KR20000069815A - Surface electron display device and fabrication process - Google Patents

Abstract

Devices useful as display elements have an electron emitter and an anode that accepts electrons emitted from the emitter. The anode has a surface portion with a different resistivity, providing an electron sink portion at the surface portion of the lowest resistivity. Preferred embodiments have a positive electrode formed by a process having side-emitting electron emitters and providing various resistive positive electrode sites including electron sink sites. The electron sink site is positioned at a position spaced laterally from the emitter tip of the device's electron emitter. In a particularly preferred manufacturing process, the anode forms the hole by depositing the base layer, precipitating and patterning the etch-interlayer with holes to form the electron-sink region, and etching the layer overlying to the etch-interlayer. And heating the base layer and the etch-stop layer to form an anode surface comprising both the electron-sink site and the cathodic phosphor for luminescence. This manufacturing process makes it possible to assemble a plurality of display element devices to produce a flat panel display.

Description

SURFACE ELECTRON DISPLAY DEVICE AND FABRICATION PROCESS

Numerous field emission device structures have been developed for electronic circuits, including diodes, tripolar vacuum tubes and quadrupole vacuum tubes. Part of the field emission device is used for display. Each pixel cell in such a display uses one or more field emission devices. Field emission displays have been considered an alternative to flat-panel liquid crystal displays due to their low manufacturing cost and simplicity, lower power consumption, higher brightness and improved viewing angle range. There is a continuing need for improved device cell structures and flattening processes for flat panel displays.

Term description

As used herein, the term "side" refers to a direction parallel to the substrate on which the electronic device is formed. "Side-emitting device" thus refers to a field-emitting device formed on a substrate such that the anode is spaced apart from the field emitter at least along a direction parallel to the substrate. Similarly, "side emitters" are field emitters made parallel to the substrate of the side device, with the emission of electrons towards the anode occurring parallel to the substrate. Examples of such side emitters formed from thin films are known in the art. "Electron sink" refers to an area on the surface where electrons tend to flow to the surface. This electron sink area is detailed below.

Related technology

Many field-emitting device structures are generally Spindt type, as disclosed in US Pat. No. 3,755,704. The following U.S. patents disclose various field release devices having side-sector emitters or methods of making the same: 5,233,263, 5,308,439 (Cronin); 5,528,099 (Xie); 5,616,061, 5,618,216, 5,628,663, 5,630,741, 5,644,188, 5,644,190, 5,647,998, 5,666,019, 5,669,802 (Potter).

U.S. Patent 5,543,684 (Kumar) discloses a long emission cathode comprising a substrate and a conductive layer disposed adjacent to the substrate. An electrically resistant pillar is disposed adjacent the conductive layer, which pillar is spaced from the substrate and has a plane parallel to the substrate. A diamond layer is disposed adjacent to the resistive pillar surface.

U.S. Patent 5,548,185 (Kumar) discloses a flat panel display comprising a plurality of light emitting anodes and long-emitting cathodes, each cathode having a plurality of electron emission sites and a space between the anode and the cathode to control the emission from the cathode to the anode. And a low work function material layer having a relatively flat electron emitting surface comprising a located grid assembly. The grid assembly includes a conductive layer deposited over a gap between the cathodes between the plurality of anodes and the cathode, the conductive layer having a hole therein and a cathode of the same size as the hole is in line with the hole.

U.S. Patent 5,659,224 (Kumar) discloses a cold cathode display device comprising a cathode having a conductive layer and a low efficiency work function material layer on the conductive layer, wherein the low efficiency work function material layers have a plurality of localities that may have discontinuous electrical properties with each other. It has an emitting surface including an electron emitting site. The emitting surface can be relatively flat. US Pat. No. 5,558,554 (Fin klea) discloses a method for manufacturing a long release device anode having a plurality of grooves for use in a flat long release panel type display.

U.S. Patent 5,449,970 (Kumar) discloses a long-emission matrix addressing diode flat panel display utilizing a diode (bipolar) pixel structure. This flat panel display includes a cathode assembly having a plurality of cathodes. Each negative electrode includes a negative electrode conductive material layer and a low efficiency work function material layer deposited on the negative electrode conductive material. This flat panel display includes an anode assembly having a plurality of anodes, each anode including a cathode conductive material layer and a cathode light emitting material layer deposited thereon. The anode assembly is located near the cathode assembly to receive the charged particles emitted from the cathode assembly, and the cathode light emitting material emits light in response to the emission of the charged particles. The flat panel display of U. S. Patent 5,449, 970 can also selectively change the long emission between a plurality of light emitting anodes and long emitting cathodes to perform the addressable gray-scale action of the flat panel display.

