WO2004067676A1 - Controlled sulfur species deposition process - Google Patents
Controlled sulfur species deposition process Download PDFInfo
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- WO2004067676A1 WO2004067676A1 PCT/CA2004/000097 CA2004000097W WO2004067676A1 WO 2004067676 A1 WO2004067676 A1 WO 2004067676A1 CA 2004000097 W CA2004000097 W CA 2004000097W WO 2004067676 A1 WO2004067676 A1 WO 2004067676A1
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- C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
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- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
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- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/0623—Sulfides, selenides or tellurides
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- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
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- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
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- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
- C23C16/45523—Pulsed gas flow or change of composition over time
- C23C16/45525—Atomic layer deposition [ALD]
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- 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 radiating surfaces
- H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
Definitions
- the present invention relates to a method for the deposition of multi element thin film compositions. More specifically, the invention is a method for the deposition of a phosphor composition where the amount of sulfur provided in the deposited phosphor composition is controlled.
- the method is particularly suitable for the deposition of phosphor compositions comprising a thioaluminate, thiogallate or thioaluminate of Group IIA and Group MB elements where the source material(s) include sulfides that contain at least some of the elements comprising the deposited phosphor film.
- the method is particularly useful for the deposition of phosphors for full colour ac electroluminescent displays employing thick film dielectric layers with a high dielectric constant.
- Thick film dielectric structures as exemplified by U.S. Patent 5,432,015 (the entirety of which is incorporated herein by reference) are typically fabricated on ceramic substrates and provide superior resistance to dielectric breakdown, as well as a reduced operating voltage compared to thin film electroluminescent (TFEL) displays fabricated on glass substrates.
- TFEL thin film electroluminescent
- the thick film dielectric structure When deposited on a ceramic substrate, the thick film dielectric structure withstands higher processing temperatures than TFEL devices on glass substrates. The increased tolerance to higher temperatures facilitates annealing of the phosphor films at higher temperatures to improve luminosity. However, even with the enhanced luminosity that is obtained, it is desirable to further increase the luminous efficiency of the devices to enable an improvement in overall energy efficiency and reduction in power consumption.
- PCT CA01/01823 discloses a method, preferably electron beam vaporization, for the deposition of a ternary, quaternary or similar phosphor composition, in which components of the composition are located on different sources.
- the compositions are thioaluminates, thiogallates or thioindates of Group 1IA and Group IIB elements, and the sulfides that form such compounds are located on the different sources.
- PCT CA01/01234 discloses a dual source phosphor deposition method using dual source electron beam deposition.
- the various compounds of the first and second sources are in the ratios required to provide the required composition of the phosphor.
- the deposited phosphors are preferably blue emitting europium activated barium thioaluminate.
- PCT CA02/00688 discloses a single-source sputtering method for depositing controlled composition multi-element phosphor films. The method utilizes a source material in the form of a single dense target that has a composition different from the desired film composition of the phosphor. The concentrations of light chemical elements relative to heavier chemical elements in the target composition of the process is higher than desired in the deposited films.
- the invention is a method for the deposition of multi element thin film compositions for thick film dielectric electroluminescent devices.
- the amount of sulfur is controlled in the deposition chamber during deposition of the thin film composition. In this manner, the amount of sulfur impinging on the deposition substrate, and thus incorporated into the thin film composition, is controlled.
- the method of the invention in particularly useful for the deposition of phosphor compositions comprising ternary, quaternary or higher sulfur-bearing compounds, preferably selected from the group consisting of thioaluminates, thiogallates and thioindates of at least one element from Groups IIA and IIB of the Periodic Table. Phosphors deposited in accordance with the method of the invention exhibit improved luminance and luminous efficiency compared with methods of the prior art.
- one or more source materials that make up the composition of the deposited phosphor are deposited onto a suitable substrate using for example, low pressure physical vapour deposition methods.
- the relative volatization of the source materials is controlled to obtain the desired ratio of metal species on the deposition substrate.
- a gettering or condensing material is provided substantially adjacent the source material(s) in order to remove, prevent and/or minimize any excess sulfur-bearing species from depositing on the deposition substrate and thus incorporating into the deposited phosphor composition. This is conducted at a temperature sufficiently low to prevent re-evaporation of the condensed sulfur-bearing species from the gettering or condensing material.
