KR20010056152A - Vacuum packaging method of field emission display device - Google Patents

Abstract

PURPOSE: An electric field display element and thereof vacuum packaging method is provided to improve confidence of the element and characteristics of life by minimizing a residual gas in the element. CONSTITUTION: An electrode layer and a fluorescence layer(12) is formed on the upper substrate(10). An electron emission part(31) is formed on the lower substrate(20). The upper substrate(10) is spaced from the lower substrate(20) by means of a spacer(29) in a predetermined interval. A gas flow holes are formed at the predetermined portion of the lower substrate(20) to exhaust a gas. A supplementary substrate is connected to the lower end of the lower substrate(20) to form a supplementary space. An exhaust hole(32) is formed at the supplementary substrate. A gate(36) is position to the supplementary space between the supplementary space and the lower substrate(20). A skirt is formed at the edge of the lower substrate(20) in a predetermined interval. The supplementary substrate is connect to the lower substrate(20) by means of a sealing agent(21).

Description

Field emission display device and vacuum packaging method thereof {Vacuum packaging method of field emission display device}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission display device, which is a type of flat panel display, which minimizes residual gas inside the device that reduces electron emission capability, thereby improving reliability of the device and shortening the exhaust time, thereby improving productivity. The present invention relates to a field emission display device and a vacuum packaging method.

1 is a schematic diagram of a general field emission display device. The basic operation principle of a general field emission display device will be described with reference to FIG. 1.

The display device shown in FIG. 1 is a full color display device. For example, R (12R), G (12G), and B (12B) phosphors formed in a stripe shape are formed on an upper substrate. It is formed on the inner surface of (10), and the ITO anode electrode layer 11, which is a kind of transparent electrode, is formed between the upper substrate 10 and the R, G, and B phosphors to apply an anode voltage.

In the lower substrate 20 where the electron emission portions are formed, an FEC array 24 including a plurality of field emission cathodes FEC is formed. Electrons are emitted from the FEC array 24, and the emitted electrons are captured by the anode electrode 11, so that the phosphors captured by the captured anode electrode 11 emit light.

Here, when the field emission is briefly described, if the applied voltage of the metal or semiconductor surface is about 10 ⁹ [V / m], the electrons will pass through the potential barrier by the tunneling effect and the electrons will be emitted in vacuum even at room temperature. This is called field emission, and the cathode that emits electrons in the same manner is called a field emission cathode or a field emission device.

In recent years, it has become possible to manufacture surface-radiated field emission cathodes consisting of micron-sized field emission cathodes utilizing semiconductor micromachining techniques, and FEC arrays in which a plurality of field emission cathodes are formed on a substrate are each emitters. By irradiating electrons emitted from the fluorescent surface, it is possible to allow them as an electron supply means constituting a flat display device or various electronic devices.

As an example of such a field emission cathode, a field emission cathode (hereinafter referred to as FEC) called a Spindt type is known.

As shown in FIG. 1, each of the FEC arrays 24 is formed on the lower substrate 20 so as to correspond to R, G, and B phosphors for full color display, respectively, and is formed orthogonal to each other. And the gate electrode layer 28 are driven in a matrix. In this case, an insulating layer 26 is formed in the middle to insulate the cathode electrode layer 22 and the gate electrode layer 28. In more detail, a stripe cathode electrode layer 22 is formed on the lower substrate 20 by patterning, and a cathode tip for emitting electrons is formed thereon to receive electrons. The insulating layer 26 is formed on the cathode electrode layer 22 over the entire lower substrate 20, and the gate electrode layer 28 is formed on the cathode electrode layer 22 by patterning. That is, the cathode electrode layer 22 and the gate electrode layer 28 are formed in a cross-shaped matrix form. Electrons emitted from the FEC array 24 fly toward the spaced-oriented top substrate 10 at a predetermined interval by a spacer 29 formed in a suitable manner.

In order to enable such an operation, a space formed between the upper substrate 10 and the lower substrate 20 is in a vacuum atmosphere. In order to maintain the vacuum atmosphere, the peripheral edge between the upper substrate 10 and the lower substrate 20 is sealed by a sealant 21. In general, a voltage of about several tens of V-several Kv is applied between the anode electrode layer 11 and the cathode electrode layer 22 to accelerate the electrons.