The problem to be solved by the present invention

In many of the long-emitting display cells available in the art, light emission from cathodic phosphors occurs in a narrow phosphor area near the electron emission tip, which narrow light emission area can be used from a wide range of viewing angles. It may not be completely visible to you. There is a need to improve the effective " fill factor ", i.e., the percentage of display cell area in which light emission occurs, for improved brightness and viewing angle range.

Objects and advantages of the present invention

An object of the present invention is a flat panel display comprising a plurality of display cells having improved brightness and fill factor. Therefore, a display cell comprising an anode having a non-uniform specific resistance is an object of the present invention. In particular, it is an object of the present invention to provide an anode for a long-emitting device that has a relatively low resistivity region compared to the rest of the anode to provide an electron sink region. An anode formed with a phosphor surface is also an object of the present invention. It is an object of the present invention for the anode to be formed integrally with the anode surface and spaced laterally away from the emitting tip of the device electron emitter. Yet another object is a method of manufacturing an improved display device structure. It is also an object of the present invention to simultaneously assemble a plurality of individual display devices in an arrangement to form a flat panel display.

summary

Devices useful as display elements have an electron emitter and an anode that accepts electrons emitted from the emitter. The anode has a surface portion with a different resistivity, providing an electron sink portion at the surface portion of the lowest resistivity. Preferred embodiments have a positive electrode formed by a process having side-emitting electron emitters and providing various resistive positive electrode sites including electron sink sites. The electron sink site is located at a position spaced laterally from the emitting tip of the device's electron emitter. In a particularly preferred manufacturing process, the anode forms a hole by precipitating the base layer, precipitating and patterning the etch-interlayer with holes, forming an electron-sink region, and etching the layer overlying to the etch-interlayer. And heating the base layer and the etch-stop layer to form an anode surface comprising both the electron-sink portion and the cathodic phosphor for luminescence. This manufacturing process makes it possible to assemble a plurality of display element devices to produce a flat panel display.

Related applications

This application is directed to Michael D. potter, "Surface Electronic Display (SED) Device" (60 / 037,787) and "Method of Manufacturing Surface Electronic Display (SED) Device," filed on December 30, 1996, with the U.S. Patent Office. And "Surface Electronic Display Device" (08/964483) and "Method of Manufacturing Surface Electronic Display Device" (08/964987) filed Nov. 5, 1997.

Technical Field

The present invention relates to a surface-electronic display device comprising a field-emitting device and a method of manufacturing the same, in particular an anode having an electronic sink manufactured by a special process.

1 is a cross-sectional view of a long release device made in accordance with the present invention.

2 is a cross-sectional view of a long emission device showing an electron path.

3 is a flow chart showing the long-emitting device manufacturing process of FIG.

4A-4G are cross-sectional views showing the results of the long release device fabrication steps.

5 is a cross-sectional view of another long release device made in accordance with the present invention.

* Code Description

10 ... long-emitting device 20 ... substrate

30 ... composite anode 35 ... base layer

40 ... Chapter Ejector 50 ... Tips

55 ... hole 60 ... insulation layer

70 ... phosphor area 80 ... electron sink area

90 ... insulation layer 100 ... electron path

110,120 ... electrode layer 130 ... insulation layer

In the surface electronic display device and its manufacturing method, the manufacturing step is indicated by " S "

1 is a cross-sectional view of a long release device 10 made in accordance with the present invention. This device has a substrate 20. Compound anode 30 accepts electrons emitted from field emitter 40 when a suitable bias voltage is applied to the anode and field emitter. The field emitter 40 has a very sharp tip 50 from which is emitted according to the Fowler-Nordheim electron tunneling phenomenon when an electric field with moderately high electrons is generated at the tip 50. Hole 55 extends from at least sidearm emitter 40 to composite anode 30. The composite anode 30 extends along the top surface of the composite anode 30 and the base layer 35 on the upper surface of the substrate 20 and is a phosphor site defining a degree of low-resistance electron-sink region 80. And 70. The electron-sink portion 80 has a very small area compared to that of the phosphor portion and the relative proportions of the portions 70 and 80 in the figure are not drawn to scale. The substrate 20 is particularly conductive to provide electrical contacts to the anode. If an insulating substrate is used, an additional conductive layer (not shown) may be disposed between the insulating substrate and the base layer 35 and buried anode contacts (not shown) to apply an anode voltage application and to carry current to an external circuit. Can be patterned to provide Device structures having such buried anode contacts and methods of fabricating such structures are disclosed in US Pat. Nos. 5,644,188 and 5,630,741. 1 shows two sidefield emitters 40 and two emitter tips 50, wherein a double-emitter device can be manufactured by the same process without further processing. However, the second emitter may be omitted since it is not necessary for device operation. If the second emitter is omitted, the electronic sink area 80 may be positioned adjacent to the edge of the hole 55 farthest from the long emitter tip 50. Thus, when the right long emitter of FIG. 1 is omitted, the electronic sink region 80 can be positioned adjacent to the right edge of the hole 55 farthest from the left emitter tip (single-emitter device showing this arrangement). The structure is shown in FIG. 5).

