JP3639738B2 - Electron emitting element, electron source using the electron emitting element, image forming apparatus using the electron source, and display apparatus using the image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electron-emitting device, an electron source using the electron-emitting device, and an image forming apparatus using the electron source.
[0002]
[Prior art]
Conventionally, two types of electron-emitting devices are known: a thermionic source and a cold cathode electron source. Cold cathode electron sources include field emission type (hereinafter abbreviated as FE type), metal / insulating layer / metal type (hereinafter abbreviated as MIM type), surface conduction electron-emitting devices, and the like.
[0003]
As an example of the FE type, W.W. P. Dyke & W. W. Dolan, “Field emission”, Advance in Electro Physics, 8, 89 (1956) or C.I. A. Spindt, “Physical Properties of Thin-Film Field Emission Catalysts with Mollybdenium Cones”, J. Am. Appl. Phys. 47, 5248 (1976).
[0004]
Examples of the MIM type include C.I. A. Mead, “Operation of Tunnel-Emission Devices”, J. Am. Apply. Phys. 32,646 (1961) and the like are known.
[0005]
Examples of surface conduction electron-emitting devices include M.I. I. Elinson, RadioEng. Electron Phys. 10, 1290, (1965) and the like.
[0006]
A surface conduction electron-emitting device utilizes a phenomenon in which electron emission occurs when a current is applied in parallel to a film surface of a small-area thin film formed on a substrate. As this surface conduction electron-emitting device, SnOl by Erinson et al.₂Using thin film, using Au thin film [G. Dimmer, Thin Solid Films, 9, 317 (1972)], ln₂O_Three/ SnO₂By thin film [M. Hartwell and C.H. G. Fonsted, IEEE Trans. ED Conf. 519 (1975)], and carbon thin film [Hisa Araki et al .: Vacuum, Vol. 26, No. 1, p. 22 (1983)] and the like have been reported.
[0007]
As a typical configuration of these surface-conduction type device emitting devices, the above-described M.P. The element structure of Hartwell is shown in FIG. In the figure, reference numeral 1 denotes an insulating substrate. 4 is a conductive thin film made of a metal oxide thin film or the like formed by sputtering in an H-shaped pattern, and a linear electron emission portion 5 is formed by an energization process called forming described later. In the figure, the element electrode interval L is set to 0.5 to 1 mm, and W is set to 0.1 mm.
[0008]
Conventionally, in these surface conduction electron-emitting devices, it has been common to form the electron-emitting portion 5 in advance by conducting an energization process called forming before conducting the electron emission. In other words, forming means applying and applying a DC voltage or a very slow rising voltage, for example, about 1 V / min, to both ends of the conductive thin film 4 to locally break, deform or alter the conductive thin film, resulting in an electrically high voltage. It is to form the electron emission portion 5 in a resistance state. In the electron emitting portion 5, a crack is generated in a part of the conductive thin film 4, and the electron is emitted from the vicinity of the crack. The surface conduction electron-emitting device subjected to the forming process emits electrons from the electron-emitting portion 5 by applying a voltage to the conductive thin film 4 on which the electron-emitting portion is formed and causing a current to flow through the device. is there.
[0009]
On the other hand, for example, as disclosed in Japanese Patent Application Laid-Open No. 7-235255, a process called activation processing may be performed on an element that has finished forming. The activation treatment process is a process in which the device current If and the emission current Ie are remarkably changed by this process.
[0010]
The activation step can be performed by applying a voltage to the element in the same manner as the forming process in an atmosphere containing an organic substance. By this treatment, carbon or a carbon compound is deposited from an organic substance present in the atmosphere in and near the electron emission portion of the device, and the device current If and the emission current Ie are remarkably changed, so that better electron emission characteristics are obtained. Can be obtained.
[0011]
FIG. 22 shows a cross-sectional shape of an electron-emitting device disclosed in Japanese Patent Laid-Open No. 7-235255. In the figure, reference numerals 1, 4 and 5 are the same as those in FIG. 2 and 3 are element electrodes for applying a voltage to the conductive thin film 4, and the voltage is applied with 2 being a low potential side electrode and 3 being a high potential side electrode. By performing the above-described activation process, the electron emission portion 5 shows a structure in which carbon or a carbon compound 6 is deposited, and realizes good electron emission characteristics.
[0012]
An image forming apparatus can be configured by using an electron source substrate on which a plurality of electron-emitting devices as described above are formed and combining with an image forming member made of a phosphor or the like.
[0013]
[Problems to be solved by the invention]
However, due to the rapid development of multimedia with the advancement of information in recent years, higher performance has been demanded for image forming apparatuses such as displays. That is, the display device has a large screen, power saving, high definition, high image quality, and space saving.
[0014]
Therefore, in the above-described electron-emitting device, it is desired that stable electron emission characteristics can be obtained with higher efficiency so that an image forming apparatus to which the electron-emitting device is applied can stably provide a bright display image.
[0015]
Here, the efficiency refers to a current (hereinafter referred to as emission) released in a vacuum with respect to a flowing current (hereinafter referred to as element current If) when a voltage is applied between a pair of opposing element electrodes of the surface conduction electron-emitting device. Current ratio) and current Ie).
[0016]
That is, it is desirable that the element current If is as small as possible and the emission current Ie is as large as possible.
If high-efficiency electron emission characteristics can be stably controlled over a long period of time, for example, in an image forming apparatus using a phosphor as an image forming member, a low-power and bright high-quality image forming apparatus such as a flat TV is realized. it can.
[0017]
However, the above-mentioned M.I. Hartwell's electron-emitting devices do not always have satisfactory electron-emitting characteristics and electron-emitting efficiency, and image forming apparatuses with high brightness and excellent operational stability using these elements There was a problem that it was extremely difficult to provide.
[0018]
That is, for use in such an application, a sufficient emission current Ie can be obtained with a practical voltage (for example, 10 V to 20 V), the emission current Ie and the device current If do not vary greatly during driving, Although it is necessary that the emission current Ie and the device current If do not deteriorate over time, the conventional surface conduction electron-emitting device has the following problems.
[0019]
As shown in FIG. 21, the surface conduction electron-emitting device has a linear electron-emitting portion 5 that is substantially perpendicular to the voltage application direction.
As described above, the electron emission portion 5 is constituted by the gap formed in the conductive thin film by forming, but the gap is not necessarily formed in a uniform width and shape as shown in FIG. Not exclusively. In the case of such a non-uniform electron emission portion form, there may be a case where a sufficient emission current Ie cannot be obtained, or the characteristic fluctuation or deterioration during driving becomes significant.
[0020]
On the other hand, according to the above-described activation process, a carbon-containing film made of carbon, a carbon compound, or the like is deposited on the conductive thin film formed in the conductive thin film and on the conductive thin film in the vicinity thereof to form a narrower gap. Is formed (FIG. 22). This electron-emitting device is expected as an electron source for display because it can obtain a sufficient emission current at a practical voltage and the fluctuation of the emission current Ie and device current If during driving is small. May be small and needed to be improved.
[0021]
The present invention pays attention to the energy distribution of electrons emitted from a device into a vacuum in order to stably obtain an electron-emitting device having a high electron-emitting efficiency in an electron-emitting device manufactured by such an activation process. It was made.
[0022]
An object of the present invention is to provide a surface conduction electron-emitting device having good electron emission characteristics, particularly high electron emission efficiency as described above, and an electron source and an image forming apparatus using the same.
[0023]
[Means for Solving the Problems]
  Therefore, as a result of intensive studies, the present inventors have found that the surface of the substrate isA pair of disposed electrodes, a pair of conductive thin films disposed opposite to each other with a first gap between the pair of electrodes, and a second gap disposed in the first gap. A pair of carbon-containing films disposed in a row, wherein one of the pair of conductive thin films is electrically connected to one of the pair of electrodes, and the other of the pair of conductive thin films is the pair. One of the pair of carbon-containing films is electrically connected to one of the pair of conductive thin films, and the other of the pair of carbon-containing films is the pair of carbon. Is electrically connected to the other conductive thin filmIn an electron-emitting device,Of the electron-emitting deviceIn the emission current during drivingelectronicHalf width HW1 of energy distribution andThe above1/4 of the emission currentEmission currentInelectronicBy providing an electron-emitting device characterized in that the ratio (HW2 / HW1) to the half-value width HW2 of the energy distribution is 0.8 or more and 1.0 or less, an electron-emitting device with high electron emission efficiency is provided. Is.
[0024]
  Here, the carbon in the film containing carbon is preferably graphitic carbon. The present invention is further characterized in that in the electron source in which a plurality of electron-emitting devices are arrayed on a substrate,pluralElectron emitterTo each ofThe above-described electron-emitting device can be used.
[0025]
  Furthermore, in an image forming apparatus having an electron source and an image forming member that forms an image by irradiating electrons emitted from the electron source, the above-described electron source can be used.. In addition, the above-described image forming apparatus can be used for a television broadcast display apparatus that includes an image forming apparatus and a circuit for causing the image forming apparatus to display a television broadcast signal.
[0026]
In order for electrons to reach an image forming member such as a phosphor from a surface conduction electron-emitting device produced by activation, the following two processes are mainly performed. Details are described in SID 97 Digest P127 Asai.
