Patent Application
20090322206
1. Field of the Invention
The present invention relates to an electron-emitting device used for a flat panel display, and a method of manufacturing the electron-emitting device, an electron source including the electron-emitting device, and an image display apparatus using the electron source.
2. Description of the Related Art
A surface conduction electron-emitting device is based on the phenomenon that a conductive film formed on an insulating substrate is supplied with a current in parallel to a surface of the conductive film, to emit electrons. Fundamentally, a pair of device electrodes are formed on the substrate. The conductive film is formed so as to connect the device electrodes to each other. A minute gap is provided in the conductive film to form a pair of conductive films. An operation called “activation” is performed to deposit a pair of carbon films in the gap and on portions of the conductive films which are close to the gap. The pair of carbon films have a minute gap and each of the carbon films is connected to corresponding one of the conductive films. When a predetermined voltage is applied between the device electrodes in the electron-emitting device, electrons are emitted from the vicinity of the gap between the conductive films and the vicinity of the gap between the carbon films.
Japanese Patent Application Laid-Open No. 2000-251628 discusses a structure in which the carbon films are deposited to extend from the vicinity of the gap between the conductive films to a portion of the substrate which is located outside the vicinity of the gap.
The extending portions of the carbon films are conductive, and accordingly there is an effect that a variation in potential of a surrounding surface of the insulating substrate is reduced. However, a sufficient gap cannot be provided between the extending portions of the pair of carbon films depending on formation conditions, and hence there is a case where end sections (sections apart from the conductive films) of the extending portions are connected to each other.
When the extending portions of the carbon films are connected to each other as described above, an ineffective current (leak current) flows between the device electrodes through the extending portions, and, as a result, there is a case where electron-emitting efficiency reduces. Long time driving or vacuum atmosphere reduction tends to cause discharge break-down. Depending on a material or surface state of the substrate on which the electron-emitting device is placed, the extending portions of the carbon films are likely to vary in shape, which tends to cause variations in electron-emitting characteristics of electron-emitting devices. The electron-emitting efficiency (η) is estimated as a ratio between a device current If flowing between the pair of device electrodes included in the electron-emitting device and an electron-emitting current Ie (current reaching the anode) and expressed by “η=Ie/If”.
A display using a large number of electron-emitting devices is required to have low power consumption and high luminance and obtain an image with high uniformity. Therefore, the electron-emitting device is required to have high efficiency and stably and uniformly obtain a large electron-emitting amount.
The present invention has been made in view of the problems described above. An object of the present invention is to provide an electron-emitting device which is excellent in electron-emitting efficiency and capable of obtaining a large electron-emitting amount and stable electron-emitting characteristics. Another object of the present invention is to provide an electron source which uses the electron-emitting device and thus which is excellent in uniformity and stability and obtains a large electron-emitting amount, and an image display apparatus which uses the electron-emitting device and thus which is excellent in display characteristics.
According to a first aspect of the present invention, there is provided an electron emitting-device, comprising: a first conductive film and a second conductive film placed on a substrate having a gap therebetween; a first carbon film having one end and the other end, the one end connected to the first conductive film, and the other end interposed in the gap between the first conductive film and the second conductive film; and a second carbon film having one end and the other end, the one end connected to the second conductive film, and the other end facing the other end of the first carbon film interposing a second gap; wherein the first carbon film and the second carbon film respectively have an extending portion along a Y axis extending from the portion between the first conductive film and the second conductive film, where an X axis is a direction from the first conductive film to the second conductive film, and the Y axis is a direction parallel to the substrate surface and orthogonal to the X axis, and wherein, in the gap between the first carbon film and the second carbon film, the substrate surface has an concave portion extending between end sections of the extending portions of the carbon films.
According to a second aspect of the present invention, there is provided an electron source comprising the multiple electron emitting-devices of the present invention.
According to a third aspect of the present invention, there is provided an image display apparatus comprising the electron source of the present invention, and a light-emitting member that emits light by being subjected to the irradiation of the electron emitted from the electron source.
According to a fourth aspect of the present invention, there is provided a manufacturing method of the electron emitting-device of the present invention, comprising: forming the first conductive film and the second conductive film having the gap therebetween on the substrate including silicon oxide on the surface; forming the first carbon film connected to the first conductive film and the second carbon film connected to the second conductive film, and, at the same time, forming the concave portion in the gap between the first carbon film and the second carbon film by applying a pulse voltage between the first conductive film and the second conductive film under an atmosphere including a carbon-containing gas; and forming the extending portions on the first carbon film and the second carbon film, respectively, by applying a pulse voltage between the first conductive film and the second conductive film under an atmosphere having a higher partial pressure of the carbon-containing gas than the atmosphere.
The manufacturing method of the electron emitting-device of the present invention, further comprising as a preferred aspect, after the forming of the extending portions on the first carbon film and the second carbon film, selectively exposing, into a solution including hydrogen fluoride, the surface of the substrate positioned in the gap between the first carbon film and the second carbon film.
According to the electron-emitting device of the present invention, the carbon films have the excellent gaps even in the extending portions, and hence problems such as the generation of leak current and the discharge break-down of the electron-emitting device which are due to the defective formation of the gaps are prevented. Therefore, the electron-emitting device can stably emit electrons from the gap between the conductive films and the gaps between the carbon films. Thus, a larger electron-emitting amount and more excellent electron-emitting efficiency can be obtained as compared with a conventional electron-emitting device.
The image display apparatus using the electron-emitting device according to the present invention realizes lower power consumption and high luminance and can stably display a high-quality image.