2, the structure and operation principle of the FEC array 24 will be described in detail. 2 is a schematic cross-sectional view of a typical conventional field emission display device cut in a vertical direction at a predetermined position. As shown in FIG. 2, a cathode electrode layer 22 is formed on the lower substrate 20, and a plurality of emitters 25 are formed on the lower substrate 20 to form a cone and emit electrons by generation of an electric field. In addition, an integral insulating layer 26 is formed between the emitters 25 so as to enclose each of these emitters in an enclosing manner, and a portion of the insulating layer 26 opposite to the cathode electrode layer 22 is common. The in-gate electrode layer 28 is formed.

In addition, the upper substrate 10 and the lower substrate 20 are spaced by the spacer 29 so that the fluorescent layer 12 and the emitter 25 face the space 30, for example, 100 μm to 3 Mm is attached spaced apart. The spacer 29 is formed in plural so that the upper substrate 10 and the lower substrate 20 face each other to form a space 30. In addition, the spacer 29 is made of a material having a high hardness and good insulation such as a ceramic including glass, an oxide or a nitride, or an insulating material such as a polymer including polyamide. Here, the spacers 29 not only attach the edges of the upper substrate 10 and the lower substrate 20 to each other, but when the field emission display device is large, that is, a large screen, hundreds to thousands are formed in the center portion. In this case, the upper substrate 10 and the lower substrate 20 are prevented from contacting each other due to the pressure difference between the space 30 in the high vacuum state and the external air pressure state.

An anode electrode layer 11 for accelerating electrons is formed on the inner surface of the upper substrate 10, and R, G, and B phosphors 12 are formed in one pixel. A black matrix 23 is formed between each phosphor to increase color purity and contrast.

As illustrated in FIG. 1, the cathode electrode layer 22 and the gate electrode layer 28 are formed in a matrix form orthogonally crosswise with an insulating layer interposed therebetween, so that each intersection point is an R phosphor 12R or a G phosphor 12G or Corresponds to the B phosphor 12B. The area where the cathode electrode layer 22 and the gate electrode layer 28 intersect is approximately In the area, about several hundred to several thousand field emission cathodes are formed in an array. 3 shows a photograph taken by a scanning electron microscope of a general spin type field emission cathode array 24 actually manufactured. A sharp tip in the round hole is the emitter 25, inside the hole an insulator layer 26 surrounds the emitter 25 and the top surface is the gate electrode layer 28. The cathode electrode layer 22 is not shown in this figure.

In order for one subpixel to emit light, a voltage of about 10V to 100V is applied between the gate electrode layer 28 and the cathode electrode layer 22. At the intersection of the cathode electrode layer 22 and the gate electrode layer 28 where this voltage difference occurs, A strong electric field is generated at the tip of the emitter 25 to cause electron emission due to the tunneling effect described above to form the electron beam 27. The electron beam 27 emitted from the emitter 25 is accelerated by a potential of several tens of V to several kV applied to the anode electrode layer 11 and impinges on the phosphor corresponding to the corresponding field emission cathode array 24. The result is a light of the desired color. This energy generated by the collision of energy electrons to the phosphor is called cathode luminescence (cathode luminescence) and the mechanism is the same as the CRT (Cathode Ray Tube) mainly used in monitors and televisions.

The interior of the space 30 formed between the upper substrate 10 and the lower substrate 20 in order for the field emission to occur easily and the electrons emitted from the emitter 25 to reach the phosphor without interference of other molecules or ions. Minimum vacuum Should be less than or equal torr

The intensity of the light emitted from the phosphor is generally controlled by the voltage difference applied between the cathode electrode layer 22 and the gate electrode layer 28, or the gray scale display can be performed by modulating the width of the applied voltage pulse. Width Modulation). Due to the difference in the structure of each emitter or the shape of the electrode, a change in the current emitted for each pixel may occur, which degrades the characteristics of the display device. In order to solve this problem, a method of forming a resistance layer between the cathode electrode layer 22 and the emitter is also used.

