JPH10153979A - Display device and aperture for application of electron beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a matrix type electron beam excitation type display device of a high contrast having a many number of scanning lines by using thin film type electron sources as electron releasing elements and making the voltages impressed on the electron releasing elements by pulses smaller than the work function on the surfaces of the time film type electron sources. SOLUTION: The matrix consisting of the thin film type electron sources laminated with lower electrodes 13, insulating layers 12 and upper electrodes 16 to 18 in this order as constituting elements is formed. The matrix is driver in the constitution of scanning pulses and the data pulses based on image signals. The impressed voltages Vd on the thin film type electron sources at the point of the time the scanning pulses are not impressed are made smaller than the work function of the upper electrode surface layer films 18. If, for example, Al is used for the upper electrodes 13, Al2 O3 for the insulating layers 12, Ir as the upper electrode boundary layer films 16, Pt as the intermediate layer films 17 and Au as the surface layer films 18, the work function of the Au is ϕ=4.8V and, therefore, the impressed voltage is merely necessitated to be set at Vd<4.8V.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device using electron-emitting devices arranged in a matrix and an electron beam apparatus.

2. Description of the Related Art As a display device using an electron-emitting device array in which an electron-emitting device is formed at each intersection of an electrode group orthogonal to each other, for example, an electric field using a field-emission electron source array (Field-Emitter Array) as the electron-emitting device Emission display (Field Emission Display, FED) is, for example, The 10th I
nternational Display Research Conference, Proceedi
ngs, pp. 374-377 (1990, vde-verlage). It consists of a substrate on which electron-emitting devices (field emission electron source array) are arranged in a matrix, a phosphor plate that emits light by irradiation with an electron beam, a face plate having an acceleration electrode for accelerating the electron beam, and a drive circuit. You. By applying an appropriate voltage waveform to the MIM-type electron source by the drive circuit, electrons are emitted only from the MIM-type electron source at a desired position, and the emitted electrons cause the phosphor on the face plate to emit light to display an image. .

[0003] Such a display device is a cathode ray tube (CR).
Since an electron beam deflecting lens system as in T) is not required, a flat panel display can be realized, and furthermore, since it is a self-luminous element, excellent display quality comparable to a CRT can be realized.

[0004]

To emit electrons only from a desired electron source among the electron-emitting devices arranged in a matrix, a so-called line-sequential driving method is used. For example, a signal line in a row direction on a substrate is connected to a first electrode (a gate electrode in the case of the known example) of each electron-emitting device, and a signal line in a column direction is connected to a second electrode (a cathode in the case of the known example). Electrode). The emission current from the electron-emitting device when the voltage applied to the electron-emitting device, that is, the voltage between the first electrode and the second electrode is V, is represented by I (V).

The basic operation principle of the line sequential driving method is as follows. A scanning pulse having a voltage amplitude Vs is sequentially applied to each signal line in the row direction, and a voltage amplitude −Vd is applied to each signal line in the column direction.
Is applied. Then, from the electron-emitting device to which the scanning pulse and the data pulse are simultaneously applied, I
A current of (Vs + Vd) is emitted, and a current of I (Vs) is emitted from the electron-emitting device to which only the scanning pulse is applied, and a current of I (Vd) is emitted from the electron-emitting device to which only the data pulse is applied. I (Vs + Vd) is I (Vs), I (V
If it is sufficiently larger than d), electrons are emitted from only the electron-emitting devices at the intersection substantially (that is, the pixel emits light).

The contrast in this case is calculated. The number of scanning lines is N. Assuming that the emission luminance of the phosphor is α times the amount of emission current, the luminance when a certain pixel is turned on is αI
(Vs + Vd). Even if the pixel is not lit, if there are n lit pixels in the column, the voltage Vd is applied n times and the voltage Vs is applied once.
I (Vd) + I (Vs)}. Therefore, in the worst case, the contrast β is β = I (Vs + Vd) / ｛(N−1) I (Vd) + I (V
s) It becomes｝. Therefore, a typical N =
In the case of 480 lines, I (Vs + Vd) / I (Vd) = 1
0 be a ^four, resulting in a contrast β = 20.