The side field emitter 40 is separated from the anode 30 by an insulating layer 60 supporting the side field emitter at a predetermined distance above the plane of the anode top surface. A second insulating layer 90 may be disposed on top of the field emitter 40. Omitting the second insulating layer 90 in principle improves the viewing angle of the display, but in fact the viewing angle improvement is very minor because a thin insulating layer 90 is used.

The device structure shown in FIG. 1 has unexpected results: electrons emitted from the long emitter tip 50 do not move directly to the anode near the emission tip 50. In this surface electronic device electrons move along the surface until they reach the low-resistance electron-sink region 80, where electrons enter the bulk material of the anode base layer 35. The effect is a bright pixel with a large effective fill factor, with cathodic luminescence occurring not only near the emitter tip 50 but across the entire area of the phosphor site 70 at the bottom of the hole 55. Means are provided for applying a suitable electrical bias to effect electromagnetic field emission from the emission tip 50 to the composite anode 30. 2 is a cross-sectional view of a long emission device showing in dashed lines a typical electron path 100 in a device made in accordance with the present invention. While these electron paths contribute to the improvement of device performance of the present invention, the present invention is not limited by any particular physical phenomenon, but only by the structure or manufacturing method described in the claims.

3 is a flow chart showing the field emission device manufacturing process of FIG. 4A-4G are cross-sectional views showing the results of process steps. The process includes providing a substrate (S1), forming an anode (S2-S3, S8) having at least one electron sink site on the substrate, forming and patterning an electron emitter spaced from the anode and at least partially aligned with the anode Steps S5 and S7 include an insulating layer disposition step S4 between the anode and the emitter.

As shown in FIG. 3, the first step S1 is a step of providing a substrate 20 such as silicon. In step S2, the base layer 35 of the first material is precipitated (FIG. 4A). The first material 35 is a precursor that can be converted to a cathode phosphor or by heat treatment. Conductive or semiconducting phosphors having a resistivity value of less than 200 micro ohm-cm should be selected. In a preferred embodiment the base layer is ZnO: Zn, ie zinc oxide doped with excess zinc. In step S3, the etch-stop layer 75 is precipitated and patterned (FIG. 4B) to form a first hole 80 defining the location of the electron-sink site. The etch-stop layer 75 is a refractory metal such as Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W or combinations or alloys thereof. In a preferred embodiment the etch-stop layer comprises Ta. Precipitation and patterning can be performed simultaneously by precipitating the etch-stop material through the patterned mask. In step S4, the first insulating layer 60 is precipitated (FIG. 4C). This may be a silicon oxide layer. In step S5 a thin emitter layer 40 is precipitated (FIG. 4D) and patterned. In a preferred embodiment the emitter layer is a Mo layer about 300 angstroms thick. In step S6, the second insulating layer 90 is precipitated if necessary (FIG. 4E). The insulating layer 90 may also be a silicon oxide layer. In step S7 the second hole 55 and the first and second insulating layers 60, 90 are formed by etching through the emitter layer 40 and the etching-interruption layer 75 is left unetched. (FIG. 4F). Etching is performed using conventional directional etching, such as reactive ion etching, referred to as "trench etching" in the semiconductor literature. This step also forms a sharp discharge tip 50 on the emitter layer 40. In step S8 (FIG. 4G), the base layer 35 and the etching-interruption layer 75 are heated to become integral with the anode 30 in which the electron-sink portion 80 is located in the first hole ( 70). In a preferred embodiment, the phosphor Ta ₂ Zn ₃ O ₈ is formed by heating the ZnO: Zn base layer material and Ta etch-interlayer to a suitable temperature for a suitable time. Heating at 900 ° C. for at least one hour or at 1200 ° C. for at least ten seconds is an example of a successful heat treatment for the formation of the phosphor Ta ₂ Zn ₃ O ₈ . This completes the manufacture of the electromagnetic field emitting device.