The larger the amount of current emitted from the emitter 25 under the same applied voltage, the higher the luminance of the display element is. In addition, ideally, all electrons emitted from the emitter 25 transfer energy to the phosphor, but in actual cases, some electrons converge on the gate electrode layer 28 to act as a leakage current, thereby increasing power consumption of the display device. Becomes

The field emission display described above requires a high vacuum panel due to its characteristics. Since the distance between the emitter 25 and the gate 28 is a very short distance, such as a micrometer, discharge and vacuum dielectric breakdown may occur if the high vacuum is not maintained reliably, and cations generated by collision with the emission electrons may be Sputtered into emitter 25 may degrade the device. In addition, in the field emission display device, the voltage between the emitter 25 and the anode 11 is about 300V to several kV, which is lower than that of a general cathode ray tube (CRT). Therefore, electrons accelerated when the vacuum in the panel internal space 30 is low. Since energy is lost due to collision with the residual gas, sufficient energy cannot be delivered when colliding with the fluorescent layer, thereby lowering the luminance of light emission. Due to the above problems, the interior of the panel must be It should be placed in a high vacuum below Torr.

Therefore, in the field emission display device, the process of evacuating and packaging gas molecules remaining inside the panel is very important and necessary.

4 (a) to 4 (f) show a process of manufacturing an emitter tip of a field emission display device. The cathode electrode 22, the insulating layer 26, and the gate electrode metal 28 are sequentially formed on the lower substrate 20, the gate electrode 28 is patterned, and the insulating layer 26 is etched. Thereafter, after depositing the sacrificial layer, the emitter material is deposited to form an emitter tip. In this way, the lower substrate 20 is formed with an emitter tip, which is an electron emission unit for emitting electrons by field emission. In this case, the electron emission unit is described above based on the most common spin type, but the electron emission unit in the present invention is not limited to the spin type, but is selected from diamond, DLC, carbon nanotube, and surface conduction emitter. Planar emitters, such as, and all cold cathode cathodes with field emission capabilities, such as metal insulator metal (MIM), metal insulator semiconductor (MIS), and the like.

In addition, an exhaust hole 32 is formed in a predetermined portion of the lower substrate to exhaust the gas. The exhaust hole 32 can be formed using an ultrasonic machine, a drill, or the like. In addition, the upper plate is formed with a phosphor 12 for emitting energy from the accelerated electrons and a plurality of spacers 29 are formed between the upper substrate 10 and the lower substrate 20 to maintain a predetermined interval. do. In addition, the circumferential edges of the upper substrate 10 and the lower substrate 20 are sealed by the sealing material 21. In the above structure, as shown in FIG. 5A, the exhaust tube 33, which is a gas exhaust glass tube, is placed in the exhaust hole 32, and the sealing material 34 such as frit glass is applied, and then the furnace is furnaced. By firing in the furnace, the exhaust tube 33 is connected to the exhaust hole.

As described above, when the connection of the exhaust tube 33 is completed, the getter 36 is mounted, the adapter is connected to the exhaust tube 33, and the gas in the device is exhausted using the vacuum pump 35. In this case, in order to efficiently exhaust the gas inside the device, it is a general method to exhaust the device while heating. After sufficient exhaustion, when the degree of vacuum inside the device reaches a certain level, the predetermined position of the exhaust tube 33 is heated to a high temperature to tip off to completely seal the inside of the device. Finally, activating the getter 36, which serves to increase the degree of vacuum by adsorbing the gas remaining inside the device, the vacuum packaging process ends. 5B is a cross-sectional view of the field emission device after vacuum packaging.

As described above, in the vacuum packaging method according to the related art, the gas inside the panel is exhausted through the exhaust hole 32 formed at a predetermined position of the lower substrate. As described above, the gap between the upper plate and the lower plate is very narrow, such as several hundreds of micrometers, so the conductance of the gas flow is low.

In other words, because the resistance to the flow of gas is large, not only exhaustion takes much time, but sufficient exhaust is not generated on the opposite side where the exhaust hole 32 is formed. Destruction may occur, and the emitter 25 may react with O ₂ , CO ₂ , H ₂ O and the like, which constitute most of the residual gas, to oxidize the surface of the emitter 25, and may also be subjected to collisions with emission electrons. The cations generated can be sputtered into emitter 25 to degrade the device. That is, it causes fatal problems that hinder the reliability of the device.

