EP0856868B1 - Feldemissionselektronenquelle und Bildschirm mit solcher Feldemissionselektronenquelle - Google Patents

Feldemissionselektronenquelle und Bildschirm mit solcher Feldemissionselektronenquelle Download PDF

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Publication number
EP0856868B1
EP0856868B1 EP98201095A EP98201095A EP0856868B1 EP 0856868 B1 EP0856868 B1 EP 0856868B1 EP 98201095 A EP98201095 A EP 98201095A EP 98201095 A EP98201095 A EP 98201095A EP 0856868 B1 EP0856868 B1 EP 0856868B1
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EP
European Patent Office
Prior art keywords
microtips
electron source
source according
etching
grids
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
Application number
EP98201095A
Other languages
English (en)
French (fr)
Other versions
EP0856868A3 (de
EP0856868A2 (de
Inventor
Robert Meyer
Pierre Vaudaine
Philippe Rambaud
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
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Publication date
Priority claimed from FR9404948A external-priority patent/FR2719155B1/fr
Application filed by Commissariat a lEnergie Atomique CEA filed Critical Commissariat a lEnergie Atomique CEA
Publication of EP0856868A2 publication Critical patent/EP0856868A2/de
Publication of EP0856868A3 publication Critical patent/EP0856868A3/de
Application granted granted Critical
Publication of EP0856868B1 publication Critical patent/EP0856868B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/30—Cold cathodes, e.g. field-emissive cathode
    • H01J1/304—Field-emissive cathodes
    • H01J1/3042—Field-emissive cathodes microengineered, e.g. Spindt-type

