JPH04292831A - Field emission cathode device - Google Patents

Abstract

PURPOSE:To improve an yield in the manufacture of a field emission cathode device and increase the lifetime thereof by preventing the occurrence of shortcircuit between a cathode electrode and a gate electrode. CONSTITUTION:A field emission cathode device in the title comprises the first electrode 11 for applying voltage to a plurality of cathodes 9, a resistance layer 12, an insulation layer 2 and the second electrode 3, respectively laminated in sequence, and a cavity 6 is formed over the range of the second electrode 3 and insulation layer 2. Furthermore, the cathodes 9 are so laid in the cavity 6 as to be adjacent to the top of the resistance layer 12, and the first electrode 11 is made to have a break beneath the cathodes 9.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission cathode device.

0002

2. Description of the Related Art A Spindt type field emission cathode device is known as a minute field emission cathode having a cathode size of several μm or less. This Spindt type field emission cathode device will be explained with reference to the schematic enlarged cross-sectional view of FIG.

In FIG. 6, reference numeral 10 denotes an insulating substrate made of glass or the like, on which a first electrode 11 made of Al or the like, that is, a cathode electrode is deposited. The cathode 9 is made of a metal with a high melting point and a low work function, such as W or Mo, and has a conical shape, for example, and has a sharp tip shape. Then, around this cathode 9, an insulating layer 2 made of SiO2 or the like having a cavity 6 with an opening width of about 1 to 1.5 μm in diameter is formed.
On this insulating layer 2, a second electrode 3, ie, a gate electrode made of a high melting point metal such as Mo, W, Cr, etc., is arranged as a counter electrode to the cathode 9.

[0004] As a method for manufacturing such a field emission type cathode device, for example, Japanese Patent Application Laid-Open No. 56-160740 by the present applicant is known.
An example of this is proposed in the Publication No. This method is
A crystalline substrate such as single-crystal Si is used as the substrate forming the above-described field emission cathode device. First, a mask layer having a required through hole is formed on one main surface of a Si substrate, etc., and crystallographic etching is performed through the through hole to form, for example, a conical recess. An electrode layer consisting of the like is deposited by vapor deposition, sputtering, etc., and an insulating reinforcing material is deposited so as to fill the inside of the recess. Then, normal or non-crystalline etching is performed on the other surface, that is, the back surface of this substrate, so as to expose the pyramidal top of the electrode layer in the recess formed on the main surface, and use this as a cathode tip; After that, an insulating layer is deposited on this back surface so as to bury the exposed cathode, and a conductive layer is further deposited, and then anisotropic etching such as RIE (reactive ion etching) or isotropic etching is performed around the cathode. A field emission type cathode device can be obtained by forming a cavity by chemical etching and exposing the cathode. If you use this method,
The tip of the cathode can be reliably formed into a sharp shape.

In the field emission type cathode device thus formed, the cathode 9 is heated by applying a voltage of about 106 V/cm or more between the gate electrode, that is, the second electrode 3, and the cathode 9. Electrons can be emitted without heating. According to such a micro-sized field emission cathode device, the gate voltage can be reduced to several tens of tens of meters.
It can be made at a voltage of about several hundred volts, making it possible to operate at a relatively low voltage. For example, when using this field emission type cathode device as an electron gun in a flat display, etc., by arranging hundreds of millions of microscopic field emission type cathode devices at a pitch of about 10 μm, low voltage and therefore low consumption can be achieved. You can get a flat screen display of power.