The decrease in contrast with an increase in the number N of scanning lines is a disadvantage of the line sequential driving method.
In order to avoid this problem, for example, in the known example, the voltage of the scanning pulse is set to Vs '= Vs + Vd, and the data pulse is set to Vd' = Vd. That is, Vd '= Vd is applied to the electron-emitting devices corresponding to the pixels not to be turned on,
Vd '= 0 is set for a pixel to be turned on. In the field emission electron source, no electrons are emitted even when a voltage of the opposite polarity is applied, so that the contrast does not decrease by the line sequential driving method by this method. However, in this method, since the voltage amplitude of the scanning pulse is increased to Vs + Vd, there is a problem that the load on the driving circuit of the scanning pulse is increased.

The above problem is not limited to a display device but is common to devices using an electron source matrix in which electron-emitting devices are arranged in a matrix. For example, an electron beam exposure apparatus using an electron source matrix is described in JP-A-6-236840. However, in an electron beam exposure apparatus, when a small amount of electrons are emitted from a non-selected electron source, an undesired portion is generated. Exposure would be a major problem.

[0009]

According to the present invention, a thin-film electron source is used as an electron-emitting device, and a voltage applied to the electron-emitting device by a data pulse is smaller than a work function of a surface of the thin-film electron source. By doing so, the above-described problem of the decrease in contrast has been solved.

The thin film type electron source has a structure in which a lower electrode, an insulating layer, and an upper electrode are laminated in this order. FIG. 2 shows an electron energy diagram when a voltage V at which the upper electrode becomes a positive voltage is applied between the lower electrode and the upper electrode. 10MV for insulating layer
When an electric field of about / cm is applied, electrons in the lower electrode flow into the conduction band of the insulating layer due to a tunnel phenomenon, and are accelerated by the electric field. These electrons lose energy due to inelastic scattering or the like in the insulating layer or the upper electrode, but those having energy of work function φ or more at the upper electrode-vacuum interface are emitted into vacuum. This is the emission current I (V). As can be seen from the energy diagram of FIG. 2, when the applied voltage V is equal to or smaller than the work function φ of the surface, there are no electrons having the energy equal to or larger than φ, so that I (V) = 0. Therefore, if the voltage applied between the upper electrode and the lower electrode during the non-application period of the scanning pulse is set to be equal to or less than the work function φ, the number of scanning lines N
The contrast does not decrease even if increases.

As described above, the present invention aims at improving the contrast by utilizing the characteristics of the thin film type electron source. According to this method, the voltage amplitude of the scanning pulse can be minimized, and the voltage amplitude of the data pulse having a large number of pulses and having a large effect on power consumption can be reduced.

In order to use the present invention, I (V) must be sufficiently changed only by changing the applied voltage V to the thin film type electron source by about φ. This can be achieved by reducing the thickness of the insulating layer of the thin-film electron source. FIG. 1 shows the I (V) -V characteristics of a thin film electron source using Al for the lower electrode, Al ₂ O ₃ having a thickness of 5.5 nm for the insulating layer, and Au for the upper electrode. Au work function φ = 4.8eV
In this case, Vd <4.8 V may be set. FIG.
As can be seen from FIG.
(V) changes by four digits, and satisfies the above condition. It is more preferable that the scanning voltage Vs is set smaller than φ in terms of contrast.

