JPS5878350A - Electric field emission generator and method of producing same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that includes an electrically insulating plate, a first electrode, an insulating layer, and a second electrode, and generates field emission in an element. The invention further relates to a special use of this device and a method for its manufacture.

It has long been known how to generate field emission from metals in vacuum. These methods often utilize one or more fine tungsten tips and utilize the electric field generated at the tip when a voltage is applied between the tip and a counter electrode. 10' at the tip to obtain a practical emission current.
An electric field strength of V/on or higher is required. Recently, this field emitter has been manufactured using a photolithography method in conjunction with a special steaming operation.
allJ, Appl, Phys. 47,12 (19
76) S, 5248).

Devices of this type are often designed for use as cold cathodes which must be supplied with direct current. However, devices of this type are also suitable for short-term releases, for example in order to fully trigger the gas discharge. M) The devices that control the discrete individual emitters within the IJ system have not been disclosed until now. Another field emission generation method uses thin-film MIM-structures (metal-
(insulator-metal) is used. There has been no attempt to fabricate a controllable emitter on top of a matrix using this structure (R,W, J.G. Simmons, Radio and Electronics J, May 1968, 265).
Lomax, J.G., Sirrwnons,
Radio and Electron,,Mait
9ss, S, 265).

However, due to its characteristics, this is only possible with a diode in front. Moreover, it is difficult to manufacture reproducibly.

It is therefore an object of the invention to provide a device of simple construction which can be used as a field emitter and which can be ignited without delay by means of a gas discharge, in particular in plasma panels.

It has been found that this object can be achieved in a technologically advanced manner with a device N of the type mentioned at the outset, which comprises a metal insel in front of the edge of the second electrode. Advantageous embodiments of the device according to the invention are defined in claims 2 to 5.
It is described in the section. Claims 6 to 14 relate to a method of manufacturing a device according to the invention. Claims 15-17 are directed to three uses.

The device according to the invention can be manufactured as follows.

When the entire electrode layer is vaporized through a mask that is insufficiently placed on the insulating layer, an insel is inevitably formed at the edge of the second electrode. The distance l1w between the mask and the absolute H1@ is advantageously 10
~50) Lm. This can be obtained by placing the mask metal loosely on the insulating layer without pressing it. evaporation source,
For example, boats or coils are not point-like, so the gaps do not cause sharp edges of the deposited layer. Rather, the layer thickness always decreases to zero within a few μm at this location.

However, the thin deposited layer, for example below about 5) LWL, is no longer continuous and has an insel structure. The cracks also appear at the tapering edges of the deposited layer.

2. Insel can also be easily manufactured by photolithography. At this time, the surface of the insulating layer becomes slightly rough. This can be obtained by, for example, forming an insulating layer on the rough surface of the insulating layer from polytetrafluoroethylene. For this, the support with the first electrode is immersed in a polytetrafluoroethylene dispersion and then sintered at 400°C. The layer thickness is approximately 2-5 pm.

In the case of materials that produce a smooth coating, fine roughening of the surface can be obtained, for example, by etching.

In the case of a Sip layer, etching can be carried out with hydrofluoric acid. The surface roughness is approximately a1 to α5%m.

Next, apply a second electrode to the rough surface using a well-known method to a thickness of approximately Q1~05μ.
Mounted by photolithography to a layer thickness of m.

The vapor-deposited metal layer is then coated with a photographic lacquer.

The single layer of photographic lacquer is made thicker than the height of the roughness of the insulating layer, exposed through a photographic mask, and developed.

The exposed areas of the photographic lacquer are removed to expose the metal layer. Next, the metal layer '1i (penetration depth of more than 11 μm,
Particularly corrosive occurs at penetration depths of u5 to 1 fim. Due to the micro-roughness of the surface of the insulating layer, the sub-corrosion is non-uniform, resulting in small floating metal insels.The invention will now be explained in more detail with reference to the accompanying drawings, which show only one embodiment.

FIG. 1 shows the individual elements of the device, consisting of an insulating substrate 1, a first electrode 2, an insulating layer 3 and a second electrode 4. FIG. When a voltage is applied between electrodes 2 and 4 and electrode 4 is made negative, a field emission will appear at the edge of electrode 4 if the voltage is high enough. This means that the electric field strength at this edge is high. This effect is known. Furthermore, it is also well known that field emission with an electric field strength of about 10' V/11 already occurs from the surface of a metal such as aluminum or magnesium on which an oxide film or dislocation film is formed. However, surprisingly, field emission occurs at electrode 40.
It has been found to be particularly strong when a small metal insel 5 is provided in front of the line. In the absence of this insel, the voltage applied between electrodes 2 and 4 must be two to three times greater than in the presence of the insel to obtain a measurable field emission.