On the other hand, between the first electrode 11, that is, the cathode electrode, and the cathode 9, there is a resistor made of a thin film of Si or the like with a thickness of several Å to several μm and a resistance of several hundred to several million Ω·cm. A structure in which layer 12 is provided has been proposed. In this way, by providing the resistance layer 12 on the cathode 9 and the first electrode 11, the amount of electrons emitted from each cathode 9 can be stabilized. This will be explained in detail with reference to FIGS. 7 and 8, which are schematic enlarged cross-sectional views of the field emission cathode device. FIG. 7 shows a case where a plurality of cathodes 91 and 92 are directly arranged and formed on the first electrode 11 without providing the resistance layer 12, and the arrow e indicates the electron flow. When a large number of cathodes 6 of submicron size are formed as in the case of application to the above-mentioned flat display, the size and shape of each cathode will vary to some extent as shown in FIG. This may result in a difference in the electric field strength required for electron emission, that is, a difference in emissivity. For example, while the cathode 91 emits electrons at 50V, the cathode 92 may not emit electrons unless a voltage of about 100V is applied, and when a voltage of about 50V is applied, only the cathode 91 emits electrons and the cathode 92 does not operate. It happens. Conversely, if a voltage of about 100 V is applied, the cathode 92 emits electrons, but there is a risk that the cathode 91 will be destroyed.

Therefore, when such a field emission cathode device is applied to a flat display, variations in electron emission due to the shape of the cathode may cause uneven shading on the screen, and some elements may be destroyed. This may lead to a shortened lifespan.

On the other hand, the resistance layer 12 is connected to the cathode and the first
Consider the case where the electrode 11 is provided between the electrode 11 and the electrode 11. By providing the resistance layer 12 in this way, resistances R1 and R2 are generated between the cathodes 91 and 92 and the first electrode 11, respectively, as shown in FIG. Then, when voltage V0 is applied here, the currents flowing through each cathode 91 and 92 are defined as i1 and i2 as shown by the arrows, i1
>i2 That is, the cathode 91 emits electrons more easily than the cathode 92. At this time, the cathode 91 has a resistor R1
Since a voltage drop occurs, the applied voltage becomes V1 = V0 - ΔV1 = V0 - R1 i1. On the other hand, the voltage applied to the cathode 92 is similarly V2 = V
0 −ΔV2 =V0 −R2 i2, and V1
<V2. Therefore, the amount of electrons emitted from the cathode 91 at the next moment decreases relative to the amount of electrons emitted from the cathode 92, resulting in averaged electron emission. Therefore, in the above-mentioned flat display or the like, variations in screen shading, etc. can be suppressed.

Furthermore, when forming the resistance layer 12 in this manner, as shown in the schematic enlarged cross-sectional view of FIG. 9, minute conductive dust 14 comes into contact with the tip of the cathode and the second electrode. Even if the resistive layer 12 is attached, complete conduction may not occur even if the resistive layer 12 is provided, and when a plurality of cathodes are arranged, a predetermined voltage may be applied between the other cathodes and the second electrode. applied, and electrons are emitted.

However, as shown in the schematic enlarged cross-sectional view of FIG. If the foreign dust 14 adheres to the tip of the cathode 9 and comes into contact with the second electrode 3, a complete short circuit will occur. Therefore, even if a plurality of cathodes are arranged, electron emission cannot be obtained from other normally shaped cathodes, which may lead to an increase in the number of defective products.

[0011] Particularly when a display is constructed by forming several hundred million cathodes as described above, such defects are likely to occur, which may lead to a decrease in yield. Furthermore, if a short circuit occurs due to dust adhesion during the operation of such a display device, etc., as described above, the cathode itself or multiple cathodes may become unable to emit electrons, making it difficult to extend the life of the display device. There's a problem.

0012

[Problems to be Solved by the Invention] The problems to be solved by the present invention are problems such as variations in electron emission characteristics, adhesion of conductive dust, etc. in the field emission type cathode device as described above, and problems with By solving the problem of short circuits caused by the presence of pinholes, etc., we aim to improve yield and extend life.

