JPH07130306A - Display device - Google Patents

Abstract

PURPOSE:To feed scanning voltage for display at low voltage by forming a switching element conducted to a focusing electrode on a substrate forming a field emission element. CONSTITUTION:A cathode electrode layer 101 is formed on a glass substrate 100, and a resistance layer 102 is formed thereon. A comical emitter 115 is deposited thereon. A gate electrode layer 104 is provided thereon through an insulating layer 103, and a focusing electrode layer 108 is provided thereon through an insulating layer 107. The electron emitted from the emitter 115 passes the electrode layers 104, 108 provided with holes of approximately 1mu, is emitted on the side of an anode electrode 121, and collides with the electrode 121 to excite phosphor material, thus inducing emission. An image is displayed by scanning an electrode 121. A reverse-stagger type TFT consisting of a gate electrode 201, a source electrode 205, and a drain 206, is provided to apply voltage to the focusing electrode 108, and scanning voltage is applied to the source electrode 204 and the gate electrode 201 of the TFT in the direction X-Y.

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 a field emission device known as a cold cathode.

[0002]

2. Description of the Related Art The applied electric field on the surface of a metal or semiconductor is reduced to 10
^{At a} voltage of about ⁹ [V / m], the tunnel effect causes electrons to pass through the barrier so that electrons are emitted in a vacuum even at room temperature. This is called field emission.
The cathode that emits electrons based on such a principle is called a field emission device FEC (Field Emission Cathode). In recent years, it has become possible to form a surface-emission type field emission cathode by simultaneously forming a large number of micron-sized field emission devices by making full use of semiconductor processing technology. Arranged in a
Techniques have been developed that are applied to flat display devices and various electronic devices by irradiating the fluorescent surface with electrons emitted for each block.

One of the methods for manufacturing the above-mentioned field emission device is a rotary oblique vapor deposition method developed by Spindt (US Pat. No. 37
89471), and another method is based on a selective etching method for a silicon single crystal plate. The former has a feature that the cathode chip material can be selected almost freely, and the latter has a feature that the current semiconductor fine processing can be applied as it is.

An outline of a method of manufacturing an FEC corresponding to the SPINDT method (JP-A-1-154426) will be briefly described below with reference to FIG. First, as shown in FIG. 6A, a cathode electrode layer 101 is formed by vapor deposition on a substrate 100 such as glass, and silicon is further laminated thereon to form a resistance layer 102,
Further, the insulating layer 103 is formed of silicon oxide. Then, a conductor is vapor-deposited thereon to form the gate electrode layer 104. Such a laminated substrate has a photoresist layer 1 on the upper surface of the gate electrode layer.
After applying 11, the patterning is performed by masking the area other than the area where the cold emitter is formed, and the resist layer is irradiated with ultraviolet rays to remove the resist layer 111 with a dedicated solution. As a result, the region forming the cold emitter becomes the opening 113 as shown in FIG.

The diameter of this opening is about 1 μm,
For example, a hole is also formed in the gate electrode layer 104 by dry etching from above with SF ₆ gas or the like. Next, isotropic etching is performed by immersing this laminated substrate in an etching solution, and a portion of the insulating layer 103 is etched to form holes 114 as shown in FIG. Then, while obliquely vapor-depositing aluminum to be the peeling layer 105 while supporting and rotating the whole laminated substrate as described above, the peeling layer 105 is not vapor-deposited in the opened hole 114 and the gate 10 is formed.
The four electrode layers are selectively deposited only on the surface.

Next, the hole 114 of such a laminated substrate is formed.
When molybdenum, which is the emitter material, is deposited from the side by normal vapor deposition, the deposited molybdenum falls from the holes 114 as shown in FIG.
5 also deposits. Then, the cone-shaped emitter 115 is formed on the resistance layer 102 while the opening is closed by molybdenum deposited on the peeling layer 105. After that, when the separation layer 105 and the emitter material layer 106 on the gate electrode layer 104 are removed by etching,
A field emission device (FEC) having a shape as shown in FIG.
Will be obtained.

In the above manufacturing method, the second insulating layer 107 is formed above the gate electrode 104 and the second gate electrode layer 108 is formed above the insulating layer 107 when forming the laminated substrate. When a laminated substrate is used, this second gate electrode layer 10 is formed as shown in FIG. 6 (f).
It is also possible to fabricate a quadrupole FEC which can use 8 as a focusing electrode.

As shown in this figure, since the FEC can make the distance between the cone-shaped emitter 115 and the gate electrode layer 104 to be submicron, the emitter 115 and the gate electrode layer 104 have a voltage of only 80 to 120 volts. By applying a voltage, the potential gradient at the tip of the emitter 115 becomes very high, so that electrons can be emitted even at room temperature in vacuum.

