JPH1050204A - Electron emitting element, electrode forming method thereof, and resist material therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provided an electrode made of a baked metallic particle body by applying a non-vapor deposition process using a specific resist in which metallic particles are dispersed. SOLUTION: To form an emitter electrode, an electromagnetic radiation sensitive resist material in which metallic particles for forming the electrode are dispersed is used instead of using vapor deposition or etching process. That is, the surface of a resist material layer in which metallic particles are dispersed is irradiated with a spot-like exposure light so that the exposure light diffused in the resist layer forms a hardened resist layer of an end-pointed shape suitable for the emitter electrode shape. The product is developed to form an intermediate structure of the electrode made of a metallic particle-dispersed resist material. The intermediate structure is first baked at a relatively low temperature to decompose and remove the resist material made of organic substance. At the same time, metallic particles are baked to form a needle-shaped emitter electrode made of sintered body of metallic particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrode of an electron-emitting device which is expected to be applied to a field emission display (FED) as a next-generation thin film display or a field emission array (FEA) as a magnetic field sensor. It is related to forming technology. In particular, the present invention relates to a novel technique for forming an electrode using a resist obtained by dispersing metal fine particles in an electromagnetic radiation-sensitive resin.

[0002]

2. Description of the Related Art In an electron-emitting device, a conical cathode (emitter electrode) having a sharp tip is usually formed on a silicon substrate, and electrons are extracted on an insulating layer formed so as to surround the emitter electrode. Gate electrode is formed. A conventional general FED structure is, as shown in FIG.
An emitter electrode 3 is formed on a silicon wafer 10 and is sealed in a glass cover 1a, 1b having a special structure to maintain an ultra-high vacuum. The inside of the glass cover is made ultra-high vacuum so that electrons can easily jump out of the emitter electrode, and a light emitting layer coated with a phosphor 8 is provided on the opposite side. Both glass substrates are hermetically sealed with a glass frit 9. A high voltage is applied between the cathode electrode 2 and the transparent anode electrode 7 in advance, and when a voltage is gradually applied between the cathode electrode 2 and the gate electrode 5, a large voltage is applied to the tip of the cone of the emitter electrode 3 and the electric field is increased. Radiation occurs and electrons fly out into the vacuum and collide with the surface of the phosphor 8. The phosphor surface has a structure in which the energy level fluctuates due to the collision and a light emission phenomenon appears.

[0003] It is preferable in terms of characteristics that the emitter electrode has a needle-like shape, and it is extremely difficult to form the emitter electrode because it is formed in a structure embedded in a concave portion. Conventionally,
The method of forming this electrode includes a method shown in FIG. 2 for forming an emitter electrode together with an insulating layer surrounding the electrode on a silicon substrate, and a self-sacrifice layer necessary for forming the emitter electrode. The method of FIG. 3 for forming is known. Hereinafter, these methods will be described slightly.

FIG. 2 is an explanatory view of a conventional method for forming an electrode on a silicon substrate. First, the surface of a silicon substrate 31 is thermally oxidized to form a thermal oxide film 32 made of SiO ₂ , and an inorganic resist layer 3 made of metal or the like is formed on the thermal oxide film.
3 is deposited (FIG. 2B). Next, an organic resist layer 34 such as a photoresist is formed on the inorganic resist layer (FIG. 2C), and the organic resist layer is exposed to light using a photomask or the like and developed to form a circular patterned organic resist. A film 34 'is formed (FIG. 2D). The lower inorganic resist layer 33 and the thermal oxide film 32 are etched through the resist film 34 ′, and the resist is stripped to leave a pattern layer composed of the inorganic resist layer 33 ′ and the oxide film 32 ′ ( FIG. 2 (f)).