[0013]

[Means for Solving the Problems] FIG. 1 shows a schematic enlarged cross-sectional view of an example of a field emission type cathode device of the present invention. As shown in FIG. 1, the present invention is made up of a first electrode 11 for applying voltage to a plurality of cathodes 9, a resistance layer 12, an insulating layer 2, and a second electrode 3, which are laminated in this order. A cavity 6 is provided across the second electrode 3 and the insulating layer 2, and a cathode 9 is disposed in the cavity 6 in contact with the resistive layer 12.
1 is a pattern having a cutout below the cathode 9.

[0014]

[Operation] As described above, in the field emission type cathode device of the present invention, the first electrode 11 is formed in a pattern lacking in the lower part of the cathode 9, so FIG. 3 shows an example of a schematic enlarged cross-sectional view. As shown, even if conductive dust 14 adheres to the tip of the cathode 9, the second electrode 3 and the first electrode 11
It is possible to avoid short-circuiting.

Furthermore, as shown in an example schematic enlarged cross-sectional view in FIG.
1 can be avoided.

Therefore, when a plurality of such cathodes 9 are arranged to constitute, for example, a flat display device, the provision of the resistive layer 12 makes it possible to make the electron emission rate of each cathode 9 uniform. , even if conductive dust 14 adheres to some of the cathodes 9 and the electron emission characteristics, e.g., emission rate, of these cathodes 9 decrease, other cathodes can still operate normally, so it is preferable to have a plurality of cathodes. It is possible to improve the yield and extend the life of the field emission cathode device formed by the present invention.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a field emission type cathode device of the present invention will be described in detail below with reference to FIGS. 1 to 5. In FIG. 1, reference numeral 10 denotes an insulating substrate made of glass or the like, on which is deposited a first electrode 11 made of Al or the like and having, for example, a circular opening 11a with a diameter φ of about several μm to 10 μm. ,
On this first electrode 11, for example, an S having a thickness of about several tens Å to several μm and a resistance value of about several hundred Ω·cm to several million Ω·cm is formed.
A resistive layer 12 made of an i-thin film or the like is deposited over the entire surface. Then, on the opening 11a of this first electrode 11, a conical shaped metal, for example, made of a high melting point and low work function metal such as W or Mo, and having a sharp tip shape, is placed on the opening 11a of the first electrode 11 via the resistance layer 12. A cathode 9 is formed. Then, around this cathode 9, an opening width w of, for example, about 1 to 1.5 μm in diameter is provided.
An insulating layer 2 made of SiO2 or the like is formed having a cavity 6 with a
, W, Nb, WSix, etc. The second electrode 3, ie, the gate electrode, is arranged as a counter electrode to the cathode 9.

As a method for manufacturing such a field emission type cathode device, for example, first, an insulating substrate 1 made of glass or the like is prepared.
0 is prepared, a metal layer made of, for example, Al is deposited thereon by vapor deposition, sputtering, etc., and then the diameter φ is formed, for example, from several μm to 10 μm by applying photolithography or the like.
A circular opening 11a having a diameter of about μm, for example about 10 μm.
A first electrode 11 serving as a base electrode is formed by drilling. Then, on top of this, for example, a 50 mm
As Å, Si or the like is deposited on the entire surface by vapor deposition, sputtering, etc., and the volume resistivity is from several hundred Ω・cm to several million Ω.
The resistance layer 12 is formed to have a resistance of, for example, 500 Ω·cm. Further, on top of this, a required thickness of, for example, 1 to 1.
SiO2, Si3 N4 with a thickness of about 5 μm
An insulating layer 2 made of materials such as W, Mo, Nb, WSix is deposited on the entire surface by CVD (chemical vapor deposition), etc.
A metal layer having a thickness of several thousand Å, for example, 4000 Å, is deposited on the entire surface by vapor deposition, sputtering, etc., and a circular shape having an opening width w of, for example, 1 μm is formed by applying photolithography to this metal layer. An opening 5 is formed to form a second electrode 3 serving as a gate electrode. This opening 5 is arranged to be located approximately above the first electrode 11, for example, so that its center is located at approximately the same position as the center of the opening 11a of the first electrode 11. Subsequently, anisotropic etching such as RIE is performed through this opening 5 to etch the insulating layer 2 to form a cavity 6. Then, on this second electrode 3, a peeling layer made of, for example, Al, which is easy to peel off and has etching selectivity with respect to the cathode material in the step of removing the cathode material layer to be described later, is applied to an extent that does not adhere to the inside of the cavity 6. For example, diagonal vapor deposition is performed while rotating the substrate 10 at an angle of about 5° to 20°, and then a layer of material that will serve as a cathode material, that is, W, Mo, etc. having a high melting point and a low work function, is vertically vaporized on top of this. The coating is formed on the entire surface. At this time, due to the oblique vapor deposition of the release layer, the diameter of the release layer is substantially narrowed and deposited on the opening 5, and accordingly, the substantial diameter of the material layer around the opening 5 is narrowed over time, and the release layer is deposited over the opening 5. The cathode 9 deposited on the substrate 1 through the cathode 5 is formed in the shape of a cone, such as a cone, whose diameter gradually decreases as its thickness grows. After this, the release layer is removed using an etching solution such as NaOH that can melt and remove only the release layer, and at the same time, a so-called lift-off is performed to remove the material layer on top of this, and the field emission type shown in FIG. A cathode device can be obtained.