[0027]
First, a voltage is applied to the device electrode to accelerate electrons from the cathode-side carbon of the electron emission portion to the positive-side carbon, and the electrons are emitted into the vacuum by elastic scattering at the positive-side carbon.
[0028]
Secondly, the electrons emitted from the positive electrode side carbon are elastically scattered on the positive electrode side carbon or the conductive thin film, whereby electrons are emitted to the image forming member side. Since the electron-emitting device has an extremely small electron-emitting region and a voltage is applied in parallel to the substrate, electrons scattered in the vacuum from the carbon on the positive electrode side are returned to the electron-emitting device side. An electric field is formed. A device with higher electron emission efficiency is obtained when the ratio of electrons reaching the anode side (phosphor side) is higher than the electric field to which these electrons are returned.
[0029]
The electron emission efficiency is determined by the above-described two processes, and the present invention is made by paying attention to the energy of electrons emitted in vacuum in the first process.
[0030]
Next, the energy distribution of electrons emitted into the vacuum from the electron-emitting device manufactured by the activation process will be described with reference to FIGS.
FIG. 4 shows the energy band of the electron emission portion of the electron emission device. In the figure, Vf is a voltage applied to the element, Wf is a work function of carbon formed by activation, Ef is a Fermi level of carbon formed by activation, and D is a voltage applied to the element. The length of the applied carbon gap, e^-Is an electron. When a voltage is applied to the element, electrons are emitted from the carbon on the negative electrode side of the element and collide with the carbon on the positive electrode side. There is a possibility that electrons having energy higher than the work function Wf out of the collided electrons are emitted into the vacuum. At this time, electrons emitted from the carbon on the negative electrode side are emitted by performing elastic scattering a plurality of times on the carbon on the positive electrode side. Details are described in SID 97 Digest P127 Asai.
[0031]
FIG. 5 is a schematic view showing the energy distribution of electrons emitted from the electron-emitting device. In the figure, the horizontal axis indicates the energy of electrons, and the vertical axis indicates the amount (intensity) of electrons emitted from the device into the vacuum with respect to the energy of electrons. The voltage 0 V on the horizontal axis is the Fermi level of the negative electrode carbon, and corresponds to the negative voltage applied to the device. If a voltage is applied to the carbon gap and electrons emitted from the Fermi level of the carbon on the negative electrode side are released into vacuum without any energy loss, the amount of electrons becomes the intensity at 0 V in the energy distribution diagram. At this time, the energy of electrons emitted into the vacuum is indicated by eVf-W shown in FIG. Further, when some energy loss occurs or the voltage applied to the device electrode is not applied to the carbon gap, the intensity corresponds to the negative voltage of the energy distribution. In the energy distribution diagram, Vp represents the energy of the peak energy of the energy distribution and the largest amount of electron emission (maximum intensity Ip). The closer to 0V, the higher the energy of electrons emitted from the device. HW is called the half width of the energy distribution, and is an energy width of a half value of the electron emission amount at the peak energy, and indicates the energy width of the emitted electrons.
[0032]
The present invention has been made paying attention to the energy distribution of the above-described surface conduction electron-emitting device. The half-value width of the energy distribution in the emission current during driving and the energy distribution in a quarter of the emission current during driving. The present inventors have found that an electron-emitting device having a high electron emission efficiency can be obtained by setting the ratio of the half-value width of (the half-value width of the energy distribution in the first emission current) to 0.8 to 1.0. I found it.
[0033]
At this time, the emission current during driving indicates an actual current value when the electron-emitting device is applied to a display or the like.
The carbon in the carbon-containing film is preferably graphite-like carbon because it has excellent electrical conductivity and is stable.
As described above, according to the present invention, an electron-emitting device with high electron emission efficiency can be obtained.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in further detail.
First, the basic configuration of the electron-emitting device according to the present invention will be described.
[0035]
FIGS. 1A and 1B are a plan view and a cross-sectional view, respectively, showing the configuration of a basic planar electron-emitting device according to the present invention. FIGS. 2A, 2B, and 2C are respectively a plan view schematically showing an enlarged structure in the vicinity of an electron emission portion of a surface conduction electron-emitting device according to the present invention, and FIG. Sectional drawing (b), (c). The basic structure of the element according to the present invention will be described with reference to FIGS.
[0036]
In FIG. 1, 1 is a substrate, 2 and 3 are element electrodes, 4 is a conductive thin film, and 5 is an electron emission portion.
In FIG. 2, 1 is a substrate, 4 is a conductive thin film, 5 is an electron emission portion, 21 and 22 are deposits having carbon deposited on the substrate in the gap formed in the conductive thin film and on the conductive thin film ( Membrane). Note that the deposit is schematically shown as being divided into left and right deposits 21 and 22 facing the substrate surface laterally with the gap 8 (second gap) as a boundary. In some cases, the departments are connected. The gaps between the conductive thin films 4 are called the first gaps, and the gaps are non-uniformly arranged as shown in the figure, and the two-dimensional shapes are meanderingly arranged. The deposits 21 and 22 are also deposited on the conductive thin film 4.
[0037]
With the above configuration, the deposits (21, 22) are electrically connected to the electrodes (2, 3). In the drawing, the deposits (21, 22), which are carbon-containing films, are connected to the electrodes (2, 3) via conductive thin films. In some cases, it is deposited up to the electrodes (2, 3) and is directly electrically connected.
[0038]
As the substrate 1, SiO formed on quartz glass, blue plate glass, blue plate glass or the like by sputtering or the like.₂And a ceramic substrate such as alumina. These substrates include SiO₂The material containing is desirable, and the electron emission portion 5 can be formed.
[0039]
Any material may be used as the material of the opposing element electrodes 2 and 3 as long as it has conductivity. For example, Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu, Metals or alloys such as Pd and Pd, Ag, Au, RuO₂, Printed conductors composed of metals such as Pd-Ag or metal oxides and glass, ln₂O_Three-SnO₂And a transparent conductor such as polysilicon and a semiconductor conductor material such as polysilicon.
[0040]
The element electrode interval L, the element electrode length W, and the shape thereof are appropriately designed according to the application form of the electron-emitting device. For example, in a display device such as a television described later, the pixel size corresponding to the screen size is designed. In particular, a high-definition television requires a small pixel size and high definition. Therefore, in order to obtain a sufficient luminance with the size of the electron-emitting device being limited, the electron-emitting device is designed to obtain a sufficient emission current.
[0041]
The element electrode interval L is several tens of nanometers to several hundred μm, and is set by the photolithography technology that is the basis of the element electrode manufacturing method, that is, the performance of the exposure machine, the etching method, and the voltage applied between the element electrodes. However, it is preferably several μm to several tens μm.
[0042]
The length W of the element electrode and the film thickness d of the element electrodes 2 and 3 are appropriately designed based on the resistance value of the electrode, the connection with the X and Y wirings described above, and the problem of the arrangement of a large number of electron sources. Usually, the length W of the element electrode is several μm to several hundred μm, and the film thickness d of the element electrodes 2 and 3 is several μm from several nm.
[0043]
Not only the configuration shown in FIG. 1 but also a configuration in which the conductive thin film 4 and the opposing element electrodes 2 and 3 are laminated on the substrate 1 in this order can be adopted.
The conductive thin film 4 is preferably a fine particle film composed of fine particles in order to obtain good electron emission characteristics. The film thickness is appropriately set in consideration of the step coverage to the device electrodes 2 and 3, the resistance value between the device electrodes 2 and 3, forming conditions described later, and the like.
[0044]
In addition, since the magnitudes of the device current If and the emission current Ie depend on the width W of the conductive thin film 4, a sufficient emission current can be obtained while the size of the electron-emitting device is limited as in the shape of the device electrode. Designed to be obtained.
[0045]
Generally, the thermal stability of the conductive thin film 4 may dominate the lifetime of the electron emission characteristics, and it is desirable to use a material having a higher melting point as the material of the conductive thin film 4. However, normally, the higher the melting point of the conductive thin film 4, the more electric power is required for energization forming described later.
[0046]
Further, depending on the form of the electron emission portion obtained as a result, there may be a problem in the electron emission characteristics such as an increase in applied voltage (threshold voltage) that can emit electrons.
In the present invention, the material of the conductive thin film 4 is not particularly required to have a high melting point, and a material / form that can form a good electron emission portion with a relatively low forming power can be selected.
[0047]
As an example of a material that satisfies the above conditions, a conductive material such as Ni, Au, PdO, Pd, or Pt is formed with a film thickness in which Rs (sheet resistance) exhibits a resistance value of 10 2 to 10 7 Ω / □. What has been used is preferably used. Rs is a value that appears when the resistance R measured in the length direction of a thin film having a thickness of t, a width of w, and a length of l is expressed as R = Rs (l / w), and the resistivity is represented by ρ. Then, Rs = ρ / t. The film thickness showing the resistance value is in the range of about 5 nm to 50 nm, and in this film thickness range, the thin film of each material has the form of a fine particle film.
[0048]
The fine particle film described here is a film in which a plurality of fine particles are aggregated, and the fine structure thereof is a state in which the fine particles are individually dispersed and arranged, or a state in which the fine particles are adjacent to each other or overlap each other (some fine particles are aggregated, Including the case where an island-like structure is formed as a whole).
[0049]
The particle diameter of the fine particles is in the range of several hundred pm to several hundred nm, preferably in the range of 1 nm to 20 nm.