As can be seen from the above description, according to the present invention, since electrons are emitted only from the electron source selected by the scanning pulse and the data pulse, a display device such as the electron beam exposure apparatus described above is used. It is also effective other than.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

In the first embodiment, a thin-film electron source (MIM type electron source) is used as an electron-emitting device. This embodiment will be described with reference to FIGS. 3, 4, 5, and 6. FIG. FIG. 4 is a plan view of the display panel viewed from the face plate side, and FIG.
FIG. 4 is a plan view of the device 4 viewed from the face plate side. AB in FIGS. 4 and 5
FIG. 3A is a cross-sectional view of the left half, and FIG. 3B is a cross-sectional view of the left half between the CDs.

First, a method of forming a thin film electron source formed on a substrate will be described. FIG. 6 shows a process for producing a thin-film electron source on the substrate 14. The right column is a plan view,
A cross-sectional view between AB is shown in the left column. Although only one element is illustrated in FIG. 6, actually, the elements are arranged in a matrix as shown in FIGS.

Al is formed as a thin film for forming the lower electrode 13 on the insulating substrate 14 such as glass, for example, to a thickness of 300 nm. For forming the Al film, for example, a sputtering method, a resistance heating evaporation method, an MBE method (molecular beam epitaxy method), or the like is used. Next, the Al film is processed into a stripe shape by photolithography resist formation and subsequent etching to form a lower electrode 13. The resist used here may be any suitable for etching, and the etching may be wet etching,
Any of dry etching is possible. The surface of the lower electrode 13 is anodized to form an insulating layer 12 having a thickness of about 5 to 10 nm. In this embodiment, the formation voltage is set to 4 V, and the thickness of the insulating layer is set to 5.5 nm. This is the state shown in FIG.

Next, a resist 501 is applied, exposed to ultraviolet rays and patterned to form a pattern shown in FIG. 6B. As the resist 501, for example, a quinonediazide-based positive resist is used. With the resist 501 still attached, anodic oxidation is performed again to form the protective layer 15. In the second anodic oxidation, the formation voltage is about 50 V, and the thickness of the protective layer 15 is about 70 nm. This is the state shown in FIG.

After the resist 501 is stripped with an organic solvent such as acetone, a resist 502 is applied and formed in a pattern shown in FIG. Next, a metal film to be the upper electrode bus line 32 is formed on the entire surface of the substrate 14. The metal film serving as the upper electrode bus line 32 has a laminated film configuration in which a metal such as Mo having excellent adhesion to the substrate 14 is used as a lower layer, and a metal such as Au which is rich in electrical conductivity and hardly oxidized is used as an upper layer. It is desirable to form a continuous film by a sputtering method or a vapor deposition method. Materials for the lower layer include Cr, T
Other metals, such as a, W, and Nb, having good adhesion to the insulating substrate may be used. In addition to the Au, Pt, Ir, R
h, Ru etc. can be used. By using these metals, electrical contact with the upper electrode 16 to be formed later can be ensured. The thickness of the metal film forming the upper electrode bus line 32 is appropriately selected according to the required specification of the wiring resistance. In this embodiment, the thickness of the Mo film is 30 nm and the thickness of the Au film is 100 nm. Subsequently, the resist 502 is washed with an organic solvent such as acetone.
Is lifted off to obtain the shape shown in FIG.

Subsequently, a resist 503 is applied, and FIG.
Patterning into the pattern of (f). In this state, anodic oxidation is performed by immersion in a chemical conversion solution. The formation voltage is set to the same voltage as when the insulating layer 12 was formed. In the case of this embodiment, it is 4V. The insulating layer 12 has been slightly damaged by a chemical such as a developing solution in the resist patterning process performed several times so far. Therefore, the damage can be repaired by anodizing the insulating layer 12 again before forming the upper electrode. Thereafter, an upper electrode interface layer film 16, an upper electrode intermediate layer film 17, and an upper electrode surface layer film 18 are formed in this order. It is desirable to use a sputtering method or the like to form these layers, and to continuously form each layer without breaking vacuum. In this embodiment, the upper electrode interface layer film 16 is made of Ir having a thickness of 1 nm, and the upper electrode intermediate layer film 17 is formed.
Pt having a thickness of 2 nm and a film thickness of 3
nm of Au was used. Further, as in the present embodiment, there is a dedicated bus line 32 for supplying an applied voltage to the upper electrode, and when the area of the upper electrode is small, except for the upper electrode surface layer film 18, for example, Ir having a film thickness of 1 nm is used. Upper electrode interface layer film 1 composed
6 and 2 of the upper electrode intermediate layer film 17 composed of Pt having a thickness of 2 nm.
The upper electrode may be composed of layers. As described above, when a material having a high sublimation enthalpy such as Ir is used for a portion in contact with the insulating layer, the life of the thin-film electron source can be extended.

