JP2004014525A - Method for manufacturing fluorescent display device - Google Patents

Abstract

An object of the present invention is to provide a fluorescent display device that performs desired display by irradiating electrons from a field electron emission element onto a fluorescent layer, has a high degree of vacuum in a space between substrates and sharpness and smoothness of the electron emission element, and is reliable and stable. Provided is a manufacturing method capable of easily and inexpensively manufacturing a good fluorescent display device.
In a method of manufacturing a fluorescent display device in which an element substrate having an electron-emitting device and an opposing substrate are bonded together via a holding body, the element substrate and the opposing substrate are placed in a vacuum. And a step of heating the holding body at a temperature equal to or higher than the temperature in the sealing step before the step of bonding and sealing via the holding body 3. In a method of manufacturing a fluorescent display device in which an element substrate 1 having an electron-emitting device and an opposite substrate 2 are attached to each other, before the step of attaching and sealing the element substrate and the opposite substrate in a vacuum. And irradiating the element substrate 1 or the counter substrate 2 with light in a vacuum.
[Selection diagram] Fig. 1

Description

The present invention relates to a fluorescent display device such as a light-emitting type character display used for displaying a watch, an in-vehicle instrument, an OA device, various information guide displays, and the like, or a small matrix display used for a viewfinder of a camcorder. The present invention relates to a method for manufacturing a fluorescent display device for performing a desired display by irradiating a fluorescent layer with electrons from a field emission device.

Recently, as a fluorescent display device as described above, it has been proposed to use a field electron emitting element as an electron source and irradiate electrons from the field electron emitting element to a fluorescent layer to perform display (for example, Technical Digest of Technology). IVMC 91).

FIG. 22 shows an example of such a fluorescent display device, in which a conductive cathode electrode 102 is formed on an element substrate 101 made of glass or the like, and a gate electrode is formed on the cathode electrode 102 via an insulating layer 103. A substantially conical field electron emission element (microchip) 105 is provided on the cathode electrode 102 in the opening formed in the insulating layer 103 and the gate electrode 104 while forming 104. Further, an anode electrode 107 made of ITO or the like is formed on the lower surface of an element substrate 106 made of glass or the like disposed above the element substrate 101, and a fluorescent layer 108 is provided on the lower surface above the field electron emission element 105. Configuration.

Then, the space S between the field emission device 105 and the fluorescent layer 108, that is, the space S between the substrates 101 and 106 is evacuated, and a predetermined voltage is applied to the cathode electrode 102, the gate electrode 104, and the anode electrode 107. Thus, electrons are emitted from the tip of the conical field electron emission element 105 and a desired display is performed by irradiating the phosphor layer 108 with the electrons.

Conventionally, for example, as shown in FIG. 23, an exhaust port 109 is formed in one of the substrates 106 and a glass tube 110 is attached outside the exhaust port 109 in order to make the space S vacuum. After the air in the space S between the two substrates 101 and 106 is sucked and discharged to create a vacuum, the glass tube is sealed off.

It is also known to use a getter material to increase the degree of vacuum. For example, in a conventional fluorescent display tube, as shown in FIG. A getter material 110 formed by filling a mixed powder 112 of BaAl ₄ and Ni in a container 111 is arranged in a fluorescent display tube, and is vaporized and revived by high frequency heating or the like to adsorb gas in the display tube, thereby obtaining a vacuum degree. Enhancements have been made.

However, the degree of vacuum in the space of the fluorescent display device is required to be further enhanced.

The present invention provides a fluorescent display device having a high degree of vacuum in the device.

The method for manufacturing a fluorescent display device according to the present invention is a method for manufacturing a fluorescent display device in which an element substrate having an electron-emitting device and an opposing substrate are bonded via a sandwiching body. Before the step of bonding and sealing via the holding body in a vacuum, a step of heating the holding body at a temperature equal to or higher than the temperature in the sealing step is provided.

Another method for manufacturing a fluorescent display device according to the present invention is a method for manufacturing a fluorescent display device, comprising bonding an element substrate having an electron-emitting device and an opposing substrate, wherein the element substrate and the opposing substrate are placed in a vacuum. And a step of irradiating the element substrate or the counter substrate with light in a vacuum before the step of bonding and sealing the substrates.