FIG. 7 is a perspective view showing a conventional technique for constructing a display device using the field emission device constructed as described above. (JP-A-2-309541)
In this figure, 100 is a glass substrate, 101 is a cathode electrode layer, 102 is a resistance layer, 103 is an insulating layer, 10
Reference numeral 4 represents a gate electrode layer. Reference numeral 120, which is arranged so as to face the laminated substrate, is a glass substrate forming a display surface, and an anode conductor layer 121 is provided as a transparent electrode on the inner surface thereof, and when an electron collides with the anode electrode layer. The fluorescent material 122 that emits light is applied in a predetermined pattern,

The space between the upper and lower glass substrates is kept in a vacuum state, and in the case of this conventional technique, a voltage for scanning the gate electrode is applied to each divided gate electrode via a thin film transistor (TFT) 117. Scanning electrode 11
8 and is configured to emit electrons from each of the emitters 115 when a voltage is applied to the gate electrode through the TFT 117.

Therefore, a scanning signal is supplied to the scanning electrode 118 (drain electrode) of the TFT 117, and a display screen signal is supplied to the scanning electrode 119 connected to the gate electrode of the TFT 117 in synchronization with this scanning signal. By providing the drive circuit, the fluorescent material applied to the anode electrode layer can emit light to display a character pattern.

[0012]

By the way, in the display device as described above, since the electrons corresponding to the image signal are sufficiently emitted from the emitter 115, the gate electrode 104 has a voltage of 40 to 80 V even without the resistance layer. It is necessary to apply a voltage, and when a resistance layer is provided, the gate electrode 1
It is necessary to apply a voltage of about 80 to 120 V to 04. Therefore, it is extremely difficult to form high withstand voltage TFTs that perform sufficient switching operation for such a voltage on the laminated substrate in units of several μ.

It is also conceivable that the anode electrode 121 is divided into pixel units and arranged in a matrix, and a scanning voltage is applied to the strip-shaped divided anode electrodes, but in this case, a higher voltage (several hundred volts) is applied. Therefore, there is a problem that the drive circuit becomes expensive and heat is generated, the cost is increased, and it is difficult to save power.

[0014]

The present invention has been made to solve the above-mentioned problems, and a large number of cone-shaped emitters for emitting electrons are vapor-deposited above a cathode conductor layer formed on a substrate. Then, a plurality of field emission devices constituted by a first gate electrode layer for emitting electrons from this emitter and a focusing electrode layer arranged above the gate electrode layer for converging the extracted electrons. And the field emission device is divided into predetermined blocks on the display surface, and X, Y is formed on the multilayer substrate.
A matrix-shaped control line extending in the direction is arranged, a switching element is formed between the intersection of the control line and the focusing electrode conductor, and a scanning signal for image display is supplied to the focusing electrode via the switching element. It is configured to be performed.

[0015]

Since the control of emitted electrons by the focusing electrode can be performed at a relatively low voltage, the switching element can be formed by a low voltage type TFT or a MIM two-terminal switching element, and the integration technology is used. By arranging them with high density, the image quality can be improved.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an enlarged view showing a part of the cross section of a field emission device adopted in a display device of the present invention, and 100 is a glass substrate as described above. A cathode electrode layer 101 is formed on the upper surface of the glass substrate by vapor deposition or the like, and a resistance layer 102 is laminated on the upper surface of the cathode electrode layer 101. Then, this resistance layer 10
The upper part of 2 is a cone-shaped emitter 11 whose tip is formed in a conical shape by the Spindt method or the like described above.
5 is vapor-deposited. The gate electrode layer 10 supported by the insulating layer 103 is provided above the emitter 115.
4 is provided, and the focusing electrode layer 108 is further provided on the upper surface of the focusing electrode layer 108 via the second insulating layer 107.

The second insulating layer 107 and the focusing electrode layer 1
08 is a well-known FEC having a quadrupole structure, and is used for forming a laminated substrate by the above Spindt method or the method previously proposed by the present applicant (Japanese Patent Application No. 5-1991848). In addition, it can be easily constructed by previously laminating the insulating layer and the focusing electrode layer, but a detailed manufacturing method thereof will be omitted.

The height of each emitter 115 is about 1 micron, and the electrons emitted from one emitter 115 pass through the gate electrode layer 104 and the focusing electrode layer 108 having holes of about 1 micron. , Are emitted toward the anode electrode side. And the anode electrode 1
Colliding with 21 causes the fluorescent substance to be excited, and that portion emits light. In the light emitting portion, several tens to several hundreds of such field emission devices form one pixel, and each pixel has a strip-shaped electrode wired in a matrix as described later by a scanning voltage. The image is displayed by scanning.