Next, when lift-off is performed with an organic solvent such as acetone, a thin-film electron source having a structure shown in FIG. 6 (g) is obtained. Through the above process, a thin-film electron source is completed on the substrate 14. In this thin-film electron source, electrons are emitted from a region defined by the resist 501. Since the protective layer 15 which is a thick insulating film is formed on the periphery of the electron emitting portion, the upper electrode
The electric field applied between the lower electrodes does not concentrate on the end of the lower electrode, and stable electron emission characteristics can be obtained for a long time.

A transparent glass or the like is used for the face plate 110. First, a black matrix 120 is formed for the purpose of increasing the contrast of the display device (FIG. 3B). The black matrix 120 is arranged between the phosphors 114 in FIG. 4, but is not shown in FIG.

The black matrix 120 is prepared by applying a solution in which graphite powder is mixed with PVA (polyvinyl alcohol) and ammonium bichromate to the face plate 110 and irradiating the black matrix 120 with a UV ray to expose the portion where the black matrix 120 is to be formed. , To remove unexposed portions.

Next, a red phosphor 114A is formed. After applying an aqueous solution in which PVA (polyvinyl alcohol) and ammonium dichromate are mixed to the phosphor particles on the face plate 110, the portions where the phosphors are to be formed are exposed to ultraviolet rays and exposed, and the unexposed portions are flushed with running water. To remove. Thus, the red phosphor 114A is patterned. The pattern is a stripe pattern as shown in FIG. This stripe pattern is just an example.
Depending on the design of the display, for example, an “RGBG” pattern in which one pixel is composed of four adjacent dots may of course be used. The thickness of the phosphor should be about 1.4 to 2 layers. Similarly, the green phosphor 114B and the blue phosphor 1
Form 14C. As the phosphor, for example, Y ₂ O ₂
S: Eu (P22-R), Zn ₂ SiO ₄ : Mn for green, ZnS: Ag (P22
-B) may be used.

Next, after filming with a film such as nitrocellulose, Al is applied to the entire face plate 110 to a thickness of 50 to 300 nm.
A metal back 122 is formed by vapor deposition of about m. This metal back 122 functions as an acceleration electrode. Then, face plate 11
0 is heated to about 400 ° C. to thermally decompose organic substances such as a filming film and PVA. In this way, the face plate 11
0 is completed.

The face plate 110 and the substrate 14 manufactured as described above are used.
And the spacer 60 are sealed. The thickness of the spacer is set so that the distance between the face plate 110 and the substrate 14 is about 1 to 3 mm. The positional relationship between the face plate 110 and the substrate 14 is as shown in FIG. FIG. 5 shows a pattern of the thin-film electron source formed on the substrate 14 corresponding to FIG. As can be seen from FIG. 6D, since the surface of the lower electrode 13 is covered with the protective layer 15, the horizontal wiring in FIG. 4 and FIG. Should be written as "protective layer 15". However, in order to clearly show the functional relationship in which the lower electrode 13 and the upper electrode bus line 32 constitute a matrix, this is intentionally described in FIGS. 4 and 5. Similarly, the upper electrode bus line 32 is correctly covered with the upper electrode surface layer film 18 in the plan views of FIGS. 4 and 5, but is described as the upper electrode bus line 32 for the same purpose. .