- the getting or condensing material is of sufficient surface area to effectively absorb or condense any excess sulfur-bearing species where such excess quantity is defined as an amount in excess of that required to provide the desired composition of the thin film phosphor composition. This is readily understood by one of skill in the art. An excess quantity of sulfur deposited within the phosphor composition may have a deleterious effect on the luminosity of the deposited phosphor composition.
- a method for the deposition of a thin film of a pre-determined composition onto a substrate comprising ternary, quaternary or higher sulfide compounds selected from the group consisting of thioaluminates, thiogallates and thioindates of at least one element from
- the method comprising: volatizing at least one source material comprising a sulfide that forms said pre-determined composition to form a sulfur-bearing thin film composition on a substrate; and minimizing any excess quantity of sulfur-bearing species volatilized from the at least one source material from impinging on said substrate.
- a method for the deposition of a thin phosphor film of a predetermined composition onto a substrate comprising ternary, quaternary or higher sulfide compounds selected from the group consisting of thioaluminates, thiogallates and thioindates of at least one element from Groups IIA and IIB of the Periodic Table, the method comprising: volatizing at least one source material comprising a sulfide that forms said pre-determined composition to form a sulfur-bearing thin film composition on a substrate; simultaneously minimizing any excess quantity of sulfur- bearing species volatilized from the at least one source material from impinging on said substrate; and condensing or removing oxygen and/or water from evaporant from said at least one source material.
- composition comprising a ternary, quaternary or higher composition
- method comprising:
- the deposited thin film composition is a phosphor composition comprising an europium activated barium thioaluminate or europium activated calcium thioaluminate phosphor composition.
- any excess quantity of sulfur-bearing species generated from the source material(s) within the deposition chamber is removed from the chamber by the provision of a gettering or condensing material substantially adjacent to the source material(s) to absorb or condense any excess sulfur-bearing species generated by the volatization of the source material(s). This is done at a temperature sufficiently low to prevent re-evaporation of the condensed sulfur-bearing species.
- the temperature to prevent re-evaporation is established as is known to those of skill in the art, by looking up the equilibrium vapor pressure data as a function of temperature for the species in question and selecting a temperature that is below that for which the equilibrium vapor pressure is below the base pressure for the deposition process.
- one or more agents may be further provided to: (a) minimize any excess of sulfur-bearing species that may also contain oxygen such as for example SO 2 ; and, (b) to condense or remove molecular oxygen and/or water from the flux of evaporant emitted from the source material(s) and prevent it impinging on the deposition substrate within the deposition chamber.
- Oxygen may originate from the evaporation sources of sulfide if they contain one or more oxygen-bearing impurities such as sulfate or sulfite compounds and water.
- Such agents are preferably provided substantially adjacent the source material(s) used in the deposition method.
- a volatile source of sulfur preferably atomic sulfur
- the volatile source of sulfur should be injected into the chamber such that the sulfur impinges uniformly on the deposition substrate.
- composition comprising a ternary, quaternary or higher composition
- method comprising:
- Figure 1 is a diagram showing the sulfur species contributing to the vapour pressure of sulfur versus temperature
- Figure 2 is a schematic representation of a section of an electroluminescent device comprising a thick film dielectric layer and a phosphor composition
- Figure 3 is a graphical representation of the luminosity versus applied voltage of a thick film dielectric electroluminescent display having a europium activated barium thioaluminate phosphor prepared according to the methods of the prior art compared to a similar device prepared according to the method of the present invention;
- Figure 4 is a top (plan) view of a phosphor deposition chamber in accordance with the present invention.
- Figure 5 is a graphical representation of the luminosity versus applied voltage of a thick film dielectric electroluminescent display having a europium activated barium magnesium thioaluminate phosphor deposited according to the method of the present invention.
- Figure 6 is a graphical representation of the luminosity versus applied voltage of a thick film dielectric electroluminescent display having a europium activated barium thioaluminate phosphor deposited using a condenser with reduced efficiency during phosphor deposition.