As described above, according to the present invention, it is possible to easily and inexpensively manufacture a highly reliable and stable fluorescent display device by adding an extremely simple process.

Hereinafter, a method for forming a fluorescent layer, a method for forming a fluorescent layer in the device, a method for vacuum sealing a space in the device, and a method for promoting the degree of vacuum will be described in detail with reference to the embodiment shown in the drawings.

FIG. 1 is a plan view showing an embodiment of a fluorescent display device according to the present invention, and FIGS. 2, 3 and 4 are sectional views taken along lines AA, B, B and C-C in FIG. The example shows an example applied to a character display that displays a clock.

In the drawing, reference numeral 1 denotes an element substrate, and in this embodiment, an n-type single crystal silicon substrate having a (100) plane orientation is used. Above the element substrate 1, a counter substrate 2 is disposed substantially in parallel at a predetermined interval, and is tightly and tightly joined by a holding body 3 interposed at a peripheral portion between the two substrates 1 and 2. A space S is formed between the substrates 1 and 2 surrounded by the holding body 3.

As the material of the opposing substrate 2, it is desirable to use a material having a thermal expansion coefficient close to that of the element substrate 1. In this embodiment, a transparent glass substrate made of borosilicate glass (# 7740, manufactured by Corning Incorporated) is used. Used.

The material of the holding body 3 is preferably a material having a thermal expansion coefficient close to that of the two substrates 1 and 2 in order to reduce the stress after the two substrates 1 and 2 are bonded together, and particularly, an intermediate value between them. Is desirable. In this embodiment, a low-melting-point powder glass having a working point of 450 ° C. and a coefficient of thermal expansion of 53 × 10 ⁻⁷ / ° C. is used as the holding body 3.

Further, it is desirable that a spacer or the like is mixed in the holding body 3 in order to hold the two substrates 1 and 2 in parallel. In this case, it is necessary to select a spacer that does not soften when the holding body 3 is heated and melt-softened to seal the two substrates 1 and 2 in this case. A spherical glass spacer having a sealing temperature or higher is used. In addition, it is necessary to use a spacer having a particle diameter larger than at least the thickness of a phosphor layer 8 described later. In this embodiment, by using a spacer having a particle diameter of 60 μm, both substrates 1 and 2 can be spaced at an interval of about 60 μm. They are arranged in parallel to face each other.

A plurality of segment electrodes 5 arranged for time display are formed on the surface of the element substrate 1 in the space S, and each of the segment electrodes 5 is provided with an electron emission source as shown in FIGS. A plurality of field emission devices 6 are provided. 5a is a segment terminal for connecting each segment electrode 5 to an external circuit, and each terminal 5a is provided on the surface of the insulating substrate 1 outside the space S, and connects each segment electrode 5 and the segment wiring 5b. Connected through.

As shown in FIG. 7, the field electron emitting element 6 is formed on the surface of the element substrate 1 except for a substantially conical projection 6a processed by an anisotropic etching method or the like and the vicinity of the projection 6a. An insulating layer 6b formed of a silicon dioxide thin film or the like, and a segment electrode (gate electrode) formed on the surface of the insulating layer 6b and formed of a molybdenum thin film or a tantalum thin film having a substantially circular opening near the upper portion of the protrusion 6a 5 is comprised.

Further, the density of the field electron emitting element 6 is desirably 4 × 10 ⁴ (pieces / cm ² ) or more. However, the above density may be determined in consideration of a distance d _AK (cm) between the field emission device 6 and a fluorescent layer 8 described later, and 1 / d _AK ² (pieces / cm ² ) or more is a standard. . In this embodiment, one field electron emission element 6 is formed at a rate of 25 μm square, and about 1000 to 2000 field electron emission elements 6 are provided in one segment.

The configuration of the field electron emitting element 6 is not limited to the above-described embodiment, but may be, for example, a Spindt type as reported in JAP, Vol. 47 (1976) p. 5248, or Technical Digest of IVMC '91 (1991). It can be applied to a lateral type as reported on p. 46, or a product produced by RIE and thermal oxidation as reported in the above Technical Digest of IVMC '91 (1991) p. 26.