In addition, when the electron emission beam 27 collides with the phosphor 12 and emits light as shown in FIG. 2 during operation of the field emission display device, gas molecules trapped between the powders of the phosphor 12 are trapped inside the panel. Components such as sulfur or zinc, which flow out to (30) and form the phosphor (12), are released and consequently lower the vacuum of the device, and in some cases these components emitter (25). This can cause a variety of problems, such as falling over and causing a short of the device. Thus, a getter is used as a method for adsorbing residual gases remaining after vacuum packaging or generated by operation of the device.

However, as shown in FIG. 5B, since the getter 36 is formed only in a very limited region inside the panel, its efficiency is also low. In addition, it is not preferable to use an evaporable getter generally used in a cathode ray tube as a getter for a field emission display device. For this reason, when the evaporation type getter is used in the field emission display device according to the related art, the getter material that is evaporated and scattered into the device is deposited on the electron emission part and the phosphor, causing malfunction of the device. Therefore, in the conventional field emission display device, a non-evaporable getter is mainly used, which is expensive in comparison with the evaporative getter and has a disadvantage in that efficiency is reduced because of its narrow surface area compared to the evaporative getter. That is, it has a problem that it becomes difficult to maintain high vacuum inside the panel which is the main purpose of using the getter 36.

As described above, when the field emission display device is manufactured by the vacuum packaging method according to the related art, the time required for the exhaust process for forming a vacuum in the panel becomes long and there is a difference in the degree of vacuum in the panel. Not only lowers the reliability of the device but also makes it difficult to maintain high vacuum inside the device due to the inefficient action of the getter 36, which causes various problems caused by the low vacuum described above. It causes problems that make life impossible.

In the present invention, in order to solve the problems described above, an additional substrate is attached to the lower surface of the lower substrate on which the main space and the electron emitting portion, which function as electrons are emitted, collide with the phosphor, and light is emitted, are formed. To form an additional space, and a plurality of gas flow passages through which gas can enter and exit between the main space and the additional space. A getter is installed in the additional space to capture the gas generated inside to maintain the internal vacuum degree high. It aims at improving the reliability and lifetime characteristics of an element.

1 is a schematic diagram of a conventional field emission display device.

2 is a cross-sectional view of a conventional field emission display device.

3 is a scanning electron micrograph of a typical field emission cathode array.

4A to 4F are emitter manufacturing process diagrams of the field emission display device according to the prior art;

5A and 5B are schematic diagrams of a vacuum packaging method of a field emission display device according to the prior art;

6 (a) and 6 (b) are schematic diagrams of a vacuum packaging method of a field emission display device according to the present invention;

7 is a schematic representation of a further substrate used in the present invention.

8 (a) and 8 (b) are schematic diagrams of still another vacuum packaging method of the field emission display device according to the present invention;

<Description of the code | symbol about the principal part of drawing>

10 upper substrate 11 anode electrode layer 12 fluorescent layer (R, G, B)

20: lower substrate 21: sealant 22: cathode electrode layer

23: Black matrix 24: Field emission cathode array (FEA)

25 emitter 26 insulating layer 27 electron beam

28: gate electrode layer 29: spacer 30: space (Gap)

31 electron emission part 32 exhaust hole

33: exhaust tube 34: sealing material

35: vacuum pump 36: getter 37: gas flow hole

38: skirt 39: additional space 40: additional substrate

Hereinafter, the configuration and operation of the present invention will be described in detail with reference to the accompanying drawings.

6 (a) and 6 (b) show schematic cross-sectional views of the field emission device by the vacuum packaging method of the present invention. The same method is used for constituting the field emission device according to the prior art described with reference to FIGS. 1 to 4. That is, the anode electrode layer and the phosphor 12 are formed on the upper substrate 10, the electron emission part 31 is formed on the lower substrate 20, and the upper substrate 10 and the lower substrate 20 are formed by the spacer 29, or the like. Spaced at predetermined intervals.

However, in the existing invention, in order to maintain high vacuum in the space between the upper substrate 10 and the lower substrate 20, an exhaust hole is formed in a predetermined portion of the lower substrate 20, and the exhaust tube is connected to the hole to use a vacuum pump. After exhausting by using the method to tip off the exhaust tube (tip-0ff) and to activate the getter, in the present invention to exhaust the one or more predetermined portions of the lower substrate 20 to compensate for the problems of the prior art as described above Gas flow holes 37 for forming and additional substrate 40 is connected to the bottom of the lower substrate 20 to form an additional space 39 and through the exhaust hole 32 formed in the additional substrate 40 Exhaust was performed and the getter 36 was positioned in an additional space between the additional substrate 40 and the lower substrate 20.