Definitions

  • the present invention relates in a manner general to emitting cathodic systems using electronic emission by field effect such as by example of the matrix flat screens used for the display of images; it relates more of a way to a process for improving the characteristics of microtip cathodes and their uniformity over large areas.
  • Figure 1 shows an already elaborate structure, comprising on a substrate 6 surmounted by an insulator 7, a system of cathode conductors 8 and grids 10a superposed in crossed form with an insulator intermediate 12 and a layer of nickel for example 23 deposited on the surface to serve as a mask during operations of making microtips.
  • This layer 23 of nickel, the grids 10a and the insulator 12 are pierced with holes 16, in the bottom of which it's a question of coming to deposit the future microtips made of a conductive metal in electrical connection with the cathode electrode 8.
  • microtips as well obtained have certain defects. These defects come first from the fact that the previous method makes it difficult to obtain micropoints with the shape is reproducible from one point to another and / or from one cathode to another, especially on large surfaces during mass production. They come from the fact that, on the other hand, obtained micropoints are far from always having the perfect conical shape that has been represented under the reference 18 in Figures 2 and 3. Usually Indeed, they have inequalities of form and majority has a radius of curvature much too high, this which gives them a domed profile as we can see in Figure 4. This dome profile decreases especially their emissivity in a considerable way, that is to say the current density emitted for a grid voltage determined micropoint.
  • the realization of the cathode requires at least one photolithography step intervening after the realization of the spikes in particular for the definition of the conductor strips forming the grids. This step creates pollution risks on the tips (organic residues, traces of cleaning,).
  • the emissivity of a point varies so exponential with the shape of the tip and its state of area.
  • a method of making electron sources at micropoints according to the invention allows both to standardize the surface condition and refine the microtip geometry.
  • This process thus makes it possible to reduce the dispersions of features from a tip to the other and from one source to another to disadvantages and make it easier to production of microtip cathodes having uniform and reproducible characteristics, than a high level of emission.
  • the process proposes to carry out, as a first step, a first cleaning step that allows to standardize the state of surface and, in a second step, a step refining which consists of a complementary engraving to give the microtips a profile as close as possible of the desired ideal, that is to say with a radius of curvature as low as possible (lower a few tens of nanometers).
  • this optimization consists of search, for microtips, of a profile as close as possible to a pointed cone tapered, in other words in search of an effect of spikes increased to ensure a large amplitude of the electric field.
  • the step is followed refining a second cleaning step, consisting of wet chemical cleaning.
  • the first cleaning step comprises a first wet chemical cleaning sub-step and a second plasma cleaning sub-step, for example by O 2 plasma.
  • the ripening stage by surface etching can be carried out by one any of the known methods that are particularly controlled chemical or electrochemical attack, reactive ion etching attack and attack by ion bombardment.
  • the superficial attack microtips is performed on a thickness of a few tens to a few thousand Angstroms.
  • One of the advantages of the process is that it applies to the treatment very large emitting surfaces, such as meet precisely in flat screens display.
  • the method thus makes it possible to correct very simply the approximate shape of the microtips obtained to date and, by removing the dispersions of emission characteristics of a peak to the other, to allow a level of emission electronics very high and significantly increased compared to those of the prior art, and therefore to allow the reduction of the supply voltage required between grids and cathode conductors for extract the electrons.
  • the principle of the process consists in choosing a method of realizing micropoints which gives for them a shape approximate (easier to achieve on large surfaces and less expensive) then to clean the micropoints and finally to improve and homogenize their radius of curvature using, in particular, a reactive ion etching or other methods of chemical or electrochemical engravings.
  • the first part (base) is of height such that its summit is about the same level as the lower plane of the grid.
  • the ripening time must be controlled: if it is too much important, the top of the tip can quickly become find below the bottom plane of the grid, this which is very unfavorable to the electronic broadcast. If it is too weak, the radius of curvature is not optimum and the effect sought by refining is not achieved.
  • the ripening time must be sufficient to obtain the optimum radius of curvature of the tip, but if it is longer, the top of the tip always stays above from the bottom plane of the grid since it rests on the material not attacked or little attacked.
  • the first part is in niobium (Nb)
  • the second part is in molybdenum, or chromium, or silicon, or iron, or in nickel.
  • the height H is such that the top of the first part is substantially at level of the lower plane of the grids.
  • the invention thus applies to sources in which microtips are not deposited directly on the cathodic conductors but by example on a resistive layer interposed between microtips and cathode conductors.
  • This last operation which lasts about ten minutes is made for example with a power of 250 Watts, a plasma pressure of 100 millitorrs and a flow rate of 100 cm 3 / min.
  • the cleaning step is followed by a step of refining or etching the tips, for example for molybdenum tips by reactive ion etching in a SF 6 plasma (same equipment as mentioned above).
  • This step allows the removal of a layer of molybdenum oxide that may have formed at the time of O 2 plasma cleaning. It also allows etching of the microtips to modify their shape and in particular to reduce their radius of curvature.
  • the conditions of action of the sulfur hexafluoride plasma are for example as follows: the operation takes about 20 seconds with a power of 400 W, a flow rate of 40 cm 3 / min under a plasma pressure of 30 millitorr. At the end of this treatment, a large proportion of microtips have the same profile which is close to the ideal cone profile of FIG. 5 and a very uniform surface state.
  • Figure 6a is a curve showing the emissivity of the microtips before the treatment ripening (dotted curve) and after treatment ripening (curve in solid line).
  • the current density in microamperes per millimeter square is plotted on the ordinate and the grid-microtip voltage in volts is plotted on the abscissa.
  • the increase in emissivity following the treatment immediately appears to be considerable. We so actually gets some microtips, for which the radius of curvature of the end is less than a few tens of nanometers.
  • Figure 6b shows the emissivity (same units that in Figure 6a) microtips after refining, but before (dashed curve) and after the second cleaning step (curve in solid line). We see that this second cleaning step still allows to improve the emissivity of an important factor.
  • refining tips can be used alternatively to that described above, for example by etching (or electrochemical) controlled or by ion bombardment.
  • the duration during which the stage is carried out ripening, must be checked in the event that the microtips are made of a single metal, sensitive for refining, for example molybdenum.
  • the grid 10a is geometrically understood between or delimited by two planes, a lower plane (I) and an upper plane (S) (see Figure 7a, on which, as in Figures 7b, 7c, 8a-c, references 6, 8, 10a, 12 have the same meaning as in Figures 1 to 5).
  • the ripening time is as we will see, much less critical.
  • a method for obtaining microtips having this structure is derived from the process already described in introduction to make microtips made of a single material.
  • a layer 18a for example in niobium on the nickel layer 23, by evaporation under vacuum at normal incidence, as in the figure 2.
  • the set then has the overall shape substantially conic of Figure 8a.
  • the height H of the base 20 must be sufficient for the vertex A of the cone obtained to be above the lower plane of the grid 10a.
  • A will lie, after the filing operations just described, above the plane upper gate 10a; for this purpose, the height H will be substantially equal to the thickness of the insulator 12, that is to say in this embodiment, at the distance separating the cathode conductor 8 from the plane bottom of the grid 10a.
  • a cathode with microtips be associated with a structure comprising at least one anode and a cathodoluminescent material to achieve a viewing device as described in US Pat. Nos. 4,857,161 (FR-2,593,953), US 4,940,916, US 5,225,820 (FR-2,633,763) or US 5,194,780 (FR-A-2,663,462).