Next, when the Si substrate 31 is etched using the inorganic resist layer 33 'as a mask, a circular inorganic resist film 33' is formed by the effect of under-etching.
(FIG. 2 (g)). When the surface of the Si substrate is thermally oxidized again, an emitter tape 36 having a sharp point is formed inside the thermal oxide film 32 (FIG. 2 (h)). In this state, when an insulator such as SiO ₂ is deposited, an insulating layer 37 is formed so as to surround the emitter tip 36.
When a metal such as Mo is deposited, a gate electrode 38 is formed on the insulating layer 37 (FIG. 2 (i)). A resist layer 39 for gate electrode patterning is formed (FIG. 2).
(J)), the resist layer is exposed, developed and patterned (FIG. 2 (k)). Next, after the gate electrode 38 is etched using the resist film 39 'as a mask (FIG.
(L)), the resist film 39 'is removed (FIG. 2)
(M)), when the oxide film 32 is etched with hydrofluoric acid or the like,
A gate opening is formed, and a conical emitter electrode 36 is formed at the center of the opening (FIG. 2 (n)).

FIG. 3 is an explanatory view of a conventional method for forming an electrode by depositing a self-sacrifice layer. In this case,
An insulating layer 42 and a gate electrode layer 48 are formed on the conductive substrate 41 of FIG. 3A by a thin film forming method (FIG. 3).
(B)). Next, an organic resist layer 44 is formed on the gate electrode layer 48 and patterned (FIG. 3D), and the gate electrode layer 48 and the insulating layer 42 are etched using the organic resist film 44 'as a mask (FIG. 3E). )). After removing the resist film 44 'on the gate electrode layer (FIG. 3
(F)) In order to form the self-sacrifice layer 43 on the gate electrode layer so as to protrude, the self-sacrifice layer 43 is formed by evaporating an evaporation material 45a from an oblique direction (FIG. 3).
(G)), using the self-sacrifice layer 43 as an applied electrode, FIG.
As shown in FIG. 3H, the emitter electrode layer forming material 45b is vapor-deposited from the vertical direction to obtain an intermediate as shown in FIG. Thereafter, the film 47 made of a mixed material of the emitter electrode forming material and the oblique deposition material is selectively removed by etching, and the emitter electrode 46 is formed at the center in FIG.
The final structure shown in (j) is obtained.

[0007] However, the method shown in FIG. 2 has a problem that it is not possible to cope with the fabrication of an FED having a larger area than the silicon substrate at present because the silicon substrate is processed. Further, in the method shown in FIG. 3, when forming a self-sacrifice layer necessary for forming an emitter electrode, it is necessary to extremely tilt and rotate the substrate with respect to the evaporation source. For this reason,
There is a problem that the vapor deposition device becomes large-scale / complex. In addition, each of these methods has a problem that the steps are complicated and require a long process.

[0008]

SUMMARY OF THE INVENTION In order to solve these problems, the present invention provides a non-evaporation process using an electromagnetic radiation-sensitive resist in which fine metal particles are dispersed. It is an object of the present invention to provide an electron-emitting device having the same and a method for forming an electrode thereof. Since this electrode can be formed on a substrate other than the Si substrate and is a non-deposition process, it is released from the size limitation due to the scale of the vapor deposition apparatus and can easily cope with an increase in area. Is what you can do.

In the present invention, a metal electrode is formed by applying and patterning a resist in which fine particles of a target electrode material are dispersed instead of forming the emitter electrode by vapor deposition, followed by firing. As a resist material, a negative type polymerized by light, electron beam, ion beam,
A positive resist can be used.

[0010]

An electron-emitting device according to the present invention for solving this problem is an electron-emitting device having an electrode composed of a fired body of metal fine particles, wherein the fired body of the metal fine particles is made of a metal. The method is characterized by being obtained by exposing an electromagnetic radiation sensitive resist layer in which fine particles are dispersed to electromagnetic radiation and developing the intermediate structure of the electrode formed by development and firing. Since the electron-emitting device of the present invention has such a configuration, the electrode tip is sharp and has a uniform shape, so that excellent performance can be exhibited.