Among the materials exemplified above, PdO can be easily formed into a thin film by firing an organic Pd compound in the air, and since it is a semiconductor, it has a relatively low electrical conductivity and a film for obtaining a resistance value Rs in the above range. It is a suitable material because it has a wide thickness process margin and can be easily reduced to metal Pd after forming a gap in the conductive thin film, so that the film resistance can be reduced. However, the effects of the present invention are not limited to PdO, and are not limited to the materials exemplified above.
[0050]
The length of the electron emitting portion 5 is substantially determined by the width W ′ of the conductive thin film 4.
The electron emission portion 5 is a film having carbon facing the first gap 8 which is narrower than the second gap formed in the conductive thin film as shown in FIG. 21 and 22.
[0051]
The carbon-containing films 21 and 22 are mainly made of graphite-like carbon, but may contain elements constituting the conductive thin film 4.
The width of the second gap 8 formed by the deposits 21 and 22 containing carbon as a main component in the present invention is the deposit 22 containing carbon as a main component, as shown in FIGS. Is the distance between the two at the closest location.
[0052]
There are cases where the deposits 21 and 22 are close to each other on the substrate surface (b), and cases where the deposits 21 and 22 are close to each other at a position higher than the substrate surface (c).
In order to describe the electron-emitting device of the present invention in detail, first, a measurement evaluation apparatus will be described with reference to FIG.
[0053]
FIG. 3 is a schematic configuration diagram of a measurement evaluation apparatus for measuring the electron emission characteristics of the device having the configuration shown in FIG. In FIG. 3, 1 is a substrate, 2 and 3 are element electrodes, 4 is a conductive thin film, and 5 is an electron emission portion. In addition, 31 is a power source for applying the element voltage Vf to the element, 30 is an ammeter for measuring the element current If flowing through the conductive thin film 4 between the element electrodes 2 and 3, and 34 is from the electron emission portion of the element An anode electrode for capturing the emission current Ie to be emitted, 33 is a high voltage power source for applying a voltage to the anode electrode 34, and 32 is a current for measuring the emission current Ie emitted from the electron emission portion 5 of the device. It is a total.
[0054]
In measuring the device current If and the emission current Ie of the current emitting device, a power source 31 and an ammeter 30 are connected to the device electrodes 2 and 3, and a power source 33 and an ammeter 32 are connected above the electron emitting device. The anode electrode 34 is disposed. The electron-emitting device and the anode electrode 34 are installed in a vacuum device.
[0055]
In FIG. 3, when a voltage is applied between the device electrodes 2 and 3 so that the device electrode 3 is at a high potential, the voltage is applied between the deposit 21 and the deposit 22 shown in FIG. A potential difference is generated according to the applied voltage. At this time, a strong electric field is generated around the closest position of the deposit 21 and the deposit 22. When this electric field is large enough to allow tunneling of electrons from the deposit 21 to the deposit 22, electrons tunnel from the deposit 21 toward the deposit 22, and the tunneled electrons are transferred to the deposit 22 on the positive electrode side. It is elastically scattered and emits electrons into the vacuum.
[0056]
Various methods are conceivable as a method of manufacturing the electron-emitting device, and an example is shown in FIG.
In the following, the manufacturing method will be described based on FIGS. 1, 2 and 7 in order.
[0057]
1) After the substrate 1 is sufficiently washed with a detergent, pure water and an organic solvent, an element electrode material is deposited by a vacuum deposition method, a sputtering method or the like, and then element electrodes 2 and 3 are formed by a photolithography technique (FIG. 7 ( a)).
[0058]
2) An organometallic film is formed by applying and drying an organometallic solution between the device electrode 2 and the device electrode 3 provided on the substrate 1. The organometallic solution is a solution of an organometallic compound containing a metal such as Pd, Ni, Au, or Pt as a main element. Thereafter, the organometallic film is heated and fired and patterned by lift-off, etching, or the like to form the conductive thin film 4 (FIG. 7B). Here, the application method of the organometallic solution has been described, but the present invention is not limited to this, and it is formed by a vacuum deposition method, a sputtering method, a CVD method, a dispersion coating method, a dipping method, a spinner method, an inkjet method, or the like. In some cases.
[0059]
3) Subsequently, when an energization process called forming is performed by applying a pulsed voltage or a boosted voltage between the device electrodes 2 and 3 by a power source (not shown), a gap 7 is formed in a part of the conductive thin film 4. A conductive thin film is formed so as to face the substrate surface in the lateral direction with the gap 7 interposed therebetween (FIG. 7C). The gap 7 may be connected at a part thereof.
[0060]
The electrical processing after the forming processing is performed in the measurement evaluation apparatus shown in FIG.
The measurement evaluation apparatus shown in FIG. 3 is a vacuum apparatus, and the vacuum apparatus includes equipment necessary for a vacuum apparatus such as an exhaust pump and a vacuum gauge (not shown). Can be measured and evaluated. The exhaust pump includes a high vacuum apparatus system such as a magnetic levitation turbo pump and a dry pump that does not use oil, and an ultra high vacuum apparatus system that includes an ion pump. In addition, this measuring apparatus is provided with a gas introducing device (not shown), and vapor of a desired organic substance can be introduced into the vacuum device at a desired pressure. Further, the entire vacuum device and the electron-emitting device can be heated by a heater (not shown).
[0061]
The forming process includes a case where a pulse having a constant pulse peak value is applied and a case where a voltage pulse is applied while increasing the pulse peak value. First, FIG. 8A shows a voltage waveform when a pulse having a constant peak value is applied.
[0062]
In FIG. 8A, T1 and T2 are the pulse width and pulse interval of the voltage waveform, T1 is set to 1 μsec to 10 msec, T2 is set to 10 μsec to 100 msec, and the peak value of the triangular wave (peak voltage at the time of forming) is appropriately selected. To do.
[0063]
Next, FIG. 8B shows a voltage waveform when a voltage pulse is applied while increasing the pulse peak value.
In FIG. 8B, T1 and T2 are the pulse width and pulse interval of the voltage waveform, T1 is 1 μsec to 10 msec, T2 is 10 μsec to 100 msec, and the peak value of the triangular wave (peak voltage at the time of forming) is, for example, Increase by about 0.1V step.
[0064]
The forming process is completed by inserting a voltage that does not cause local destruction or deformation of the conductive thin film 4 between the forming pulses, for example, a pulse voltage of about 0.1 V, and measuring the element current to determine the resistance value. For example, when a resistance of 1 MΩ or more is indicated, the forming is terminated.
[0065]
When forming the gap 7 described above, a forming process is performed by applying a triangular wave pulse between the electrodes of the element. However, the waveform applied between the electrodes of the element is not limited to the triangular wave, but a rectangular wave or the like. A desired waveform may be used, and the peak value, pulse width, pulse interval, etc. are not limited to the above values, but according to the resistance value of the electron-emitting device so that the gap 7 can be satisfactorily formed. Select an appropriate value.
[0066]
The first gap of the conductive thin film formed by the above forming is two-dimensionally arranged (meandering) on the substrate as shown in FIG.
4) Next, an activation process is performed on the element for which forming has been completed. The activation process is performed by introducing a gas of an organic substance into the vacuum apparatus shown in FIG. 3 and applying a voltage between the electrodes of the element in an atmosphere containing organic molecules. Along with the alteration, a film containing carbon is deposited on the element from an organic substance present in the atmosphere, and the element current If and the emission current Ie change remarkably.
[0067]
In the present invention, it is necessary to deposit a film containing carbon by an activation process to form the gap 8 having a desired value interval with good control. The interval of the gap 8 depends on the voltage waveform applied to the element, the pressure of the organic substance to be introduced, the diffusion mobility on the element surface, the average residence time on the element surface, and the like. Ease of handling such as ease of introduction into a vacuum apparatus and ease of exhaustion after activation is also important. From the above viewpoint, as a result of examining various organic substances, it was found that the tolunitrile compound is effective. The reason why the tolunitrile compound is preferably used is not exactly understood, but it is considered that the adsorption state on the element surface via the nitrile group (—C≡N) is in conformity with the above conditions.
[0068]
Below, the formation process of the deposit which is a film | membrane which has carbon in the activation process of this invention is demonstrated using FIG. In FIG. 9, 1 is a substrate, 2 and 3 are element electrodes, 4 is a conductive thin film, 7 is a first gap formed in the conductive thin film, 21 and 22 are deposits which are films containing carbon, and 8 A narrower second gap formed within the first gap by deposits 21,22.
[0069]
FIG. 9A schematically shows the vicinity of the electron emission portion of the electron-emitting device before the activation process. In addition, the element is once 10^-6The pressure is reduced to a pressure on the order of Pa, and is then placed in a vacuum apparatus into which an organic substance gas is introduced (FIG. 3). Here, a case where trinitrile is used as an organic substance will be described as an example. The suitable pressure of tolunitrile to be introduced is slightly affected by the shape of the vacuum apparatus and the members used in the vacuum apparatus, but 1 × 10^-FivePa ~ 1 × 10^-3It is about Pa.
[0070]
In the activation step (step of depositing a carbon-containing film), it is applied between the device electrodes 2 and 3 (gap 7). As a result, the organic substance in the atmosphere starts to be deposited in the gap 7 and on the conductive thin film 4 in the vicinity thereof. In this process, the deposits 21 and 22 are simultaneously deposited in the direction perpendicular to the paper surface.
