JP4019568B2 - Method for manufacturing electron-emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electron-emitting device, and more particularly, to a method for manufacturing an electron-emitting device characterized by a method for manufacturing a cathode.
[0002]
[Prior art]
US Pat. No. 4,857,161 discloses a flat display device in which a large number of electron-emitting devices are arranged in a matrix, the electrons are discharged in a vacuum, the electrons are irradiated on the phosphor, and the phosphor emits light. ing. As shown in FIG. 2A, the electron-emitting device of this flat surface device has an insulating film 112, a gate electrode film 113, and an organic film 114 formed in this order on a cathode wiring 111 formed on a substrate 110. . Next, the organic film 114 is patterned by a lithography technique to form a mask. Further, the gate electrode film 113 and the insulating film 112 are etched using the organic film 114 as a mask to form a circular hole 121 in the gate electrode 113. Thereafter, a refractory metal film 115 is deposited on the organic film 114. At that time, a refractory metal film 115 is also deposited on the cathode wiring 111.
[0003]
Next, the refractory metal film 115 formed thereon is removed together with the organic film 114 by a lift-off method. As a result, as shown in FIG. 1B, a part of the refractory metal film 115 is left on the cathode wiring 111, the cathode electrode 116 is formed, and the electron-emitting device 101 is completed.
[0004]
[Problems to be solved by the invention]
However, in the conventional technique, since the refractory metal film is formed by the vapor deposition method, the film formation time becomes very long and sometimes takes about 24 hours. This makes mass production difficult. In addition, in the electron-emitting device, it is necessary to form the gate electrode with a high precision so that the center of the cathode electrode coincides with the center of the gate electrode. ing. In the vapor deposition method, since the vapor deposition source is a single point, the center of the cathode electrode is shifted in the periphery of the large substrate.
[0005]
Usually, the strength of electrolysis when electrons are emitted depends on the distance from the tip of the cathode electrode to the gate electrode. For this reason, as described above, the distance between the tip of the cathode electrode and the gate electrode needs to be formed uniformly in the substrate. However, when the refractory metal film is formed by the above-described vapor deposition method, the height of the cathode portion is determined by the step coverage of the refractory metal film, so that it is very difficult to control the height. In addition, the distribution of the height of the cathode portion in the plane of the large-sized substrate has a large variation, and accordingly, in the display device using the electron-emitting device, the variation in the luminance of the display device becomes large.
[0006]
Thus, as explained in the prior art, it is extremely difficult to form a cathode electrode uniformly and with good controllability on a large substrate by a method for manufacturing an electron-emitting device using a vapor deposition method.
[0007]
[Means for Solving the Problems]
The present invention provides a method for manufacturing an electron-emitting device for solving the above-described problem, wherein a contact hole that leads to the cathode wiring is formed in an insulating film that covers the cathode wiring formed on the substrate, and then the contact hole is formed. A step of embedding the first cathode electrode material film by sputtering or CVD (including a step of etching back the first electrode material), and the height of the first cathode electrode material film in the contact hole Etching back to be lower than the opening, and forming a hole that leads to the contact hole in the stopper layer and the gate electrode film after sequentially forming a gate electrode film and a stopper layer on the insulating film When a step of forming a second cathode electrode material film by CVD in said hole and said stopper layer above, A step of burying a mask in a recess formed on the surface of the second cathode electrode material film by the hole; and etching back the second cathode electrode material film using the mask to form a pointed shape. forming a cathode electrode, thereby removing the stopper layer is sequentially provided manufacturing method of removing the insulating film of the upper periphery of the cathode electrode.
[0008]
In the method for manufacturing the electron-emitting device, since the first cathode electrode material film is formed by sputtering or CVD, the film formation time is significantly shortened as compared with film formation by the conventional vapor deposition method. Therefore, mass production becomes easy. In addition, after the first and second cathode electrode materials are embedded in the contact holes, a mask is formed in a recess formed on the central portion of the contact holes, and the second and first cathode electrode materials are etched back. Thus, the cathode electrode is formed so that the center of the cathode electrode is arranged at the center of the hole formed in the gate electrode. Furthermore, since the first and second cathode electrode materials are formed by two film formations, it becomes easy to control the height of the cathode electrode by the film thickness of the second cathode electrode material film. The height of the cathode electrode can be easily controlled. Therefore, the electron-emitting device is formed on a large substrate with good controllability.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An example of an embodiment according to the present invention will be described with reference to the manufacturing process diagram of FIG.
[0010]
As shown in FIG. 1A, a laminated film for forming the cathode wiring 12 is formed on the substrate 11 by sputtering. The laminated film is, for example, a titanium film having a thickness of 20 nm, a titanium nitride film having a thickness of 20 nm, a titanium film having a thickness of 5 nm, an aluminum-copper alloy film having a thickness of 400 nm, a thickness on the substrate 11. Are formed by sequentially stacking a titanium film having a thickness of 5 nm and a titanium nitride film having a thickness of 100 nm. Thereafter, a resist mask (not shown) for forming a cathode wiring is formed by resist coating and lithography technique, and the laminated film is etched using the resist mask as an etching mask to form the cathode wiring 12. Thereafter, the resist mask is removed.
