JPH04284324A - Electric field electron emitter - Google Patents

Abstract

PURPOSE:To provide an electric field electron emitter capable of deficiency relief in such a manner so as to prevent a normal cathode electrode operation from being hindered due to a short-circuiting deficiency in the case where the short-circuiting deficiency is generated between the cathode electrodes and gate electrodes. CONSTITUTION:A gate electrode containing a plurality of cathode electrodes is divided into a plurality of gate electrode elements 3. A gate branch line 6 constituted of a fusible resistor is inserted between the gate electrode element 3 and a gate main line 7. The gate branch line 6 is broken due to an exceesive current flowing upon short-circuiting between the cathode electrode 5 and gate electrode element 3 in the same manner as a fuse, thus separating the gate electrode element 3 where a short-circuiting deficiency is generated by itself. Consequently, the cathode electrode 3 in a normal operation can be operated without difficulty.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to the structure of a field electron emission device that emits electrons from a cathode electrode by a field effect.
More specifically, the present invention relates to a structure of a field emission device capable of relieving a short circuit defect between a cathode electrode and a gate electrode.

0002

[Prior Art] Conventional field emission devices include Spindt (
C. A. Spindt et al. A. P. 47, pp.
5248-5263 (1976), and those reported by H.F. Gray et al. in IEDM86, pp. 7
76-779 (1986). FIG. 3 is a schematic perspective view of a conventional field emission device. In this device, an insulating layer 2 and a gate electrode 10 are laminated on the surface of a flat substrate 1 made of a conductive single crystal silicon substrate, and an opening 4 is formed in the insulating layer 2 and the gate electrode 10 at the same location.
In this structure, a protrusion-shaped cathode electrode 4 is provided on the surface of the flat substrate 1 inside the opening 4. A plurality of cathode electrodes 5 are provided on the surface of the planar substrate 1, and these are electrically connected to each other by a conductive substrate. Further, one gate electrode 10 is provided with a plurality of cathode electrodes 5, and the amount of electrons emitted from the plurality of cathode electrodes 5 is controlled by one gate electrode 10.

0003

However, since the conventional field electron emission device has a plurality of cathode electrodes 5 provided on one gate electrode 10, it has several problems as described below. there were. That is, if one of the cathode electrodes 5 is destroyed due to a structural defect or excessive current, a short circuit defect occurs in which the gate electrode 10 is electrically connected to the cathode wiring or the conductive substrate. At this time, although the cathode electrodes 5 other than the broken one among the plurality of cathode electrodes 5 are normal, due to the short circuit defect, the normal cathode electrodes 5 and the gate electrode 10
A sufficient voltage necessary for electron emission cannot be applied between the two. As a result, a field emission device in which a short-circuit defect has occurred is unable to operate normally, resulting in a problem of lowering the reliability and yield of the field emission device.

[0004] Furthermore, in a portion where the cathode electrode 5 does not exist, the gate electrode 10 and the conductive planar substrate 1 overlap with the insulating layer 2 in between;
A short circuit between the gate electrode 10 and the flat substrate 1 caused by poor breakdown voltage or foreign matter causes problems similar to those described above.

[0005] Therefore, the present invention has been made to overcome the problems of the prior art, and its purpose is to solve the problem when a short circuit defect occurs between the cathode electrode 5 and the gate electrode 10. The object of the present invention is to provide a field electron emission device that can repair defects so that short-circuit defects do not interfere with the normal operation of the cathode electrode 5.

[0006]

Means for Solving the Problems The field electron emission device of the present invention includes a flat substrate, a plurality of cathode electrodes each having a protrusion shape provided on the surface of the flat substrate, and a plurality of cathode electrodes provided on the surface of the flat substrate. an insulating layer having an opening in the vicinity of the cathode electrode; and a gate electrode provided on a surface of the insulating layer having an opening in the vicinity of the cathode electrode. In the field electron emission device, at least a part of the gate wiring connected to the gate electrode is a soluble resistor,
Further, the gate electrode includes a plurality of divided gate electrode elements, and the gate wiring includes a plurality of gate branch lines connected to each of the gate electrode elements, and a gate line connected to each of the gate branch lines. The gate electrode element is divided and provided for each cathode electrode, and the gate branch line is a thin film at least a part of which is made of a conductive thin film. The thin film soluble resistor is characterized in that it is a soluble resistor, and the thin film soluble resistor is characterized in that it has a bridge shape.