On the other hand, on the surface of the opposing substrate 2 in the space S, an anode electrode 7 common to all the segments on the element substrate 1 is formed. The anode electrode 7 is made of an ITO thin film in this embodiment, and has a thickness of 2000 Å. In the figure, reference numeral 7a denotes an anode terminal for connecting the anode electrode 7 to an external circuit. In this embodiment, a Cr thin film is formed on the anode electrode 7 protruding outside the space S. An external circuit can be directly connected to the anode electrode 7 protruding outside S.

(4) A fluorescent layer 8 is provided on the surface of the anode electrode 7. In the present invention, the fluorescent layer 8 is made of a phosphor containing a low-melting glass serving as an adhesive.

In this embodiment, ZnO: Zn which emits green light is used as the above-mentioned phosphor. However, in addition to the phosphor emitting green light, ZnS: Cl + In ₂ O ₃ emitting blue light, ZnS: Ag + In ₂ O ₃ emitting orange light, or the like may be used. Further, multicolor display or full-color display can be performed by using a plurality of kinds of phosphors having different colors as described above.

Further, as the low melting point glass, a glass having a thermal expansion coefficient substantially equal to that of the opposite substrate 2 supporting the fluorescent layer 8 may be used. For example, the thermal expansion coefficient is 20 × 10 ⁻⁷ / ° C. to 90 × 10 ⁻⁷ / ° C. Use the one in the range. Specifically, for example, frit glass (T436, manufactured by Iwaki Glass Co., Ltd.), crystallized low-melting glass, or the like can be used. In this embodiment, the above frit glass is used, the coefficient of thermal expansion is 60 × 10 ⁻⁷ / ° C., and the working point is 450 ° C. In addition, an alkali metal silicate-based inorganic adhesive or a phosphate-based inorganic adhesive having an adhesive effect can be used as the low-melting glass.

In forming the fluorescent layer 8, for example, a powdered fluorescent substance and a low-melting glass are mixed, a binder is mixed therewith to form a paste, and the paste is applied to the surface of the anode electrode 7 and dried. What is necessary is just to bake.

有機 As the binder, for example, an organic binder such as a vehicle can be used. In this example, a mixture of butyl carbitol acetate and 2 to 5% nitrocellulose was used.

The mixing ratio of the above-mentioned phosphor and the low-melting glass is such that if the low-melting glass is too small relative to the phosphor, the adhesive force is reduced, and if it is too large, the resistance becomes high or the display becomes dark. It is desirable that the content of the low melting point glass is in the range of 20 to 70% by weight based on the total weight of the phosphor and the low melting point glass.

If the ratio of the binder is small, the thickness of the applied layer becomes large, and if the ratio is too large, the thickness becomes small. Therefore, it may be appropriately adjusted in consideration of the thickness of the fluorescent layer 8 to be formed. In order to form a film having a thickness of about 10 μm, when butyl carbitol acetate mixed with 3% nitrocellulose is used as a binder, the weight of the phosphor and the low melting point glass is 20 to 80 wt. % Is appropriate.

FIG. 8 shows the suitability of the adhesive strength of the fluorescent layer with respect to the electric field strength when the amount of the low melting glass was mixed with 1.4 g of the phosphor and 3.6 g of a binder was added thereto to form the phosphor layer 8. The result of examining is shown. The actual electric field intensity in the vicinity of the field electron emitting element 6 in the above example was about 7 × 10 ⁴ V / cm, but it was found that the mixing amount of frit glass in this case required about 1.2 g or more. .

FIG. 9 shows the blending weight ratio of the above-mentioned phosphor, low-melting glass and binder, and various characteristics due to the blending ratio. The figure shows the result of examining what ratio is appropriate when the ratio of the phosphor is x, the ratio of the low melting point glass is y, the ratio of the binder is z, and x + y + z = 1. In addition, it was found that the vicinity of the circle in the figure where the mixing weight ratio of the phosphor, the low melting point glass, and the binder was x: y: z = 0.2: 0.29: 0.51 was most appropriate.