Further features of the present invention become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, while referring to the drawings, a detailed description is given to a preferred embodiment of the present invention for an illustrative purpose. Note that the size, material, shape, relative position, etc. of components, which are described in the embodiment, are not intended to limit the scope of the present invention to given examples unless specifically mentioned.
The electron-emitting device according to the present invention includes the first conductive film 4a and the second conductive film 4b which are provided on the substrate 1 and opposed to each other through a first gap 5. One end of the first conductive film 4a is connected to the first electrode 2. One end of the second conductive film 4b is connected to the second electrode 3. The first gap 5 is provided between the other end of the first conductive film 4a and the other end of the second conductive film 4b, and the other end of the first conductive film 4a and the other end of the second conductive film 4b are opposed to each other through the first gap 5 (
A first carbon film 6a1 is connected to the first conductive film 4a. A second carbon film 6b1 is connected to the second conductive film 4b. One end of the first carbon film 6a1 covers at least a portion of the first conductive film 4a in the X axis. One end of the second carbon film 6b1 covers at least a portion of the second conductive film 4b in the X axis. The other end of the first carbon film 6a1 and the other end of the second carbon film 6b1 are opposed to each other through a second gap 7a (
The second gap 7a is located between the first conductive film 4a and the second conductive film 4b (within first gap 5). The surface of the substrate 1 has a first concave portion 9a provided in the second gap 7a (directly below second gap 7a) along the second gap 7a.
The first carbon film 6a1 is provided with first extending portions 6a2 outwardly extending from a region in which the first conductive film 4a and the second conductive film 4b are opposed to each other in the Y axis. The second carbon film 6b1 is provided with second extending portions 6b2 outwardly extending from the region in the Y axis. The first extending portions 6a2 are provided on both sides of the first carbon film 6a1 so as to sandwich the first carbon film 6a1. Similarly, the second extending portions 6b2 are provided on both sides of the second carbon film 6b1 so as to sandwich the second carbon film 6b1.
The first extending portions 6a2 are opposed to the second extending portions 6b2 with a third gap 7b therebetween (
The first extending portions 6a2 and the second extending portions 6b2 are conductive carbon films directly provided on the surface of the substrate 1 (provided on surface of substrate 1 without through first conductive film 4a and second conductive film 4b). The first extending portions 6a2 and the second extending portions 6b2 are located outside a region surrounded by the first conductive film 4a and the second conductive film 4b (that is, region defined by first gap 5). The first carbon film 6a1 and the first extending portions 6a2 are continuously provided. The second carbon film 6b1 and the second extending portions 6b2 are continuously provided. The third gap 7b and the second gap 7a are continuously provided.
For the sake of convenience, the first and second carbon films 6a1 and 6b1 are described separately from the first and second extending portions 6a2 and 6b2. However, as described above, the first and second extending portions 6a2 and 6b2 are made of carbon, and accordingly there is no clear boundary between the first and second carbon films 6a1 and 6b1 and the first and second extending portions 6a2 and 6b2. Therefore, the first and second extending portions 6a2 and 6b2 can be assumed as portions of the first and second carbon films 6a1 and 6b1. For the sake of convenience, the third gap 7b and the second gap 7a are also separately described. However, the third gap 7b and the second gap 7a are also continuously provided, and accordingly the third gap 7b can be assumed as a portion of the second gap 7a.
Thus, in the following description, the first and second carbon films 6a1 and 6b1 in the region in which the first conductive film 4a and the second conductive film 4b are opposed to each other are referred to as facing portions of the carbon films. The opposed portion 6a1 and the two extending portions 6a2 sandwiching the opposed portion 6a1 are collectively referred to as a carbon film 6a. The opposed portion 6b1 and the two extending portions 6b2 sandwiching the opposed portion 6b1 are collectively referred to as a carbon film 6b.
The greatest feature of the electron-emitting device according to the present invention is that the surface of the substrate 1 has a second concave portion 9b not only directly below the second gap 7a (within second gap 7a) but also directly below the third gap 7b (within third gap 7b) (
When the second concave portion 9b is provided as described above, electrons can be stably emitted from not only the second gap 7a but also the third gap 7b. A leak current generated between the first and second extending portions 6a2 and 6b2 can be reduced. As a result, it is possible to obtain an electron-emitting device having high electron-emitting efficiency, a large electron-emitting amount, and stable electron-emitting characteristics.
Glass (such as quartz glass, glass having reduced content of impurity such as Na, or soda lime glass), ceramic such as alumina, and silicon can be used for the substrate 1. Such a material is desirably used as a base material 10 and a passivation layer 8 is desirably provided on a surface of the base material 10 to produce the substrate 1. The passivation layer 8 is a sufficient-high-resistance layer serving as an insulator, and thus can be referred to an insulating layer.
A material of the passivation layer 8 is desirably an insulating material (sufficient-high-resistance material) which has a high heat resistance (desirably exceeding 1,000K) and suppresses the diffusion of Na ions to the first and second conductive films 4a and 4b sides. Specifically, in order to obtain excellent electron-emitting characteristics by an activation operation described later, a silicon oxide layer (typically, SiO2 layer) is desirably used. However, the material of the passivation layer 8 desirably satisfies the requirement described above, and thus is not limited to silicon oxide.
The passivation layer 8 desirably covers the entire surface of the base material 10 in a simple manner. The passivation layer 8 can also be provided only between a region of the electron-emitting device (first and second conductive films 4a and 4b, first and second carbon films 6a and 6b, and second and third gaps 7a and 7b) and the base material 10. The passivation layer 8 is desirably provided in at least a region between a group including the third gap 7b and the first and second extending portions 6a2 and 6b2 and a group including the base material 10.