The shape of the spacer 60 is, for example, as shown in FIG. In this case, the columns of the spacers are provided for each of the dots emitting light of R (red), G (green), and B (blue), that is, for each of the three rows of the upper electrodes, but the number of the columns ( Density) can be reduced. In manufacturing the spacer 60, a hole having a desired shape is formed in an insulating plate such as glass or ceramic having a thickness of about 1 to 3 mm by, for example, a sand blast method.

The sealed panel is evacuated to a vacuum of about 1 × 10 ⁻⁷ Torr and sealed. Thus, a display panel using the thin-film electron source is completed.

As described above, in this embodiment, since the distance between the face plate 110 and the substrate 14 is as long as about 1 to 3 mm, the acceleration voltage applied to the metal back 122 can be as high as 3 to 6 KV. Therefore, as described above, a phosphor for a cathode ray tube (CRT) can be used as the phosphor 114.

FIG. 7 is a connection diagram to the drive circuit of the display device panel 100 manufactured as described above. FIG. 7 shows a case of 3 × 3 pixels for simplicity. Lower electrode 13
Is connected to the lower electrode drive circuit 41 and the upper electrode bus line 32
Is connected to the upper electrode drive circuit 42. Metal back 122
Is connected to the acceleration electrode drive circuit 43. nth lower electrode 13K
The dot at the intersection of the n-th and m-th upper electrode bus line 32Cm is represented by (n, m).

FIG. 8 shows the waveform of the voltage generated by each drive circuit. A voltage of about 3 to 6 KV is constantly applied to the metal back 122.

At time t ₀ , no voltage is applied to any of the electrodes, so that no electrons are emitted, and thus the phosphor 114 does not emit light.

At time t ₁ , the lower electrode 13K1 has −V ₁
A scanning pulse 401 having a voltage of
A data pulse 402 having a voltage of + V ₂ is applied to C1 and C2. Since a voltage of (V ₁ + V ₂ ) is applied between the lower electrode 13 and the upper electrode of the dots (1, 1) and (1, 2),
If (V ₁ + V ₂ ) is set to be equal to or higher than the electron emission start voltage, electrons are emitted from the thin-film electron source of these two dots in a vacuum 10
Released during. The emitted electrons are metal back 144
After being accelerated by the voltage applied to, the phosphor 114 collides with the phosphor 114 and causes the phosphor 114 to emit light.

[0034] In time t _2, the application of a -V ₁ becomes voltage to the lower electrode 13K2, by applying a V ₂ becomes voltage to the upper electrode bus line 32C1, similarly dots (2,1) is turned on. Thus, when the voltage waveform of FIG. 8 is applied, only the hatched dots in FIG. 7 are turned on.

As described above, a desired image or information can be displayed by changing the signal applied to the upper electrode bus line 32. Here, the data pulse 402
The value of the voltage amplitude V ₂ of the set smaller than the work function of the surface material of the upper electrode (work function 4.8 eV in this case Au). In the present embodiment, V ₂ = 3.5V and V ₁ = 4V.

In order to display an image having a gradation in luminance, the pulse width of the data pulse 402 may be adjusted according to the gradation.

The voltage amplitude V ₂ of the data pulse 402 may be modulated according to the gradation. In this case, the video signal input to the image display device is, for example, 8 bits (256 gradations).
If the signal is clearly limit, etc., the value of V ₂ corresponding to the upper limit value may be set smaller than φ the work function of the upper electrode surface.

Alternatively, of the voltage values of V ₂ that change with time according to the video signal, the time ratio of the voltage value smaller than the work function φ may be 80% or more. In this case, the component of V ₂ that contributes to lowering the contrast is at most 20%.
There is a contrast improvement effect of 1 / 0.2 = 5 times that of the conventional method.