[0011]
Further, an insulating film 13 covering the cathode wiring 12 is formed on the substrate 11 with, for example, a silicon oxide film. This silicon oxide film is formed by, for example, a plasma CVD method using tetraethoxysilane (TEOS) as a source gas. For example, it is formed to a thickness of 700 nm. Thereafter, a resist mask (not shown) for forming a contact hole is formed by resist application and lithography, and the insulating film 13 is etched using the resist mask as an etching mask, leading to the cathode wiring 12. For example, the contact hole 14 having a diameter of 0.5 μm is formed. Thereafter, the resist mask is removed.
[0012]
Next, as shown in FIG. 1B, a first adhesion layer 15 is formed on the inner surface of the contact hole 14 and the insulating film 13 by depositing titanium nitride to a thickness of 30 nm, for example, by sputtering. . Further, a first cathode electrode material film 16 is formed by depositing tungsten, for example, to a thickness of 600 nm inside the contact hole 14 and on the insulating film 13 by low pressure CVD.
[0013]
Thereafter, the first cathode electrode material film 16 and the first adhesion layer 15 are etched back. As a result, as shown in FIG. 1C, the first cathode electrode material film 16 remains only in the contact hole 14 via the first adhesion layer 15. At this time, the etching back is performed so that the height of the first cathode electrode material film 16 is about 0.1 μm lower than the opening 14 a of the contact hole 14.
[0014]
For etching back the first cathode electrode material film 16 made of tungsten, for example, an etching gas containing sulfur hexafluoride (SF ₆ ) alone, sulfur hexafluoride (SF ₆ ), and argon (Ar) is used. A mixed gas, a mixed gas of sulfur hexafluoride (SF ₆ ) and nitrogen (N ₂ ), or a mixed gas of sulfur hexafluoride (SF ₆ ) and chlorine (Cl ₂ ) is used. Etchback of the first adhesion layer 15 includes chlorine (Cl ₂ ) alone gas, mixed gas of chlorine (Cl ₂ ) and argon (Ar), chlorine (Cl ₂ ) and nitrogen (N ₂ ). A mixed gas or a mixed gas of chlorine (Cl ₂ ) and boron trichloride (BCl ₃ ) is used.
[0015]
Next, as shown in FIG. 1 (4), a gate electrode film 17 is deposited on the insulating film 13, the first cathode electrode material film 16, etc., and titanium nitride is deposited to a thickness of 100 nm by, for example, sputtering. Form. Further, a stopper layer 18 is formed on the gate electrode film 17 by depositing, for example, silicon oxide to a thickness of 50 nm. Next, a resist mask (not shown) for forming a hole having a diameter larger than that of the contact hole 14 is formed by resist coating and lithography, and the stopper layer 18 and the gate electrode film 17 are formed using the resist mask as an etching mask. Etching is performed to form a hole 19 having a diameter of 0.55 μm, for example, leading to the contact hole 14. Thereafter, the resist mask is removed. In this way, the gate electrode 21 is formed.
[0016]
Next, as shown in FIG. 1 (5), a second adhesion layer 22 is formed on the inner surface of the hole 19 and the stopper layer 18 by depositing titanium nitride to a thickness of 30 nm, for example, by sputtering. To do. Further, a second cathode electrode material film 23 is formed on the second adhesion layer 22 by low pressure CVD, for example, by depositing tungsten to a thickness of 550 nm. The thickness of the second cathode electrode material film 23 is the length of the diameter of the hole 19 or a length equal to or less than the diameter. In the film formation of the second cathode electrode material film 23, a depression 24 is formed on the hole 19 due to the film formation characteristics.
[0017]
Next, after a resist film 25 is formed to a thickness of, for example, 350 nm on the second cathode electrode material film 23 by a normal resist coating technique, the resist film 25 is etched back to obtain (6) in FIG. As shown, a mask 26 is formed by leaving the resist film 25 only in the depressions 24 formed in the second cathode electrode material film 23. Since the second cathode electrode material film 23 is formed by the low pressure CVD method, the depression 24 is formed on the central portion of the hole 19 due to the characteristics of the film formation.
[0018]
Next, the second cathode electrode material film 23 and the second adhesion layer 22 are etched back. As a result, as shown in FIG. 1 (7), the second cathode electrode material film 23 is formed inside the contact hole 14 on the first cathode electrode material film 16 via the second adhesion layer 22. Make sure it remains pointed. In this manner, the pointed cathode electrode 27 composed of the first cathode electrode material film 16 and the second cathode electrode material film 23 is formed via the first and second adhesion layers 15 and 22.
[0019]
For the etch back of the second cathode electrode material film 23, an etching gas similar to the etch back of the first cathode electrode material film 16 is used, and the selection of the resist film 25 and the second cathode electrode material film 23 is performed. For example, the etching is performed under such an etching condition that the ratio is about 3. For etching back the second adhesion layer 22, a chlorine-based etching gas similar to the etch back of the first adhesion layer 15 is used.