[0071]
Further, when the activation process is continued, the carbon-containing film forms a gap between the second gaps 8 and is almost fixed, and the activation process is finished (FIG. 9B).
Here, the interval between the second gaps 8 tends to become wider as the voltage applied for the activation process is larger. The size of the interval depends on the type of organic substance introduced during the activation process, It also changes depending on the partial pressure.
[0072]
Next, the carbon of the deposits 21 and 22 which is a film having carbon in the present invention will be described.
Carbon in the present invention has a complete graphite crystal structure (so-called HOPG), has a crystal grain of about 20 nm and has a slightly disturbed crystal structure (PG), or has a crystal grain of about 2 nm and has a disordered crystal structure. Further increased ones (GC), amorphous carbon (refers to amorphous carbon and a mixture of amorphous carbon and the above-mentioned microcrystals of graphite). That is, it can be preferably used even if there is a disorder of the layer such as a grain boundary between graphite particles.
[0073]
6) A stabilization process is preferably performed on the electron-emitting device thus manufactured. This step is a step of exhausting the organic substance in the vacuum vessel. Although it is desirable to eliminate the organic substance in the vacuum vessel as much as possible, the partial pressure of the organic substance is 1 to 3 × 10.^-8Pa or less is preferable. The pressure including other gases is 1 to 3 × 10.^-6Pa or less is preferable, and further 1 × 10^-7Pa or less is particularly preferable. A vacuum exhaust device that exhausts the vacuum vessel uses a device that does not use oil so that the oil generated from the device does not affect the characteristics of the element. Specifically, vacuum exhaust apparatuses such as a sorption pump and an ion pump can be used. Further, when the inside of the vacuum vessel is evacuated, the whole vacuum vessel is heated so that the organic substance molecules adsorbed on the inner wall of the vacuum vessel and the electron-emitting device can be easily evacuated. The heating conditions at this time are preferably 150 to 350 ° C., preferably 200 ° C. or higher, for as long as possible. However, the heating conditions are not particularly limited to this, and the size and shape of the vacuum vessel, the arrangement of the electron-emitting devices, etc. It is performed under conditions appropriately selected according to various conditions.
[0074]
The atmosphere at the time of driving after the stabilization process is preferably maintained at the end of the stabilization process, but is not limited to this, and the pressure itself is sufficient if the organic substance is sufficiently removed. Can maintain sufficiently stable characteristics even if it rises somewhat.
[0075]
By adopting such a vacuum atmosphere, the deposition of new carbon or carbon compounds can be suppressed, so that the shape of the film containing carbon of the present invention is maintained, and as a result, the device current If and the emission current Ie are stabilized.
[0076]
The basic characteristics of an electron-emitting device to which the present invention can be applied manufactured by the manufacturing method as described above will be described with reference to FIGS. FIG. 10 shows the current-voltage characteristics of the electron-emitting device.
[0077]
FIG. 10 shows typical examples of the emission current Ie, the device current If, and the device voltage Vf of the device after stabilization measured by the measurement evaluation apparatus shown in FIG. In FIG. 8, since the emission current Ie is remarkably smaller than the device current If, it is shown in arbitrary units, and both are linear scales. As is clear from FIG. 10, the electron-emitting device has three properties with respect to the emission current Ie.
[0078]
First, when an element voltage higher than a certain voltage (referred to as threshold voltage, Vth in FIG. 10) is applied to the element, the emission current Ie increases abruptly. On the other hand, the emission current decreases below the threshold voltage Vth. Ie is hardly detected. That is, it is a non-linear element having a clear threshold voltage Vth with respect to the emission current Ie.
[0079]
Second, since the emission current Ie depends on the element voltage Vf, the emission current Ie can be controlled by the element voltage Vf.
Thirdly, the emitted charge trapped by the anode electrode 34 depends on the time during which the device voltage Vf is applied. That is, the amount of charge trapped by the anode electrode 34 can be controlled by the time during which the element voltage Vf is applied.
[0080]
Next, energy distribution measurement of electrons emitted from the device into the vacuum will be described.
FIG. 6 is a schematic explanatory diagram showing a commonly used quadrupole energy analyzer. Although not shown in the figure, the apparatus is placed in a vacuum vessel. The vacuum atmosphere in the vacuum vessel is an ultra-high vacuum atmosphere that is almost the same as that in the stabilization process, and is formed in vacuum by the oil-free vacuum pump described above.
[0081]
In FIG. 6, 60 is an electron-emitting device, 61, 62, 63 and 64 are electrodes for energy analysis, 65 is a power source for applying a voltage to the electrode 61, 66 is a power source for applying a voltage to the electrode 64, 67 is a power source for applying a voltage to the electrode 62 and the electrode 63. The electrode 61, the electrode 62, and the electrode 63 have a structure in which a large number of holes are opened so that electrons pass through each electrode.
[0082]
The electrode 61, the electrode 62, the electrode 63, and the electrode 64 have a hemispherical shape, and an electron-emitting device is placed at the center thereof. The electrons emitted from the electron-emitting device enter the energy analyzer (the above four electrodes) by setting the voltage of the electrode 61 appropriately. Although the details of the energy analysis method are omitted, the energy analysis of the electrons emitted from the electron-emitting device is performed by measuring the amount of current that the incident electrons are modulated by the voltage applied to the electrodes 62 and 63 and reach the electrodes 64. Done.
[0083]
Next, an actually used voltage (a voltage that generates an emission current with sufficient brightness in the case of an image display device) is applied to the electron-emitting device to generate an electron (current) Ie1 that is emitted into the vacuum, thereby generating an emission current. Measure the energy distribution. The half width of the energy distribution at this time is HW1. Subsequently, the drive voltage is reduced so as to be a quarter of Ie1, and the energy distribution is measured. The half-value width of the energy distribution at this time is HW2. The ratio of half widths (HW2 / HW1) is calculated. An electron-emitting device having the half-width ratio (HW2 / HW1) of 0.8 or more and 1.0 or less has a high electron emission efficiency.
[0084]
The voltage applied to the electron-emitting device is not limited to this, and may be set in the vicinity of the voltage for actually driving the electron-emitting device.
In order to set the ratio of the half width of the energy distribution to 0.8 or more and 1.0 or less, it can be obtained by performing an appropriate activation using an organic substance of tolunitrile in the activation step described above. The reason why the device manufactured in this activation process falls within the above-described half-width ratio range and a device with high efficiency is not clearly understood, but the following is presumed.
[0085]
The carbon formed in the electron emission part in the above-described activation process has a large amount of carbon formed not only on the electron emission part but also on the conductive thin film and is excellent in conductivity. Therefore, since the applied voltage is efficiently applied to the second carbon gap, the energy of electrons emitted from the negative electrode side carbon of the electron emission portion is high, and the scattering efficiency of carbon on the positive electrode side is high. It is considered to be obtained. Such an element is considered to be capable of obtaining an efficient element with a small change in energy distribution even if the voltage applied to the element is changed.
[0086]
Conventionally, when the activation process is performed without using an organic substance of tolunitrile, the conductive thin film is formed unevenly or the length of the first gap in the forming process is formed unevenly in the device. In some cases, the half-value width of the energy distribution may differ depending on the amount of emission current, and an element with poor efficiency may be formed. In the present invention, by performing appropriate activation using an organic substance of tolunitrile as an activation material, a device in which the half-value width of energy changes with the amount of emission current is small, and as a result, electron emission efficiency is obtained. An element with a high height is obtained.
[0087]
In addition, the ratio of the half-value width of the energy distribution described above is not only obtained by optimizing the activation process, for example, optimization of the conductive thin film and the forming process. It is thought that it can be obtained by doing.
[0088]
If the characteristics of the electron-emitting device as described above are used, the electron-emitting characteristics can be easily controlled according to the input signal. Furthermore, since the electron-emitting device according to the present invention has stable and high-brightness electron emission characteristics, it can be expected to be applied to various fields.
[0089]
Application examples of the electron-emitting device to which the present invention can be applied will be described below.
A plurality of electron-emitting devices according to the present invention can be arranged on a substrate to constitute, for example, an electron source or an image forming apparatus.
[0090]
With respect to the arrangement of elements on the substrate, for example, a large number of electron-emitting devices are arranged in parallel, and a plurality of rows of electron-emitting devices in which both ends of each element are connected by wiring (referred to as a row direction) are arranged. An arrangement form (called a ladder type) in which electrons are controlled and driven by a control electrode (called a grid) installed in a space above the electron source in a direction perpendicular to the wiring (called a column direction), and then On the m X-direction wirings to be described, n Y-direction wirings are installed via an interlayer insulating layer, and the X-direction wirings and the Y-direction wirings are respectively connected to a pair of element electrodes of the surface conduction electron-emitting device. A sequence form is mentioned. This is hereinafter referred to as a simple matrix arrangement.
[0091]
Next, this simple matrix arrangement will be described in detail.
According to the characteristics of the above-mentioned three basic characteristics of the surface conduction electron-emitting device according to the present invention, electrons emitted from the surface conduction electron-emitting device are applied between the device electrodes facing each other at a threshold voltage or higher. It can be controlled by the peak value and width of the pulse voltage. On the other hand, it is hardly emitted below the threshold voltage. According to this characteristic, even when a large number of electron-emitting devices are arranged, a surface conduction electron-emitting device can be selected according to an input signal by appropriately applying the pulse voltage to each device, and the electron The amount of release can be controlled.