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Cold Cathode And The Manufacture (AREA)
  • Inks, Pencil-Leads, Or Crayons (AREA)
  • Chemical Or Physical Treatment Of Fibers (AREA)

Claims (8)

  1. Mikrospitzen-Elektronenquelle, ein System aus Kathodenleitern (8) und darüber befindlichen Gittern (10a) mit einem Zwischenisolator (12) umfassend, sowie Mikrospitzen (18), abgeschieden in Löchern (16), vorgesehen in den Gittern und dem Isolator, wobei die Gitter geometrisch zwischen einer unteren Ebene (I) und einer oberen Ebene (S) enthalten sind und die Mikrospitzen jeweils wenigstens zwei Teile umfassen:
    einen ersten, kegelstumpfförmigen Teil (20) mit der Höhe H aus einem ersten leitenden oder halb-leitenden Material,
    einen zweiten Teil (22), gebildet durch eine konische Spitze, abgeschieden auf dem ersten Teil, aus einem zweiten leitenden oder halb-leitenden Material,
    wobei das erste und das zweite Material so gewählt werden, dass eine selektive Ätzung nur das zweite Material angreift and nicht das erste.
  2. Mikrospitzen-Elektronenquelle nach Anspruch 1, wobei die selektive Ätzung vom Typ kontrollierter chemischer Angriff oder elektrochemischer Angriff oder lonenbeschuss ist.
  3. Mikrospitzen-Elektronenquelle nach einem der Ansprüche 1 oder 2, wobei die Höhe H des ersten Teils so ist; dass dessen Oberseite sich im Wesentlichen auf demselben Niveau wie die untere Ebene (I) der Gitter (10a) befindet.
  4. Mikrospitzen-Elektronenquelle nach einem der Ansprüche 1 bis 3, bei der der erste Teil (20) aus Niobium (Nb) ist.
  5. Mikrospitzen-Elektronenquelle nach einem der Ansprüche 1 bis 4, bei der der zweite Teil (22) aus Molybdän (Mo), aus Silicium (Si), aus Chrom (Cr), aus Eisen (Fe) oder aus Nickel (Ni) ist.
  6. Mikrospitzen-Elektronenquelle nach einem der Ansprüche 1 bis 5, bei der die Mikrospitzen einem Reinigungsschritt unterzogen worden sind.
  7. Mikrospitzen-Elektronenquelle nach einem der Ansprüche 1 bis 6, bei der der zweite Teil der Mikrospitzen einem Verfeinerungsschritt durch Oberflächenätzung unterzogen worden ist.
  8. Kathodolumineszenz-Bildschirm mit einer Mikrospitzen-Elektronenquelle nach einem der Ansprüche 1 bis 7.
EP98201095A 1994-04-25 1995-04-24 Feldemissionselektronenquelle und Bildschirm mit solcher Feldemissionselektronenquelle Expired - Lifetime EP0856868B1 (de)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
FR9404948 1994-04-25
FR9404948A FR2719155B1 (fr) 1994-04-25 1994-04-25 Procédé de réalisation de sources d'électrons à micropointes et source d'électrons à micropointes obtenue par ce procédé.
FR9413972 1994-11-22
FR9413972A FR2719156B1 (fr) 1994-04-25 1994-11-22 Source d'électrons à micropointes, les micropointes comportant deux parties.
EP95400910A EP0689222B1 (de) 1994-04-25 1995-04-24 Herstellungsverfahren einer Mikrospitzelektronenquelle

