JPH06243777A - Cold cathode - Google Patents

Abstract

PURPOSE:To reduce an influence of gate electric potential change between adjacent individual cathode segments by providing a shielding electrode between plural micro-cold cathodes, which consists of an emitter and a gate provided around the emitter, so as to surround the cold cathodes. CONSTITUTION:A shielding electrode 5 is separated from a gate 4 in a groove 6 part of an insulating layer 3 and each of the gates 4 is also separated from each other. The fixed voltage, for example, 100V on the basis of an emitter 2 on a semiconductor base plate 1, is always impressed to the electrode 5. When proper wiring is inserted to the gate 4, and for example, a control voltage varying 0-100V on the basis of the emitter 2 is impressed, a current emitted from the emitter 2 is varied. Even when the distance between adjacent emitters 2 is as extremely snort, as 10mum or less, the electrode 5 between the emitters 2 works as a shield, so that an influence on an emission electron beam orbit due to a change in an adjacent electric field is reduced to the extent that can be ignored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold cathode that serves as an electron emission source, and more particularly to a cold cathode that forms a plurality of electron beams whose emission currents can be independently controlled.

[0002]

2. Description of the Related Art FIG. 6 is a cross-sectional view of a conventional cold cathode called Spindt type among micro cold cathodes using vacuum microelectronics (Journal of).
Applied Physics, Vol. 47, N
o. 12, pp-5248-5263, 1976. ).
An emitter 2 having a sharp tip, an insulating layer 3, and a gate 4 are formed on a semiconductor substrate 1. The emitter 2, the insulating layer 3 and the opening of the gate 4 form a micro cold cathode. The gate 4 is electrically separated from the adjacent gate 4 at the insulating layer trench 6. A positive voltage is applied to the gate 4 with the emitter 2 and the semiconductor substrate 1 having the same potential as the reference as a reference. Since the tip of the emitter 2 is made extremely sharp,
A high electric field is applied to this part. An amount of electrons corresponding to the voltage applied to the gate 4 is emitted from the emitter 2.

Since the current emitted from one emitter 2 is about 5 to 50 μA at the maximum, a large number of emitters 2 are arranged on a plane for use as a cathode of an electron tube. In such a cathode, it is possible to easily provide a function that cannot be realized by the conventional hot cathode or is difficult to realize by controlling independently by one or a plurality of emitters 2 as a unit (JP-A-55-55). 25910, JP-A-57-38528). For example, a gate 4 that can be independently controlled in units of one or more emitters 2
A large number of cathode segments in which this emitter is combined are arranged linearly to form a cathode, which is housed in a CRT (picture tube) and scanned in the direction perpendicular to the direction in which the many cathode segments are lined up, and at the same time, the gate 4 of each cathode segment. If the voltage is controlled, the scanning lines corresponding to the number of cathode segments can be displayed simultaneously.

FIGS. 7A and 7B show another example of the prior art (Japanese Patent Laid-Open No. 3-250534). In FIG. 7, 1
01 is a substrate, 102 is an emitter, 103 is an insulator, 10
4 is a gate, 105 is an electron collector electrode, 106 is a light emitter thin film, 107 is an electron shield, 108 is a transparent encapsulant, and 101 to 107 are one unit light emitter.
The electrons emitted from the emitter 102 are controlled by the voltage applied to the gate 104, and the four electron collector electrodes 105
One of the above is reached and the light-emitting body thin film 106 above it is caused to emit light.

In the conventional example shown in FIG. 7, since the direction of the electron beam is changed by 180 degrees, the electron beam does not correctly reach the target electron collector electrode 105 due to a slight change in the voltage of the gate 104 or the electron collector electrode 105. There is a fear. In order to prevent this, the electron shield 107 forms a barrier of negative potential, and the target electron collector electrode 105 is formed.
It works to repel the electrons that are about to come off. Further, between the gates 104 of the adjacent unit light emitters, the light emitter thin film 106 emits light, and the direction of the electron beam accelerated by a strong electric field that causes field emission of electrons from the tip of the emitter 102 is further changed. Since there are two electron collector electrodes to which a sufficient voltage is applied to attract, it is expected that the change in voltage of the gates 104 of the adjacent unit light emitters has an extremely small effect on the electron beam trajectory. Therefore, the electron shield 107 has a gate 10
There is no shielding effect for the voltage change of No. 4.