[0092]
Hereinafter, the configuration of the electron source substrate configured based on this principle will be described with reference to FIG.
The m X-directional wirings 102 are made of DX1, DX2,..., DXm, and are formed on the substrate 1 by a vacuum evaporation method, a printing method, a sputtering method, or the like, and made of a conductive metal or the like having a desired pattern. The material, film thickness, wiring width, etc. are designed so that a substantially uniform voltage is supplied to a large number of surface conduction electron-emitting devices. Between these m X-direction wirings 102 and n Y-direction wirings 103, an interlayer insulating layer (not shown) is installed and electrically separated to form a matrix wiring (both m and n are both Positive integer).
[0093]
The interlayer insulating layer (not shown) is made of SiO formed by vacuum deposition, printing, sputtering, etc.₂The film is formed in a desired shape on the entire surface or a part of the substrate 101 on which the X-direction wiring 102 is formed, and in particular, a film so as to withstand the potential difference at the intersection of the X-direction wiring 102 and the Y-direction wiring 103. The thickness, material, and manufacturing method are appropriately set. The X-direction wiring 102 and the Y-direction wiring 103 are drawn out as external terminals, respectively.
[0094]
Further, in the same manner as described above, opposing electrodes (not shown) of the surface conduction electron-emitting device 104 include m X-direction wirings 102 (DX1, DX2,..., DXm) and n Y-direction wirings 103 (DY1). , DY2,..., DYn) and a connection 105 made of a conductive metal or the like.
[0095]
Here, the conductive metals of the element electrodes facing the m X-directional wirings 102, the n Y-directional wirings 103, and the connection 105 are different from each other even if some or all of the constituent elements are the same. May be. These materials are appropriately selected from, for example, the above-described element electrode materials.
[0096]
Although not described in detail later, the X-direction wiring 102 is not shown for applying a scanning signal for scanning a row of surface conduction electron-emitting devices 104 arranged in the X direction according to an input signal. On the other hand, a modulation signal for modulating each column of surface conduction electron-emitting devices 104 arranged in the Y direction according to an input signal is applied to the Y direction wiring 103. Electrically connected to a modulation signal generating means (not shown).
[0097]
Further, the driving voltage applied to each element of the surface conduction electron-emitting device is supplied as a differential voltage between the scanning signal and the modulation signal applied to the element.
Next, an example of an electron source using the electron source substrate manufactured as described above and an image forming apparatus used for display or the like will be described with reference to FIGS. FIG. 13 is a basic configuration diagram of the image forming apparatus, and FIG. 14 is a fluorescent film.
[0098]
In FIG. 13, reference numeral 101 denotes an electron source substrate on which a plurality of electron-emitting devices are arranged, 111 denotes a rear plate on which the electron source substrate 101 is fixed, and 116 denotes a face in which a fluorescent film 114 and a metal back 115 are formed on the inner surface of a glass substrate 113. It is a plate. Reference numeral 112 denotes a support frame. The rear plate 111, the support frame 112, and the face plate 116 are coated with frit glass, and sealed in the air or in nitrogen at 400 to 500 ° C. for 10 minutes or more. Thus, the envelope 118 is configured.
[0099]
In FIG. 13, reference numeral 104 corresponds to the surface conduction electron-emitting portion shown in FIG. Reference numerals 102 and 103 denote an X-direction wiring and a Y-direction wiring connected to a pair of device electrodes of the surface conduction electron-emitting device. In addition, the wiring to these element electrodes may be referred to as element electrodes when the element electrodes and the wiring material are the same.
[0100]
As described above, the envelope 118 is configured by the face plate 116, the support frame 112, and the rear plate 111. However, the rear plate 111 is provided mainly for the purpose of reinforcing the strength of the substrate 101, and therefore, the substrate 91 itself. In the case of sufficient strength, the separate rear plate 111 is not necessary. Even if the support frame 112 is sealed directly to the substrate 101, the envelope 118 is configured by the face plate 116, the support frame 112, and the substrate 101. Good.
[0101]
On the other hand, by installing a support body (not shown) called a spacer between the face plate 116 and the rear plate 111, the envelope 118 having sufficient strength against atmospheric pressure can be configured.
[0102]
FIG. 14 shows a fluorescent film. In the case of a monochrome film, the fluorescent film 114 is made of only a fluorescent material. In the case of a color fluorescent film, the fluorescent film 114 is composed of a black conductive material 121 and a fluorescent material 122 called a black stripe or a black matrix depending on the arrangement of the fluorescent materials. . The purpose of providing the black stripes and the black matrix is to make the mixed colors and the like inconspicuous by making the separate portions between the phosphors 122 of the three primary color phosphors necessary for color display, and in the phosphor film 114 The purpose is to suppress a decrease in contrast due to external light reflection. The material of the black stripe is not limited to the material which is not only a material mainly composed of graphite, which is usually used well, but also a material having conductivity and low light transmission and reflection.
[0103]
As a method of applying the phosphor on the glass substrate 113, a precipitation method, a printing method, or the like is used regardless of monochrome or color.
A metal back 115 is usually provided on the inner surface side of the fluorescent film 114. The purpose of the metal back is to improve the brightness by specularly reflecting the light emitted from the phosphor toward the inner surface to the face plate 116 side, to act as an electrode for applying an electron beam acceleration voltage, For example, the phosphor is protected from damage caused by the collision of negative ions generated in the envelope. The metal back can be produced by performing a smoothing process (usually called filming) on the inner surface of the phosphor film after the phosphor film is produced, and then depositing Al using vacuum evaporation or the like.
[0104]
The face plate 116 may be provided with a transparent electrode (not shown) on the outer surface side of the fluorescent film 114 in order to further increase the conductivity of the fluorescent film 114.
When performing the above-described sealing, in the case of a color, it is necessary to correspond to each color phosphor and the electron-emitting device, so that sufficient alignment is required.
[0105]
The envelope 118 is 1 × 10 through an exhaust pipe (not shown).^-7Sealing is performed after a vacuum level of about Torr. In addition, a getter process may be performed in order to maintain the degree of vacuum after the envelope 118 is sealed. This is because the getter disposed at a predetermined position (not shown) in the envelope 118 is heated by a heating method such as resistance heating or high-frequency heating immediately before or after sealing the envelope 118. This is a process for forming a deposited film. The getter is usually composed mainly of Ba or the like, and, for example, 1 × 10 6 by the adsorption action of the deposited film.^-FiveOr 1 × 10^-7The degree of vacuum of Torr is maintained.
[0106]
In the image display device of the present invention completed as described above, each electron-emitting device is caused to emit electrons by applying a voltage through the container outer terminals Dox1 to Doxm, Doy1 to Doyn, and through the high voltage terminal 117 to the metal back 115. Alternatively, an image is displayed by applying a high voltage of several kV or more to a transparent electrode (not shown), accelerating the electron beam, colliding with the fluorescent film 114, and exciting and emitting light.
[0107]
The above-described configuration is a schematic configuration necessary for producing a suitable image forming apparatus used for display or the like. For example, detailed portions such as materials of each member are not limited to the above-described contents. It selects suitably so that it may suit the use of an image forming apparatus.
[0108]
Next, a configuration example of a driving circuit for performing television display based on an NTSC television signal on a display panel configured using an electron source having a simple matrix arrangement will be described with reference to FIG.
[0109]
FIG. 15 is a block diagram showing an example of a driving circuit for performing display in accordance with an NTSC television signal. In FIG. 15, 131 is a display panel, 132 is a scanning signal generation circuit, 133 is a timing control circuit, Reference numeral 134 denotes a shift register. Reference numeral 135 is a line memory, 136 is a synchronizing signal separation circuit, 137 is a modulation signal generating circuit, and Vx and Va are DC voltage sources.
[0110]
The display panel 131 is connected to an external electric circuit via terminals Dox1 to Doxm, terminals Doy1 to Doyn, and a high voltage terminal Hv. For the terminals Dox1 to Doxm, in order to sequentially drive one row (n elements) of an electron source provided in the display panel, that is, a group of surface conduction electron-emitting devices arranged in a matrix of m rows and n columns. The scanning signal is applied. Modulation signals for controlling the output electron beams of the surface conduction electron-emitting devices in one row selected by the scanning signal are applied to the terminals Doy1 to Doyn. The high-voltage terminal Hv is supplied with a DC voltage of, for example, 10 kV from the DC voltage source Va, which gives sufficient energy to excite the phosphor to the electron beam emitted from the surface conduction electron-emitting device. It is an acceleration voltage to do.
[0111]
The scanning signal generation circuit 132 includes m switching elements therein (schematically indicated by S1 to Sm in the drawing). Each switching element selects either the output voltage of the DC voltage source Vx or 0 V (ground level), and is electrically connected to the terminals Dox1 to Doxm of the display panel 131. Each of the switching elements S1 to Sm operates based on a control signal Tscan output from the control circuit 133, and can be configured by combining switching elements such as FETs.
[0112]
In the case of this example, the direct current voltage source Vx has a driving voltage applied to an element not scanned based on the characteristics (electron emission threshold voltage) of the surface conduction electron-emitting element. Is set to output a constant voltage.