Similarly, a method of forming an electrode for an electron-emitting device according to the present invention comprises the steps of sequentially forming an insulating layer and a gate electrode layer on a smooth substrate from the substrate side, and photo-etching the gate electrode layer and the insulating layer. Forming an opening in the electrode receiving portion, and applying an electromagnetic radiation-sensitive negative resist in which metal fine particles are dispersed in the opening, and exposing the electrode forming portion of the negative resist in the opening to electromagnetic radiation The process of
Baking an intermediate structure of the electrode obtained by developing the resist to form an electrode. Since the method for forming an electrode for an electron-emitting device of the present invention has such a configuration, an electrode having a sharp tip and a uniform shape can be easily formed.

The resist material of the present invention comprises at least light,
The present invention is characterized in that metal fine particles are dispersed in a polymer material having chemical reactivity to an electron beam and an ion beam.
By using such a resist material, an electrode for an electron-emitting device having excellent performance can be easily formed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, instead of forming an emitter electrode by vapor deposition or etching, the emitter electrode is formed by using an electromagnetic radiation-sensitive resist in which a material composed of metal fine particles for forming a target electrode is dispersed. What we are trying to do. That is, by giving spot-like exposure from the surface to the resist material layer in which the metal fine particles are dispersed, the exposure light scattered in the resist layer forms a tapered cured resist layer adapted to the shape of the emitter electrode. Form. This is developed to form an intermediate structure of the emitter electrode made of a metal fine particle dispersed resist material. First, the intermediate structure is fired at a relatively low temperature to decompose and remove the organic resist material, and fire the metal fine particles to form a needle-shaped emitter electrode made of a sintered metal fine particle. It is assumed that.

Next, the materials and process conditions used in the present invention will be described. First, the substrate material used in the present invention can be used without any particular limitation as long as the surface on which the emitter electrode is formed is conductive or can be made conductive. For example, ordinary optical glass or a material in which a conductive layer is formed on a quartz substrate can be used as appropriate.

An insulating layer made of silicon oxide for supporting the lower electrode layer and the gate electrode and a gate electrode are formed on the substrate by sputtering, vapor deposition or the like. As a material for the lower electrode and the gate electrode, a metal such as molybdenum is generally used. After forming these layers on the substrate, an opening for accommodating the emitter electrode is formed on the substrate by a normal photoetching process. Thereafter, an emitter electrode is formed in the opening using an electromagnetic radiation-sensitive resist material in which metal fine particles characteristic of the present invention are dispersed.

As the resist material, an electromagnetic radiation sensitive material can be widely used. That is, a negative resist that is polymerized by visible light, ultraviolet light, electron beam, or ion beam can be suitably used. Specifically, Waycoat-HR-100, Waycoat-HR-200
(Manufactured by Hunt Chemical Company), OSR, SVR, OMR-
81, OMR-83 (synthetic rubber + bisazide system), OM
R-83-SR, OMR-83-SS (manufactured by Tokyo Ohka Kogyo Co., Ltd.), KPR (polyvinyl cinnamate), KMR-
747 (manufactured by Kodak Co., Ltd.), and epoxidized 1,4 polybutadiene, silicone SH410 (manufactured by Toray Industries, Inc.) and the like. The resist material is preferably a negative type for forming the shape of the electrode. However, if the resist material is not extremely affected by scattering, a positive type can be used.

As the metal fine particles dispersed in the resist material, nickel, platinum, copper, silver or an alloy thereof can be used. Generally, nickel, platinum and copper are preferred. These metals need to be hard to form an oxide in an oxidizing atmosphere. As the particle diameter of the metal particles, about 2 nm to 1 μm can be used, but since the electrode itself has a fine structure of about 1 μmφ, it is preferable to use a fine particle having a diameter smaller than this. . When forming an emitter electrode utilizing these characteristics, the gate electrode surface is also oxidized in the process,
The gate electrode needs to be formed with a sufficient thickness so that the entire gate electrode does not become an oxide film.