[0006]

In the structure of the conventional example shown in FIG. 6, when the current is taken out from the emitter 2, the potential of the gate 4 is set to a positive voltage of 20 to 100 V with reference to the emitter 2 (semiconductor substrate 1). When the current is applied and the current is not taken out, the potential of the gate 2 is applied to the same level as that of the emitter 4 or slightly positive voltage. Now, when current is taken from a certain cathode segment (first cathode segment) and the current from the adjacent cathode segment (second cathode segment) is turned on / off, the gate 4 potential in the immediate vicinity becomes 2
Since the voltage varies from 0 to 100 V, the electron beam from the first cathode segment is affected by this, and the position on the CRT screen changes. Therefore, the scan line and the pattern formed on the CRT screen based on the scan line are distorted.

In the conventional example shown in FIG. 7, since two electron collector electrodes 105 are interposed between the gates 104 of the adjacent unit light emitters and are considerably separated from each other, the adjacent unit light emitters are separated from each other. It is expected that the influence of the voltage change of the gate on the electron beam is extremely small. Therefore, in this conventional example, there is no technical idea of providing an electron shield in order to shield the influence of the voltage change of the gate of the adjacent light emitter on the electron beam.

[0008]

SUMMARY OF THE INVENTION In the present invention, a shield electrode having a constant potential is installed between the gates, which are the current control electrodes of each cathode segment, so that the cathode segments of adjacent cathode segments located at an extremely short distance can be separated from each other. It reduces the influence of the gate potential change on the electron beam trajectory.

[0009]

In the present invention, a constant potential electrode is provided between the gates of the cathode segments. Therefore, even if the emission current of the adjacent cathode segment is controlled, the trajectory of the electron beam from the cathode segment of interest is less affected, and if this is applied to the CRT, stable and distortion-free scanning on the display screen is achieved. Lines or patterns can be realized.

[0010]

The present invention will be described in detail with reference to the drawings. FIG. 1 is a cathode showing a first embodiment of the present invention, FIG. 1 (a) is a plan view and FIG. 1 (b) is a sectional view. In FIG. 1, 1 is a semiconductor substrate, 2 is an emitter, 3 is an insulating layer,
Reference numeral 4 is a gate, 5 is a shield electrode, and 6 is an insulating layer groove. Figure 1
The embodiment shown in FIG. 6 differs from the conventional technique shown in FIG. 6 in that a shield electrode 5 and an insulating layer groove 6 are added.
The shield electrode 5 is separated from the gate 4 at the insulating layer groove 6, and at the same time, the gates 4 are also separated from each other. A constant voltage, for example 100V with reference to the emitter 2, is always applied to the shield electrode 5. A control voltage is applied to the gate 4 through an appropriate wiring, and if this voltage is changed in the range of 0 to 100 V with the emitter 2 as a reference, the current emitted from the emitter 2 changes. The distance between the emitters 2 of adjacent cathode segments may be located very close, less than 10 μm.

However, since there is a shield electrode 5 having a constant potential between the two emitters 2, this shield electrode 5 acts as a shield that separates the two gates 4, and the voltage of the adjacent gate 4 changes. However, the change in the electric field near the emitter 2 is small. As a result, the influence of the trajectory of the electron beam emitted from the emitter 2 can be reduced to a negligible level. The constant voltage applied to the shield electrode 5 is determined by factors such as the amount of strain that can be tolerated on the screen, the interval between adjacent micro cold cathodes, and the voltage change of the gate 4 necessary for controlling the electron beam current. It is a design element. If the cold cathode of this embodiment is used as the cathode of the electron gun of a CRT, a stable and distortion-free scanning pattern can be obtained on the display screen.

The insulating layer groove 6 shown in FIG. 1 is formed at the same time when the opening portion for forming the emitter 2 on the semiconductor substrate 1 is formed by etching. By forming the groove, the insulating layer groove 6 and the gate 4 are shielded. Although it has the effect of improving the breakdown voltage between the electrodes 5, it is not always necessary to process the insulating layer into a groove shape. Further, a cold cathode having the same function can be prepared by using a metal substrate instead of the semiconductor substrate 1.