- the present invention is a method for depositing thin film compositions and in particular thin film phosphor compositions comprising ternary, quaternary or higher sulfur-bearing compounds where the amount of sulfur deposited onto the deposition substrate, and thus into the deposited phosphor composition is controlled by controlling the amount of sulfur-bearing species in the vapour deposition atmosphere. This is accomplished by gettering or condensing any excess sulfur-bearing species volatized from the source or sources into the deposition atmosphere to prevent an excess of sulfur impinging or the deposition substrate and thus incorporating into the deposited phosphor composition.
- the vapour deposition method of the invention is particularly useful for the deposition of phosphor compositions onto substrates where the phosphor compositions are selected from the group consisting of thioaluminates, thiogallates and thioindates of at least one element from Groups IIA and IIB of the Periodic Table having a controlled and desired sulfur content.
- phosphors with a high luminosity and useful emission colour are obtained.
- the vapour deposition method of the present invention may be effected from a single source material or alternatively multiple source materials, so long as the selected single source or multiple sources form the pre-determined composition on the substrate including the activator species.
- a variety of vapour deposition methods may be used in the present invention including but not limited to sputtering, electron beam, or thermal evaporation. The preferred method is electron beam deposition.
- the temporal variation of deposition of the components onto the substrate from the source material(s) used that form the deposited phosphor composition is monitored and controlled to effect simultaneous vapour deposition from the source material(s) as taught in Applicant's PCT CA01/01823 (the disclosure of which is incorporated herein by reference in its entirety).
- the flux of sulfur incident on the deposition substrate is controlled to obtain the desired sulfur content in the deposited film.
- the sulfur deposition flux may be controlled by controlling the partial pressure of sulfur within the deposition chamber.
- the sulfur-bearing species comprising the process atmosphere must on average contain a constant number of sulfur atoms per molecule of vapour. If the sulfur-bearing species contain a variable number of sulfur atoms, then the mass density of the sulfur in the chamber will not bear a fixed relationship to the partial pressure of sulfur and the deposition rate of sulfur will vary in accordance with the relative abundance of molecules with different numbers of sulfur atoms.
- the sulfur molecules comprising the vapour in the deposition chamber originate from different locations.
- the vapour molecules arise from elemental sulfur that has condensed on the walls of the chamber that are at a temperature below about 500°C, the evaporated sulfur, will comprise predominantly rings of sulfur atoms such as S ⁇ , S 7 or S ⁇ .
- Figure 1 shows the equilibrium abundance of sulfur species contributing to the sulfur vapour pressure as a function of temperature. If the vapour molecule is hydrogen sulfide, it contains only one sulfur atom.
- the sulfur bearing species may comprise a range of species from atomic sulfur to S 8 to molecules or molecular clusters of the sulfide source material.
- the mass density of sulfur in the deposition chamber can vary by as much as a factor of eight at a given partial pressure of sulfur species, depending on the mix of these species. If other vapour species such as oxygen, water or sulfur dioxide are present, control of the mass density of vaporized sulfur becomes even more difficult.
- the present invention overcomes the aforementioned limitations by providing a mechanism to control the sulfur content of a deposited phosphor film by controlling the mass transport of sulfur vapour impinging on the deposition substrate and thus being deposited into the deposited phosphor composition.
- This control ensures that the sulfur-containing vapour molecular species caused to impinge on the deposition substrate have on average a substantially time invariant number of sulfur atoms per molecule.
- the sulfur partial pressure during the deposition process is controlled to a value commensurate with the desired sulfur content in the deposited film.
- Suitable sulfur partial pressure ranges to be used in the present invention are commensurate with that known in the art for sulfide film deposition using electron beam, thermal evaporation or sputtering techniques and further using one or more source materials.
- sulfur may be provided as hydrogen sulfide at a partial pressure range of about 1 x 10 "5 to 1 x 10 "4 torr.
- the time invariant mix of sulfur-bearing species may include sulfide molecules or clusters of sulfide molecules, molecular sulfur, atomic sulfur or hydrogen sulfide.
- the fraction of molecular sulfur species making up the mix is kept to a minimum.