In addition, the compounding weight ratio (x = 0.05 to 0.30% by weight, y = 0.15 to 0.55% by weight, z = 0.15 to 0.80%) in the region shown by the dotted line in FIG. % By weight), the adhesive strength is good, and the mixing ratio can be appropriately selected in this region in consideration of transmittance and conductivity.

Further, when the fluorescent layer 8 was formed on the surface of the anode electrode 7 at the above-mentioned compounding weight ratio, the fluorescent layer 8 adhered well to the anode electrode 7 and an electric field of 8 × 10 ⁴ V / cm (400 V at a gap of 50 μm) or more. And a sufficient practical level of adhesive strength was obtained. FIG. 10 shows the phosphor layer formation schedule at that time.

Next, in the above-described fluorescent display device, it is necessary to evacuate the space S between the field emission device 6 and the fluorescent layer 8, that is, the space S between the two substrates 1 and 2, as in the above-described conventional example. A description will be given of an example of a structure for achieving the vacuum and a vacuum sealing method.

In FIGS. 1 and 4, reference numeral 2a denotes an exhaust port for exhausting air in the space S surrounded by the substrates 1 and 2 and the holding body 3 to create a vacuum. After the air in the space S is exhausted and evacuated, the exhaust port 2 a is sealed with solder 9.

FIG. 11 shows an example of a state in which the exhaust port 2a is sealed with the solder 9 as described above. The solder 9 is embedded in the exhaust port 2a formed in the counter substrate 2 from the outside. As the solder 9, for example, a Pb.Sn alloy or the like may be used. In this embodiment, a Pb.Sn alloy containing 37% by weight of Pb is used.

す る と If the outer opening of the exhaust port 2a is formed in a funnel shape as shown in the illustrated example, the joining surface with the solder 9 is widened and the joining strength can be increased.

Further, an intermediate member may be interposed between the opposing substrate 2 and the solder 9 as necessary in order to improve the adhesion between the two. In this embodiment, Cr is used between the opposing substrate 2 and the solder 9. A first intermediate member 9a and a second intermediate member 9b made of an Au.Sn alloy containing 80% by weight of Au are sequentially interposed.

The first intermediate member 9a made of Cr described above has good adhesion to the counter substrate 2 and the second intermediate member 9b made of Au / Sn alloy, and the second intermediate member 9b and the solder 9 The solder 9 can be firmly and airtightly fixed to the counter substrate 2 via the intermediate members 9a and 9b because of its good adhesion.

FIG. 12 is a cross-sectional view showing another specific example in which the exhaust port 2a is sealed with solder 9. In this example, the solder 9 is provided so as to extend to the inner surface of the element substrate 1 facing the counter substrate 2, and the same intermediate members 9a and 9b as described above are interposed between the element substrate 1 and the solder 9. Have been.

When the solder 9 is provided so as to extend to the inner surface of the element substrate 1 facing the opposite substrate 2 as described above, the element substrate 1 and the opposite substrate 2 can be more firmly fixed via the solder 9, The space S between the two substrates 1 and 2 can be evacuated to increase the pressure resistance when the pressure difference between the inside and the outside increases, and can also have a function as a spacing spacer between the two substrates 1 and 2.

す る に は To seal the exhaust port 2a with the solder 9 as described above, for example, the following procedure may be performed. First, the exhaust port 2a is formed in the counter substrate 2 in advance using, for example, an ultrasonic processing machine or the like. In this case, when the hole is drilled from the surface in contact with the space S by an ultrasonic processing machine or the like, the end of the hole is cut off when the hole is finally pulled out, so that the hole is inevitably formed in a funnel shape as shown in FIGS. Can be formed.

Next, the intermediate members 9a and 9b are formed in the openings of the exhaust ports 2a by vapor deposition or sputtering. Intermediate members 9a and 9b can be formed, and if combined after combining both substrates 1 and 2, intermediate members 9a and 9b can be simultaneously formed on both opposing substrate 2 and element substrate 1 as shown in FIG. .