In the field emission device employed in the display device of the present invention, an inverted stagger type thin film transistor (TFT) is formed on its side surface during the manufacturing process. That is, the gate electrode 201 of the TFT is formed by vapor deposition or the like above the portion where the insulating layer 103 of FIG. 1A is extended, and the gate insulating layer 202 made of SiO ₂ is formed thereon. Then, the second insulating layer 1 extending in the lateral direction
Amorphous silicon layer 203 and an adjacent n + amorphous silicon layer 204 are formed on 07 to form TF.
A channel region serving as a T signal path is formed. The source electrode 205 and the drain electrode 206 of the TFT are provided at both ends of this channel region.
Then, the drain electrode 206 is formed at the same time when the conductor forming the focusing electrode layer 108 of the field emission device is deposited.

As is well known, in such an inverted stagger type TFT, when a voltage is applied to the gate electrode 201 of the TFT, charges can move in the channel,
The source electrode 205 and the drain electrode 206 are controlled to be conductive. As a result, the potential of the focusing electrode 108 becomes equal to the potential applied to the source electrode 205.

In the above embodiment, the gate electrode 104 and the focusing electrode 108 each having an opening above each cone-shaped emitter 115 are formed, but as shown in FIG. As the electrode 108, the emitter 115
It is also possible to have a slightly wider opening so that two or four of them can be collectively controlled.

In the above-described embodiment, the TFT formed on the same substrate is used as the switching element for applying the voltage to the focusing electrode 108, but the switching element is shown in FIG. MIM (Me
The tai Insulater Metal) two-terminal switching element may be configured by the same method. That is, as shown in FIG. 4A, a conductive material (Ta) is vapor-deposited on the upper surface of the insulating layer 103 extending in the lateral direction, and one terminal 207 is vapor-deposited in a strip shape, and above it. Ta ₂ O ₂ is coated as an insulating layer 208. The material forming the focusing electrode is extended and vapor-deposited above the insulating layer to form terminals 209 in the other direction, and MIM (Metal Insulate) in which the terminals are on / off controlled by a tunnel effect.
r Metal) Two-terminal switching element is formed. Note that, as shown in FIG. 1B, FIG.
A cross-sectional view in the case where the focusing electrode 108 is commonly provided for two or four emitters 115 is shown.

The field emission device employed in the display device of the present invention has a focusing electrode layer 108 having a function of converging electrons emitted from the emitter 115, as embodied in the above-described cross-sectional structure. Drain electrode 2 of TFT
06 are connected on the laminated substrate. Therefore, when the source electrode 205 and the gate electrode 201 of this TFT are connected to the intersections of the control lines arranged on the matrix and the operation voltage is sequentially applied, the video signal is displayed as described in the conventional display device. Will be able to.

FIGS. 3 (a) and 3 (b) show loci of electrons simulating how the electrons emitted from the emitter of the field emission device as described above are affected by the focusing electrode. Yes, the gate hole diameter is 1μ
m, cone height 1 μm, focusing electrode hole diameter 1.2 μm,
When the distance between the gate and the focusing electrode is 1 μm, the thickness of the gate electrode layer and the focusing electrode layer is 0.4 μm, and the distance from the cone bottom to the anode electrode is 200 μm, the right half emitted electrons emitted from the top center point P of the emitter The locus is drawn.

In the trajectory of electrons obtained by this simulation, it is assumed that the point of emitting electrons is at the apex P of the emitter, and the gate electrode G1 for emitting electrons is provided with a slight gap (1 μm), Further, it is assumed that the focusing electrode G2 is arranged above the anode electrode layer A and the anode electrode layer A is arranged above the anode electrode layer A with the above-described dimensions. When 120 V is applied to the gate electrode G1 and 400 V is applied to the anode electrode, and the focusing electrode G2 is 0 V, most of the electrons emitted from the apex P of the emitter are caused by the space charge effect as shown in FIG. It can be seen that it has not reached the anode electrode.

However, in this state, 10 V is applied to the focusing electrode G2.
When a certain voltage is applied, as shown in FIG. 3B, the flow of electrons drifting due to space charge is significantly improved, and most of the electrons reach the anode electrode. The flow changes and the anode current increases.

FIG. 4 shows the emitter 11 for electron emission described above.
5 shows a field emission device cell (hereinafter referred to as a cell) 300, which is formed by blocking a plurality of cells 5 into blocks, and shows a drive circuit for dynamically driving each cell. That is, each cell 300 has a plurality of emitters 11.
5 and the gate electrode 104 for each emitter 115
And focusing electrode 108. Each cell 30
One TFT is provided in 0, and this TFT
Gate electrodes of the control lines G1, G2, G3 ...
... Connected to Gn. Further, the source electrodes of the TFTs are connected to the control lines S1, S2, S3 ...