[0007]

[Example] (Example 1) Figure 1 is for explaining the first example of the present invention, in which a gate main line, a gate branch line, and a gate electrode are made of a thin film of the same layer. FIG. This device includes a planar substrate 1 made of a conductive n-type single crystal silicon substrate, a protruding cathode electrode 5 provided on the surface of the planar substrate 1, and a planar substrate 1.
an insulating layer 2 made of a silicon oxide film provided on the surface of the insulating layer 2 and opened near the cathode electrode 5; and a gate electrode element made of a polycrystalline silicon thin film provided on the surface of the insulating layer 2 and opened near the cathode electrode 5. 3, and gate electrode element 3
A gate branch line 6 made of a polycrystalline silicon thin film connected to
and gate main line 7 are the main components. The gate electrode comprises four gate electrode elements 3.

The cathode electrode 5 is formed integrally with the planar substrate 1 by anisotropic etching of a silicon substrate, and has a generally conical shape with a height of 1 μm and an apex angle of 90 degrees. The radius of curvature of the cross section at the tip is approximately 300 Å. The insulating layer 2 is made of a silicon oxide film with a thickness of 5000 Å formed by low pressure CVD. One gate electrode element 3 is formed independently on each cathode electrode 5. One gate branch line 6 is formed for each gate electrode element 3 and connects the gate electrode element 3 and the gate main line 7. Gate electrode element 3, gate branch line 6 and gate main line 7
is composed of the same layer of polycrystalline silicon thin film. The polycrystalline silicon thin film was formed by low pressure CVD method, and the film thickness was 3000 Å.
, the specific resistance is 4×10 −3 Ω·cm. The gate branch line 6 has a width of 2 μm and a length of 10 μm, and the gate main line 7 has a width of 40 μm.
μm, length 150 μm. The resistance value of the gate branch line 6 is about 1.3 times that of the gate main line 7, and it is important to keep the resistance value of the gate branch line 6 large.

This field electron emission device has a vacuum degree of 1×10
When placed in a vacuum of about -7 Torr and applying a gate voltage (VGK) of 120V to the gate main line 7 with respect to the cathode electrode 5, the total cathode current (IK) released from the cathode electrode 5 was 8 x 10-7A. Met. Moreover, the emission current was a tunnel current according to the FN plot. From these operation results, the gate voltage is applied to each gate electrode element 3 through the gate main line 7 and gate branch line 6.
was applied, and electron emission was obtained from all four cathode electrodes 5, confirming the normal operation of the field electron emission device.

Next, when the gate voltage was increased to VGK=150V and the total cathode current was increased, V
GK=140V and IK=2×10-5A to 1.4×1
Although the phenomenon of decreasing to 0-5A was observed, VGK=
At 150V, IK=3×10 −5 A was obtained. VGK=
In order to investigate the cause of the change in the total cathode current at 140 V, the field emission device was observed under a microscope, and a short circuit defect between the cathode electrode 5 and the gate electrode element 3 was discovered.

FIG. 2 is a partial schematic perspective view of the field electron emission device after the occurrence of a short circuit defect in this embodiment. In one gate electrode element 3' of the four gate electrode elements 3, there is a short circuit contact 8 formed by fusing the gate electrode element 3' and the cathode electrode 5', and a short circuit in which both electrodes are electrically connected is present. A defect has occurred. This short circuit defect is considered to be caused by heating due to excessive current emitted from the cathode electrode 5' or by collision energy of gas molecules turned into plasma.

What is important here is that there is a disconnection 6 in the gate branch line connected to the gate electrode element 3' where the short-circuit defect has occurred.
'is an acceptable point. When the short-circuit defect occurs, an excessive current flows through the gate branch line 6 connected to it, and the gate branch line 6, which is a thin film fusible resistor, is heated to a high temperature by Joule heat, melts like a fuse, and breaks. This disconnection 6' instantly separates the gate electrode element 3' from the gate main line 7 and from the other three gate electrode elements 3. Therefore, the remaining three cathode electrodes 5 continue to emit electrons normally. In the above operation results, IK is approximately 3/4 at VGK = 140V.
The fact that the number of cathode electrodes 5 decreased to 100% is evidence that one of the four cathode electrodes 5 was instantly separated.

