EP0109589A1 - Elektrolumineszente Dünnfilm-Anzeigevorrichtung - Google Patents

Elektrolumineszente Dünnfilm-Anzeigevorrichtung Download PDF

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Publication number
EP0109589A1
EP0109589A1 EP19830110973 EP83110973A EP0109589A1 EP 0109589 A1 EP0109589 A1 EP 0109589A1 EP 19830110973 EP19830110973 EP 19830110973 EP 83110973 A EP83110973 A EP 83110973A EP 0109589 A1 EP0109589 A1 EP 0109589A1
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EP
European Patent Office
Prior art keywords
thin film
display device
silicon nitride
film display
deposited
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.)
Withdrawn
Application number
EP19830110973
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English (en)
French (fr)
Inventor
John L. Plumb
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.)
Osram Sylvania Inc
Original Assignee
GTE Products Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by GTE Products Corp filed Critical GTE Products Corp
Publication of EP0109589A1 publication Critical patent/EP0109589A1/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional [2D] radiating surfaces
    • H05B33/22—Light sources with substantially two-dimensional [2D] radiating surfaces characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers

Definitions

  • the present invention relates in general to electroluminescent thin film display devices and the associated process of fabrication. More particularly, the present invention pertains to an electroluminescent thin film display device that has dielectric layers that provide for improved electrical and chemical protection of the phosphor thin film of the device.
  • FIG. 1 shows the normal sequence of layers disposed between the glass substrate and a protective glass.
  • the purpose of the yttria dielectric films is to provide electrical protection for the phosphor film.
  • the dielectric films make it possible to apply an AC voltage across the phosphor film of sufficient magnitude for electroluminescence. Electric breakdown at defects or thin areas of the phosphor is prevented because the dielectric films limit the electric charge that may flow each half cycle of the applied AC voltage.
  • the limiting of electric charge is effective only when the yttria films are optimally of uniform thickness.
  • the electric field in the yttria films is not uniform if the thickness of the films is not uniform.
  • the limit on the electric charge that may flow is determined by the electric
  • the yttria film tends to be thin over edges of the electrode pattern on the substrate and also tends to be thin over any protruberances that may be present in the phosphor film. Because of non-uniformities of the yttria film thickness the.electric field is likewise non-uniform resulting in a relatively low electric breakdown level which in turn limits operating lamp brightness.
  • an object of the present invention to provide an electroluminescent thin film display device that has thin film dielectric layers that provide for improved electrical and chemical protection-of the phosphor thin film of the device.
  • Another object of the present invention is to provide an improved dielectric film used for protection of the phosphor layer in an electroluminescent display device ana instrumental in achieving higher operating lamp brightness.
  • a further object of the present invention is to provide an improved thin film dielectic layer deposited on either side of the phosphor layer and which is characterized by providing-improved chemical protection of the phosphor layer including protection against humidity conditions and protection against diffusion of halogen ions from the substrate.
  • Still another object of the present invention is to provide an electroluminescent thin film display device in which the dielectric layers that sandwich the phosphor thin film layer of the device are capable of being deposited to a more uniform thickness.
  • Still a further object of the present invention is to provide an electroluminescent thin film display device having protective dielectric layers for the phosphor thin film selected to enable greater charge flow levels before breakdown in comparison with existing dielectric layers.
  • a silicon nitride dielectric film which has been found to provide more electrical and chemical protection to the phosphor film than the previously used yttria dielectric films. Furthermore, this improved performance has been accomplished without sacrificing electroluminescent performance.
  • the-silicon. nitride dielectric films permit more electric charge to flow each half cycle of the AC cycle so as to achieve higher operating lamp brightness in comparison with prior display devices employing the previously used yttria films. Silicon nitride is also more impervious to water or OH-ions, and thus provides protection to the phosphor layer from the adverse effects present in a humid atmosphere.
  • the silicon nitride is more impervious to halogen ions, and is thus a barrier against diffusion of such halogen ions from the base substrate. It has also been found that the silicon nitride is deposited in a more uniform layer providing a more uniform thickness thereof which is particularly important in areas where the silicon nitride layer is over underlying surface irregularities.
  • a silicon nitride dielectric film which is deposited on either side of the phosphor layer for providing both electrical and chemical protection thereof.
  • the silicon nitride films have been found to provide more electrical and chemical protection than was previously provided with the use of yttria dielectric films. Moreover, the electrical and chemical protection is provided without sacrificing electroluminescent performance and in fact performance is enhanced with the use of the silicon nitride films.
  • Silicon nitride has a lower permittivity than yttria and as such one would expect that voltage breakdown would occur at a lower electric charge level than with the higher permittivity yttria.
  • the silicon nitride has a greater dielectric strength than the yttria and can sustain a higher electric field, and therefore greater electric charge, without breakdown, in comparison with the yttria films.
  • the higher dielectric strength of the silicon nitride may be related to the band gap of the material.
  • the "band gap" relates to the energy that is required to dislodge electrons from each ion.
  • the improved electrical protection and chemical protection is due at least in part to the fact that silicon nitride characteristically is deposited in a more uniform thickness which is particularly significant for depositions over underlying surface irregularities.
  • FIG. 1 shows a sequence of thin film layers that may be used in constructing a device in accordance with the present invention.
  • a glass substrate 20 In FIG. 1 there is provided a glass substrate 20.
  • FIG. 1 shows each of the layers essentially exploded off of the glass substrate 20. However, it is understood that each of these thin film layers are deposited, one on top of the other. The layers are then protected by a rear glass 22 and associated hermetic seal 24.
  • a more detailed description of the manner in which the layers are deposited is given.
  • the thin film layers schematically illustrated in FIG. 1 include a transparent conductor 26, a rear electrode 28, a dark field layer 30, and a phosphor layer 32.
  • the deposition of the phosphor thin film 32 is preceded by a deposition of a silicon nitride film layer 34, and is followed by the deposition of a second silicon nitride dielectric layer 36.
  • the phosphor layer is essentially sandwiched between two silicon nitride thin film layers 34, 36.
  • the following is one example of a lamp fabricated with dielectric layers of silicon nitride.
  • the lamp is fabricated by depositing successive films onto a tin oxide-coated soda lime float glass substrate. This deposition is carried out by sputtering.
  • tin oxide as a transparent conductor, one may also use indium tin oxide.
  • the substrate is initially baked in an oven under vacuum and at a temperature higher than it is to be subjected to at any other time in the deposition process.
  • Upon the tin oxide transparent conductor is deposited silicon nitride. This deposition is by sputtering a silicon target in a magnetron plasma in nitrogen at three micrometers pressure and 100 sccm flow at relatively low substrate temperature.
  • the deposition temperature is carried out over a deposition period to provide a thickness of, for example, 150 nm (nanometers).
  • the next step in the process is to reheat the substrate.
  • zinc sulphide and manganese for example, may be deposited by known sputtering techniques to provide a phosphor layer of a thickness of say 500 nm.
  • the second silicon nitride film is deposited in the same manner as the first, but without substrate heat. Also, the second layer is cooled in the presence of nitrogen.
  • an aluminum electrode is deposited by vacuum evaporation to a thickness of say about 400 nm.
  • the deposition of the silicon nitride may be with the use of either a silicon target or a silicon nitride target.
  • the sputtering gas may include argon if a higher deposition rate is desired.
  • the deposition pressure used in the sputtering technique may be in the range of 1-20 micrometers, and the flow may be less than 100 standard cubic centimeters per minute (sccm) if residual gas flow is low.
  • the degree of electrical and chemical protection that is provided by the silicon nitride depends at least to some extent upon the thickness of the deposited films. Increased thickness, in general, provides increased protection, provided that the silicon nitride maintains structural integrity.
  • the silicon nitride film thickness is on the order of 150 nm. Actually, it has been found that the thickness is preferably in the range of 100 nm-300 nm. Thicknesses below this range do not-provide sufficient protection and thicknesses above this range tend to be characterized by degraded structural integrity of the silicon nitride.