The passivation layer 8 desirably has a sufficient thickness (equal to or larger than 100 nm and equal to or smaller than 1 μm in practical use) equal to or larger than a depth of the concave portion 9b formed directly below the second gap 7a (within second gap 7a). It is necessary to provide the passivation layer 8 with a sufficient length (equal to or larger than 10 μm and equal to or smaller than 100 μm in practical use) from both end portions of the first and second conductive films 4a and 4b in the Y axis.
The first and second electrodes 2 and 3 can be made of a normal conductor material. For example, the conductor material is selected as appropriate from metal such as Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu, or Pd or an alloy thereof, but is not limited thereto. An interval (electrode interval) L between the first electrode 2 and the second electrode 3, an electrode length W, and a shape of the first and second conductive films 4a and 4b are designed as appropriate in view of applied patterns. The electrode interval L can be practically set in a range of 1 μm to 100 μm, more desirably, in a range of 5 μm to 10 μm. The electrode length W can be set in a range of 1 μm to 500 μm in view of an electrode resistance value and electron-emitting characteristics. A film thickness d of the first and second electrodes 2 and 3 is set in a range of 10 nm to 5 μm.
A material of the first and second conductive films 4a and 4b is selected from: metal such as Pd, Pt, Ru, Ag, Au, Ti, In, Cu, Cr, Ni, Fe, Zn, Sn, Ta, W, or Pb; and an alloy containing those metal, for example. However, the material is not limited thereto. Taking into consideration that “energization forming operation” process described later is carried out in order to obtain satisfactory electron-emitting characteristics, in practice, it is desirable that a resistance value Rs of the conductive film 4 be in the range of from 102Ω/□ to 107Ω/□. It is to be noted that Rs is a value expressed as R=Rs(l/w) where R is resistance in the length direction of a film having the width w and the length l.
There are various methods of manufacturing the electron-emitting device according to the present invention as described above. An example of the manufacturing method is described below with reference to
(Step-1)
The base material 10 is cleaned with a cleaning solution, deionized water, and an organic solvent. Then, the passivation layer 8 containing silicon oxide as a main ingredient is laminated on the base material 10 by various known film formation processes such as a sputtering process, a sol gel application process, and a CVD process, to prepare the substrate 1 (
The passivation layer 8 may be formed into a predetermined shape by patterning on the substrate 10. When a material which does not substantially contain an alkali component, such as quartz or non-alkali glass, is used as the base material 10, the passivation layer 8 may not be necessarily provided.
(Step-2)
A material of the first and second electrodes 2 and 3 is deposited on the substrate 1 by a known film formation process such as a vacuum evaporation process or a sputtering process. After that, the first electrode 2 and the second electrode 3 are formed on the substrate 1 by, for example, a photolithography technique (
(Step-3)
A conductive film 4 for connecting the first electrode 2 and the second electrode 3 to each other is formed on the substrate 1 on which the first and second electrodes 2 and 3 are provided (
(Step-4)
Then, the first gap 5 is formed in the conductive film 4. An example of an operation called an “energization forming operation” is described below.
Specifically, when a voltage is applied between the first and second electrodes 2 and 3, the first gap 5 can be provided in a portion of the conductive film 4. In other words, as a result, the first and second conductive films 4a and 4b separated from each other by the first gap 5 can be formed as a pair (
As described above, the first and second conductive films 4a and 4b separated from each other by the first gap 5 are formed as a pair by the energization forming operation. Even in a case of a known method which does not include energization, such as electron-beam (EB) lithography, the first and second conductive films 4a and 4b separated from each other by the first gap 5 can be provided as a pair on the substrate 1. Therefore, Steps 3 and 4 can be collectively referred to as a step of providing the first and second conductive films 4a and 4b as a pair on the substrate 1.
The energization forming operation and subsequent electrical operations can be performed in, for example, a vacuum processing apparatus as illustrated in
In
(Step-5)
Next, the facing portions 6a1 and 6b1 of the pair of carbon films which are separated from each other by the second gap 7a are provided on the first and second conductive films 4a and 4b and a surface of the substrate 1 which is located in the first gap 5 (
The facing portions 6a1 and 6b1 of the carbon films can be formed by, for example, a known activation operation. Specifically, when a pulse voltage is applied between the first conductive film 4a and the second conductive film 4b under an atmosphere including a carbon-containing gas, the carbon films can be deposited on the first and second conductive films 4a and 4b and in the first gap 5.
As the carbon-containing gas, for example, an organic substance gas can be used. As the organic substance, it is possible to provide aliphatic hydrocarbon such as alkane, alkene, or alkyne, aromatic hydrocarbon, alcohol, aldehyde, ketone, amine, organic acid such as phenol, carboxylic acid, or sulfonic acid. More specifically, it is possible to use saturated hydrocarbon expressed by CnH2n+2, such as methane, ethane, or propane, unsaturated hydrocarbon expressed by a composition formula of CnH2n or the like, such as ethylene or propylene. It is also possible to use benzene, toluene, methanol, ethanol, formaldehyde, acetaldehyde, acetone, methyl ethyl ketone, methylamine, ethylamine, phenol, formic acid, acetic acid, propionic acid, or the like. In particular, tolunitrile is preferably used.
When the surface of the substrate 1 which is located in the second gap 7a contains silicon oxide, the first concave portion 9a can be formed in the surface of the substrate 1 by the activation operation (
Note that the facing portions 6a1 and 6b1 of the carbon films can be formed by selectively irradiating a predetermined region on the substrate 1 with an electron beam in the carbon-containing gas. Therefore, the method of forming the facing portions 6a1 and 6b1 of the pair of the carbon films which are separated from each other by the second gap 7a is not limited to the activation operation.
