JP2004281206A - Forming method of getter film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forming method of a getter film in which film-thickness distribution of the getter film can be homogenized, in which deterioration of brightness characteristic is prevented, and in which it is possible to manufacture a picture display device to maintain a high performance over a long period of time. <P>SOLUTION: In a vacuum atmosphere, the subject member 11 and a plurality of getter materials 40 countered at this subject member are arranged, getter flash is carried out by heating the getter materials, and the getter films are piled up and formed by the getter flash from respective getter materials in the getter film forming region of the subject member. On that occasion, neighboring getter materials are arranged with a spacing so that among the getter films formed by the getter flash of the respective getter materials, a region of a film thickness of 50±25% or less to the film thickness of the center part of the getter film may be overlapped with the getter film formed by the getter flash of the other getter material, and the getter flash is carried out. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a getter film forming method for forming a getter film on a target member in a vacuum atmosphere.
[0002]
[Prior art]
2. Description of the Related Art In recent years, various flat-panel image display devices have attracted attention as next-generation lightweight and thin display devices that replace cathode ray tubes (hereinafter, referred to as CRTs). For example, a plasma display (PDP) using light emission of a phosphor due to a discharge phenomenon, and a field emission display (hereinafter, referred to as FED) mainly using electron emission by an electric field are known.
[0003]
These image display devices have, as a basic configuration, a front substrate and a rear substrate that are arranged to face each other at a predetermined interval, and these substrates constitute an envelope by joining peripheral portions of each other. In the FED, a phosphor layer is formed on an inner surface of a front substrate, and electron-emitting devices, which are electron emission sources for exciting the phosphor, are arranged corresponding to each pixel on an inner surface of the rear substrate. Further, between the two substrates, a large number of spacers such as plate-like, columnar, or bead are arranged in order to maintain a gap between the substrates.
[0004]
In these image display devices, it is important that the space between the front substrate and the rear substrate, that is, the inside of the vacuum envelope is maintained at a high degree of vacuum. If the degree of vacuum is low, stable electron emission cannot be performed, and the life of the image display device will be shortened.
[0005]
Therefore, in order to maintain the inside of the envelope at a high degree of vacuum for a long period of time, a getter material for adsorbing gas is provided in the envelope and plays an important role. For example, as a method of forming a getter film in an image display region where gas emission is likely to occur during operation, a front substrate and a rear substrate are put into a vacuum chamber, and after evacuating, a region covering the image display region of the front substrate is formed. There has been proposed a method in which a getter film is formed, and furthermore, both substrates facing each other are sealed in a vacuum (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP 2001-229824 A
[Problems to be solved by the invention]
When an evaporable getter material is used as such a getter material, the getter material is heated and vapor-deposited in a vacuum processing apparatus of about 10 ⁻⁴ Pa or less to form a getter film on the inner surface of the envelope. In this case, a method of forming a getter film in a film formation region of the envelope using a plurality of getter materials is conceivable. However, when a plurality of getter materials are heated and vapor-deposited, the thickness of the getter material to be formed greatly changes due to the arrangement of the getter materials themselves, the flash amount, and the distance from the getter material to the film formation region. Therefore, there is a possibility that the thickness of the getter film formed in the film formation region becomes uneven. When the thickness of the getter film becomes non-uniform, the luminance characteristics in the envelope constituting the image display device are not uniform, and it is difficult to maintain high display performance for a long time. .
[0008]
The present invention has been made in view of the above points, and its object is to make the thickness distribution of the getter film uniform, prevent deterioration of the luminance characteristics, and maintain high performance for a long time. It is an object of the present invention to provide a method for forming a getter film capable of manufacturing an image display device.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a getter film forming method according to an aspect of the present invention includes a getter film forming method for forming a getter film on a target member, the method comprising: The getter material is disposed, the plurality of getter materials are heated to perform getter flash, and a getter film is overlapped on the getter film formation region on the target member by the getter flash from each getter material. At this time, two getter materials that are adjacent to each other are formed such that a region having a thickness of 50 ± 25% or less with respect to the thickness of the central portion of the getter film in the getter film formed by the getter flash of each getter material is formed on the other. It is characterized in that the getter flash is performed by arranging at intervals so as to overlap with a getter film formed by getter flash of a getter material.