The gate electrodes 104 of the cells 300 are connected in common and are connected to a predetermined acceleration voltage (E1), and the emitters 115 of the cells 300 are collectively connected by a cathode electrode which is conductive through a resistance layer. Then, the wiring is provided so that a predetermined voltage (usually the zero-level voltage E2) is supplied. The stray capacitance C formed on the drain side of the TFT
Although not shown, the terminals G are all grounded.

The display drive circuit described above includes, for example, control lines G1, G2, G3 ... Which are arranged in the horizontal direction of the screen.
.. Connected to a drive circuit that sequentially supplies scan pulses in a time-divisional manner to the control line S, which will be arranged in the vertical direction
When S1, S2, S3 ... Are sequentially supplied with video signals (character and graphic signals) for one horizontal period in synchronization with the scanning pulse, as described above, the cells 300 are focused when the TFTs are turned on. A voltage as low as about 10 V is applied to the electrode 108, and the electrons emitted from the emitter in this cell strike the anode electrode as shown in FIG. 3 (b). As a result, the cell 300 in which the TFT is made conductive
The fluorescent substance located above is emitted, and an image can be displayed corresponding to the video signal. Although the switching element shown in FIG. 4 is formed by one TFT, it is preferable that the switching element is formed by a C-MOS type switching element using two TFTs.

FIG. 5 shows that the above-mentioned field emission device block is M
The example of the circuit which drives the cell 301 comprised by the IM2 terminal switching element is shown, and each cell 301 is shown.
Are configured to be activated by the MIM two-terminal switching element. In this case, as in the case of FIG. 4, the control lines G1, G2, G3 provided in the horizontal direction are arranged.
.... and the control line S provided in the vertical direction
The cell 301 located at the intersection of 1, S2, S3, ... Emits electrons. Since this switching element has two terminals, it performs an off-through control operation, that is, when the potentials of the control lines G1, G2, G3, ... Are high, the control lines S1, S2, S3.・
The cell at the intersection where the scanning voltage for scanning ... Is reverse bias is activated, and the focusing electrode 10 of this cell is activated.
A voltage will be applied to 8.

In the above embodiment, the case where the focusing electrode 108 has one layer has been described, but it goes without saying that the technique of the present invention can be applied to an FEC having a pentode structure in which the focusing electrode has two layers. Nor.

[0032]

As described above, the display device of the present invention includes a field emission device having a quadrupole structure including at least a gate electrode for extracting electrons to the emitter and a focusing electrode for limiting the spread of the extracted electrons. A switching element that is electrically connected to the focusing electrode is formed on the substrate on which the field emission element is formed by an integration technique. Therefore, a low voltage signal for scanning is provided to the focusing electrode via the switching element. Can be applied. Therefore, it is easy to integrate the dimensions of the switching element in the order of μm, and the resolution of the display screen can be improved.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a part of a field emission device adopted in a display device of the present invention.

FIG. 2 is an enlarged sectional view of a part of a field emission device showing another embodiment of the present invention.

FIG. 3 is an explanatory diagram that simulates a trajectory of electrons extracted from a field emission device.

FIG. 4 is a wiring diagram showing an example of a drive circuit of a display device including the field emission device of the present invention.

5 is a wiring diagram showing an example of a drive circuit when the field emission device of FIG. 3 is used.

FIG. 6 is an explanatory diagram showing an example of a method for manufacturing a field emission device.

FIG. 7 is a perspective view showing a conventional example of a display device configured by FEC.

[Explanation of symbols]

 100 Glass Substrate 101 Cathode Electrode Layer 102 Resistance Layers 103 and 107 Insulating Layer 104 Gate Electrode Layer 108 Focusing Electrode Layer 121 Anode Electrode Layer 201 TFT Gate Electrode 205 TFT Source Electrode 206 Drain Electrode

Claims (4)

[Claims] 1. A plurality of cone-shaped emitters for emitting electrons are vapor-deposited above a cathode conductor layer formed on a substrate, and a gate electrode layer for emitting electrons from the emitters and the extracted electrons are provided. A laminated substrate provided with a plurality of field emission devices constituted by one or two focusing electrode layers arranged above the gate electrode layer for converging, and a fluorescent substance arranged on the upper surface of the laminated substrate. In a display device in which an anode electrode to which a material is attached is enclosed in a vacuum container, the plurality of field emission devices are divided into predetermined blocks in a display surface and extend in the X and Y directions on the laminated substrate. The control lines arranged in a matrix are arranged, a switching element is formed between the intersection of the control lines and the focusing electrode of the field emission element, and the switching element is formed through the switching element. Display device characterized by progressive scanning signal into a bundle electrode is configured to be supplied. 2. The display device according to claim 1, wherein the switching element is composed of a thin film transistor. 3. The display device according to claim 1, wherein the switching element is composed of a MIM two-terminal switching element. 4. The display device according to claim 1, wherein the focusing electrode is configured to simultaneously control the plurality of emitters as a group.