(Step-6)
Next, the first and second extending portions 6a2 and 6b2 of the carbon films are provided. In order to provide the first and second extending portions 6a2 and 6b2, for example, after the activation operation is completed, a pulse voltage is repeatedly applied under an atmosphere in which a carbon-containing gas partial pressure is higher than the carbon-containing gas partial pressure for the activation operation. The first and second extending portions 6a2 and 6b2 can be provided by selectively irradiating, with an electron beam, a predetermined region in which the first and second extending portions 6a2 and 6b2 are to be provided, under the atmosphere including the carbon-containing gas.
Steps 5 and 6 are separately set. However, Steps 5 and 6 can be successively performed. In such a case, Steps 5 and 6 can be assumed as a single step.
(Step-7)
Next, the first and second concave portions 9a and 9b each having a sufficient width and depth are formed in a surface portion of the substrate 1 which is located in the second gap 7a (directly below second gap 7a) and in a surface portion of the substrate 1 which is located in the third gap 7b (directly below third gap 7b).
When the first concave portion 9a is previously provided by the activation operation in Step-5, at least the second concave portion 9b may be desirably formed in Step-7. When the first concave portion 9a previously provided in Step-5 does not have an insufficient size, the size of the first concave portion 9a can be increased in Step-7.
When the third gap 7b is not sufficiently formed in Step-6 and thus the first extending portions 6a2 are connected to the second extending portions 6b2 in the extending portions (particularly, end sections of extending portions), the degree of electrical connection between the extending portions can be reduced in Step-7. Typically, the third gap 7b is extended to the end sections of the extending portions or a width of the third gap 7b in the extending portions is widened.
According to Step-7, for example, when the surface portion of the substrate 1 which is located in the second gap 7a and the surface portion of the substrate 1 which is located in the third gap 7b are selectively exposed to an aqueous solution containing hydrogen fluoride, the first and second concave portions 9a and 9b can be formed by etching.
With respect to the structures of the first and second concave portions 9a and 9b, a practical depth is desirably equal to or larger than 30 nm and equal to or smaller than 100 nm and a practical width is desirably equal to or larger than 5 nm and equal to or smaller than 20 nm. For example, a practical concentration of the aqueous solution containing hydrogen fluoride, which is used in Step-7 is desirably equal to or larger than 0.1 weight % and equal to or smaller than 10 weight %. When the first and second concave portions 9a and 9b are formed, however, the concentration is not limited to the range described above. The aqueous solution containing hydrogen fluoride includes a buffer solution containing hydrogen fluoride. In order to easily form the first and second concave portions 9a and 9b by such wet etching, a porous silica film (not shown) is desirably formed in advance on a portion of the passivation layer 8 which is located directly under a region in which at least the third gap 7b is to be formed. In Step-7, the wet etching using hydrogen fluoride is used as an example of etching. However, various etching methods including dry etching can be used as appropriate.
According to Step-7, the first and second concave portions 9a and 9b each having a predetermined width and depth can be formed by control. As a result, electrons can be stably emitted from the first and second extending portions 6a2 and 6b2. A current component leaked through the first extending portions 6a2 and the second extending portions 6b2 can be reduced, and accordingly an increase in electron-emitting amount, stable electron emission, and the improvement of electron-emitting efficiency can be achieved. The shapes of the first and second concave portions 9a and 9b can be controlled, and accordingly the uniformity of electron-emitting characteristics can be improved in a case where multiple electron-emitting devices are formed.
(Step-8)
The electron-emitting device obtained through Steps 1 to 7 described above is desirably subjected to a stabilization step.
Step-8 is a step of removing unnecessary organic substances from the electron-emitting device or a surface portion of the substrate 1 which is located close to the electron-emitting device under an atmosphere with a high degree of vacuum (degree of vacuum higher than degree of vacuum during activation process in case where activation process is performed). With respect to the degree of vacuum, an organic substance partial pressure is desirably equal to or smaller than 10−6 Pa, and more desirably equal to or smaller than 10−8 Pa. A total pressure is desirably minimized. A practical total pressure is desirably equal to or smaller than 10−5 Pa, and more desirably equal to or smaller than 10−6 Pa.
The electron-emitting device according to the present invention can be formed through the steps described above.
An atmosphere during the operation of the electron-emitting device according to the present invention is desirably maintained to the atmosphere when the stabilization step is completed. However, when organic substances are sufficiently removed, sufficiently stable characteristics can be maintained even in a case of a slight increase in pressure. When such a vacuum atmosphere is employed, carbon or a carbon compound can be suppressed from being newly deposited on the electron-emitting device or the surface portion of the substrate 1 which is located close to the electron-emitting device. As a result, the device current If and the emitting current Ie stabilize.
Next, examples in which multiple electron-emitting devices each of which is the electron-emitting device according to the present invention are arranged on a substrate to produce an electron source and an image display apparatus are described.
Various arrangements of the electron-emitting devices can be employed. A matrix arrangement schematically illustrated in
In
The X axis wirings 52 include m wirings Dx1, Dx2, . . . , and Dxm, and are each formed of a conductive metal etc. formed through a vacuum evaporation process, a printing process, a sputtering process, or the like. The material, thickness, and width of the wirings may be appropriately designed. The Y axis wirings 53 include n wirings Dy1, Dy2, . . . , and Dyn, and are each formed similarly to the X axis wirings 52. Interlayer insulating layers (not shown) are provided between those m X axis wirings 52 and the n Y axis wirings 53 to electrically separate the wirings from each other (m and n each indicate a positive integer).