According to the getter film forming method configured as described above, the getter flash is performed in a state in which the plurality of getter materials are arranged at the above intervals, so that the thickness of the getter film is 50 ± 25% with respect to the thickness of the central portion of the getter film. Regions having the following film thicknesses are formed so as to overlap each other, and a getter film having a uniform film thickness over the entire region can be obtained. Accordingly, it is possible to provide an image display device capable of maintaining high display performance over a long period of time with uniform luminance characteristics in an envelope constituting the image display device.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a getter film forming method according to an embodiment of the present invention will be described in detail with reference to the drawings.
First, an image display device including a front substrate as a member on which a getter film is formed will be described. Here, an FED provided with a surface conduction electron-emitting device will be described as an example.
[0011]
As shown in FIGS. 1 and 2, the FED includes a front substrate 11 and a rear substrate 12 each made of a rectangular glass plate as an insulating substrate, and these substrates are opposed to each other with a gap of 1 to 2 mm. Have been. The front substrate 11 and the rear substrate 12 are joined to each other via a rectangular frame-shaped side wall 13 to form a flat rectangular vacuum envelope 10 whose inside is maintained in a vacuum state. .
[0012]
A plurality of spacers 14 are provided inside the vacuum envelope 10 to support an atmospheric pressure load applied to the front substrate 11 and the rear substrate 12. As the spacer 14, a plate-shaped or columnar spacer or the like can be used.
[0013]
On the inner surface of the front substrate 11, a phosphor screen 15 having a red, green, and blue phosphor layer 16 and a matrix black light shielding layer 17 is formed as an image display surface. These phosphor layers 16 may be formed in a stripe shape or a dot shape. On the phosphor screen 15, a metal back 20 made of an aluminum film or the like is formed, and further, a getter film 22 is formed so as to overlap the metal back.
[0014]
On the inner surface of the rear substrate 12, a large number of surface conduction electron-emitting devices 18 each emitting an electron beam are provided as electron sources for exciting the phosphor layer 16 of the phosphor screen 15. These electron-emitting devices 18 are arranged in a plurality of columns and a plurality of rows corresponding to each pixel. Each of the electron-emitting devices 18 includes an electron-emitting portion (not shown), a pair of device electrodes for applying a voltage to the electron-emitting portion, and the like. In addition, on the inner surface of the back substrate 12, a number of wirings 21 for supplying a potential to the electron-emitting devices 18 are provided in a matrix shape, and the ends thereof are led out of the vacuum envelope 10.
[0015]
In such an FED, when displaying an image, an anode voltage is applied to the phosphor screen 15 and the metal back 20, and the electron beam emitted from the electron-emitting device 18 is accelerated by the anode voltage to collide with the phosphor screen. . Thereby, the phosphor layer 16 of the phosphor screen 15 is excited to emit light, and a color image is displayed.
[0016]
Next, a method of manufacturing the FED configured as described above will be described. In particular, a method for forming the getter film 22 on the front substrate 11 will be described.
As shown in FIG. 3, the getter film forming apparatus includes a vacuum chamber 31 formed by a vacuum processing tank, and a vacuum pump 32 for evacuating the vacuum chamber. A first transfer mechanism 34 for supporting and transferring the front substrate 11 is provided in the vacuum chamber 31, and the front substrate 11 is supported by the first transfer mechanism. In the vacuum chamber 31, a second transfer mechanism 36 for transferring the getter material to a predetermined position is provided. The support jig 38 is supported by the second transport mechanism 36 so as to be movable and height-adjustable.
