette couche de grille et la couche électriquement isolante, au niveau de chaque conducteur cathodique, eton forme, dans chaque trou, une micropointe (62) qui est faite d'un matériau métallique émetteur d'électrons et qui repose sur le conducteur cathodique correspondant à ce trou,on forme une couche de protection électriquement isolante (50) sur la couche de grille (16),on forme un dépôt chimique du matériau métallique émetteur d'électrons au fond des trous jusqu'à ce que ce matériau métallique déborde de ceux-ci,on élimine la couche de protection (50), eton réalise une attaque électrolytique du matériau métallique déposé, de manière à obtenir les micropointes (62) à partir de ce matériau métallique.
- Procédé selon la revendication 1, caractérisé en ce que le dépôt chimique du matériau métallique émetteur d'électrons est un dépôt électrolytique.
- Procédé selon l'une quelconque des revendications let 2, caractérisé en ce qu'on utilise la couche de grille (16) comme cathode pour l'attaque électrolytique du matériau métallique.
- Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce qu'on forme la couche de protection (50) en déposant, sous incidence rasante, une couche d'un matériau électriquement isolant sur la couche de grille (16).
- Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce qu'on forme la couche de protection par oxydation anodique de la couche de grille (16).
- Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce que la couche de grille (16) est faite d'un matériau choisi dans le groupe comprenant le niobium, le tantale et l'aluminium.
- Procédé selon l'une quelconque des revendications 1 à 6, caractérisé en ce que le matériau métallique est choisi dans le groupe comprenant le fer, le nickel, le chrome, le Fe-Ni, l'or, l'argent et le cuivre.
- Procédé selon l'une quelconque des revendications 1 à 7, caractérisé en ce que la couche de protection (50) est éliminée par attaque chimique.
- Procédé selon l'une quelconque des revendications 1 à 7, caractérisé en ce que la couche de protection (50) est éliminée par gravure ionique réactive.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR9410041A FR2723799B1 (fr) | 1994-08-16 | 1994-08-16 | Procede de fabrication d'une source d'electrons a micropointes |
FR9410041 | 1994-08-16 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0697710A1 EP0697710A1 (fr) | 1996-02-21 |
EP0697710B1 true EP0697710B1 (fr) | 1998-11-11 |
Family
ID=9466324
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP95401863A Expired - Lifetime EP0697710B1 (fr) | 1994-08-16 | 1995-08-09 | Procédé de fabrication d'une source d'électrons à micropointes |
Country Status (5)
Country | Link |
---|---|
US (1) | US5676818A (fr) |
EP (1) | EP0697710B1 (fr) |
JP (1) | JPH0869749A (fr) |
DE (1) | DE69505914T2 (fr) |
FR (1) | FR2723799B1 (fr) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5766446A (en) * | 1996-03-05 | 1998-06-16 | Candescent Technologies Corporation | Electrochemical removal of material, particularly excess emitter material in electron-emitting device |
US5893967A (en) * | 1996-03-05 | 1999-04-13 | Candescent Technologies Corporation | Impedance-assisted electrochemical removal of material, particularly excess emitter material in electron-emitting device |
FR2757999B1 (fr) * | 1996-12-30 | 1999-01-29 | Commissariat Energie Atomique | Procede d'auto-alignement utilisable en micro-electronique et application a la realisation d'une grille de focalisation pour ecran plat a micropointes |
US6120674A (en) * | 1997-06-30 | 2000-09-19 | Candescent Technologies Corporation | Electrochemical removal of material in electron-emitting device |
US6007695A (en) * | 1997-09-30 | 1999-12-28 | Candescent Technologies Corporation | Selective removal of material using self-initiated galvanic activity in electrolytic bath |
FR2770683B1 (fr) * | 1997-11-03 | 1999-11-26 | Commissariat Energie Atomique | Procede de fabrication d'une source d'electrons a micropointes |
FR2778757B1 (fr) * | 1998-05-12 | 2001-10-05 | Commissariat Energie Atomique | Systeme d'inscription d'informations sur un support sensible aux rayons x |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE68913419T2 (de) * | 1988-03-25 | 1994-06-01 | Thomson Csf | Herstellungsverfahren von feldemissions-elektronenquellen und anwendung zur herstellung von emitter-matrizen. |
US5026437A (en) * | 1990-01-22 | 1991-06-25 | Tencor Instruments | Cantilevered microtip manufacturing by ion implantation and etching |
FR2663462B1 (fr) * | 1990-06-13 | 1992-09-11 | Commissariat Energie Atomique | Source d'electrons a cathodes emissives a micropointes. |
JP2961334B2 (ja) * | 1991-05-28 | 1999-10-12 | セイコーインスツルメンツ株式会社 | 尖鋭な金属針を持つ原子間力顕微鏡のカンチレバー製造法 |
US5151061A (en) * | 1992-02-21 | 1992-09-29 | Micron Technology, Inc. | Method to form self-aligned tips for flat panel displays |
-
1994
- 1994-08-16 FR FR9410041A patent/FR2723799B1/fr not_active Expired - Fee Related
-
1995
- 1995-08-09 US US08/512,827 patent/US5676818A/en not_active Expired - Fee Related
- 1995-08-09 DE DE69505914T patent/DE69505914T2/de not_active Expired - Fee Related
- 1995-08-09 EP EP95401863A patent/EP0697710B1/fr not_active Expired - Lifetime
- 1995-08-15 JP JP20825195A patent/JPH0869749A/ja active Pending
Also Published As
Publication number | Publication date |
---|---|
US5676818A (en) | 1997-10-14 |
FR2723799A1 (fr) | 1996-02-23 |
JPH0869749A (ja) | 1996-03-12 |
FR2723799B1 (fr) | 1996-09-20 |
DE69505914T2 (de) | 1999-06-10 |
EP0697710A1 (fr) | 1996-02-21 |
DE69505914D1 (de) | 1998-12-17 |
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