The interlayer insulating layer (not shown) is made of SiO2 etc. formed through a vacuum evaporation process, a printing process, a sputtering process, or the like, insulating metal oxide, or a mixture thereof. For example, the interlayer insulating layer is formed into a desired shape on the entire surface or a part of the electron source substrate 51 in which the X-axis wirings 52 are formed. In particular, a film thickness, a material, and a manufacturing method of the interlayer insulating film are set as appropriate so as to be able to withstand potential differences at intersections of the X-axis wirings 52 and the Y-axis wirings 53. The X-axis wirings 52 and the Y-axis wirings 53 are led out as external terminals.
The first and second electrodes 2 and 3 included in the electron-emitting devices 54 are electrically connected to the m X-axis wirings 52 and the n Y-axis wirings 53.
The X-axis wirings 52, the Y-axis wirings 53, and the first and second electrodes 2 and 3 are made of materials whose constituting elements may be completely the same, partially the same, or different from each other. Those materials are appropriately selected from, for example, the above-mentioned electrode materials. When the material of the electrodes is the same as that of the wiring, the wiring connected to the electrode can be also regarded as the electrode.
A scanning signal application unit (not shown) for applying a scanning signal for selecting one of rows arranged in the X axis of the electron-emitting device 54 is connected to the X axis wirings 52. On the other hand, a modulation signal generation unit (not shown) for modulating the columns arranged in the Y axis of the electron-emitting device 54 in accordance with the input signal is connected to the Y axis wirings 53. A drive voltage to be applied to the respective electron-emitting devices is supplied in the form of a difference voltage between the scanning signal and the modulation signal applied to the respective electron-emitting device.
According to the above-mentioned structure, the electron-emitting devices are individually selected, thus allowing the devices to be individually driven by using simple matrix wirings.
While referring to
The electron-emitting devices 54 each of which is the electron-emitting device illustrated in
As described above, the enclosure 68 is structured by the face plate 66, the supporting frame 62, and the rear plate 61. The rear plate 61 is provided for a purpose of enhancing the strength of the electron source substrate 51 mainly, and hence when the electron source substrate 51 itself has a sufficient strength, it is unnecessary to separately provide the rear plate 61. In other words, the enclosure 68 may be structured by bonding the supporting frame 62 directly to the electron source substrate 51 and only using the face plate 66, the supporting frame 62, and the electron source substrate 51.
The image forming apparatus according to the present invention described above may be employed as an image forming apparatus for a photo printer arranged by using a photosensitive drum and the like, in addition to a television broadcasting display device, display devices for a television conference system, a computer, and so forth.
Hereinafter, specific examples of the present invention are described. The present invention is not limited to the examples and thus includes cases where element exchanges and modifications in design are made within the scope within which the object of the present invention can be achieved.
The electron-emitting device illustrated in
(Step-a)
The glass base material 10 (produced by Asahi Glass Co. Ltd., PD200) was sufficiently cleaned with a cleaning solution, deionized water, and an organic solvent. Then, the passivation layer 8 made of SiO2 was deposited on the base material 10 at a thickness of approximately 250 nm using an Rf sputtering apparatus, to prepare the substrate 1 (
(Step-b)
A Ti layer having a thickness of 5 nm and a Pt layer having a thickness of 40 nm were successively deposited on the substrate 1 by a sputtering process. Then, an etching mask (photoresist) was formed so as to cover a pattern of the first and second electrodes 2 and 3. Next, dry etching using Ar plasma was performed and subsequently a remaining portion of the etching mask was removed by dissolving to form the first and second electrodes 2 and 3 (
(Step-c)
A mask having an aperture portion, corresponding to a pattern of the conductive film 4 for connecting the first and second electrodes 2 and 3 to each other was formed. Next, a Pd film having a thickness of 10 nm was deposited by a sputtering process. The mask was dissolved using an organic solvent to lift off an unnecessary portion of the Pd film, thereby forming the conductive film 4 made of Pd (
(Step-d)
The substrate 1 provided with the conductive film 4 was placed in the vacuum container 45 illustrated in
In this example, the pulse width T1 was set to 1 msec., the pulse interval T2 was set to 10 msec., and the peak of the square wave was gradually increased from 0 V in steps of 0.1 V. During the energization forming operation, a resistance measurement pulse having a peak of 0.1 V was inserted between adjacent pulses to measure a current, thereby detecting a resistance. When the resistance exceeded 1 MΩ, the energization forming operation was completed.
(Step-e)
Subsequently, the vacuum container 45 was further evacuated by the exhaust device. After the pressure became equal to or smaller than 5×10−6 Pa, the valve 48 connected to the carbon compound (material) source 47 containing tolunitrile was opened to introduce a tolunitrile gas into the vacuum container 45. The pressure was 1.0×10−4 Pa.
Next, as illustrated in
When the square wave pulse was being applied in the presence of tolunitrile, the value of If increased. After a lapse of approximately 50 minutes, the increase in value of If was slow and the value of If substantially saturated. The application of the pulse voltage was further continued for 10 minutes, and then stopped. The vacuum container 45 was evacuated. Then, the activation operation was completed. In this step, the first and second carbon films 6a1 and 6b1 were deposited, the second gap 7a was formed, and the first concave portion 9a was formed.
(Step-f)
Subsequently, tolunitrile was introduced into the vacuum container 45 again at a pressure (2.7×10−3 Pa) higher than the pressure in Step-e. Then, a pulse voltage was applied between the first and second electrodes 2 and 3 for 20 minutes. An applied waveform and peak of the pulse voltage are the same as in Step-e.
After the procedure described above, the electron-emitting device was observed using an optical microscope. As a result, it was determined that the electron-emitting device having the structure schematically illustrated in
The first and second extending portions 6a2 and 6b2 and the facing portions 6a1 and 6b1 are subjected to Auger analysis. As a result, it is found that the first and second extending portions 6a2 and 6b2 and the facing portions 6a1 and 6b1 are made of carbon.