[0017]
A plurality of getter materials 40 are held on the support jig 38 and face the front substrate 11. The getter members 40 are arranged in a plurality of columns and a plurality of rows at predetermined intervals d on the upper surface of the support jig. As the getter material 40, for example, a reactive getter that vacuum-deposits Ba by a thermal reaction between BaAl ₄ powder and Ni powder can be used. A heating unit 42 for heating the getter material 40 is provided on the lower surface side of the support jig 38. The heating unit 42 is configured, for example, as a high-frequency heating system capable of heating the getter material 40 in a non-contact manner, and includes a high-frequency coil and a high-frequency generator (not shown) for applying a high frequency to the high-frequency coil. Then, the heating unit 42 heats the getter material 40 from the lower surface side of the support jig 38 via the support jig. The support jig 38 is formed of a non-dielectric material such as ceramic or glass which is not affected by high-frequency heating.
[0018]
Next, a process of forming a getter film on the front substrate 11 using the getter film forming apparatus configured as described above will be described.
First, a plurality of getter members 40 are provided on the upper surface of the support jig 38 in a predetermined arrangement. When a getter film is formed using a plurality of getter materials 40, the arrangement of the getter material, the flash amount, and the distance from the getter material to the film formation region are appropriately determined in determining the thickness distribution of the formed getter film. Must be set to Therefore, the Cosine rule was modified as a calculation formula necessary for determining the film thickness distribution as follows, and an experimental approximation value formula was obtained. Equations 1 and 2 show the results of comparison between the experimental values and the approximate values.
[0019]
Cosine rule: t / t0 = 1 / [1+ (L / H) ² ] ^{( 3/2 )} Equation 1
Approximate expression: t / t0 = 1 / [1+ (L / H) ² ] ^{( 5/2 )} Expression 2
Here, L: the horizontal distance from the getter material H: the distance from the getter material to the getter film-shaped region (adhered surface) t: the getter film thickness t0 set at a specific location: the thickest getter film thickness ing.
[0020]
From the above equations 1 and 2, the thickness distribution of the getter film formed by the getter flash of one getter material 40 is such that the center of the getter film formation region facing the center of the getter material, as shown in FIG. Thickest, thinner horizontally away from the center, almost bell-shaped. The actual getter film has a shape with a slightly reduced width as shown by a wavy line.
[0021]
Based on the above experimental results, in the present embodiment, the getter materials are arranged so that regions where the thickness of the getter film formed by the getter flash of each getter material 40 becomes thin overlap with each other. That is, as shown in FIG. 5, the distance d between the two adjacent getter materials among the plurality of getter materials 40 arranged is determined by the getter film formed by the getter flash of each getter material. The region having a thickness of 50 ± 25% or less with respect to the thickness of the central portion C is set to have an interval overlapping with the getter film formed by getter flash of the other getter material.
[0022]
With the plurality of getter materials 40 placed on the support jig 38 at the above-described interval d, the support jig is carried into the vacuum chamber 31 and positioned at a predetermined getter flash position facing the front substrate 11. I do. The inside of the vacuum chamber 31 is previously maintained at a high vacuum of about 10 ⁻⁵ Pa by the vacuum pump 32. Further, each getter material 40 is previously heated to a temperature lower than the evaporation temperature of the getter material, for example, 500 ° C., and degassed in advance.
[0023]
After the plurality of getter materials 40 are positioned at the getter flash position, the getter materials are sequentially heated by the high frequency coil of the heating unit 42 to a temperature equal to or higher than the evaporation temperature to perform the getter flash. With the getter flash from each getter material 40, a getter film is sequentially vacuum-deposited on the fluorescent surface side of the front substrate 11 as a member to be formed, and the getter films are formed to overlap. As shown in FIG. 6, the getter film 22 having a substantially uniform film thickness distribution over the entire region can be formed in the getter film forming region of the front substrate 11 by the above-described process.