To disperse the metal fine particles in the resist,
Disperse using an ultrasonic disperser. If the amount of the metal fine particles is too small, a dense metallic electrode cannot be formed, and if the amount is too large, it becomes difficult to apply a resist. To apply the resist on the substrate, spin coating is generally performed using a spinner, but a coater or the like capable of applying a uniform film thickness may be used. In order to irradiate these resists with electromagnetic radiation, exposure can be performed using a photomask, or in the case of an electron beam resist, direct writing can be performed while controlling the position using an electron beam writing apparatus. In the case of performing exposure by these methods, even if the surface of the negative resist is exposed in a spot shape, an exposed region having a broadened bottom side with respect to the tip end portion can be formed under the influence of scattering by metal fine particles and organic molecules.

[0019]

【Example】

(Embodiment 1) Embodiment 1 of the present invention will be described with reference to FIG. Although only a single electron-emitting device is shown in FIG. 1, many such devices are actually arranged in a matrix. On a clean quartz glass substrate 11 having a thickness of 3 mm (FIG. 1A), a molybdenum (Mo) layer having a thickness of 3 μm was formed by sputtering onto a lower electrode layer 13.
Deposited and formed. Next, a silicon oxide (SiO ₂ ) layer was formed as an insulating layer 12 to a thickness of 10 μm by sputtering.
And a gate electrode layer 1 on the SiO ₂ layer.
As molybdenum (Mo), 8
It was deposited and formed with a film thickness of μm (FIG. 1B).

Next, a positive photoresist ("OFPR-800" manufactured by Tokyo Ohka Kogyo Co., Ltd.) is spin-coated with a spinner.
By rotating at 500 rpm for 2 minutes and applying,
An organic resist layer 14 having a thickness of 5 μm was formed. afterwards,
After prebaking for 30 minutes in an oven maintained at 80 ° C., it was allowed to cool to room temperature (FIG. 1C). The organic resist layer 14 is exposed through a photomask, and developed with a developing solution (“NMD-3” manufactured by Tokyo Ohka Kogyo Co., Ltd.) to leave the remaining portion of the photoresist. After forming ', post-baking was performed for 30 minutes in an oven maintained at 120 ° C, and the mixture was allowed to cool to room temperature (Fig. 1 (d)). When viewed from above, the electrode forming portion had a circular opening of 2 μmφ.

Next, the substrate is immersed in an etching solution ("MR-ES" manufactured by The Inktech Co., Ltd.) to etch the gate electrode layer 18 made of molybdenum.
The insulating layer 12 made of silicon oxide is etched with an etchant (H
F: NH ₄ F = 1: 6). The gate electrode 18 'and the insulating layer 12' etched remain on the lower electrode of the substrate (FIG. 1E).
Finally, the organic resist film 1 remaining after immersing the substrate in acetone
4 'is removed (FIG. 1 (f)). The substrate has a diameter of about 2μm
A circular electrode forming portion opening 19 of φ was formed in a matrix.

Epoxidized 1,4 polybutadiene (weight average molecular weight: 50,000) as a negative type electron beam resist
Was dissolved in N-methylpyrrolidone (NMP) to give 70
(%) Solution, in which platinum (Pt) fine particles having a particle size of about 200 ° φ are uniformly dispersed to prepare an organic resist in which fine metal particles are dispersed. This preparation was applied to a substrate on which an opening for an emitter electrode was formed by a spinner at 3500 rpm.
m for 2 minutes to form a coating with a thickness of 7 μm. Next, it was dried in a vacuum oven maintained at 150 ° C. for 1 hour to form a metal fine particle-dispersed organic resist layer 16 having a thickness of 3 to 4 μm (FIG. 1 (g)). On this occasion,
The organic fine particle-dispersed organic resist is also filled in the opening 19 of the electrode forming portion as shown in the figure.

On the metal fine particle-dispersed organic resist layer 16, only the position where the emitter electrode is to be formed at the gate electrode forming portion is spot-shaped (about 1 μm in diameter) by an electron beam writer.
(φ) and developed with a predetermined developer (TMAH: tetramethylammonium hydroxide aqueous solution). However, it is necessary to perform development with care so that the resist in the exposed portion is not removed only in all the convex portions of the emitter electrode (FIG. 1 (h)). By this development, the emitter electrode is formed as a cured layer of the metal fine particle dispersed organic resist layer. Next, the resist layer is baked for 1 hour in an oven maintained at 300 ° C. to decompose and remove the organic molecules of the resist layer, and to form an emitter electrode 15 made of acicular platinum (Pt) in the concave portion (FIG. 1 (i)). ).