In the step of forming the cavity 6 described above, once an opening for the second electrode 3, which is circular in shape, for example, is formed with an opening width w, isotropic etching is performed, for example, to form an opening over the insulating layer 2. When etching is performed, the peripheral part of the opening 5 of the second electrode 3 can be configured to protrude like a canopy from the inner wall of the cavity 6 of the insulating layer 2, as shown in FIG.

Next, the case where conductive dust adheres to the vicinity of the cathode in the field emission type cathode device of the present invention thus formed will be discussed with reference to FIGS. 3 to 5.

FIG. 3 shows a field emission type cathode device in a normal state, when conductive dust 14 has adhered so as to come into contact with the tip of the cathode 9 and the second electrode 3. Since the resistance layer 12 is provided between the first electrode 11 and the second electrode 3, a short circuit between the first electrode 11 and the second electrode 3 can be avoided, and the influence on other cathodes can be avoided. .

FIG. 4 shows a field emission type cathode device in which a pinhole 20 leading to a substrate 10 is formed in the lower part of the cathode 9, in which conductive dust 14 is attached so as to be in contact with the cathode 9 and the second electrode 3. Indicates the case where In this case, since the pattern is such that the first electrode 11 is not present under the cathode 9, it is possible to avoid short-circuiting between the first electrode 11 and the second electrode 3 through the cathode 9, impact can be avoided.

FIG. 5 shows the resistance layer 12 in the cavity 6.
2 is a schematic enlarged sectional view of a field emission type cathode device in which a cathode 9 is adhered and formed in a state in which the cathode 9 is peeled off. Even if the resistance layer 12 is peeled off in this way, the first layer remains under the cathode 9.
Since there is no electrode 11, even if conductive dust 14 that comes into contact with the tip of the cathode 9 and the second electrode 3 adheres, a short circuit between the first electrode 11 and the second electrode 3 is avoided. It is possible to avoid the influence on other cathodes.

As shown in FIGS. 3 to 5, according to the field emission cathode device of the present invention, short circuit between the first electrode 11 and the second electrode 3 can be reliably avoided. In particular, the presence of pinholes 20 and the resistance layer 12 as shown in FIGS.
Peeling etc. is highly likely to occur, for example, when a field emission cathode device is used as an electron gun for a flat display device and hundreds of millions of cathodes are manufactured at a pitch of about 10 μm. Even if conductive dust adheres to the cathode when a defect occurs in this way, short circuit between the first electrode 11 and the second electrode 3 can be reliably avoided. Therefore, even if some cathodes malfunction due to adhesion of such conductive dust, a predetermined voltage can be applied between the other cathodes and the gate electrode, that is, the second electrode, and the other The cathode of the device can be ensured to operate normally. Therefore, it is possible to improve the yield of field emission cathode devices having a plurality of cathodes.