Finally, the space S between the two substrates 1 and 2 is evacuated and the exhaust port 2a is sealed with the solder 9. For example, as shown in FIG. The spherical solder 9 is placed on the gantry 21 in the vacuum chamber 20 with the port 2a facing downward, and between the gantry 21 and the exhaust port 2a as shown in FIG. The inside of the vacuum chamber 20 is evacuated and the air in the space S between the two substrates 1 and 2 is exhausted from between the exhaust port 2a and the solder 9 to make it vacuum, and then the solder 22 is heated and melted by the heater 22. Then, the discharge port 2a is filled, the solder 9 is hardened, and the exhaust port 2a is sealed as shown in FIG. In FIG. 13, 23 is a weight, and 24 is a thermocouple.

FIG. 15 shows an example of a time schedule when the space S between the substrates 1 and 2 is evacuated as described above and the exhaust port 2a is sealed with the solder 9.

With the above arrangement, the step of evacuating the space S between the substrates 1 and 2 and the step of sealing the exhaust port 2a can be continuously and easily performed. Further, the outer surface of the solder 9 can be formed flat as shown in FIG. 14B by its own weight of the substrates 1 and 2 and the like.

Further, if a getter material is provided in the space S that has been evacuated as described above, the degree of vacuum in the space S can be further increased. A configuration example of the getter material and a method of promoting the degree of vacuum using the getter material Will be described.

1 and 2, reference numeral 10 denotes a getter material for adsorbing the gas remaining in the space S, which is formed in advance in a thin film on the inner surface of the counter substrate 2 by vapor deposition or the like, and the space S is evacuated. Thereafter, the getter material 9 is irradiated with a laser beam to evaporate and revive, thereby adsorbing the gas remaining in the space S.

As the getter material, for example, AlMg alloy, AlBa alloy, Ti, Zr alloy, Hf alloy, or the like can be used. If the thickness of the getter material 10 is too small, the effect of adsorbing the residual gas is small. On the other hand, if the thickness is too large, the getter material 10 cannot be evaporated by a laser beam. In this embodiment, an AlMg thin film containing 10% of Mg is used, and its thickness is formed to about 3000 Å. Also, the area for forming the getter material may be widened according to the size of the vacuum layer, and is set to 20 mm ² in this embodiment.

In forming the getter material 10, before the substrates 1 and 2 are bonded to each other, the getter material 10 is formed on a counter substrate in advance by a vacuum deposition method or the like. Then, after bonding the two substrates 1 and 2 to evacuate the space S, a laser beam L is irradiated toward the getter material 10 from the outside of the counter substrate 2 as shown by an arrow in FIG. Irradiation is sequentially performed in the form of spots as indicated by a chain line 16.

When the getter material 10 is irradiated with the laser beam as described above, the getter material 10 is evaporated and scattered as fine particles 10a as shown in FIG. Can be enhanced.

{As the above laser light, for example, a YAG laser, a CO2} laser, an Ar ion laser, an excimer laser, a dye laser, or the like can be used.

It is desirable that the bonding of the two substrates 1 and 2 be performed in a vacuum, so that deterioration of the getter material due to oxidation or the like can be reduced.

Next, an example of a manufacturing process of the entire fluorescent display device will be described based on a flowchart shown in FIG.

First, the projections 6a shown in FIG. 7 are formed on the surface of the silicon substrate as the element substrate 1 by anisotropic etching, and the silicon dioxide thin film and the segment electrodes 5 which become the insulating layer 6b are formed on the surface of the silicon substrate by sputtering. A tantalum thin film is formed, and the tantalum thin film and the silicon dioxide thin film on the protrusion 6a are selectively removed by a selective etching method, and an opening is made to expose the protrusion 6a. The tantalum thin film is patterned into the segment electrodes 5, and a nickel thin film that is easily soldered is formed on each segment terminal 5a to form a mounting terminal.

Since the above-mentioned tantalum thin film can easily form a stable tantalum oxide film (TaOx) on its surface, it is possible to prevent disconnection due to electric field corrosion generated at a contact portion with the sandwiching body 3 and realize highly reliable wiring. There are advantages that can be done.