[0020]
Thereafter, as shown in FIG. 1 (7), the stopper layer 18 (see FIG. 1 (5)) is removed by wet etching, and the insulating film 13 around the upper portion of the cathode electrode 27 is etched. . In this wet etching, hydrofluoric acid is used because the stopper layer 18 and the insulating film 13 are formed of a silicon oxide film. As a result, the electron-emitting device 10 in which the pointed portion 27a of the cathode electrode 27 is located at the center of the hole 19 formed in the gate electrode 21 is formed.
[0021]
In the above manufacturing method, tungsten is used for the first and second cathode electrode material films 16 and 23. However, it is possible to use a refractory metal material such as molybdenum, titanium, niobium, tantalum, or chromium. In addition, the resist film 25 is used to form the cathode electrode 27 in a pointed shape. However, when the second cathode electrode material film 23 is etched back, any material film having an etch back selection ratio of about 3 can be used. Anything can be used, for example, a polyimide film, an SOG film, or the like can be used. Further, as a method of leaving the resist film 25 in the recess 24 formed in the second cathode electrode material film 23, a polishing method such as chemical mechanical polishing can be used in addition to the etch back described above.
[0022]
Since the gate electrode 21 is formed after the first cathode electrode material film 16 is etched back (first etch back), the first cathode electrode material film 16 is not excessively etched in the first etch back. There is a need to.
[0023]
In the manufacturing method of the electron-emitting device, since the first cathode electrode material film 16 is formed by sputtering or CVD, the film formation time is significantly shortened as compared with film formation by a conventional vapor deposition method. The first and second cathode electrode material films 16 and 23 are buried in the contact hole 14 twice, and then a mask is formed in the depression 24 formed on the center of the contact hole 14. Since the second cathode electrode material film 23 is etched back, the cathode electrode 27 is formed so that the center of the cathode electrode 27 is arranged at the center of the hole 19 formed in the gate electrode 21. Furthermore, since the first and second cathode electrode material films 16 and 23 are formed by two film formations, the height of the cathode electrode 27 can be controlled by the film thickness of the second cathode electrode material film 23. It becomes easy.
[0024]
Further, when the second cathode electrode material film 23 is formed, the second cathode electrode material film 23 formed on the first cathode electrode material film 16 has a portion with excellent orientation as the tip of the electrode. Therefore, the life of the electron emission performance of the cathode electrode 27 can be improved.
[0025]
【The invention's effect】
As described above, according to the present invention, after embedding the first and second cathode electrode materials in the contact hole by two film formations, a mask is formed in the recess formed on the center portion of the contact hole. Since the second and first cathode electrode material films are formed and etched back, the center of the cathode electrode can be arranged at the center of the hole formed in the gate electrode. Furthermore, since the cathode electrode material film is formed twice, the height of the cathode electrode can be easily controlled by the film thickness of the second cathode electrode material film. Therefore, the distance between the cathode electrode and the gate electrode can be determined with high accuracy by etching back the second cathode electrode material film. Therefore, when a plurality of electron-emitting devices are formed on a large substrate, the in-plane distribution of the cathode electrode shape of each electron-emitting device becomes uniform, and variations in brightness of the surface devices are reduced, improving the quality of the surface device. Can be planned.
[0026]
In addition, since the gate electrode is formed after the first cathode electrode material film is etched back once, and the stopper layer is formed on the gate electrode film, deterioration of the gate electrode is prevented, and a stable electron-emitting device can be obtained. Can be manufactured.
[0027]
Furthermore, since the first cathode electrode material film is formed by sputtering or CVD, the film formation time can be significantly shortened as compared with the conventional film formation by vapor deposition.
[Brief description of the drawings]
FIG. 1 is a manufacturing process diagram showing an example of an embodiment according to the present invention.
FIG. 2 is a manufacturing process diagram showing a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Board | substrate, 12 ... Cathode wiring, 13 ... Insulating film, 14 ... Contact hole, 16 ... 1st cathode electrode material film, 17 ... Gate electrode film, 18 ... Stopper layer, 19 ... Hole, 23 ... 2nd cathode Electrode material film, 24 ... depression, 26 ... mask, 27 ... cathode electrode

Claims (1)

1. Forming a contact hole leading to the cathode wiring in an insulating film covering the cathode wiring formed on the substrate, and then embedding a first cathode electrode material film in the contact hole by sputtering or CVD ;
   Performing etch back so that the height of the first cathode electrode material film is lower than the opening of the contact hole;
   Forming a hole leading to the contact hole in the stopper layer and the gate electrode film after sequentially forming the gate electrode film and the stopper layer on the insulating film;
   Forming a second cathode electrode material film on the stopper layer and in the hole by a CVD method ;
   Embedding a mask in a recess formed in the surface of the second cathode electrode material film by the hole;
   Etching back the second cathode electrode material film using the mask to form a cathode by forming a pointed shape; and
   And a step of removing the stopper layer and removing the insulating film around the upper portion of the cathode electrode in order .

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