The polycrystalline silicon thin film gate branch line 6, which serves as a thin film soluble resistor, melts at a temperature of 1420° C. or higher. The power required for this melting is about 100 mW, and when the gate voltage is 140V, a current of about 1 mA momentarily flows through the gate branch line 6. At this time, the resistance value of the gate branch line 6 is as large as about 140 kΩ. This is because the conductivity of the polycrystalline silicon thin film decreases at high temperatures. Note that the power required to melt and cut a thin film soluble resistor varies depending on the material, dimensions, structure, thermal conductivity of the surrounding environment, etc. of the resistor. The resistance value of the thin film soluble resistor suitable for the field electron emission device of the present invention is 10Ω~ at room temperature.
The resistance is 1MΩ, more preferably 50Ω to 50kΩ.

As described above, the field electron emission device of the present invention has the following features:
The gate electrode element 3' in which a short-circuit defect has occurred is not separated from the gate main line 7 by the fuse action of the thin-film fusible resistor, and the normal cathode electrode 5 continues to operate. be. (Example 2) FIG. 4 is for explaining a second example of the present invention, which is a field electron emission device in which the material of the gate branch line as a thin film soluble resistor is different from the material of the gate main line or the gate electrode. FIG. Planar board 1
, the structures of the insulating layer 2 and the cathode electrode 5 are the same as those of the first embodiment. Gate electrode element 3 and gate main line 7
The film was formed by sputtering and had a thickness of 2000 Å and a specific resistance of 2.
It is made of tantalum (Ta) thin film of 0 μΩ·cm. The gate branch line 6 is made of chromium silicide (CrSi2) with a film thickness of 500 Å and a specific resistance of 150 μΩ·cm formed by sputtering.
Consists of a thin film. The gate branch line 6 has a width of 2 μm and an effective length of 10 μm, and the overlap with the gate electrode element 3 and the gate main line 7 is about 5 μm.

The feature of the field electron emission device of this embodiment is that it is realized by forming the gate main line 7, which requires low resistance, and the gate branch line 6, which requires high resistance, using different materials and processes. (Embodiment 3) FIG. 5 is a partial schematic perspective view of a field electron emission device having a gate branch line having a bridge shape, for explaining a third embodiment of the present invention. In this device, the configurations of the planar substrate 1, insulating layer 2, gate electrode element 3, cathode electrode 5, gate main line 7, and gate branch line 6 are similar to those of the field electron emission device described in Example 1. However, the insulating layer groove 9 crosses the gate branch line 6 and the insulating layer 2
As a result, the gate branch line 6 has a bridge shape spanning the air. The bridge-shaped gate branch line 6 has better properties as a soluble resistor. That is, since the bridge-shaped gate branch line 6 is entirely surrounded by a vacuum having low thermal conductivity in the portion of the insulating layer groove 9, the fusible resistor has a property that it is difficult to dissipate heat and is easily heated. As a result, the fusible resistor has the advantage of being disconnected by smaller Joule heat. This means that gate branch line 6
This is equivalent to making the resistance lower, and as a result, it is possible to use a material with low resistivity for the gate wiring, or to form a high-density cathode electrode 5 by shortening the distance between the gate main line 7 and the gate electrode element 3. can. In fact, the Joule heat required to break the wire was about 30% compared to that of Example 1, and the effect was confirmed.

The thickness of the insulating layer 2 is 5000 Å, whereas the depth of the insulating layer trench 9 is as small as 2000 Å. This is flat board 1
By not exposing the gate branch line 6, contact between the gate branch line 6 and the flat substrate 1 is prevented. Of course, there is no problem in using the insulating layer groove 9 which is formed by opening the insulating layer 2 and exposing the planar substrate 1. Furthermore, instead of forming a groove in the insulating layer 2, the gate branch line 6 may be raised upward in the shape of a bridge to serve as a fusible resistor.

Further, in the field electron emission device of this embodiment, the gate electrode element 3 includes four cathode electrodes 5. In a field emission device having such a structure, the formation density of the cathode electrodes 5 can be increased, and the total cathode current can be increased with a device having a small area.

In the three embodiments described above, a thin film soluble resistor made of a polycrystalline silicon thin film or a chromium silicide thin film was used as the soluble resistor, but the present invention is not limited to this range, and for example, lead Thin film soluble resistors and fine wire soluble resistors are made of low melting point alloys containing tin, high resistivity materials such as semiconductors, oxide conductors, and intermetallic compounds, or nonlinear junction structures such as pn junctions and Schottky junctions. Available.