On the other hand, an ITO thin film serving as the anode electrode 7 is formed on a glass substrate as the opposite substrate 2 and patterned into a predetermined shape, and the above glass substrate is cut into a desired size and shape, whereby the anode electrode is formed on the surface. 7 is formed. Next, a hole is formed in the glass substrate to form the exhaust port 2a.

Further, the holding body 3 is formed by mixing the spherical glass spacer and the low-melting-point powder glass with a liquid organic binder to form a paste having fluidity, and screen-printing the paste on a sealing portion around the counter substrate 2. Form. The holding body 3 is dried by heating at, for example, 120 ° C. for about 20 minutes in order to evaporate the solvent of the organic binder contained therein.

Next, on the anode electrode surface of the counter substrate 2, the phosphor and the low-melting glass were mixed at a predetermined ratio as described above, and a liquid organic binder was mixed to form a paste having fluidity. The fluorescent layer 8 is formed by applying a screen printing method or the like. In the case of performing multi-color display or full-color display, phosphors of three colors of red, green, and blue light are separately mixed with a low-melting glass and a binder, and screen printing is performed three times.

The phosphor layer 8 is also dried by heating at, for example, 120 ° C. for about 20 minutes in order to evaporate the solvent of the organic binder contained therein. Thereafter, the phosphor layer 8 is baked simultaneously with, for example, stepwise heating from about 340 ° C. to about 450 ° C. at the same time as the preliminary baking of the holding body 3. Further, a getter material 10 is provided on the opposite substrate 2 by vapor deposition or the like.

Next, the opposing substrate 2 and the element substrate 1 having the above-mentioned field emission device 6 are aligned and opposed to each other in parallel via the sandwiching member 3, and a load is applied to both substrates 1 and 2. To set in the vacuum chamber.

(4) In a state where the vacuum chamber is evacuated, in order to discharge and remove the residual gas and the organic material in the space S from the exhaust port 2a, sufficient heating is performed at a sealing temperature or lower to perform a degassing process. Then, the substrates 1 and 2 are vacuum-bonded and sealed by heating to, for example, 450 ° C. to melt and bake the holding body 3. Next, the air in the space S is evacuated from the exhaust port 2a, and the exhaust port 2a is sealed with a sealing member 9 such as solder, so that the space S is maintained in a vacuum state.

Finally, the two substrates 1 and 2 bonded together are taken out of the vacuum chamber, and the getter material 10 provided on the surface of the counter substrate 2 is irradiated with a laser from the outer surface side of the counter substrate 2 and heated to heat the element. The gas is evaporated and scattered on the surface of the substrate 1 and the like, and the gas generated or remaining in the space S is absorbed to increase the degree of vacuum.

The fluorescent display device is completed by connecting a drive circuit to each electrode formed as described above via terminal mounting and substrate mounting.The fluorescent display device completed in this embodiment has a thickness of about It was extremely thin, 2 mm, 15 mm long and 25 mm wide, and could be reduced in size and weight. Among them, the size of the display portion was 12 mm in length and 22 mm in width, and the size of 7 segments for time display was 4 mm in length and 2.5 mm in width.

In the above process, before the step of bonding and bonding the opposed substrate 2 and the element substrate 1 in a vacuum via the sandwich 3, the sandwich 3 formed on the opposed substrate 2 is sealed at a sealing temperature. When the heat treatment step is performed as described above, the degree of vacuum can be improved. This is because a gas and an organic material contained in the holding body 3 are degassed by heat-treating the holding body 3 in a vacuum at a temperature equal to or higher than the melting point. And a fluorescent display device with good airtightness can be realized.

In addition, before the step of bonding and sealing the opposed substrate 2 and the element substrate 1 in a vacuum via the holding body 3, a step of irradiating the opposed substrate 2 or the element substrate 1 with light in a vacuum to deaerate. May be added. This is to activate and remove gas molecules, organic materials, etc. attached to the substrate surface by irradiating each substrate surface with light using a mercury lamp, halogen lamp, laser light, etc. containing ultraviolet light as a light source in a vacuum. To perform surface cleaning. In particular, it is effective for cleaning the surface of the projection 6a of the field emission device 6. This light irradiation step has effects such as uniformity, low threshold voltage, and improvement in stability of emission current, and as a result, a highly reliable fluorescent display device can be obtained.