A cross sectional shape including the third gap 7b located between the first extending portion 6a2 and the second extending portion 6b2, of each of the portions (end sections) most distant from the center of the electron-emitting device was observed using a focused ion beam scanning electron microscope (FIB-SEM). At this time, the presence of the second concave portion 9b could not be clearly determined. The end sections of the first and second extending portions 6a2 and 6b2 were in a state in which whether or not the first extending portion 6a2 and the second extending portion 6b2 are separated from each other by the third gap 7b is unknown (state in which it is difficult to determine second gap 7b).
A cross sectional shape including the second gap 7a located between the facing portions 6a1 and 6b1 was observed. As a result, the presence of the first concave portion 9a was determined and it was determined that the depth thereof was 20 nm to 50 nm.
(Step-g)
Subsequently, the substrate 1 was exposed to an air atmosphere and immersed in a 0.4% hydrofluoric acid aqueous solution for one minute, and then cleaned with deionized water for 5 minutes to remove the hydrofluoric acid aqueous solution.
After the procedure described above, the cross sectional shape including the third gap 7b located between the first and second extending portions 6a2 and 6b2 was observed using the FIB-SEM. As a result, it was observed that the second concave portion 9b as illustrated in
(Step-h)
Next, the stabilization operation was performed. The stabilization step was performed in the vacuum processing apparatus as illustrated in
After that, a pulse voltage (16 V/1 msec.) was applied between the first and second electrodes 2 and 3 at a frequency of 60 Hz. In order to measure a leak current, a pulse (5V/100 μsec.) was set in the end of the pulse voltage to form a stepped pulse. The anode was provided above the electron-emitting device at a distance of 2 mm therefrom and applied with a voltage of 1 kV. As a result obtained by measurement, the leak current was approximately 1.1 μA, the initial device current If was approximately 1.2 mA, and the initial emitting current Ie was approximately 3.5 μA. The electron-emitting efficiency η was as large as approximately 0.29%. The emitting current value was stable because of a small fluctuation.
With regard to the electron-emitting device manufactured without the operation using the aqueous solution containing hydrogen fluoride, which is performed in Step-g, the leak current was approximately 6.3 μA, the initial device current If was approximately 2.3 mA, the initial emitting current Ie was approximately 5.1 μA, and the electron-emitting efficiency η was approximately 0.22%.
Therefore, when the operation using the aqueous solution containing hydrogen fluoride was performed, the reduction in leak current, an improvement of the electron-emitting efficiency η by approximately slightly more than 30%, and the increase in emitting current Ie were found.
An electron-emitting device manufactured in this example is different from Example 1 in that the passivation layer 8 is not used. Hereinafter, a method of manufacturing the electron-emitting device according to this example is described step by step with reference to
(Step-a)
A quartz glass substrate was sufficiently cleaned with deionized water and an organic solvent to prepare the substrate 1.
Step-b to Step-d were performed in the same manner as in Example 1.
Step-e and Step-f were performed in the same manner as in Example 1, except that the peak was adjusted to ±15 V.
After the steps, an observation using an optical microscope was performed. As a result, it was determined that the electron-emitting device having the structure schematically illustrated in
The first and second extending portions 6a2 and 6b2 and the facing portions 6a1 and 6b1 were subjected to Auger analysis. As a result, it was found that the first and second extending portions 6a2 and 6b2 and the facing portions 6a1 and 6b1 were made of carbon.
The cross sectional shape including the third gap 7b located between the first extending portion 6a2 and the second extending portion 6b2, of each of the portions (end sections) most distant from the center of the electron-emitting device was observed using the FIB-SEM. At this time, the presence of the second concave portion 9b could not be clearly determined. The end sections of the first and second extending portions 6a2 and 6b2 were in the state in which whether or not the first extending portion 6a2 and the second extending portion 6b2 are separated from each other by the third gap 7b is unknown (state in which it is difficult to determine second gap 7b).
The cross sectional shape including the second gap 7a located between the facing portions 6a1 and 6b1 was observed. As a result, the presence of the first concave portion 9a was determined and it was determined that the depth thereof was 30 nm to 40 nm.
Step-g was also performed in the same manner as in Example 1. After that, the cross sectional shape including the third gap 7b located between the first and second extending portions 6a2 and 6b2 was observed using the FIB-SEM. As a result, it was observed that the second concave portion 9b as illustrated in
Step-h was also performed as the stabilization operation in the same manner as in Example 1.
After that, a pulse voltage (15 V/1 msec.) was applied between the first and second electrodes 2 and 3 at a frequency of 60 Hz. In order to measure a leak current, a pulse (5V/100 μsec.) was set in the end of the pulse voltage to form a stepped pulse. The anode was provided above the electron-emitting device at a distance of 2 mm therefrom and applied with a voltage of 1 kV. As a result obtained by measurement, the leak current was approximately 1.0 μA, the initial device current If was approximately 1.1 mA, and the initial emitting current Ie was approximately 3.2 μA. The electron-emitting efficiency η was as large as approximately 0.29%. The emitting current value was stable because of a small fluctuation.
With regard to the electron-emitting device manufactured without the operation using the aqueous solution containing hydrogen fluoride, which is performed in Step-g, the leak current was approximately 6.1 μA, the initial device current If was approximately 2.4 mA, the initial emitting current Ie was approximately 5.0 μA, and the electron-emitting efficiency η was approximately 0.21%.