- the method of the invention provides that any excess molecular sulfur species whose concentration varies with time during the deposition are condensed or absorbed and thus removed from the deposition atmosphere to prevent such species from impinging on the deposition substrate thus not be incorporated into the deposited phosphor composition.
- This is also effected by maintaining a low deposition atmosphere pressure, as discussed above, that the mean free path for sulfur-bearing vapour species is sufficiently long that there is no substantial probability of collisions between the various sulfur-bearing species in the deposition atmosphere so as to create a time varying population distribution of species containing different numbers of sulfur atoms.
- the control of the sulfur content being deposited onto the substrate is effected by the use of a material or materials that absorb or condense and thus essentially remove any excess sulfur-bearing species from the deposition atmosphere.
- a material(s) is herein referred to as a gettering or condensing material and is defined as any material known to those of skill in the art that absorb or condense sulfur species, the overall effect being removal of excess sulfur species from the deposition atmosphere and prevent it impinging on the deposition substrate.
- Such materials may include but are not limited to selective getters for sulfur species as well as cold traps or cold fingers with a temperature sufficiently low that the vapour pressure of the condensed sulfur species is substantially below the working pressure of desirable sulfur species in the deposition atmosphere.
- An example of a cold trap is a pipe through which liquid nitrogen is caused to flow at a sufficient rate and which has sufficient surface area to adequately condense the sulfur species.
- An example of a getter material for use in the method of the invention is a titanium sponge. The positioning of the gettering or condensing material is important so that the excess sulfur species are absorbed and/or condensed before they impinge on the deposition substrate. A preferred location for the gettering or condensing material is substantially adjacent to the primary source of the species, which is the one or more sulfide source material(s) used for deposition.
- one or more additional agents may be used to remove sulfur dioxide, molecular oxygen and/or water originating from impurities in the sulfide sources such as metal sulfates or sulfites to keep the oxygen partial pressure in the deposition chamber within acceptable bounds.
- such an agent minimizes excess sulfur bearing species that may also contain oxygen such as for example SO 2 that may be volatized from the source material(s) used.
- SO 2 may be condensed using a liquid nitrogen cold trap.
- the acceptable pressure range is determined by routine experimentation by measuring the oxygen or water content of the deposited films relative to the desired content.
- the oxygen partial pressure is kept to a value lower than the base pressure for the deposition environment prior to deposition and prior to introduction of sulfur-bearing species. It should be ensured that the sulfur-bearing species do not contain oxygen.
- a water absorbent material such as molecular sieve, as known to those of skill in the art, can be used to remove water originating from impurities in the sulfide sources or from the walls of the deposition chamber. Such water absorbent materials are but chosen so that the residual water vapour pressure above the materials is adequately low as is understood by one of skill in the art.
- the method of the invention is used to control any excess sulfur- bearing species from impinging on the deposition substrate and thus into the phosphor material being deposited. However, it is still important to ensure that the deposited phosphor composition have sufficient sulfur therein in order to possess desirable luminance and luminous efficiency.
- a suitable source of sulfur in addition to the one or more sources comprising sulfide compounds for the purpose of ensuring that the deposited film is not deficient in sulfur is hydrogen sulfide. It is preferable that the hydrogen sulfide be cracked into atomic sulfur and hydrogen prior to admission into the deposition chamber so that atomic hydrogen is not present at the surface of the phosphor film as it is being deposited.
- Atomic hydrogen is highly reactive and mobile within crystal lattices, and may adversely affect the properties of the phosphor film and the underlying substrate structure.
- the injection rate for the hydrogen sulfide may be varied to adjust the sulfur content of the phosphor film to the desired value.
- the deposition temperature, deposition pressure, deposition rate and the composition of the deposition atmosphere can be adjusted to achieve the desired phosphor film composition, as known in the art.
- FIG. 2 shows a cross-section of a thick film dielectric electroluminescent device incorporating a sulfur-bearing phosphor.
- the device generally indicated by 10, has a substrate 12 on which is located row electrode 14.
- Thick film dielectric 16 has thin film dielectric 18 thereon.
- Thin film dielectric 18 is shown with three pixel columns, referred to as 20, 22 and 24, located thereon.