This manufacturing process provides a plurality of display element device manufacturing methods for manufacturing flat panel displays by simultaneously performing as many display devices as necessary for the flat panel display manufacturing using the steps described above.

5 is a cross-sectional view of a field emission device having one or more control electrodes or gates 110, 120 for controlling the flow of electrons from emitter tip 50 to anode 30. Although two control electrode layers 110 and 120 are shown in FIG. 5 disposed above and below the emitter layer 40, the device can be manufactured using only one control electrode layer (one of the control electrode layers 110 and 120 may be omitted). Can be). The control electrode layers 110 and 120 are fabricated by precipitating and patterning conductive material on the insulating layers 60 and 90 and by depositing additional insulating layers, such as the insulating layer 130 required to insulate the control electrode layer from other conductive elements. do. The control electrode manufacturing step is not shown in FIGS. 3 and 4A-4G. Control electrode manufacturing processes and the required materials are disclosed in US Pat. Nos. 5,644,188 and 5,630,741. Means are provided for applying suitable electrical control signals to the control electrodes 110, 120.

The present invention provides a flat panel display comprising a plurality of display cells having improved brightness and fill factor. The present manufacturing process provides different resistive positive electrode sites. The present invention also provides a method of simultaneously manufacturing a plurality of display element devices for manufacturing flat panel displays having improved brightness and fill factor.

For example, various phosphors with various cathodic luminescent colors are possible to provide a color display in place of the phosphor materials described in embodiments of the present invention.

Claims (49)