In each of the above examples, since the gate voltage is applied between the cathode 9 and the second electrode 3 via the resistance layer 12, the first It is desirable to provide the electrode 11 and the cathode 9 as close as possible. Therefore, as mentioned above, for example, in the case of a circular opening 11a, the diameter φ is set to several μm to 10 μm.
It is desirable to keep it at a certain level.

In the above example, the opening 5 of the second electrode 3 is circular, and the cathode 9 is conical. Alternatively, the opening 5 may be formed in a line shape extending in a direction perpendicular to the paper surface of FIG. 1, and the cathode 9 may be formed in a line shape extending in the same direction. In addition, the shape of the opening 11a of the first electrode 11 can be made into various shapes such as a square or a circle. opening 1
1a may be provided. In this case, it is desirable to appropriately set the distance between each cathode 9 and the edge of the opening 11a to about several μm.

Furthermore, in the above example, Si was used as the material for the resistance layer 12, but its resistance value is several hundred ohms in volume resistance.
cm to several million Ω·cm, and it is preferable to use a semiconductor material. By providing the resistance layer 12 in this way, the applied voltage can be controlled by increasing or decreasing the current, so it is possible to suppress variations in electron emission caused by differences in electron emission characteristics due to the cathode shape, and substantially A uniform amount of electron emission can be obtained.

[0028]

As described above, according to the field emission cathode device of the present invention, by providing the resistance layer 12, it is possible to suppress variations in electron emission caused by differences in electron emission characteristics depending on the shape of the cathode. , it is possible to obtain a substantially uniform amount of electron emission, and also to reliably avoid a short circuit between the first electrode 11 and the second electrode 3, that is, to avoid an influence on other cathodes. The cathode 9 can be reliably operated normally.

Therefore, when the field emission cathode device of the present invention is used as an electron gun for a flat display device, for example, even if conductive dust adheres to some cathodes during operation, other cathodes can operate normally. Therefore, it is possible to maintain uniform light emission from the screen of such a flat display device, thereby improving the yield and extending the life of a field emission cathode device having multiple cathodes. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic enlarged sectional view of an example of a field emission cathode device of the present invention.

FIG. 2 is a schematic enlarged sectional view of another example of the field emission cathode device of the present invention.

FIG. 3 is a schematic enlarged cross-sectional view of an example of a field emission cathode device of the present invention.

FIG. 4 is a schematic enlarged cross-sectional view of an example of a field emission cathode device of the present invention.

FIG. 5 is a schematic enlarged cross-sectional view of an example of a field emission cathode device of the present invention.

FIG. 6 is a schematic enlarged cross-sectional view of an example of a conventional field emission cathode device.

FIG. 7 is a schematic enlarged cross-sectional view of an example of a conventional field emission cathode device.

FIG. 8 is a schematic enlarged cross-sectional view of an example of a conventional field emission cathode device.

FIG. 9 is a schematic enlarged cross-sectional view of an example of a conventional field emission cathode device.

FIG. 10 is a schematic enlarged cross-sectional view of an example of a conventional field emission cathode device.

[Explanation of symbols]

2 Insulating layer 3 Second electrode 5 Opening 6 Cavity 9 Cathode 10　Substrate 11 First electrode 11a Opening 12 Resistance layer 14 Conductive dust

Claims (1)

[Claims] 1. A first electrode for applying a voltage to a plurality of cathodes, a resistance layer, an insulating layer, and a second electrode are sequentially stacked, and the second electrode and the insulating layer are stacked one after another. A field emission type, characterized in that a cavity is provided across the cavity, the cathode is disposed in the cavity in contact with the resistive layer, and the first electrode has a pattern having a cutout below the cathode. Cathode device.