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
EP95400910A Division EP0689222B1 (de) 1994-04-25 1995-04-24 Herstellungsverfahren einer Mikrospitzelektronenquelle

Publications (3)

Publication Number Publication Date
EP0856868A2 EP0856868A2 (de) 1998-08-05
EP0856868A3 EP0856868A3 (de) 1998-09-30
EP0856868B1 true EP0856868B1 (de) 2003-07-02

Family

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Family Applications (2)

Application Number Title Priority Date Filing Date
EP95400910A Expired - Lifetime EP0689222B1 (de) 1994-04-25 1995-04-24 Herstellungsverfahren einer Mikrospitzelektronenquelle
EP98201095A Expired - Lifetime EP0856868B1 (de) 1994-04-25 1995-04-24 Feldemissionselektronenquelle und Bildschirm mit solcher Feldemissionselektronenquelle

Family Applications Before (1)

Application Number Title Priority Date Filing Date
EP95400910A Expired - Lifetime EP0689222B1 (de) 1994-04-25 1995-04-24 Herstellungsverfahren einer Mikrospitzelektronenquelle

Country Status (5)

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US (1) US5635790A (de)
EP (2) EP0689222B1 (de)
CA (1) CA2146528A1 (de)
DE (2) DE69531220T2 (de)
FR (1) FR2719156B1 (de)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5702281A (en) * 1995-04-20 1997-12-30 Industrial Technology Research Institute Fabrication of two-part emitter for gated field emission device
US6356014B2 (en) * 1997-03-27 2002-03-12 Candescent Technologies Corporation Electron emitters coated with carbon containing layer
US6004180A (en) * 1997-09-30 1999-12-21 Candescent Technologies Corporation Cleaning of electron-emissive elements
JP2002083555A (ja) * 2000-07-17 2002-03-22 Hewlett Packard Co <Hp> セルフアライメント型電子源デバイス
US6873097B2 (en) * 2001-06-28 2005-03-29 Candescent Technologies Corporation Cleaning of cathode-ray tube display
CN1300818C (zh) * 2003-08-06 2007-02-14 北京大学 一种场发射针尖及其制备方法与应用

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2593953B1 (fr) * 1986-01-24 1988-04-29 Commissariat Energie Atomique Procede de fabrication d'un dispositif de visualisation par cathodoluminescence excitee par emission de champ
FR2623013A1 (fr) * 1987-11-06 1989-05-12 Commissariat Energie Atomique Source d'electrons a cathodes emissives a micropointes et dispositif de visualisation par cathodoluminescence excitee par emission de champ,utilisant cette source
US5225820A (en) * 1988-06-29 1993-07-06 Commissariat A L'energie Atomique Microtip trichromatic fluorescent screen
EP0434330A3 (en) * 1989-12-18 1991-11-06 Seiko Epson Corporation Field emission device and process for producing the same
FR2658839B1 (fr) * 1990-02-23 1997-06-20 Thomson Csf Procede de croissance controlee de cristaux aciculaires et application a la realisation de microcathodes a pointes.
FR2663462B1 (fr) * 1990-06-13 1992-09-11 Commissariat Energie Atomique Source d'electrons a cathodes emissives a micropointes.
US5203731A (en) * 1990-07-18 1993-04-20 International Business Machines Corporation Process and structure of an integrated vacuum microelectronic device
US5382867A (en) * 1991-10-02 1995-01-17 Sharp Kabushiki Kaisha Field-emission type electronic device
GB9210419D0 (en) * 1992-05-15 1992-07-01 Marconi Gec Ltd Cathode structures

Also Published As

Publication number Publication date
EP0689222A2 (de) 1995-12-27
EP0689222A3 (de) 1996-02-07
DE69514576T2 (de) 2000-08-10
EP0856868A3 (de) 1998-09-30
EP0689222B1 (de) 2000-01-19
DE69531220T2 (de) 2004-05-27
US5635790A (en) 1997-06-03
DE69514576D1 (de) 2000-02-24
FR2719156B1 (fr) 1996-05-24
DE69531220D1 (de) 2003-08-07
EP0856868A2 (de) 1998-08-05
CA2146528A1 (en) 1995-10-26
FR2719156A1 (fr) 1995-10-27

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