[0024]
Since the support jig 38 is formed of a non-dielectric material that is not affected by high-frequency heating, it is possible to control the heating of only the getter material 41.
The front substrate 11 on which the getter film 22 is formed is transported to another vacuum chamber without being exposed to the atmosphere, and is sealed with the rear substrate in a vacuum atmosphere. Thereby, an FED is obtained.
[0025]
According to the getter film forming method configured as described above, the getter flash is performed in a state where a plurality of getter materials are arranged at predetermined intervals, so that the thickness of the getter film is 50 ± 25 with respect to the thickness of the central portion of the getter film. %, And a getter film having a uniform film thickness over the entire region can be obtained. At the same time, the thickness of the getter film can be easily adjusted. Accordingly, it is possible to provide an image display device capable of maintaining high display performance over a long period of time with uniform luminance characteristics in an envelope constituting the image display device.
[0026]
The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, the dimensions of each component, the getter material, and the like are not limited to the numerical values and the getter material described in the above-described embodiment, and can be variously selected as needed. Further, the method of heating the getter material in the getter flash is not limited to the high frequency heating described above, and resistance heating in which electric current is applied to the getter material to heat it can also be used. In addition, in the present invention, the member for forming the getter film is not limited to the front substrate of the FED, and various members can be selected.
[0027]
【The invention's effect】
As described in detail above, according to the present invention, it is possible to manufacture an image display device that can make the thickness distribution of the getter film uniform, prevent deterioration in luminance characteristics, and maintain high performance for a long period of time. A possible method of forming a getter film can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an FED as an example of an image display device.
FIG. 2 is a sectional view of the FED taken along line AA in FIG. 1;
FIG. 3 is a sectional view showing a getter film forming apparatus used for manufacturing the FED.
FIG. 4 is a diagram showing a relationship between a horizontal distance from a getter material and a film thickness.
FIG. 5 is a diagram for explaining an arrangement distribution of a plurality of getter materials.
FIG. 6 is a view showing a film thickness distribution of a formed getter film.
[Explanation of symbols]
10: vacuum envelope, 11: front substrate, 12: rear substrate,
13 ... side wall, 15 ... phosphor screen, 18 ... electron-emitting device,
20: metal back, 22: getter film, 31: vacuum chamber,
40 ... getter material

Claims (4)

In a getter film forming method for forming a getter film on a target member,
Arranging the target member and a plurality of getter materials facing the target member in a vacuum atmosphere,
A getter flash is performed by heating the plurality of getter materials, and a getter film is superimposed and formed by getter flash from each getter material in a getter film forming region on the target member,
Two getter materials that are adjacent to each other are formed such that, of the getter films formed by the getter flash of each getter material, a region having a thickness of 50 ± 25% or less with respect to the thickness of the central portion of the getter film is formed of the other getter material. A getter film forming method, wherein the getter flash is performed by arranging at intervals so as to overlap a getter film formed by getter flash. 2. The method according to claim 1, wherein the plurality of getter materials are sequentially getter-flashed. The getter film forming method according to claim 1, wherein a reactive getter material is used as at least one of the getter materials. A getter film is formed on the front substrate in an image display device including a front substrate having a phosphor screen and a rear substrate disposed to face the front substrate and having an electron source for exciting the phosphor screen. In the getter film forming method,
Arranging the front substrate and a plurality of getter materials facing the phosphor screen of the front substrate in a vacuum atmosphere,
A getter flash is performed by heating the plurality of getter materials, and a getter film is superimposed and formed by getter flash from each getter material in the getter film formation region on the phosphor screen,
Two getter materials that are adjacent to each other are formed such that, of the getter films formed by the getter flash of each getter material, a region having a thickness of 50 ± 25% or less with respect to the thickness of the central portion of the getter film is formed of the other getter material. A getter film forming method, wherein the getter flash is performed by arranging at intervals so as to overlap a getter film formed by getter flash.

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