The emitter electrode 15 has a bottom diameter of 1 μm.
m, a uniformly tapered shape having a height of 4 μm from the substrate to the tip was obtained.

[0025]

The electrode of the electron-emitting device according to the present invention has a very uniform shape because the fired body of fine metal particles is formed by curing and firing an electromagnetic radiation sensitive resist in which fine metal particles are dispersed. Therefore, since the variation in the radiation efficiency of each electrode is small, when used for a display or the like, the in-plane brightness is excellent in uniformity. In addition, since the electrodes are tapered and the tips are long needle-shaped, constant brightness can be maintained for a long time after the start of discharge. Also,
According to the method for forming an electrode for an electron-emitting device of the present invention, an electrode having excellent characteristics can be easily formed by exposing the resist to electromagnetic radiation using an electromagnetic radiation-sensitive negative resist in which fine metal particles are dispersed. Therefore, an electrode can be manufactured very easily and with high precision as compared with the conventional method. Further, the FED of the present invention
Since the method for forming the electrode is a non-evaporation process, it is free from the size limitation caused by the evaporation apparatus, and a substrate having a large area can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a view showing a step of forming an electrode for an electron-emitting device of the present invention.

FIG. 2 is an explanatory view of a conventional method for forming an electrode on a silicon substrate.

FIG. 3 is an explanatory view of a conventional method for forming an electrode by depositing a self-sacrifice layer.

FIG. 4 is a diagram showing a cross-sectional shape of a conventional general FED element.

[Explanation of symbols]

 1a, 1b Glass substrate 2 Cathode electrode 3 Emitter electrode 4 Insulating layer 5 Gate electrode 7 Transparent anode electrode 8 Phosphor 9 Glass frit 10 Silicon wafer 11 Quartz glass substrate 12, 37, 42 Insulating layer 13 Lower electrode layer 14, 34, 44 Organic resist layer 14 ', 34', 44 'Organic resist film 15, 36, 46 Emitter electrode 16 Metal fine particle dispersed organic resist layer 18, 38, 48 Gate electrode 19 Opening of electrode forming portion 31, 41 Substrate 32 Thermal oxide film 32 'Patterned thermal oxide film 33 inorganic resist layer 33' patterned inorganic resist layer 39 resist layer 39 'resist film 43 self-sacrifice layer 45a deposition material 45b emitter electrode formation material 47 composed of emitter electrode formation material and deposition material Film 49 Electric field application electrode hole

Claims (6)

[Claims] 1. An electron-emitting device having an electrode formed of a fired body of metal fine particles, wherein the fired body of metal fine particles comprises:
An electron-emitting device characterized by being obtained by exposing an electromagnetic radiation-sensitive resist layer in which metal fine particles are dispersed to electromagnetic radiation and baking an intermediate structure of an electrode formed by development. 2. The electron-emitting device according to claim 1, wherein the metal fine particles are nickel, platinum, and copper. 3. A method for forming an electrode for an electron-emitting device, comprising the steps of sequentially forming an insulating layer and a gate electrode layer on a smooth substrate from the substrate side, and photo-etching the gate electrode layer and the insulating layer. Forming an opening of the electrode housing portion by
A step of applying an electromagnetic radiation-sensitive negative resist in which metal fine particles are dispersed in the opening, exposing an electrode forming portion of the negative resist in the opening to electromagnetic radiation, and an electrode obtained by developing the resist Forming an electrode by firing the intermediate structure of (1). 4. The method for forming an electrode for an electron-emitting device according to claim 3, wherein the metal fine particles are nickel, platinum, and copper. 5. A resist material comprising fine metal particles dispersed in a polymer material having chemical reactivity at least with respect to light, electron beam and ion beam. 6. The resist material according to claim 5, wherein the metal fine particles are nickel, platinum, and copper.