Therefore, when the operation using the aqueous solution containing hydrogen fluoride was performed, the reduction in leak current, an improvement of the electron-emitting efficiency η by approximately slightly more than 40%, and the increase in emitting current Ie were found.
The electron-emitting device according to this example is different from that of Example 1 in that the conductive film 4 of the electron-emitting device according to Example 1 was formed by an ink-jet process and the passivation layer 8 was formed using a polysilazane solution. Others are fundamentally performed in the same manner as in Example 1.
Hereinafter, a method of manufacturing the electron-emitting device according to this example is described step by step with reference to
(Step-a)
A glass substrate made of soda lime glass was sufficiently cleaned with a cleaning solution, deionized water, and an organic solvent. The polysilazane solution, Aquamica (produced by AZ Electronic Materials, NN110-20) was spin-applied onto the glass substrate for 30 seconds at 2,000 revolutions/minute. Subsequently, the glass substrate was dried at 100° C. for 10 minutes and then baked in an atmosphere of atmospheric pressure containing water at 500° C. for one hour. Therefore, the substrate 1 provided with the passivation layer (silicon oxide layer) 8 having a thickness of approximately 380 nm was manufactured (
(Step-b)
The first and second electrodes 2 and 3 were formed on the substrate 1 by the same manufacturing method as in Example 1 (
(Step-c)
In order to connect the first and second electrodes 2 and 3 to each other, an aqueous solution containing Pd was applied between the first and second electrodes 2 and 3 using a bubble-jet (registered trademark) type ink-jet apparatus. The aqueous solution contains palladium acetate monoethanolamine complex (0.15 Pd mass %), isopropyl alcohol (15 mass %), ethylene glycol (1 mass %), and polyvinyl alcohol (0.05 mass %).
After that, the substrate 1 was baked at 350° C. for 30 minutes to form the conductive film 4 (
(Step-d)
The energization forming operation was performed by the same method as in Example 1 (
(Step-e)
Subsequently, the same activation operation as in Example 1 was performed. In this example, the tolunitrile gas pressure was set to 1.0×10−4 Pa and the peak was set to ±18 V.
(Step-f)
Subsequently, similarly to Example 1, tolunitrile was introduced into the vacuum container 45 again at a pressure (2.7×10−3 Pa) higher than the pressure in Step-e. Then, a pulse voltage was applied between the first and second electrodes 2 and 3 for 20 minutes (
After the procedure described above, the electron-emitting device was observed using an optical microscope. As a result, it was determined that the electron-emitting device having the structure schematically illustrated in
The first and second extending portions 6a2 and 6b2 and the facing portions 6a1 and 6b1 were subjected to Auger analysis. As a result, it was found that the first and second extending portions 6a2 and 6b2 and the facing portions 6a1 and 6b1 were made of carbon.
The cross sectional shape including the third gap 7b located between the first extending portion 6a2 and the second extending portion 6b2, of each of the portions (end sections) most distant from the center of the electron-emitting device was observed using the FIB-SEM. At this time, the presence of the second concave portion 9b could not be clearly determined. The end sections of the first and second extending portions 6a2 and 6b2 were in the state in which whether or not the first extending portion 6a2 and the second extending portion 6b2 are separated from each other by the third gap 7b is unknown (state in which it is difficult to determine second gap 7b).
The cross sectional shape including the second gap 7a located between the facing portions 6a1 and 6b1 was observed. As a result, the presence of the first concave portion 9a was determined and it was determined that the depth thereof was 20 nm to 50 nm.
(Step-g)
Subsequently, the electron-emitting device was exposed to an air atmosphere and immersed in a 0.4% hydrofluoric acid aqueous solution for one minute, and then cleaned with deionized water for 5 minutes to remove the hydrofluoric acid aqueous solution.
After the procedure described above, the cross sectional shape including the third gap 7b located between the first and second extending portions 6a2 and 6b2 was observed using the FIB-SEM. As a result, it was observed that the second concave portion 9b as illustrated in
(Step-h)
Next, the stabilization operation was performed in the same manner as in Example 1.
After that, a pulse voltage (18 V/1 msec.) was applied between the first and second electrodes 2 and 3 at a frequency of 60 Hz. In order to measure a leak current, a pulse (5V/100 μsec.) was set in the end of the pulse voltage to form a stepped pulse. The anode was provided above the electron-emitting device at a distance of 2 mm therefrom and applied with a voltage of 1 kV. As a result obtained by measurement, the leak current was approximately 0.8 μA, the initial device current If was approximately 1.0 mA, and the initial emitting current Ie was approximately 3.1 μA. The electron-emitting efficiency η was as large as approximately 0.31%. The emitting current value and the device current value were stable because of a small fluctuation.
With regard to the electron-emitting device manufactured without the operation using the aqueous solution containing hydrogen fluoride, which is performed in Step-g, the leak current was approximately 6.6 μA, the initial device current If was approximately 2.1 mA, the initial emitting current Ie was approximately 4.9 μA, and the electron-emitting efficiency η was approximately 0.23%.
Therefore, when the operation using the aqueous solution containing hydrogen fluoride was performed, the reduction in leak current, an improvement of the electron-emitting efficiency η by approximately slightly more than 30%, and the increase in emitting current Ie were found.
In this example, the image display apparatus schematically illustrated in
In this example, multiple pairs of first and second electrodes 2 and 3 were formed by the same steps as Step-a and Step-b in Example 3, and then conventional known matrix wirings were formed. After that, Step-c to Step-g in Example 3 were performed in order and sealing was performed using a face plate and a support frame under a vacuum atmosphere to manufacture a display panel.
A method of manufacturing an electron source substrate according to this example is described more detail in the step order. Note that Step-a to Step-g described below are substantially the same steps as in Example 3.