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  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Electroluminescent Light Sources (AREA)
EP19830110973 1982-11-15 1983-11-03 Elektrolumineszente Dünnfilm-Anzeigevorrichtung Withdrawn EP0109589A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US44181982A 1982-11-15 1982-11-15
US441819 1982-11-15

Publications (1)

Publication Number Publication Date
EP0109589A1 true EP0109589A1 (de) 1984-05-30

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Family Applications (1)

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EP19830110973 Withdrawn EP0109589A1 (de) 1982-11-15 1983-11-03 Elektrolumineszente Dünnfilm-Anzeigevorrichtung

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EP (1) EP0109589A1 (de)
JP (1) JPS59101795A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3712855A1 (de) * 1986-09-29 1988-04-07 Ricoh Kk Duennschicht-elektrolumineszenzvorrichtung
DE4019988A1 (de) * 1989-06-23 1991-01-10 Sharp Kk Duennfilm-eld
EP0751699A3 (de) * 1995-06-26 1997-05-07 Hewlett Packard Co Verfahren und Vorrichtung zum Abdichten einer Dünnfilm-Elektrolumineszenzanordnung

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH027390A (ja) * 1988-06-27 1990-01-11 Nippon Soken Inc 薄膜エレクトロルミネセンス素子

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2260205B2 (de) * 1972-12-08 1979-03-15 Institut Poluprovodnikov Akademii Nauk Ukrainskoj Ssr, Kiew (Sowjetunion) Elektrolumineszenz-Anordnung
GB2039146A (en) * 1978-12-29 1980-07-30 Gte Sylvania Inc High contrast display device having a dark layer
GB1602895A (en) * 1977-09-16 1981-11-18 Sharp Kk Thin-film electroluminescent element

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2260205B2 (de) * 1972-12-08 1979-03-15 Institut Poluprovodnikov Akademii Nauk Ukrainskoj Ssr, Kiew (Sowjetunion) Elektrolumineszenz-Anordnung
GB1602895A (en) * 1977-09-16 1981-11-18 Sharp Kk Thin-film electroluminescent element
GB2039146A (en) * 1978-12-29 1980-07-30 Gte Sylvania Inc High contrast display device having a dark layer

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3712855A1 (de) * 1986-09-29 1988-04-07 Ricoh Kk Duennschicht-elektrolumineszenzvorrichtung
DE4019988A1 (de) * 1989-06-23 1991-01-10 Sharp Kk Duennfilm-eld
EP0751699A3 (de) * 1995-06-26 1997-05-07 Hewlett Packard Co Verfahren und Vorrichtung zum Abdichten einer Dünnfilm-Elektrolumineszenzanordnung

Also Published As

Publication number Publication date
JPS59101795A (ja) 1984-06-12

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Inventor name: PLUMB, JOHN L.