a) electron emission emitter; And b) an electromagnetic field emitting device comprising an anode arranged to receive said electrons and comprising an electron sink site. a) electron emission emitter; And b) an anode arranged to receive said electrons and having at least first and second portions having first and second resistivity, said first resistivity being less than said second resistivity, thereby providing an electron sink region in said first portion; Electromagnetic field emitting device comprising a. The device of claim 1, wherein an anode portion adjacent to the electron sink portion has a specific resistance higher than that of the electron sink portion. The device of claim 1, wherein an anode portion adjacent to the electron sink portion has a reactance higher than that of the electron sink portion. The device of claim 1, wherein the anode comprises at least one phosphor that emits light when stimulated by the electrons. 2. The device of claim 1, wherein the anode is spaced at least laterally from the emitter to form a sideload emitting device. 3. The device of claim 2, wherein the anode is spaced at least laterally away from the emitter to form a sideload emitting device. The device of claim 2, wherein the anode comprises at least one phosphor that emits light when stimulated by the electrons. A display comprising at least one field emission device of claim 5. 6. The device of claim 5, wherein said at least one phosphor comprises at least one conductive phosphor. 6. The device of claim 5, wherein said at least one phosphor comprises at least one semiconducting phosphor. 6. The device of claim 5, wherein said at least one phosphor comprises Ta ₂ Zn ₃ O ₈ . A display comprising at least one field emission device of claim 8. 9. The device of claim 8, wherein the second portion of the anode comprises at least one phosphor. 9. The device of claim 8, wherein the first and second portions of the anode comprise at least one phosphor. 10. The device of claim 8, wherein the at least one phosphor is disposed at a second portion of the anode. The device of claim 8, wherein the at least one phosphor comprises at least one conductive phosphor. 9. The device of claim 8, wherein said at least one phosphor comprises at least one semiconducting phosphor. The device of claim 8, wherein the at least one phosphor comprises Ta ₂ Zn ₃ O ₈ . The device of claim 10, wherein the at least one conductive phosphor has a resistivity of less than 200 microohm-centimeters. 18. The device of claim 17, wherein the at least one conductive phosphor has a resistivity of less than 200 microohm-centimeters. 2. The device of claim 1, further comprising c) means for applying an electrical bias to the anode sufficient to emit electrons from the emitter. 2. The device of claim 1, further comprising: c) at least one control gate spaced from the emitter and anode and d) means for applying a control signal to the control gate to control the electron flow. 3. The device of claim 2, further comprising c) means for applying an electrical bias to the anode sufficient to emit electrons from the emitter. 3. The device of claim 2, further comprising c) at least one control gate spaced from the emitter and anode and d) means for applying a control signal to the control gate to control the electron flow. a) electron emission emitter; And b) an anode arranged to receive said electrons, The anode is spaced apart from the emitter in at least the lateral direction to form a sidefield emitting device, the anode having first and second portions having first and second resistivity, the first resistivity being the second An electromagnetic field emission device that is lower than a resistivity to provide an electron sink site, wherein at least one of the first and second sites of the anode comprises at least one phosphor that emits light when stimulated by the electrons. a) electron emission emitter; b) arranged to accept electrons in between, The anode is spaced apart from the emitter in at least the lateral direction to form a sidefield emitting device, the anode having first and second portions having first and second resistivity, the first resistivity being the second An anode comprising a cathode that is lower than a resistivity to provide an electron sink site, wherein at least one of the first and second sites of the anode comprises at least a phosphor that emits light when stimulated by the electrons; c) at least one control gate spaced from the emitter and anode; And d) means for applying a control signal to a control gate to control the electron flow. 27. The device of claim 26, wherein the at least one phosphor comprises Ta ₂ ZnO ₈ disposed on a second portion of the anode. 28. The device of claim 27, wherein the at least one phosphor comprises Ta ₂ ZnO ₈ disposed on a second portion of the anode. a) providing a substrate; b) forming an anode having at least one electron sink on said substrate; c) forming and patterning an electron emitter spaced from the anode and at least partially aligned with the anode along a direction parallel to the substrate; d) disposing an insulating layer between said anode and said emitter. a) providing a conductive substrate; b) placing a base layer on the conductive substrate; c) an etch-intermediate layer disposed on the base layer; d) patterning said etching-interruption layer to form a first hole for an electronic sink; e) disposing a first insulating layer on the etch-stop layer; f) disposing and patterning a conductive material to form an emitter layer of several hundred angstroms thick on the first insulating layer; g) a second insulating layer disposed on the emitter layer; h) etching the second hole through the emitter and the first and second insulating layers while leaving the etch-interruption layer unetched; i) heating the base material and the etch-stop layer at a suitable temperature and time to form a composite to form an anode having at least one electron sink site in the at least one first hole and to complete the field emission device manufacturing step A method of manufacturing an electromagnetic field emitting device comprising the step of 32. The method of claim 31, wherein said step of providing a conductive substrate is performed by providing a silicon substrate. 32. The method of claim 31, wherein providing a conductive substrate step a) is performed by depositing a conductive material on another substrate. 32. The method of claim 31, wherein the base material layer is disposed by precipitating a phosphor or a material that can be converted to a phosphor by heat treatment. 32. The method of claim 31 wherein the etch-stop layer is disposed by precipitating the refractory metal. 32. The method of claim 31 wherein said first insulating layer placement step e) is performed by precipitating silicon oxide. 32. The method of claim 31 wherein said second insulating layer placement step g) is performed by precipitating silicon oxide. 32. The method of claim 31, wherein said second hole etching step h) is performed by reactive ion etching. 32. The method of claim 31 wherein the step of forming said emitter layer is performed by precipitating and patterning a metal layer. 32. The method of claim 31, wherein the base layer comprises zinc plated zinc oxide (ZnO: Zn), the etch-stop layer comprises Ta, and the heating step i) forms Ta ₂ Zn ₃ O ₈ at a temperature of 900 ° C. or higher. Characterized in that it is carried out by heating for a suitable time to form. 32. The method of claim 31, wherein the composite material comprises Ta ₂ Zn ₃ O ₈ . 34. The method of claim 33, further comprising patterning the conductive material to form a patterned anode contact. 35. The method of claim 34, wherein the phosphor is zinc plated zinc oxide (ZnO: Zn). 56. The method of claim 55, wherein the refractory metal is selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W or combinations or alloys thereof. 40. The method of claim 39, wherein the metal layer is a 300 angstrom thick molybdenum layer. 41. The method of claim 40, wherein said composite material comprises Ta ₂ Zn ₃ O ₈ . a) providing a silicon substrate; b) precipitation of a first material layer comprising ZnO: Zn; c) etching-interrupted Ta layer precipitation; d) patterning said etching-interruption layer to form a first hole for an electronic sink; e) precipitation of the first insulating layer of silicon oxide; f) precipitating and patterning the Mo layer to form a 300 angstrom thick emitter layer; g) precipitation of a second insulating layer of silicon oxide; h) etching the second hole through the emitter layer and the first and second insulating layers while leaving the etch-interruption layer unetched; i) an anode having at least one electron sink site located in said first hole by heating said ZnO: Zn material and said etching-interruption layer at a temperature of 900 [deg.] C. or more for a suitable time to form Ta ₂ Zn ₃ O ₈ ; And forming the field emission device manufacturing step. 48. The method of claim 47, wherein said heating step i) comprises heating for at least 1 hour. 48. The method of claim 47, wherein said heating step i) comprises heating to a temperature of at least 1200 seconds for at least 10 seconds.