- the pixel columns contain sulfur bearing phosphors to provide the three basic colours viz. red, green and blue.
- Pixel column 20 has red phosphor 26 located in contact with thin film dielectric 18.
- Another thin film dielectric 28 is located on red phosphor 26, and column electrode 30 is located on thin film dielectric 28.
- pixel column 22 has green phosphor 32 on thin film dielectric 18, with the thin film dielectric 34 and column electrode 36 thereon.
- Pixel column 24 has blue phosphor 38 on thin film dielectric 18, with thin film dielectric 40 and column electrode 42 thereon.
- the method provides for the deposition of thin film phosphors comprising rare earth activated thioaluminates achieving high energy efficiency and high luminosity.
- the method can be used to deposit phosphors in the form of ternary or quaternary compounds keeping the ratio of the three or four, or more, constituent elements controlled to close tolerances to achieve optimum phosphor performance and to reduce the likelihood that the phosphor material may form into more than one crystal phase.
- the method is such to ensure that the concentration of impurities such as oxygen are kept to a minimum.
- the method of the invention is applicable to thin film phosphors with the range of phosphor compositions listed above incorporated into a thick film dielectric electroluminescent display as taught for example in Applicant's U.S. Patent 5,432,015 (the disclosure of which is incorporated herein in its entirety). It is understood that the various source materials for these compositions include one or more sulfide-containing materials.
- the phosphor compositions may be activated with a variety of dopants, especially europium and cerium.
- Stoichiometry of the deposited phosphor compositions may be controlled as disclosed in the Applicant's PCT CA01/01823 (the disclosure of which is incorporated herein by reference in its entirety). Control of stoichiometry during deposition is effected using two or more deposition source materials with different chemical compositions, together with a deposition rate measuring system for the source materials that measures the deposition rate for the sources independently from each other and a feedback system that controls the relative deposition rates commensurate with the measured rates.
- a thick film dielectric electroluminescent device was constructed incorporating thin film phosphor layers of barium thioaluminate activated with europium.
- the thick film substrate was a 5 cm by 5 cm alumina substrate having a thickness of 0.1 cm.
- Onto this substrate was deposited a gold electrode, followed with a thick film high dielectric constant dielectric layer in accordance with the methods exemplified in Applicant's co-pending international application PCT CA00/00561 filed May 12, 2000 (the disclosure of which is incorporated herein in its entirety).
- a 100-200 nm thin film dielectric layer of barium titanate was deposited on top of the thick film dielectric layer using the sol gel technique described in Applicant's co-pending U.S. Patent Application 09/761 ,971 filed January 17, 2001 (the entirety of which is incorporated herein by reference).
- a 600 nm thick barium magnesium thioaluminate phosphor film activated with about 3 atomic percent of europium with respect to barium was electron beam deposited onto the barium titanate layer according to the methods of Applicant's International Patent Application PCT CA01/01823 (the disclosure of which is incorporated herein in its entirety).
- the mix of sulfur species was not controlled during the deposition of the phosphor.
- the deposited phosphor was annealed under nitrogen in a belt furnace with a peak temperature of 700°C to 750°C for about one minute.
- a 50 nanometer thick aluminum nitride layer was then sputter-deposited onto the phosphor layer followed by deposition of an indium tin oxide upper conductor film according to the methods of Applicant's International Patent Application PCT CA00/00561 (the disclosure of which is incorporated herein in its entirety).
- the completed device was annealed in air at about 550°C and then annealed under nitrogen at about 550°C following deposition of the indium tin oxide and prior to testing.
- the device was tested by applying a 240 Hz alternating polarity square wave voltage waveform with a pulse width of 30 nanoseconds and an amplitude of 60 volts about the optical threshold voltage.
- Figure 3 shows the luminance as a function of applied voltage for the device. As can be seen from the data the luminance at 60 volts above the threshold voltage of 160 volts was about 65 candelas per square meter.
- a second phosphor film was deposited on a silicon wafer adjacent to the test device during the same deposition run and analyzed by x-ray diffraction (XRD) analysis.