[0113]
The timing control circuit 133 has a function of matching the operation of each unit so that appropriate display is performed based on an image signal input from the outside. The timing control circuit 133 generates Tscan, Tsft, and Tmry control signals for each unit based on the synchronization signal Tsync sent from the synchronization signal separation circuit 136.
[0114]
The synchronization signal separation circuit 136 is a circuit for separating a synchronization signal component and a luminance signal component from an NTSC television signal input from the outside, and can be configured using a general frequency separation (filter) circuit or the like. The synchronization signal separated by the synchronization signal separation circuit 136 includes a vertical synchronization signal and a horizontal synchronization signal, but is illustrated here as a Tsync signal for convenience of explanation. The luminance signal component of the image separated from the television signal is expressed as a DATA signal for convenience. The DATA signal is input to the shift register 134.
[0115]
The shift register 134 is for serial / parallel conversion of the DATA signal input serially in time series for each line of the image, and operates based on the control signal Tsft sent from the timing control circuit 133. (That is, the control signal Tsft can be said to be a shift clock of the shift register 134). Data for one line (corresponding to drive data for N electron-emitting devices) subjected to serial / parallel conversion is output from the shift register 134 as N parallel signals ld1 to ldn.
[0116]
The line memory 135 is a storage device for storing data for one line of an image for a necessary time, and appropriately stores the contents of ld1 to ldn according to a control signal Tmry sent from the timing control circuit 133. The stored contents are output as l′ d1 to l′ dn and input to the modulation signal generator 107.
[0117]
The modulation signal generator 137 is a signal source for appropriately driving and modulating each of the surface conduction electron-emitting devices according to each of the image data l′ d1 to l′ dn, and an output signal thereof is output from the terminals Doy1 to Doy1. The voltage is applied to the surface conduction electron-emitting device in the display panel 131 through Doyn.
[0118]
As described above, the electron-emitting device to which the present invention can be applied has the following basic characteristics with respect to the emission current Ie. That is, there is a clear threshold voltage Vth for electron emission, and electron emission occurs only when a voltage equal to or higher than Vth is applied. For voltages above the electron emission threshold, the emission current also changes with changes in the voltage applied to the device. For this reason, when a pulsed voltage is applied to the device, for example, electron emission does not occur even when a voltage lower than the electron emission threshold is applied, but when a voltage higher than the electron emission threshold is applied, the electron beam is not Is output. At that time, the intensity of the output electron beam can be controlled by changing the pulse peak value Vm. Further, it is possible to control the total amount of charges of the output electron beam by changing the pulse width Pw. Therefore, a voltage modulation method, a pulse width modulation method, or the like can be adopted as a method for modulating the electron-emitting device in accordance with the input signal.
[0119]
When implementing the voltage modulation method, a voltage modulation method circuit is used as the modulation signal generator 137, which generates a voltage pulse of a certain length and appropriately modulates the peak value of the pulse according to the input data. be able to.
[0120]
When implementing the pulse width modulation method, the modulation signal generator 137 generates a voltage pulse having a constant peak value and modulates the width of the voltage pulse as appropriate according to the input data. A circuit can be used.
[0121]
The shift register 134 and the line memory 135 can adopt either a digital signal type or an analog signal type. This is because the serial / parallel conversion and storage of the image signal may be performed at a predetermined speed.
[0122]
When the digital signal system is used, it is necessary to convert the output signal DATA of the synchronization signal separation circuit 136 into a digital signal. For this purpose, an A / D converter may be provided at the output unit 136. In this connection, the circuit used in the modulation signal generator 137 is slightly different depending on whether the output signal of the line memory 135 is a digital signal or an analog signal. That is, in the case of a voltage modulation method using a digital signal, for example, a D / A conversion circuit is used as the modulation signal generator 137, and an amplifier circuit or the like is added as necessary. In the case of the pulse width modulation method, the modulation signal generator 137 includes, for example, a high-speed oscillator and a counter that counts the wave number output from the oscillator, and a comparator that compares the output value of the counter with the output value of the memory A circuit combining (comparators) is used. If necessary, an amplifier can be added to amplify the voltage of the pulse width modulated modulation signal output from the comparator to the driving voltage of the surface conduction electron-emitting device.
[0123]
In the case of a voltage modulation method using an analog signal, for example, an amplifier circuit using an operational amplifier or the like can be adopted as the modulation signal generator 137, and a bell shift circuit or the like can be added if necessary. In the case of the pulse width modulation method, for example, a voltage controlled oscillation circuit (VCO) can be adopted, and an amplifier for amplifying the voltage up to the driving voltage of the surface conduction electron-emitting device can be added as necessary.
[0124]
In the image display apparatus to which the present invention that can take such a configuration can be applied, electron emission occurs by applying a voltage to each electron-emitting device via the external terminals Dox1 to Doxm and Doy1 to Doyn. A high voltage is applied to the metal back 115 or the transparent electrode (not shown) via the high voltage terminal Hv to accelerate the electron beam. The accelerated electrons collide with the fluorescent film 114, light is emitted, and an image is formed.
[0125]
The configuration of the image forming apparatus described here is an example of an image forming apparatus to which the present invention can be applied, and various modifications can be made based on the technical idea of the present invention. As for the input signal, the NTSC system is mentioned, but the input signal is not limited to this, and other than this, the PAL, SECAM system, and the like, more than this, the TV signal (for example, the MUSE system is used). High-definition TV) can also be adopted.
[0126]
The image forming apparatus of the present invention can be used as an image forming apparatus as an optical printer configured using a photosensitive drum or the like in addition to a display apparatus for a television broadcast, a video conference system, a computer, or the like. it can.
[0127]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
(Examples 1, 2, and 3)
The basic structure of the electron-emitting device according to the present embodiment is shown in the plan view and cross-sectional view of FIGS. 1A and 1B, and the enlarged plan view and cross-section of FIGS. 2A and 2B. It is the same as the figure.
[0128]
The manufacturing method of the surface conduction electron-emitting device according to this example is basically the same as that shown in FIGS. Hereinafter, the basic structure and manufacturing method of the element according to the present embodiment will be described with reference to FIGS. 1, 2, 7, and 8.
[0129]
Hereinafter, the manufacturing method will be described in order based on FIGS. 1, 2, 7, and 8.
Step-a
First, SiO on the cleaned blue plate substrate₂On the substrate 1 having a thickness of 1 μm, a pattern to be the gap L between the device electrodes is formed with photoresist, and 5 nm thick Ti and 30 nm thick Pt are sequentially deposited by electron beam evaporation. . The photoresist pattern was dissolved in an organic solvent, the Pt / Ti deposited film was wrist-off, and device electrodes 2 and 3 having a device electrode interval L of 20 μm and a device electrode width W of 500 μm were formed (FIG. 7 a).
[0130]
Step-b
A 100 nm thick Cr film is deposited by vacuum deposition and patterned to have an opening corresponding to the shape of the conductive thin film described later, and then an organic palladium compound solution (ccp4230, manufactured by Okuno Pharmaceutical Co., Ltd.) is rotated by a spinner. Application and heat baking treatment at 300 ° C. for 12 minutes were performed. The film thickness of the conductive thin film 4 composed of the fine particles of PdO as the main component thus formed is 6 nm to 15 nm, and the sheet resistance Rs is 0.5 × 10 4 Ω / mouth to 4 × 10 4 Ω / It was a mouth. Note that the fine particle film described here is a film in which a plurality of fine particles are aggregated as described above.
[0131]
Step-c
The Cr film and the fired conductive thin film 4 were etched with an acid etchant to form the conductive thin film 4 having a desired pattern so that the width W ′ of the conductive thin film 4 was 300 μm (FIG. 7B).
[0132]
Through the above steps, the device electrodes 2 and 3 and the conductive thin film 4 were formed on the substrate 1.
In addition, the element of Example 2, 3 and the element of a comparative example were produced according to the completely same process.
[0133]
Step-d
Next, it installs in the measurement evaluation apparatus of FIG. 3, evacuates with a vacuum pump, and 1x10.^-6After reaching the degree of vacuum of Pa, a voltage is applied between the element electrodes 2 and 3 of the element from the power source 31 for applying the element voltage Vf to the element, forming processing is performed, and the first gap is formed in the conductive thin film. 7 was formed. The voltage waveform of the forming process is as shown in FIG. 8A (FIGS. 7C and 9A).
[0134]
In FIG. 8A, T1 and T2 are the pulse width and pulse interval of the voltage waveform. In this example, T1 was set to 1 msec and T2 was set to 16.7 msec, and the forming process was performed. In addition, since each element of Examples 1, 2, 3 and the comparative example is different in resistance value, film shape and film structure of the conductive element film, the maximum voltage value of forming in order to form the gap 7 in the entire element. Changed. After forming, the resistance between the elements was 1 M ohm or more.
Furthermore, hydrogen was introduced into the measurement / evaluation apparatus so as to have a pressure of 100 Pa, and the conductive thin film of this element was reduced to reduce the resistance.