According to the invention, the electrode 4 preferably consists of an aluminum film with a thickness of approximately Q5 m. This electrode is manufactured according to one of the methods described above to form an insel at the edge. When produced by photolithography, this electrode can simply be constructed in such a way that the entire length of its edge facing electrode 2 is as large as possible. In the embodiment of FIG. 2, the opening is realized by a window opening 6. In the embodiment shown in FIG. The individual elements are very small, e.g. about IQ
, umx I gkm.

In the apparatus shown in FIG. 3, field emission is measured using a secondary electron multiplier (channeltron). Therefore, from electrode 4 to approximately 50. Another electrode 7 is attached with a spacer at a distance of A4rrL to form a -nk net. Finally, set up Channeltron's hopper 8 about 5 points above Net 7. Channeltron amplification is approximately 10 times easier. Approximately 10-
Evacuate to 11 mbar.

+2.5 kV-L5kV to terminal 9 of channeltron
, 5·ζ', and apply a voltage of +100v to 200v to net 7. Electrode 4 is connected to earth potential. Approximately 10 to electrode 2
When a voltage pulse of 0V is applied, field emission occurs at the edge of the electrode 4. A part of the emitted electrons is accelerated to the channeltron by the acceleration net 7 and amplified. After a delay time of approximately 25n8 (travel time in the Keynertron), the amplified signal can be measured at terminal 10. The field emission is about 100
The operation is carried out only within a time period of ns, and even if the voltage is continuously applied to the electrode 2, it is interrupted again after this time has elapsed. When performing field emission again, reverse the voltage polarity of electrode 2,
Again the emission of about 100'rL8 has to be carried out again. This effect can be explained by the state of charge of the in-cell placed in front of the edge of the electrode 4. The in-cell is charged positively or negatively depending on the pre-sign of the potential of the electrode 2 during discharge to the edge. This state of charge is maintained even after the voltage between electrodes 2 and 4 is removed. - The field emission in such a device is shown in Figures 4a) to 4g), in which the individual cells are shown in cross section.

The in-cell 5 has a capacitance C+k with the electrode 2, and a capacitance C! with the grounded second electrode 4. (Figure 4a). For simplicity, C,=C.

Assume that Voltage -U (e.g. -150V) k on electrode 2
When added, it becomes incell 5 S/2 (Fig. 471)). However, since the distance to the edge of the second electrode 4 is short, a high electric field strength is generated toward this electrode. This action causes electron emission from the in-cell 5 to the edge, and the potential of the in-cell 5 becomes positive by ΔU (Figure 4C).

When the potential difference -U/2+ΔU is so small that it does not cause field emission, or when aluminum is used as the electrode material and the surface state on the oxide film (surface state with a sufficiently small work function) is empty. , the emission is interrupted.

After turning off the voltage -U-q, a positively charged in-cell 5 remains behind (Fig. 4d). Reapplying the voltage -U no longer causes emission.

Next, voltage +Uf is applied to electrode 1 and electrode 2 (Fig. 48). Kon
As a result, the potential of the in-cell 5 increases to +U/2+ΔU, and field emission can now occur from the edge of the electrode to the in-cell 5. Due to this, the potential of the in-cell 5 is not small (
(FIG. 47)), the release is interrupted again when the potentiometer U/2-ΔU1. After switching off the voltage +U, the in-cell 5 is now in a negative charging state (FIG. 4g)).

Next, by applying the voltage -U again to the first electrode 2, the illustrated cycle can be started from the beginning.

In the example shown in FIG. 4, the limit voltage of field emission is approximately 85 m'
It is. Because of this limitation, matrix control of many individual elements is possible, as shown in FIG. 6 α) and b).

Electrodes 2 are formed in rows of a matrix, electrodes 4 are formed in columns, and
An insulating layer 3 separates both from each other. In steady state, for example, all electrodes are connected to earth potential. Now one side of the electrode 2
For example, -50Vf is applied to the other electrode 1, and +5o is applied to the other electrode 1.
When V is applied, a potential difference of 100 V exists at the intersection of both electrodes, and this potential difference causes field emission at this location if the in-cell state of charge is appropriate. No field emission can occur anywhere else in the matrix since the potential difference does not exceed 50 T'. Detection of the release is carried out using the apparatus shown in FIG.

It can also be used to start a gas discharge without delay in an electret storage device as described in Example 9 or German Patent Application No. 2 627 249 for triggering a gas discharge in a plasma panel.

The structure of the electret storage device is shown in FIG.