2 (a) to 2 (d), the first shown in FIG.
An example of a method of manufacturing the cold cathode of the embodiment will be described. First,
As shown in FIG. 2A, the silicon semiconductor substrate 1 is thermally oxidized to form a silicon oxide insulating layer 3 on its surface, and then a gate metal layer 11 is formed on the insulating layer 3 by vapor deposition or sputtering. Laminate by means. Next, as shown in FIG. 2B, a part of the gate metal layer 11 is removed by means of lithography, the gate 4 and the shield electrode 5 are formed from the gate metal layer 11, and the gate 4 and the shield electrode 5 are further formed. Part of the insulating layer 3 is removed by etching using the as a mask. Next, as shown in FIG. 2C, by a lithographic method,
The resist 13 is left so as to cover the groove 6 between the gate 4 and the shield electrode 5, and the semiconductor substrate 1 is further set in the vapor deposition apparatus.
The semiconductor substrate 1 is set in an oblique direction and rotated so that the evaporation material may come from the oblique direction of the obliquely-deposited metal layer 12
To form. Next, as shown in FIG. 2D, when the emitter metal is vapor-deposited from directly above the semiconductor substrate 1, the emitter metal layer 14 is laminated on the obliquely vapor-deposited metal layer 12, and at the same time, the obliquely vapor-deposited metal layer 14 is formed. An emitter 2 having a tapered tip is formed on the semiconductor substrate 1 through the opening formed in. Finally, the resist 13, the obliquely evaporated metal layer 12,
By removing the emitter metal layer 14, the cold cathode having the structure shown in FIG. 1 is obtained.

FIG. 3 is a plan view of the second embodiment of the present invention.
A sectional view is shown in FIG. In FIG.
Reference numeral 7 is a second insulating layer, and 8 is a shield electrode formed on the second insulating layer 7. Similar to the first embodiment shown in FIG. 1, the gates 4 are insulated from each other, and the voltages are independently applied through appropriate wirings although not shown. A constant voltage of, for example, 100 V is applied to the shield electrode 8 with the emitter 2 as a reference. In this embodiment, since the shield electrode 8 has a three-dimensional structure in which the shield electrode 8 is laminated on the second insulating layer 7, a higher shield effect is realized, the influence of the voltage of the adjacent gate 4 is reduced, and the electron beam is emitted. Has less effect on the orbit.

FIG. 4 is a plan view of the third embodiment of the present invention.
A cross-sectional view is shown in FIG. FIG. 4 shows nine minute cold cathodes arranged vertically and horizontally as a set of cathode segments, and each cathode segment can be independently accessed by time-divisionally driving vertically and horizontally. Alternatively, it is possible to drive them in a time division manner in the vertical direction and simultaneously in the horizontal direction. By incorporating the cathode having such a structure in the CTR, a complicated function can be realized.

In FIG. 4, 9 is an insulator layer formed on the semiconductor substrate 1, and 10 is an electrode C. This electrode C10
Are vertically separated. In this third embodiment, the gate 4 is a common electrode for a plurality of vertically arranged cathode segments in FIG. 4 (a). On the other hand, by forming the insulator layer 9 on one surface of the semiconductor substrate 1, the emitters 2 of the side-by-side cathode segments are electrically separated from the side-by-side cathode segments of the other stages. There is. The emitter of each cathode segment is electrode C10.
Is formed on. When the current is not taken out from the emitter 2, the emitter 2 is applied with the same or slightly negative voltage as the gate 4, and when the current is taken out from the emitter 2, the emitter 2 applies a negative voltage of about 100 V to the gate 4. Since a voltage of 100 V is constantly applied to the shield electrode 5 over the entire surface of the cathode, the electron beam trajectories emitted from the emitters 2 of the cathode segments are always kept constant even if the cathode segments arranged side by side are simultaneously driven. Be drunk

In the third embodiment, the insulating layer 9 is provided on the semiconductor substrate 1, and the emitter 2 and the like are formed on the electrode C10 provided thereon. Instead of the body layer 9, it can be directly formed on an insulating substrate such as a glass substrate. Further, the electrodes C may be provided separately in the lateral direction, and the shield electrode may be provided so as to be orthogonal to this.