Example 1: Forming voltage 12V
Example 2: Forming voltage 15V
Example 3: Forming voltage 15V
Step-e
Subsequently, the hydrogen introduced in the above step was sufficiently evacuated, and then the measurement evaluation apparatus and element were baked at 200 ° C. for 2 hours. When the temperature returned to room temperature, the degree of vacuum in the measurement evaluation apparatus was measured, and 1 × 10^-6It reached Pa. Here, in order to perform the activation process, tolunitrile is introduced into the vacuum apparatus through a slow leak valve, and 0 × 10^-FourPa to 5.0 × 10^-FourThe pressure of Pa was maintained. One hour after the introduction of tolunitrile, a voltage pulse was applied to the element subjected to the forming treatment via the element electrodes 2 and 3. FIG. 16 shows the waveform of the applied voltage. In Example 1, the applied voltage value was 15V. Energization was stopped 60 minutes after the start of voltage application, the slow leak valve was closed, and the activation process was terminated.
On the other hand, the activation process was performed by applying a voltage to the elements of Examples 2 and 3 subjected to the same forming process as the element of Example 1 under the following conditions.
[0135]
Element of Example 2: The activation process was completed by applying current for 60 minutes at an applied voltage of 16 V under the same conditions as the element of this example.
Device of Example 3: The activation process was completed by applying current at an applied voltage of 16 V for 40 minutes under the same conditions as the device of this example.
[0136]
Further, in this embodiment, the shape of the element electrode as shown in FIG. 11, that is, the oblique structure with respect to the substrate makes the electrical connection between the conductive element film and the electrode stable. This is a desirable structure when the element film is particularly thin.
[0137]
In any element, the element in the vicinity of the gap is subjected to elemental analysis by electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy. Was confirmed to be the main component.
[0138]
Step-f
Subsequently, a stabilization process is performed. While the vacuum device and the electron-emitting device were heated by a heater and maintained at about 300 ° C., the vacuum device was continuously evacuated. After 20 hours, heating with the heater was stopped and the temperature was returned to room temperature.^-8It reached about Pa.
[0139]
Subsequently, electron emission characteristics and energy analysis were measured.
The distance H between the anode electrode 34 and the electron-emitting device was 4 mm, and a potential of 3 kV was applied to the anode electrode 34 by the high voltage power source 33. In this state, a rectangular pulse voltage having a peak value of the final voltage applied during the activation process is applied between the device electrodes 2 and 3 using the power source 31 and driven by the ammeter 30 and the ammeter 32. The device characteristics of this example were evaluated.
[0140]
Moreover, the energy analysis of the electron discharge | released in the vacuum from each electron-emitting element with the energy analyzer shown in FIG. 6 was evaluated. Here, first, the emission current Ie1 from each electron-emitting device is set between 2 μA and 5.0 μA, and the half width HW1 of the energy distribution at that time is measured. Next, the full width at half maximum HW2 was measured by setting the emission current Ie1 to an emission current of ¼.
[0141]
As a result, HW1 of the device of Example 1 was 1.8 eV, HW2 was 1.75 eV, HW2 / HW1 was 0.97, and electron emission efficiency (emission current / device current) was 0.28.
[0142]
The device of Example 2 had HW1 of 2.22 eV, HW2 of 2.0 eV, HW2 / HW1 of 0.9, and electron emission efficiency (emission current / device current) of 0.24.
The device of Example 3 had an HW1 of 2.6 eV, an HW2 of 2.0 eV, an HW2 / HW1 of 0.8, and an electron emission efficiency (emission current / device current) of 0.2.
[0143]
Example 4
This embodiment is an example of an image forming apparatus using an electron source in which a large number of surface conduction electron-emitting devices are arranged in a simple matrix.
[0144]
A plan view of a part of the electron source is shown in FIG. FIG. 18 is a cross-sectional view taken along the line AA ′ in the drawing. However, in FIGS. 17 and 18, the same symbols indicate the same items. Here, 101 is a substrate, 102 is an X-direction wiring (also referred to as a lower wiring) corresponding to DXm in FIG. 12, 103 is a Y-direction wiring (also referred to as an upper wiring) corresponding to DYn in FIG. 2, 3 are element electrodes, 171 is an interlayer insulating layer, and 172 is a contact hole for electrical connection between the element electrode 2 and the lower wiring 102.
[0145]
Next, the manufacturing method will be specifically described according to the order of steps with reference to FIG.
Step-a
After sequentially depositing 5 nm of Cr and 0.6 mm of Au by vacuum deposition on the substrate 1 on which a silicon oxide film having a thickness of 0.5 mm is formed by sputtering on a cleaned blue plate glass, a photoresist is formed. (AZ1370 Hoechst Co., Ltd.) was spin-coated and baked with a spinner, and then the photomask image was exposed and developed to form a resist pattern for the lower wiring 102, and the Au / Cr deposited film was wet etched to obtain a desired shape. The lower wiring 102 is formed (FIG. 19A).
[0146]
Step-b
Next, an interlayer insulating layer 171 made of a silicon oxide film having a thickness of 1.0 μm is deposited by RF sputtering (FIG. 19B).
[0147]
Step-c
A photoresist pattern for forming the contact hole 172 is formed in the interlayer insulating layer 171 deposited in the step-b, and the interlayer insulating layer 171 is etched using this as a mask to form the contact hole 172 (FIG. 19C). .
[0148]
Step-d
Thereafter, a pattern to be the gap L between the device electrode 2 and the device electrode was formed with photoresist, and 5 nm thick Ti and 0.1 mm thick Pt were sequentially deposited by sputtering. The photoresist pattern was dissolved in an organic solvent, the Pt / Ti deposited film was lifted off, and element electrodes 2 and 3 having an element electrode interval L = 20 μm and an element electrode width W = 0.3 mm were formed (FIG. 16D )).
[0149]
Step-e
After forming the photoresist pattern of the upper wiring 103 on the device electrodes 2 and 3, Ti having a thickness of 5 nm and Au having a thickness of 0.5 mm are sequentially deposited by vacuum deposition, and unnecessary portions are removed by lift-off, An upper wiring 103 having a desired shape was formed ((e) of FIG. 20).
[0150]
Step-f
A Cr film 191 having a thickness of 0.1 mm is deposited and patterned by vacuum deposition, and an organic palladium compound solution (ccp4230 manufactured by Okuno Seiyaku Co., Ltd.) is spin-coated with a spinner on the film, and is heated and baked at 300 ° C. for 10 minutes. (F of FIG. 20). The conductive thin film 4 made of fine particles of Pd as the main element thus formed had a thickness of 10 nm and a sheet resistance value of 1 × 10 4 Ω / mouth.
[0151]
Process-g
The Cr thin film 191 and the fired conductive thin film 4 were etched with an acid etchant and lifted off to form a conductive thin film 4 having a desired pattern (FIG. 20 (g)).
[0152]
Step-h
A pattern for applying a resist was formed on portions other than the contact hole 172, and 5 nm thick Ti and 0.5 mm thick Au were sequentially deposited by vacuum evaporation. The contact hole 172 was filled by removing unnecessary portions by lift-off ((h) in FIG. 20).
[0153]
Through the above steps, the lower wiring 102, the interlayer insulating layer 171, the upper wiring element electrodes 2 and 3, and the conductive thin film 4 were formed on the insulating substrate 1.
Next, an example in which an electron source and a display device are configured using the electron source substrate manufactured as described above will be described with reference to FIGS.
[0154]
After the substrate 1 on which the element was manufactured as described above was fixed on the rear plate 111, the face plate 116 (a fluorescent film 114 and a metal back 115 were formed on the inner surface of the glass substrate 113, 5 mm above the substrate 1). Was placed through the support frame 112, frit glass was applied to the joint portion of the face plate 116, the support frame 112, and the rear plate 111, and sealed by baking at 400 ° C. for 10 minutes in the atmosphere. The substrate 1 was fixed to the rear plate 111 with frit glass.
[0155]
In this embodiment, reference numeral 104 in FIG. 10 denotes an electron-emitting device (for example, corresponding to FIG. 5B) before forming the electron-emitting portion, and reference numerals 102 and 103 denote element wirings in the X direction and Y direction, respectively.
[0156]
In the case of monochrome, the phosphor film 114 is made of only a phosphor, but in this embodiment, the phosphor has a stripe shape. First, black stripes were formed, and phosphors of each color were applied to the gaps to produce the phosphor film 114. A material mainly composed of graphite, which is commonly used as a black stripe material, was used. A slurry method was used as a method of applying the phosphor on the glass substrate 113.
[0157]
A metal back 115 is usually provided on the inner surface side of the fluorescent film 114. The metal back was produced by performing a smoothing process (usually called filming) on the inner surface of the phosphor film after producing the phosphor film, and then vacuum-depositing Al.
[0158]
The face plate 116 may be provided with a transparent electrode (not shown) on the outer surface side of the fluorescent film 114 in order to further increase the conductivity of the fluorescent film 114. However, in this embodiment, the metal plate alone is sufficient for conducting. I omitted it because it was good.
[0159]
When performing the above-described sealing, in the case of a color, each color phosphor must correspond to the electron-emitting device, so that sufficient alignment was performed.
The atmosphere in the glass container completed as described above is exhausted by a vacuum pump through an exhaust pipe (not shown), and after reaching a sufficient degree of vacuum, electrons are emitted through the external terminals Doxl to Doxm and Doyl to Doyn. A voltage was applied between the electrodes 2 and 3 of the element 104 to form the conductive thin film 4. The voltage waveform of the forming process is the same as (b) of FIG. The maximum voltage applied during forming was about 14V.