- the second phosphor film had orthorhombic sulfur present as well as barium thioaluminate phases, indicating that excess sulfur was present in or on the film. This indicated that a greater quantity of sulfur was volatilized from the sulfide sources than that expected if the volatilized species were sulfide molecules or clusters thereof .
- Some of the extra sulfur was in the form of elemental sulfur that condensed on the walls of the deposition chamber and re-evaporated due to fluctuations in the wall temperature to impinge and condense on the deposition substrate along with the deposited phosphor film.
- FIG. 1 A device similar to that of example 1 was constructed but incorporating a cold trap adjacent to the barium sulfide source used for phosphor deposition.
- the cold trap was used to condense excess sulfur, oxygen and other volatile impurities.
- Figure 3 shows the luminance as a function of applied voltage for this device. As can be seen from the data the luminance at 60 volts above the threshold voltage of 160 volts was about 240 candelas per square meter, more than three times that of the device of example 1.
- a phosphor film deposited on a silicon wafer adjacent to the test sample was analyzed using XRD. It showed no sign of elemental sulfur. This example shows the benefits of the invention in preventing excess sulfur incorporation into the film and the attendant improvement realized in the device performance.
- a thick film dielectric electroluminescent display of the type generally shown in Figure 2 was fabricated.
- the thick film dielectric electroluminescent display was constructed on a 5 cm by 5 cm by 1.8 mm thick PD200 glass substrate obtained from Asahi Glass Co Ltd of Tokyo, Japan onto which was deposited a 200 nm thick barrier layer of aluminum nitride.
- a 0.8 ⁇ m thick gold electrode film was formed on the coated substrate by printing and firing a TR1207 gold-containing paste from Tanaka Kikinzoku International of Tokyo, Japan.
- a composite thick film dielectric layer was fabricated on the gold lower electrode using the general methods described in Applicant's co-pending U.S. Patent Application 60/341 ,790 filed December 21 , 2002 (the entirety of which is incorporated herein by reference) but with specific process modifications described herein below.
- the composite thick film dielectric layer was formed on the alumina coated glass using the following process.
- a thick film paste for this structure was prepared using a mixture of PMN powders, one with a particle size distribution having a d50 of 0.45 micrometers and a d90 of 0.63 and the other with a particle size distribution having a d50 of 0.36 micrometers and a d90 of 0.63.
- Each powder was prepared by grinding in a planetary ball mill for 2 hours and 16 hours, respectively. The powders were then mixed in a weight ratio of 1.14:1 and used to formulate the thick film paste.
- a first thick film layer having a thickness of about 5 ⁇ m was printed on the substrate, densified by compression and fired in the range of about 700°C to about 720° for about 18 minutes.
- the second step in forming the composite thick film dielectric layer was to deposit and fire, at about 700°C for about 7 minutes, a 0.5 ⁇ m thick layer of PZT.
- This deposition was done using the MOD process described in Applicant's U.S. Patent Application 09/540,288 filed March 31 , 2000 (the entirety of which is incorporated herein by reference), with the MOD solution adjusted to have a viscosity in the range of about 9 to about 15 centipoise.
- the third step in forming the composite thick film dielectric layer was to deposit, density and fire a second PMN dielectric layer, also of a thickness of about 5 ⁇ m.
- the fourth step was to form a 1.6 ⁇ m thick film dielectric layer of PZT using the same process as for the second step.
- the fifth step was to complete the composite dielectric layer by applying a fifth layer of PZT, about 0.5 ⁇ m thick, using the same process that was used to increase the thickness of the topmost PZT layer to about 1 ⁇ m.
- the final step was to deposit a 150 nanometer thick barium titanate layer on the thick dielectric layer, as described in Applicant's co-pending U.S. Patent Application 09/761 ,971 filed January 17, 2001 (the entirety of which is incorporated herein by reference).
- a 0.5 ⁇ m thick europium activated barium thioalumnate phosphor layer was electron-beam deposited on the barium titanate layer using the method described in example 2.
- the electron beam deposition system had four e-beam sources, two with europium doped barium sulfide and the remaining two with aluminum sulfide as the source material.
- the deposition system was arranged with the electron guns and sources arranged in the lower part of the chamber as indicated in the plan (top) view of the chamber shown in Figure 4.