Furthermore, in addition to the types of field electron emission devices described in the embodiments, the present invention can be applied to vertical field electron emission devices such as Spindt type or Gray type, or horizontal field electron emission devices. (Embodiment 4) FIG. 6 is a partial schematic plan view of a matrix type field emission device for explaining a fourth embodiment of the present invention. The matrix type field emission device is
For example, it can be applied to a light-emitting flat display that excites phosphors. This device is a vertical field emission device in which a gate electrode element 3 including one cathode electrode 2 is connected to a gate wiring 12 through a gate branch line 6 and a gate main line 7. Each gate main line 7 is connected to six gate electrode elements 3, and the six gate electrode elements 3 and the cathode electrode 2 form one pixel 1.
3 is formed. A plurality of pixels 13 are arranged in a matrix, and cathode wiring 11 is formed in a stripe shape including each pixel 13 arranged in a column, and is connected to each cathode electrode 2. The gate wiring 12 is connected to the gate electrode element 3 of each pixel 13 arranged in a row so as to be perpendicular to the cathode wiring 11, and is formed in a striped shape. A multiplex method can be used as a driving method for the matrix type field emission device.

According to the configuration of the pixel 13 of such a matrix type field emission device, even if one cathode electrode 2 is cut off due to a short-circuit defect, the remaining five cathode electrodes 2 operate normally. Pixel 1 although there is a current decrease of
It functions and plays the role of 3. In the conventional technology, when one short circuit defect occurs, all pixels or vertical and horizontal lines become malfunctioning. As described above, the present invention has excellent performance in defect relief.

[0021]

Effects of the Invention The field electron emission device of the present invention has the effects of the invention as described below. That is, first, even if a short-circuit defect occurs between the gate electrode and the cathode electrode, the short-circuit defect region is electrically disconnected and the normal electron emission operation is enabled, which improves yield and reliability. It is a field electron emission device. Furthermore, since it instantly disconnects itself when a short circuit defect occurs, the field electron emission device has a self-repair effect and is easy to handle. Furthermore, even in the case of defects that occur during the manufacturing process that cannot be cut out automatically, the defective part can be artificially separated from the gate branch line or gate main line using a laser repair device, etc., and field electron emission can improve manufacturing yield. It is a device.

[Brief explanation of the drawing]

FIG. 1 is a partial schematic perspective view of a field electron emission device in which a main gate line, a gate branch line, and a gate electrode are made of thin films of the same layer, for explaining a first embodiment of the present invention.

FIG. 2 is a partial schematic perspective view of the field emission device after a short-circuit defect occurs in the first embodiment.

FIG. 3 is a schematic perspective view of a conventional field emission device.

FIG. 4 is for explaining a second embodiment of the present invention, and is a partial diagram of a field emission device in which the material of the gate branch line as a thin film soluble resistor is different from the material of the gate main line or gate electrode. It is a schematic perspective view.

FIG. 5 is a partial schematic perspective view of a field emission device including a gate branch line having a bridge shape, for explaining a third embodiment of the present invention.

FIG. 6 is a partial schematic plan view of a matrix type field emission device, for explaining a fourth embodiment of the present invention.

[Explanation of symbols]

1 Plane board 2 Insulating layer 3 Gate electrode element 3’ Gate electrode element 4 Opening 5 Cathode electrode 5’ Cathode electrode 6 Gate branch line 6’　Disconnection 7 Gate main line 8 Short circuit contact 9 Insulating layer groove 10 Gate electrode 11 Cathode wiring 12 Gate wiring 13 pixels

Claims (5)

[Claims] 1. A planar substrate, a plurality of cathode electrodes having a protrusion shape provided on the surface of the planar substrate, and an insulating layer provided on the surface of the planar substrate with an opening near the cathode electrode. and a gate electrode provided on the surface of the insulating layer and having an opening in the vicinity of the cathode electrode. A field emission device characterized in that at least a part of the gate wiring is a soluble resistor. 2. The gate electrode of claim 1 comprises a plurality of divided gate electrode elements, and the gate wiring includes a plurality of gate branch lines connected to each of the gate electrode elements, and a plurality of gate branch lines connected to each of the gate electrode elements. A field electron emission device comprising at least a gate main line connected to a gate branch line. 3. A field emission device characterized in that the gate electrode element according to claim 2 is divided and provided for each cathode electrode. 4. A field electron emission device according to claim 2, wherein at least a part of the gate branch line is a thin film soluble resistor made of a conductive thin film. 5. A field electron emission device, wherein the thin film soluble resistor according to claim 4 has a bridge shape.