The storage device is constructed between two glass plates 1 and 11. A conductor track 2.21 parallel to the length of the glass plate and an insulating layer 3, 3' are mounted thereon.

Next, a net is made thereon, which completely forms the second electrodes 4, 41 and the preceding incells, and also places the mesh opposite the conductor track 2.21. Finally, insulating layer 3.
3"I (formation) of light using the fluid contact method, the glass pieces are attached using spacers so that the conductor paths 2.21 attached to the glass pieces are orthogonal to each other. Neon+α1 is placed in the gap.
Fill with thiargon to form a gas discharge section. Conductor track 2
, 21 , that is, the meshes of both nets 4 and 41 , are provided with one memory collection. 4.4" to ground, and conductor path 2゜2' to ignite the element at the intersection.
k-balance control. The full ignition voltage Uz exists only at the intersection of the two first electrodes. At the same time, the controlled first electrodes 2, 2
′ and the meshes 4, 4-, a voltage Uz/2
, and field emission occurs at the edge of the network with in-cells. At this time, electrons are emitted and a gas discharge is ignited without delay at the intersection of the first electrodes 2 and 210.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the structure of the individual element, Figure 2 is a plan view of the individual element, Figure 3 is an apparatus for measuring field emission in the element of the present invention, Figure 4 a) to g) are the second electrodes. 5 is an exploded view of the structure of a dynamic memory device, and FIG. 6 is a matrix that can be composed of a number of individual elements. 2...First electrode, 3...Insulating layer, 4...Second
Electrode, 5...Small metal incell, 6...Window opening. Figure 1 Figure 2

Claims (1)

[Claims] L In a device that includes an electrically insulating plate, a first electrode, an insulating layer, and a second electrode and generates field emission in an element, a small metal insel ( 5) Device 2. Device according to claim 1, characterized in that the insel (5) consists of an electrode material. a. Claim 1 or 2, characterized in that the electrodes (2, 4) of a plurality of elements form rows and columns of a matrix, and an insulating layer (3) separates the electrodes from each other. The equipment described in section. The device according to any one of claims 1 to 3, characterized in that the edge of the second electrode (4) is extended by an arbitrary structure. h The device according to claim 4, characterized in that the second electrode (4) has a window opening (6) and is provided with an insel (5)'Ik in front of it along the edge of the window opening. . G. A first electrode and an insulating layer are attached to the electrical insulating plate by a well-known method, and then a metal mask is attached to the shape of the second electrode, leaving a slight gap between the mask and the insulating layer. A second electrode is obtained by vapor deposition from a non-point source and is placed on top of the insulating layer, reducing the thickness of the electrode layer to form a metal insel just below the edge of the mask. A method for manufacturing an apparatus according to any one of claims 1 to 5. 7. A method according to claim 6, characterized in that the gap between the mask and the insulating layer is about 10 to 50 tones. & The method according to claim 6 or 7, characterized in that a gap is obtained between the mask and the insulating layer by placing the mask loosely on the insulating layer without pressing it. a. Attach a first electrode to an electrically insulating plate using a well-known method and an insulating layer thereon, make the surface of the insulating layer slightly rough, attach a second electrode on top of the insulating layer using a well-known photolithography method, and expose to light. After removal of the photographic lacquer, the exposed electrode layer is removed.
Claim 1, characterized in that a metal layer is formed at the edge of the electrode layer by etching the photographic lacquer remaining on the edge until it sub-corrodes and roughening the surface of the insulating layer. A method for manufacturing the device according to any one of Items 5 to 5. 1a The method according to claim 9, characterized in that the surface roughness of the insulating layer is 01 to Q5P. IL The penetration depth of sub-corrosion under one layer of photographic lacquer is 11
11. The method according to claim 9 or 10, characterized in that Lnh is 421 or more, in particular a5-l)Lnh. 12. Thickness k of the metal layer forming the second electrode (11~(1
5. The thickness of one layer of photographic lacquer is 1. 12. The method according to any one of claims 9 to 11, characterized in that the method is a transliteration. 1a. Process according to any one of claims 9 to 12, characterized in that the rough surface of the insulating layer is obtained by selecting a suitable material, for example polytetrafluoroethylene. 14. The method according to any one of claims 9 to 12, characterized in that the rough surface of the insulating layer is obtained by etching. 15. Use of a device according to any one of claims 1 to 5 as a digital storage device with an erasable reader. 1G Any of claims 1 to 5 for causing gas discharge without delay in a plasma panel
or 1. How to use the device described in item 1. 17. Use of the device according to any one of claims 1 to 5 for causing a gas discharge without any delay in an electret storage device.