The configuration and operation of the present invention will be described in more detail with reference to FIGS. 6A and 6B. As described above, the additional substrate 40 is connected to the lower end of the lower substrate 20, and a schematic structure thereof is illustrated in FIG. 6. The additional substrate 40 is composed of a skirt portion 38 to be connected to the lower substrate 20 and a portion for forming the additional space 39. As the material, it is preferable to use a glass material in the same manner as the upper and lower plates. Do. A predetermined portion of the additional substrate 40 is provided with a main space 30 in which the electron emitting portion, a phosphor, and the like are formed, and an exhaust hole 32 for exhausting the interior of the additional space 39.

The gas flow hole 37 is formed in a circular hole at regular intervals in the vicinity of each spacer for maintaining the space between the lower substrate 20 and the upper substrate 10, the cathode array of the lower substrate 20 The gas flow holes can be formed as a plurality of gas exhaust holes on the outside of the region in which the is formed.

In addition, the additional substrate 40 is joined to the lower portion of the lower substrate 20, the skirt 38 of a predetermined height is formed at the edge to form an additional space, any portion of the bottom surface to form the additional space. One exhaust hole 32 is formed in the exhaust pipe 32, and the exhaust tube is connected to the outside of the exhaust hole 32.

In FIG. 5A, the seal member 21 is used to connect the additional substrate 40 and the lower substrate 20, which is a seal for connecting the upper substrate 10 and the lower substrate 20. It is preferable to use the same material as the material 21, and it is preferable to perform simultaneously with the process of connecting the upper and lower substrates in order to simplify the manufacturing process and shorten the time. At this time, in the additional space 39, the getter 36 for removing residual gas after sealing the device is positioned.

In the present invention, since the getter 36 is located in the additional space 39, the efficiency may be higher than that of the getter located in the narrow space, which is limited as in the prior art. In other words, the use of a planar getter increases the probability of trapping the residual gas inside the device. In this case, the getter used may use a non-evaporable getter, but the evaporation getter may be used to increase the efficiency of the getter. At this time, since the getter material vaporized and scattered is deposited only on the inner wall of the additional space 39 and the bottom of the lower substrate 20, there is no problem of malfunction of the device. In addition, since the getter does not need to be located in the exhaust tube, the length of the exhaust tube may be shortened to tip off, thereby reducing the overall volume of the device.

Then, the process of connecting the exhaust tube 33 to the exhaust hole 32, exhausting the vacuum pump 35 to tip off, and then activating the getter is the same as in the prior art. 6B is a schematic cross-sectional view of the field emission device vacuum packaged according to the present invention. Although not shown in this figure, the use of a spacer as used in the main space if necessary in the additional space 39 between the lower substrate 20 and the additional substrate 40 is also included as an embodiment of the present invention.

In addition, the gas flow hole 37 formed in the lower substrate 20 is formed as a small hole in the vicinity of the spacer 29 in the region where the cathode array is formed, the outer edge of the cathode array region in the cathode array region It forms a larger gas flow hole than the hole that is formed.

8 (a) and (b) are diagrams showing still another embodiment according to the present invention. That is, as described above, the lower substrate 20 and the additional substrate 40 are directly connected in a vacuum atmosphere by using an electrostatic bonding method without using a sealing material. The vacuum atmosphere is to bond the upper and lower substrates and the additional substrate in the vacuum cavity. The additional substrate in which the upper and lower substrates and the getter are deposited is placed in the vacuum cavity, and the vacuum cavity is made to have a constant vacuum, and then the substrate bonding process is performed. do. In this case, it is not necessary to form the exhaust hole in the additional substrate 40, nor is it necessary to use the exhaust tube and the vacuum pump. In addition, since the exhaust action occurs directly in each gas flow hole 37, it is possible to shorten the process time and maintain the vacuum inside the final device much higher than the conventional method. When a sufficient vacuum atmosphere is reached, the lower substrate 20 and the additional substrate 40 are contacted, and then heat and voltage are applied to perform electrostatic bonding. Since the electrostatic bonding method uses the same method as in the literature and patents, detailed principles and methods will be omitted. FIG. 8B is a schematic cross-sectional view of the field emission device vacuum packaged according to the present invention. That is, an additional space is formed in the lower portion of the lower substrate 20 and a getter is located in the additional space, and the additional substrate has a structure in which the additional substrate is sealedly bonded to the lower portion of the lower substrate without an exhaust hole.