In order to drive the fluorescent display device prepared as described above, a positive potential gate voltage V _GK is applied to the segment electrode 7 as a gate electrode with respect to the projection 6a serving as a cathode electrode, and the tip of the projection 6a is applied. A strong electric field is applied to the vicinity, whereby electrons are emitted from the vicinity of the tip of the projection 6a into the vacuum space S by a tunnel effect. The emitted electrons are accelerated by the positive potential anode voltage V _AK applied to the anode electrode 7, irradiated and flow into the fluorescent layer 8 to excite the fluorescent layer 8, and the phosphor in the fluorescent layer 8 is excited. The desired display is performed by emitting light.

At this time, electrons flying out from the protrusion 6a is spread reverse conical whose vertices tips of the projections 6a, the surface of the fluorescent layer 8, electrons are irradiated substantially d _AK circular whose radius. At that time, the anode current I _AK flowing into the fluorescent layer 8 is controlled by V _GK when V _AK >> V _GK . The anode current I _AK per field emission device was I _AK = 5 × 10 ⁻¹⁰ A (V _AK = 200 V) when V _GK = 70 V.

By the way, when the anode voltage becomes equal to or lower than the gate voltage, the emitted electrons also flow to the gate electrode, so that the reactive current increases. In order to prevent this, the voltage is preferably set so that V _AK > 2V _GK .

In the above embodiment, the exhaust port is provided in the counter substrate 2 to exhaust the air in the space S. However, the exhaust port may be provided in the element substrate 1 or both the substrates. The air may be exhausted when the first substrate 1 and the counter substrate 2 are sealed via the holding body 3. For example, the holding member 3 is formed on one of the substrates 1 and 2 and the other substrate is stacked below the sealing temperature of the holding member 3. Then, the surface of the holding body 3 has fine irregularities, and a gap is generated between the holding body 3 and the other substrate holding body 3. By putting this in a vacuum chamber or the like, the air in the space is exhausted from the gap, and in this state, the gap is heated to a sealing temperature or higher and sealed to close the gap.

  In the above embodiment, the getter material 10 is provided on the inner surface of the opposing substrate 2 by vapor deposition or the like. However, the getter material 10 may be provided on the element substrate side, and may be provided by sputtering or other means without being limited to vapor deposition. Alternatively, for example, as shown in FIG. 19, a concave portion 2b may be formed in the opposite substrate 2, and the getter material 10 may be embedded in the concave portion.

Although the above embodiment is applied to a 7-segment type character display for displaying time, it can also be applied to other fluorescent display devices. FIGS. 20 and 21 show an example in which the present invention is applied to a matrix fluorescent display device.

In the figure, reference numeral 11 denotes a matrix element substrate made of a silicon substrate or the like, on which the same field electron emission element 6 as described above is provided. The field electron emission device is not limited to the above configuration, and may be a Spindt type, a lateral type, or the like formed on a glass substrate. On the other hand, a conductive ITO thin film 7 serving as an anode electrode is formed on the counter substrate 2, and a fluorescent layer 8 that emits a fluorescent color is formed thereon.

(4) The matrix element substrate 11 and the counter substrate 2 are hermetically bonded to each other by a sandwiching body 3, and both substrates are held at a predetermined interval by a spacer 12 manufactured by a photo process. As the spacer 12, SiOX # or the like formed by a spin coating method is used, and as shown in FIG. 21, the stripe gate electrode 13 where the field emission element 6 does not exist and the insulating layer 6b where the stripe cathode electrode 14 does not exist as shown in FIG. It is formed in a column shape.

{Circle around (4)} On the outer periphery of the matrix element substrate 11, a gate wiring 13a of the stripe gate electrode 13 for connecting an external circuit and a cathode wiring 14a of the stripe cathode electrode 14 are formed.

マ ト リ ク ス The matrix type fluorescent display device as described above is used, for example, for a color view finder of a camcorder.