(Step-a)
A glass substrate made of glass for plasma display (produced by Asahi Glass Co. Ltd., PD200) was sufficiently cleaned with a cleaning solution, deionized water, and an organic solvent. Then, a polysilazane solution, Aquamica (produced by AZ Electronic Materials, NN110-20) was applied onto the glass substrate by an ink-jet process. Positions to be applied were separately set for respective areas for forming the electron-emitting devices. Subsequently, the glass substrate was dried at 100° C. for 10 minutes and then baked in an atmosphere of atmospheric pressure containing water at 550° C. for one hour. Therefore, the passivation layers (Na blocking layers) 8 each of which has a diameter of 120 μm and an average film thickness of 350 nm within a region with a radius of 50 μm from the center and is made of silicon oxide were formed.
(Step-b)
N pairs of first and second electrodes 2 and 3 which are located in the X axis and m pairs of first and second electrodes 2 and 3 which are located in the Y axis were formed on the substrate 1 by the same method as in Example 1 (m and n each indicate positive integer). The interval L between the first and second electrodes 2 and 3 was set to 20 μm and the width W thereof was set to 300 μm.
Subsequently, matrix wirings were formed. The matrix wirings include the m X-axis wirings 52 expressed by Dx1, Dx2, . . . , and Dxm. A metal paste material containing Ag as a main ingredient was printed by a screen printing process and baked at 480° C. for 10 minutes to form the matrix wirings.
An interlayer insulating layer (not shown) was provided in regions in which the m X-axis wirings 52 are to be overlapped with the n Y-axis wirings 53, to electrically separate the m X-axis wirings 52 from the n Y-axis wirings 53.
A glass material which contains lead oxide and is formed by a screen printing process was used for the interlayer insulating layer (not shown). The interlayer insulating layer (not shown) was baked at approximately 480° C. for 20 minutes. The printing and baking were repeated two times to form two laminated layers. The Y-axis wirings 53 which are the n wirings Dy1, Dy2, . . . , and Dyn were also formed in the same manner as the X-axis wirings 52.
(Step-c)
An aqueous solution containing Pd was applied between the first and second electrodes 2 and 3 of each of the electron-emitting devices by the same method as in Example 3 to form the conductive (Pd) films 4 each having a film thickness of approximately 10 nm into a circular shape having a diameter of approximately 80 μm. Each of the Pd films was provided within a region of each of the passivation layers 8 formed in Step-a.
(Step-d)
An energization forming operation was performed between the first and second electrodes 2 and 3 through the wirings Dx1 and Dy1 illustrated in
(Step-e)
The activation operation was performed under the same conditions as in Example 3.
(Step-f)
Subsequently, similarly to Example 3, tolunitrile was introduced into the vacuum container 45 again at a pressure (2.7×10−3 Pa) higher than the pressure in Step-e. Then, a pulse voltage was applied between the first and second electrodes 2 and 3 for 20 minutes. An applied waveform and peak of the pulse voltage were the same as in Step-e.
After the procedure described above, the electron-emitting device was observed using an optical microscope. As a result, in the first and second extending portions 6a2 and 6b2, Xc of
The first and second extending portions 6a2 and 6b2 and the facing portions 6a1 and 6b1 were subjected to Auger analysis. As a result, it was found that the first and second extending portions 6a2 and 6b2 and the facing portions 6a1 and 6b1 were made of carbon.
The cross sectional shape including the third gap 7b located between the first extending portion 6a2 and the second extending portion 6b2, of each of the portions (end sections) most distant from the center of the electron-emitting device was observed using the FIB-SEM. At this time, the presence of the second concave portion 9b could not be clearly determined. The end sections of the first and second extending portions 6a2 and 6b2 were in the state in which whether or not the first extending portion 6a2 and the second extending portion 6b2 are separated from each other by the third gap 7b is unknown (state in which it is difficult to determine second gap 7b).
The cross sectional shape including the second gap 7a located between the facing portions 6a1 and 6b1 was observed. As a result, the presence of the first concave portion 9a was determined and it was determined that the depth thereof was 20 nm to 50 nm.
(Step-g)
Subsequently, the electron source substrate was exposed to an air atmosphere and immersed in a 0.4% hydrofluoric acid aqueous solution for one minute, and then cleaned with deionized water for 5 minutes to remove the hydrofluoric acid aqueous solution.
After the procedure described above, the cross sectional shape including the third gap 7b located between the first and second extending portions 6a2 and 6b2 was observed using the FIB-SEM. As a result, it was observed that the second concave portion 9b as illustrated in
(Step-h)
Next, the stabilization operation was performed in the same manner as in Example 3.
(Step-i)
Next, the thus manufactured electron source substrate 51 in which the multiple conductive films 4 are arranged in matrix and the face plate 66 provided with the fluorescent film 64 and the metal back 65 on the glass substrate 63 were used to manufacture an image display panel (
Then, the container external terminals Dx1 to Dxm and Dy1 to Dyn and the high-voltage terminal 67 of the image display panel were connected to driver circuits to complete an image display apparatus.
Scanning signals and modulation signals were applied from signal generation units (not shown) to the respective electron-emitting devices through the container external terminals Dx1 to Dxm and Dy1 to Dyn, to emit electrons. Then, a high voltage equal to or larger than several kV was applied to the metal back 65 through the high-voltage terminal 67 so that the emitted electrons were collided with the fluorescent film 64 to emit light, thereby displaying an image.
As a result, the image display apparatus according to this example could display an image having high luminance and uniformity for a long period with low power consumption.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2008-168752, filed Jun. 27, 2008, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-168752 | Jun 2008 | JP | national |