A fourth embodiment of the present invention is shown in FIG. Figure 5
Is an example of a cold cathode of MIM (metal-insulator-metal) type, and 1
Reference numeral 5 is an insulating substrate, 16 is a conductor layer, and 17a and 17b are metal electrodes. A part of the metal electrode 17 and the insulating layer 3 is thinner than the others, and when a voltage is applied between the conductor layer 16 and the metal electrode 17, electrons are emitted from the thin part by a tunnel effect. To be done. Although not shown in the figure, the metal electrodes 17a and 17b can be independently applied with a voltage. Since a constant voltage is applied to the shield electrode 8, the trajectory of the electron beam emitted from the adjacent metal electrode 17 (micro cold cathode) is affected even if the voltage applied to the metal electrode 17 is changed to control the emission current. Do not receive

In the first, second and fourth embodiments, an example in which a single micro cold cathode is separated from each other has been shown, but in the case of collectively controlling the emission current of a plurality of micro cold cathodes. By using this as a unit and disposing a shield electrode of a constant voltage around this, the same effect can be obtained.

Further, although the field emission type element and the MIM type element are shown as the electron emission sources in the embodiments, the MIS type element and the P type element are used.
It is obvious that the present invention can be applied by using an N junction element, a Schottky junction element and the like.

Further, it is apparent that the same effect can be obtained and the idea of the present invention can be applied not only to a CRT but also to a device and a device using a plurality of electron beams whose current amounts are independently controlled. Is.

[0022]

As described above, in the cold cathode of the present invention, the trajectories of the electron beams emitted from the emitters are extremely close to each other and are not affected by the voltage for controlling the adjacent emitters or groups of emitters. , This cold cathode CR
When applied to T, it is possible to obtain a stable scan line or a pattern formed by scan lines that is always stable on the display screen.

[Brief description of drawings]

1A and 1B are a plan view and a cross-sectional view of a cold cathode showing a first embodiment of the present invention.

2A to 2D are cross-sectional views of a manufacturing process of a cold cathode showing a first embodiment of the present invention.

3 (a) and 3 (b) are a plan view and a cross-sectional view of a cold cathode showing a second embodiment of the present invention.

4A and 4B are a plan view and a sectional view of a cold cathode showing a third embodiment of the present invention.

FIG. 5 is a cross-sectional view of a cold cathode showing a fourth embodiment of the present invention.

6A and 6B are a plan view and a cross-sectional view showing a conventional example.

7A and 7B are a plan view and a cross-sectional view showing another conventional example.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Emitter 3 Insulating Layer 4 Gate 5,8 Shielding Electrode 6 Insulating Layer Groove 7 Second Insulating Layer 9 Insulating Layer 10 Electrode C 11 Gate Metal Layer 12 Obliquely Evaporated Metal Layer 13 Resist 14 Emitter Metal Layer 15 Insulating Substrate 16 Conductor layer 17 Metal electrode 101 Substrate 102 Emitter 103 Insulator 104 Gate 105 Electron collector electrode 106 Light emitter thin film 107 Electronic shield 108 Transparent encapsulant

Claims (4)

[Claims] 1. A micro cold cathode is surrounded by a plurality of micro cold cathodes having an emitter provided on a conductive substrate and a gate provided on the substrate around the emitter via an insulating layer. A cold cathode comprising a shield electrode. 2. A plurality of micro cold cathodes having an emitter provided on a conductive substrate and a gate provided on the substrate around the emitter via an insulating layer, and laminated on the insulating layer. A cold cathode comprising a shielding electrode provided via a second insulating layer. 3. A metal layer vertically or laterally separated via an insulating layer on a conductive substrate, a large number of micro cold cathodes are provided on the metal layer, and a plurality of these micro cold cathodes are provided. A cold cathode characterized by being separated by a shield electrode provided so as to be orthogonal to the metal layer. 4. A conductive layer and an insulating layer are laminated on an insulating substrate, a plurality of metal electrodes are provided on the insulating layer, and a shield electrode is provided around these metal electrodes with a second insulating layer interposed therebetween. And a part of the insulating layer below the metal electrode is thinned.