In the above embodiment, an example in which a MIM electron source using a metal for the lower electrode has been described. However, an MIS (Metal-Insulator-Semiconductor) using a semiconductor for the lower electrode has been described.
It goes without saying that the effect of the present invention can be obtained even if an r) type electron source is used.

As another embodiment of the present invention, an example of an electron beam exposure apparatus will be described. With the structure and method described in the previous embodiment, a substrate in which thin-film electron sources are arranged in a matrix is manufactured. By incorporating this thin-film electron source matrix as an electron source in a vacuum apparatus together with a wafer stage, a reduction optical system, and, if necessary, a deflection system, a basic configuration of an electron beam exposure apparatus can be achieved. For details, refer to
236840. Also in this case, the emission current from the non-selected electron source can be reduced by setting both the voltage of the scanning pulse applied to the thin film electron source matrix and the voltage of the data pulse to be equal to or less than the work function φ of the surface of the thin film electron source. Can be zero. Thereby, erroneous exposure can be prevented.

[0041]

According to the present invention, a matrix-type electron-beam-excited display device having a large number of scanning lines and high contrast can be realized. Also, when applied to electron beam application equipment, the amount of emission current can be controlled accurately.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an I (V) -V characteristic of a thin-film electron source.

FIG. 2 is an electron energy diagram of a thin-film electron source.

FIG. 3 is a cross-sectional view of a first embodiment of the display device according to the present invention.

FIG. 4 is a plan view showing a phosphor screen position in the first embodiment of the display device according to the present invention.

FIG. 5 is a plan view of a substrate in the first embodiment of the display device according to the present invention.

FIG. 6 is a diagram showing a substrate forming process in the first embodiment of the display device according to the present invention.

FIG. 7 is an example of a connection diagram to a drive circuit of a display device according to the present invention.

FIG. 8 is an example of a drive voltage waveform diagram of the display device according to the present invention.

[Explanation of symbols]

10 vacuum, 11 upper electrode, 12 insulating layer, 13 lower electrode, 14 substrate, 15
Protective layer, 16: electrode terminal, 16: upper electrode interface layer film, 17: upper electrode intermediate layer film, 18: upper electrode surface layer film, 20: drive voltage, 32 ... -Upper electrode bus line, 60 ... spacer, 110 ... face plate, 114 ... phosphor, 120 ... black matrix, 122 ... metal back, 41 ... lower electrode drive circuit, 42- ..The upper electrode driving circuit, 43... Accelerating electrode driving circuit, 401... Scanning pulse, 402.
Data pulse, 501, resist, 502,
Resist, 503 ... resist.

Claims (5)

[Claims] 1. A display comprising a substrate on which a matrix having a thin-film electron source as a constituent element in which a lower electrode, an insulating layer and an upper electrode are laminated in this order is formed, and a face plate provided with a phosphor and an accelerating electrode. In a display device having a panel, a driving circuit for driving the thin-film electron source matrix by a combination of a scanning pulse and a data pulse based on an image signal, the thin-film electron beam is not applied when the scanning pulse is not applied. A display device, wherein a voltage applied to a source is smaller than a work function of the upper electrode. 2. The display device according to claim 1, wherein a voltage value of the data pulse is smaller than a work function of the upper electrode. 3. The display device according to claim 1, wherein when the data pulse voltage value is modulated according to a video signal, a maximum value of the voltage value is smaller than a work function of the upper electrode. 4. When the data pulse voltage value is modulated according to a video signal, a time ratio of the voltage value exceeding the work function of the upper electrode is not more than 20%. 2. The display device according to 1. 5. A combination of a thin-film electron source matrix in which thin-film electron sources in which a lower electrode, an insulating layer, and an upper electrode are laminated in this order, in a matrix, a scanning pulse, and a data pulse based on an image signal. In an electron beam application device having a drive circuit for driving the thin film type electron source matrix, a voltage applied to the thin film type electron source when the scan pulse is not applied is smaller than a work function of the upper electrode. Electron beam applied equipment.