- a pumping port was connected to one side of the chamber and a hydrogen sulfide sparger was located on the opposite side of the chamber.
- a tube through which liquid nitrogen flowed during the deposition process was located on the same side of the chamber as the pumping port to act as a cryogenic condensing surface.
- the condensing surface was positioned above the sources, but below the pumping port.
- a 50 nm thick upper dielectric layer of aluminum nitride and a transparent electrode comprising indium tin oxide was deposited on the phosphor layer as for example 1 and the display was sealed to protect it from the ambient environment.
- the completed thick film dielectric electroluminescent display was tested using the test procedure defined in example 1.
- the luminance versus voltage data for this device is shown in Figure 5.
- the luminance at 60 volts above the threshold voltage was about 600 candelas per square meter with a high degree of uniformity, substantially greater than for similar devices with phosphors deposited without using a cryogenic condenser.
- a device was constructed similar to that of Example 3, however, the phosphor layer was deposited using only the two sources closest to the condensing surface.
- the phosphor also contained some magnesium, with a magnesium to barium atomic ratio of about 0.02 to 0.04.
- the luminance versus voltage data for this device is shown in Figure 6.
- the luminance at 60 volts above the threshold voltage of 180 volts was about 830 candelas per square meter.
- the condensation of sulfur and other impuritiy species was more efficient than for the device of example 3, since the condensing surface was close to all of the e- beam sources, not just half of them as in example 3. Without being bound by theory, it appears that the improved luminance of this device is a result of the more efficient condensation of undesirable species.
- a device was constructed similar to that of example 4, however, the phosphor layer was deposited using the two sources furthest from the condensing surface, resulting in less efficient condensation of undesirable species.
- the luminance data for this device is shown in Figure 6.
- the luminance at 60 volts above the threshold voltage of 150 volts was about 380 candelas per square meter, less than half that of example 4 with efficient condensation and about 65% that of the device of example 3 fabricated using an intermediate condensation efficiency. This result further supports the correlation between the condensing efficiency and the device luminance.
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Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
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JP2006501395A JP2006516663A (en) | 2003-01-30 | 2004-01-26 | Sulfur species controlled deposition method |
DE602004004076T DE602004004076T2 (en) | 2003-01-30 | 2004-01-26 | PROCESS FOR THE TAXED DEPOSITION OF SULFUR SPECIES |
CA002512395A CA2512395A1 (en) | 2003-01-30 | 2004-01-26 | Controlled sulfur species deposition process |
EP04705034A EP1587894B1 (en) | 2003-01-30 | 2004-01-26 | Controlled sulfur species deposition process |
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US44354003P | 2003-01-30 | 2003-01-30 | |
US60/443,540 | 2003-01-30 |
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WO2004067676A1 true WO2004067676A1 (en) | 2004-08-12 |
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PCT/CA2004/000097 WO2004067676A1 (en) | 2003-01-30 | 2004-01-26 | Controlled sulfur species deposition process |
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US (1) | US7811634B2 (en) |
EP (1) | EP1587894B1 (en) |
JP (1) | JP2006516663A (en) |
KR (1) | KR20050110623A (en) |
CN (1) | CN100360637C (en) |
AT (1) | ATE350429T1 (en) |
CA (1) | CA2512395A1 (en) |
DE (1) | DE602004004076T2 (en) |
TW (1) | TW200420740A (en) |
WO (1) | WO2004067676A1 (en) |
Cited By (1)
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US8193705B2 (en) | 2005-11-02 | 2012-06-05 | Ifire Ip Corporation | Laminated conformal seal for electroluminescent displays |