[0160]
In this embodiment, T1 is 1 msec, T2 is 10 msec, and about 1.3 × 10^-3It was performed in a vacuum atmosphere of Pa.
Thereafter, a mixed gas in which hydrogen was diluted to 2% with nitrogen was introduced into the container up to atmospheric pressure, and the conductive thin films of all the elements on the electron source substrate were reduced to reduce the resistance.
[0161]
Subsequently, after sufficiently exhausting the mixed gas of hydrogen and nitrogen introduced in the above step, the entire panel was baked at 200 ° C. for 2 hours. When the pressure in the panel was measured after returning to room temperature, 1 × 10^-6It reached Pa.
Next, the total pressure is 6.0 × 10 through the exhaust pipe of the panel.^-FourTolunitrile was introduced into the panel to maintain Pa and maintained. When two hours have passed since the introduction of tolunitrile, a voltage began to be applied from 10 V between the electrodes 2 and 3 of the electron-emitting device 104 through the container outer terminals Doxl to Doxm and Doyl to Doyn with the same waveform as in FIG. The voltage was increased to 16 V, and then held at a constant voltage of 16 V for 60 minutes, and the process was terminated.
[0162]
In this way, forming and activation processes were performed, and the electron-emitting device 104 was manufactured.
Next, the entire panel is evacuated while being heated to 300 ° C., and the temperature is lowered to room temperature, so that the inside is 10^-7After setting the pressure to about Pa, the exhaust pipe (not shown) was welded by heating with a gas burner to seal the envelope.
[0163]
Finally, in order to maintain the pressure after sealing, getter treatment was performed by a high-frequency heating method.
In the image display device of the present invention completed as described above, a scanning signal and a modulation signal are applied to each electron-emitting device from the signal generation means (not shown) through the external terminals Doxl to Doxm and Doyl to Doyn, respectively. Thus, electrons are emitted, a high voltage of 5 kV or higher is applied to the metal back 115 or the transparent electrode (not shown) through the high-voltage terminal 117, the electron beam is accelerated, collides with the fluorescent film 114, and is excited and emitted. The image was displayed with.
[0164]
The image display apparatus in this example was able to display a good image with high efficiency.
(Example 5)
In this embodiment, an example of a display device configured to be able to display image information provided from various image information sources such as television broadcasting is shown. The image forming apparatus shown in FIG. 13 was displayed according to the NTSC television signal using the drive circuit shown in FIG.
[0165]
In this display device, the depth of the display device can be reduced because the display panel using the surface conduction electron-emitting device as an electron beam source can be easily thinned. In addition, a display panel using a display-conduction electron-emitting device as an electron beam source is easy to enlarge, has high brightness, and excellent viewing angle characteristics. It is possible to display with high visibility.
[0166]
The display device in this example was able to stably display a television image corresponding to the NTSC television signal with high luminance.
[0167]
【The invention's effect】
As described above, according to the electron-emitting device of the present invention, the substrate has a pair of conductive thin films that are electrically connected to the pair of electrodes on the surface of the substrate, respectively. A film having a pair of carbons disposed opposite to each other with a first gap between the pair of electrodes, and facing the second gap in the first gap, In an electron-emitting device in which a carbon-containing film is electrically connected to one of the pair of conductive thin films, and the other carbon-containing film is electrically connected to the other of the pair of conductive thin films. The ratio (HW2 / HW1) of the half-value width HW1 of the energy distribution in the emission current to the half-value width HW2 of the energy distribution in the quarter of the emission current is set to 0.8 or more and 1.0 or less. An electron-emitting device with high emission efficiency can be obtained.
[0168]
Furthermore, in the electron source or the image forming apparatus using the electron-emitting device having high electron-emitting efficiency according to the present invention, even if a large number of electron-emitting devices are arranged, the luminance is very high, and particularly an image using a phosphor. As the display device, an image display device with high luminance and low power consumption was obtained.
[Brief description of the drawings]
1A and 1B are schematic views of an electron-emitting device of the present invention, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view.
FIG. 2 is an enlarged schematic view of the vicinity of an electron emission portion of the present invention, where (a) is a plan view and (b) and (c) are cross-sectional views, respectively.
FIG. 3 is a schematic diagram showing an example of a vacuum processing apparatus having a measurement evaluation function.
FIG. 4 is an energy band diagram for explaining an electron-emitting device of the present invention.
FIG. 5 is an energy distribution diagram of electrons emitted from the electron-emitting device of the present invention.
FIG. 6 is a schematic diagram showing an energy analyzer for measuring the energy distribution of electrons emitted from the electron-emitting device of the present invention.
FIG. 7 is a schematic view showing a part of the manufacturing process of the electron-emitting device of the present invention.
FIG. 8 is a schematic diagram showing an example of a voltage waveform that can be used in a forming process that is a part of the manufacturing process of the electron-emitting device of the present invention.
FIG. 9 is a schematic view showing an activation process which is a part of the manufacturing process of the electron-emitting device of the present invention.
FIG. 10 is a graph showing the relationship between the emission current Ie, device current If, and device voltage Vf of the electron-emitting device of the present invention.
FIG. 11 is a schematic view of an electron-emitting device having an improved electrode shape according to the first embodiment of the present invention.
FIG. 12 is a schematic view showing an example in which the electron-emitting device of the present invention is applied to an electron source arranged in a simple matrix.
FIG. 13 is a schematic view showing an example in which the electron-emitting device of the present invention is applied to an image forming apparatus.
FIG. 14 is a schematic diagram showing an example of a fluorescent film.
FIG. 15 is a block diagram of a driving circuit for performing display in accordance with an NTSC television signal when the electron-emitting device of the present invention is applied to an image forming apparatus.
FIG. 16 is a schematic diagram showing voltage waveforms used in the activation process which is a part of the manufacturing process of the electron-emitting device of the present invention.
FIG. 17 is a schematic view showing an example in which the electron-emitting device of the present invention is applied to an electron source arranged in a simple matrix.
18 is a partial cross-sectional schematic view taken along the polygonal line AA ′ in FIG. 17;
FIG. 19 is a schematic diagram for explaining an electron source manufacturing process according to an embodiment of the present invention.
FIG. 20 is a schematic diagram for explaining an electron source manufacturing process according to an embodiment of the present invention.
FIG. 21 is a schematic view showing a configuration of a conventional electron-emitting device.
FIG. 22 is a schematic diagram showing the configuration of another conventional electron-emitting device.
[Explanation of symbols]
1 Substrate
2, 3 electrodes
4 Conductive thin film
5 Electron emission part
6 Carbon or carbon compounds
7 First gap formed in the conductive thin film
8 Second gap formed in a deposit narrower than the first gap
21, 22 Deposits mainly composed of carbon
30 Ammeter for measuring element current If flowing through the conductive thin film 4 between the element electrodes 2 and 3
31 Power supply for applying device voltage Vf to the electron-emitting device
32 Ammeter for measuring the emission current Ie emitted from the electron-emitting device
33 Voltage power source for applying voltage to the anode electrode 34
34 Anode electrode for accelerating and capturing electrons emitted from the electron-emitting device
60 Electron emitter
61, 62, 63, 64 Electrodes of quadrupole energy analyzer
65, 66, 67 Power supply for applying voltage to the electrodes of the quadrupole energy analyzer
101 Electron source substrate
102 X direction wiring
103 Y-direction wiring
104 Electron emitting device
111 Rear plate
112 Support frame
113 Glass substrate
114 phosphor film
115 metal back
116 face plate
117 High voltage terminal
118 Envelope
121 Black member
122 phosphor
131 Display panel
132 Scanning circuit
133 Control circuit
134 Shift register
135 line memory
136 Sync signal separation circuit
137 Modulation signal generator
Vx, Va DC power supply
171 Interlayer insulation layer
172 Contact hole

Claims (5)

A pair of electrodes disposed on the surface of the substrate, a pair of conductive thin films disposed opposite to each other with a first gap between the pair of electrodes, and a second gap in the first gap. A film having a pair of carbons placed opposite to each other,
One of the pair of conductive thin films is electrically connected to one of the pair of electrodes, and the other of the pair of conductive thin films is electrically connected to the other of the pair of electrodes,
One of the pair of carbon-containing films is electrically connected to one of the pair of conductive thin films, and the other of the pair of carbon-containing films is electrically connected to the other of the pair of conductive thin films. In the electron-emitting device
The electron-emitting half width HW1 the electron energy distribution in the emission current during driving of the element, the ratio of the half width HW2 the electron energy distribution in one-quarter of the emission current of the discharge current (HW2 / HW1) is 0.8 to 1.0, an electron-emitting device,   2. The electron-emitting device according to claim 1, wherein carbon in the carbon-containing film is graphitic carbon. In an electron source having an array form a plurality of electron-emitting devices on a substrate, an electron source, wherein each of said plurality of electron-emitting devices, an electron-emitting device according to claim 1 or 2. In the image forming apparatus having an electron source and an image forming member for forming an image by irradiation with electrons emitted from the electron source, wherein said electron source is an electron source according to claim 3 An image forming apparatus.   5. A television broadcast display device comprising: an image forming device; and a circuit for causing the image forming device to display a television broadcast signal, wherein the image forming device is the image forming device according to claim 4. A display device for television broadcasting, characterized in that there is.

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