As described above, the manufacturing of the electric field display device according to the present invention has the advantage of minimizing the residual gas inside the device, which lowers the electron emission ability, thereby improving the reliability of the device and shortening the exhaust time, thereby improving productivity. do.

Claims (10)

An upper substrate having a fluorescent layer and an anode electrode layer for providing energy to the fluorescent layer, a lower substrate having a field emission cathode array for emitting electrons thereon, and keeping the two substrates spaced at a predetermined interval In the field emission display device comprising a spacer, A gas flow hole is formed in at least one predetermined portion of the lower substrate, and the additional substrate is sealed and bonded to the lower portion of the lower substrate to form a predetermined additional space between the lower substrate and the additional substrate, and a getter is placed in the additional space. And forming an exhaust hole at a predetermined position of the additional substrate, evacuating through the hole, and sealing the same to ensure the degree of vacuum inside the element. According to claim 1, wherein the getter placed in the additional space, A vacuum packaging method of a field emission display device, characterized in that by depositing the getter material on the inner wall of the additional space and the bottom of the lower substrate using an evaporation getter. The method of claim 1, wherein the bonding of the additional substrate and the lower substrate, In the process of joining the upper substrate and the lower substrate, the vacuum packaging method of the field emission display device characterized in that the bonding using the same sealing material at the same time as the step of connecting the additional substrate to the lower substrate to the upper and lower substrates. . The method of claim 1, wherein the additional substrate 40 is It is composed of a skirt portion 38 to be connected to the lower substrate 20 and a portion for forming an additional space 39, and the glass material is used as the upper and lower substrates as the material of the field emission display device. Vacuum packaging method. An upper substrate having a fluorescent layer and an anode electrode layer for providing energy to the fluorescent layer, a lower substrate having a field emission cathode array for emitting electrons thereon, and keeping the two substrates spaced at a predetermined interval In the vacuum packaging method of the field emission display device comprising a support means, A gas flow hole is formed in at least one predetermined portion of the lower substrate, and an additional substrate is connected to the lower portion of the lower substrate to form a predetermined additional space between the lower substrate and the additional substrate so that a getter is placed in the additional space. And evacuating the lower substrate and the additional substrate in a vacuum atmosphere, and then electrostatically joining the lower substrate and the additional substrate to ensure the degree of vacuum inside the device. An upper substrate having a fluorescent layer and an anode electrode layer for providing energy to the fluorescent layer, a lower substrate having a field emission cathode array for emitting electrons thereon, and keeping the two substrates spaced at a predetermined interval A field emission display device comprising support means, Forming a gas flow hole in one or more predetermined portions of the lower substrate, The additional substrate is connected to the lower part of the lower substrate to form a predetermined additional space between the lower substrate and the additional substrate so that the getter is placed in the additional space. A field emission display device comprising an exhaust hole formed at a predetermined position of the additional substrate, exhausted through the hole, and sealed and vacuum-packed. The gas flow hole of claim 6, The field emission display device according to claim 1, wherein a circular hole is formed at regular intervals at a position close to each spacer for maintaining space between the lower substrate and the upper substrate. The method of claim 6, wherein the gas flow hole, And a plurality of gas exhaust holes formed outside the region where the cathode array of the lower substrate is formed. The field emission display device of claim 6, further comprising a plurality of spacers for maintaining an additional space between the lower substrate and the additional substrate. The method of claim 6, wherein the additional substrate, A skirt having a predetermined height is formed at the edge to be bonded to the lower part of the lower substrate to form additional space. One exhaust hole is formed in any part of the bottom surface forming the additional space, A field emission display device comprising an exhaust tube connected to an outer side of the exhaust hole and sealing the exhaust tube after exhausting by a vacuum pump.