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US8057856B2 (en) * | 2004-03-15 | 2011-11-15 | Ifire Ip Corporation | Method for gettering oxygen and water during vacuum deposition of sulfide films |
EP2360289A1 (en) * | 2010-02-23 | 2011-08-24 | Saint-Gobain Glass France | Device and method for deposing a layer composed of at least two components on a substrate |
GB2493022B (en) * | 2011-07-21 | 2014-04-23 | Ilika Technologies Ltd | Vapour deposition process for the preparation of a phosphate compound |
EP3715499A1 (en) * | 2019-03-29 | 2020-09-30 | Picosun Oy | Substrate coating |
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WO2002051960A1 (en) * | 2000-12-22 | 2002-07-04 | Ifire Technology Inc. | Multiple source deposition process |
WO2002097155A1 (en) * | 2001-05-29 | 2002-12-05 | Ifire Technology Inc. | Single source sputtering of thioaluminate phosphor films |
EP1279718A2 (en) * | 2001-07-27 | 2003-01-29 | TDK Corporation | EL panel |
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AUPM967194A0 (en) * | 1994-11-25 | 1994-12-22 | University Of South Australia | Surface modification of kaolinite |
US5725801A (en) | 1995-07-05 | 1998-03-10 | Adrian H. Kitai | Doped amorphous and crystalline gallium oxides, alkaline earth gallates and doped zinc germanate phosphors as electroluminescent materials |
US5788882A (en) | 1996-07-03 | 1998-08-04 | Adrian H. Kitai | Doped amorphous and crystalline alkaline earth gallates as electroluminescent materials |
US6153123A (en) | 1997-02-24 | 2000-11-28 | Superior Micropowders, Llc | Sulfur-containing phosphor powders, methods for making phosphor powders and devices incorporating same |
US6241477B1 (en) * | 1999-08-25 | 2001-06-05 | Applied Materials, Inc. | In-situ getter in process cavity of processing chamber |
TW576873B (en) * | 2000-04-14 | 2004-02-21 | Asm Int | Method of growing a thin film onto a substrate |
US6583434B2 (en) | 2000-04-26 | 2003-06-24 | Agfa-Gevaert | System for digital radiography and dosimetry |
US20020122895A1 (en) | 2000-09-14 | 2002-09-05 | Cheong Dan Daeweon | Magnesium barium thioaluminate and related phosphor materials |
KR100731033B1 (en) | 2000-12-27 | 2007-06-22 | 엘지.필립스 엘시디 주식회사 | Electro luminescence device and method for manufacturing the same |
KR100685917B1 (en) | 2000-12-27 | 2007-02-22 | 엘지.필립스 엘시디 주식회사 | Electro luminescence device and method for manufacturing the same |
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2004
- 2004-01-20 TW TW093101602A patent/TW200420740A/en unknown
- 2004-01-26 JP JP2006501395A patent/JP2006516663A/en not_active Withdrawn
- 2004-01-26 AT AT04705034T patent/ATE350429T1/en not_active IP Right Cessation
- 2004-01-26 EP EP04705034A patent/EP1587894B1/en not_active Expired - Lifetime
- 2004-01-26 WO PCT/CA2004/000097 patent/WO2004067676A1/en active IP Right Grant
- 2004-01-26 DE DE602004004076T patent/DE602004004076T2/en not_active Expired - Fee Related
- 2004-01-26 KR KR1020057013974A patent/KR20050110623A/en not_active Application Discontinuation
- 2004-01-26 CN CNB2004800031324A patent/CN100360637C/en not_active Expired - Fee Related
- 2004-01-26 CA CA002512395A patent/CA2512395A1/en not_active Abandoned
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WO2002051960A1 (en) * | 2000-12-22 | 2002-07-04 | Ifire Technology Inc. | Multiple source deposition process |
WO2002097155A1 (en) * | 2001-05-29 | 2002-12-05 | Ifire Technology Inc. | Single source sputtering of thioaluminate phosphor films |
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US8193705B2 (en) | 2005-11-02 | 2012-06-05 | Ifire Ip Corporation | Laminated conformal seal for electroluminescent displays |
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CN1745158A (en) | 2006-03-08 |
US20050042376A1 (en) | 2005-02-24 |
KR20050110623A (en) | 2005-11-23 |
ATE350429T1 (en) | 2007-01-15 |
EP1587894B1 (en) | 2007-01-03 |
JP2006516663A (en) | 2006-07-06 |
DE602004004076T2 (en) | 2007-11-15 |
CA2512395A1 (en) | 2004-08-12 |
EP1587894A1 (en) | 2005-10-26 |
US7811634B2 (en) | 2010-10-12 |
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DE602004004076D1 (en) | 2007-02-15 |
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