The fluorescent layer 8 in the above embodiment can be provided by the same configuration and the same forming method as in the above embodiment. Also in the above embodiment, the space S between the two substrates 11 and 2 is evacuated. In this case, though not shown in the drawing, an exhaust port is formed in one of the substrates as in the above embodiment. Can be sealed with solder. Also in this case, a getter material similar to that of the above embodiment is provided on the inner surface of the substrate, and a laser is irradiated to the getter material to increase the degree of vacuum.

As described above, in the present invention, before the step of bonding and sealing the element substrate and the opposing substrate via the holding body in a vacuum, the holding body is heated at a temperature of the sealing step or higher. By adding the step of performing heat treatment, the gas, the organic material, and the like contained in the holding body are degassed, so that a fluorescent display device with a high degree of vacuum and airtightness can be provided. In addition, before the step of bonding and sealing the element substrate and the counter substrate in a vacuum, a step of irradiating the element substrate or the counter substrate with light in a vacuum is added, so that the light irradiation adheres to the substrate surface. The activated gas molecules, organic materials, and the like are activated and removed, whereby the projection surface of the electron-emitting device is particularly cleaned, and the effect of improving the stability of the emission current is exhibited. As a result, a highly reliable fluorescent display device can be obtained.

FIG. 1 is a plan view showing one embodiment of a fluorescent display device according to the present invention. FIG. 2 is a sectional view taken along line AA in FIG. 1. FIG. 2 is a sectional view taken along line BB in FIG. 1. FIG. 2 is a sectional view taken along line CC in FIG. 1. FIG. 4 is an enlarged plan view of one segment in the embodiment. FIG. 6 is a sectional view taken along line DD in FIG. 5. FIG. 3 is an enlarged cross-sectional view of the field emission device in the embodiment. 4 is a graph showing the suitability of adhesive strength with respect to the amount of low-melting glass mixed. 4 is a graph showing an optimum composition ratio of a phosphor, a low-melting glass, and a binder. 7 is a graph showing a phosphor layer formation schedule. Sectional drawing which shows an example of the sealing structure of the exhaust port by solder. Sectional drawing which shows the other example of the sealing structure of the exhaust port by solder. FIG. 3 is a longitudinal sectional view of a vacuum chamber. (A) And (b) is explanatory drawing which shows the sealing point of an exhaust port. Explanatory drawing which shows the time schedule of a vacuum sealing process. FIG. 4 is a plan view of a main part showing a procedure for irradiating a getter material with laser light. Sectional drawing of the principal part in the state which irradiated the laser beam to the getter material. The flowchart figure which shows an example of the manufacturing process of a fluorescent display device. Sectional drawing of the example which embedded the getter material in the recessed part formed in the counter substrate. FIG. 9 is a plan view of a main part showing another embodiment of the fluorescent display device according to the present invention. The longitudinal section in the other examples of the above. FIG. 7 is a longitudinal sectional view of a conventional fluorescent display device. FIG. 5 is a schematic vertical sectional view showing a conventional vacuum sealing structure. (A) and (b) are a plan view and a sectional view of a conventional getter material.

Explanation of reference numerals

REFERENCE SIGNS LIST 1 element substrate 2 opposing substrate 3 sandwiching body 5 segment electrode 6 electron-emitting device 7 anode electrode 8 phosphor layer 9 solder 10 getter material

Claims (4)

In a method for manufacturing a fluorescent display device obtained by bonding an element substrate having an electron-emitting element and an opposing substrate via a sandwiching body,
Before the step of bonding and sealing the element substrate and the counter substrate via the holding body in a vacuum, a step of heating the holding body at a temperature equal to or higher than the temperature in the sealing step is included. A method for manufacturing a fluorescent display device, comprising: 2. The method of manufacturing a fluorescent display device according to claim 1, wherein in the heat treatment step of the holding body, a gas contained in the holding body is degassed. In a method of manufacturing a fluorescent display device by bonding an element substrate having an electron emitting element and a counter substrate,
Prior to the step of bonding and sealing the element substrate and the counter substrate in a vacuum, a step of irradiating the element substrate or the counter substrate with light in a vacuum is provided. Production method. 4. The method of manufacturing a fluorescent display device according to claim 3, wherein in the step of irradiating the light, gas molecules attached to the surface of the substrate are removed to clean the surface.

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