JP3094464B2 - Method of manufacturing field emission type microcathode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a field emission type micro-cathode, and is suitable for use in manufacturing a field emission type flat CRT, for example.

[0002]

2. Description of the Related Art Heretofore, a so-called Spindt type microcathode has been known as a field emission type microcathode having a size on the order of microns. The manufacturing method is as follows. That is, as shown in FIG. 8, a silicon dioxide (SiO ₂ ) film 10 is first formed on a conductive silicon (Si) substrate 101 by a thermal oxidation method, a CVD method, or a sputtering method.
After the formation of the gate electrode 2, a molybdenum (Mo) film 103 is formed as a material for forming a gate electrode on the SiO ₂ film 102 by a sputtering method or an electron beam evaporation method. here,
The thickness of the SiO ₂ film 102 is about 1 to 1.5 μm,
The thickness of the film 103 is, for example, about several thousand Å. Thereafter, a resist pattern 104 having a shape corresponding to the gate electrode to be formed is formed on the Mo film 103 by lithography.

Next, using the resist pattern 104 as a mask, the Mo film 103 is etched by a wet etching method or a dry etching method to form a gate electrode 105 as shown in FIG. This gate electrode 10
5 has a circular opening 105a having a diameter of about 1 μm, for example. Next, the resist pattern 104 and the gate electrode 1
The SiO ₂ film 102 is etched by wet etching using the mask 05 as a mask to form a cavity 102a as shown in FIG.

[0004] Next, after removing the resist pattern 104, as shown in FIG. 11, oblique vapor deposition is performed by an electron beam vapor deposition method from a direction inclined at a predetermined angle with respect to the substrate surface, for example, on the gate electrode 105. A release layer 106 made of aluminum (Al) is formed. Note that the oblique deposition is performed while rotating the Si substrate 1 around its center. Next, Mo is vapor-deposited from a direction perpendicular to the substrate surface as a material for forming a cathode by electron beam vapor deposition. Thus, as shown in FIG. 12, the cathode 107 is formed on the Si substrate 101 inside the cavity 102a. Reference numeral 108 denotes a release layer 106 during this deposition.
2 shows a Mo film formed thereon. The thickness of the Mo film 108 is 1
About 2 μm.

After that, the release layer 106 and the Mo film 108 formed thereon are removed by a lift-off method, and FIG.
As shown in FIG. 3, the intended field emission type microcathode is completed. Since the electron emission from the cathode 107 needs to be performed in a vacuum of about 10 ⁻⁶ Torr or less, it is actually vacuum-sealed thereafter by an opposing plate or other members not shown.

[0006]

In the above-described conventional method for manufacturing a field emission type microcathode, in order for the Mo film 108 to be actually lifted off, an etchant for lift-off is required under the Mo film 108 at the time of lift-off. Release layer 10
Need to reach 6. However, as shown in FIG. 12, the Mo film 108 is formed so as to almost completely cover the substrate surface, and the lift-off etchant is
The only place that can enter the lower side of the film 108 is the portion having a small film thickness just above the cathode 5. For this reason, the lift-off etchant hardly reaches the peeling layer 106, and it is actually difficult to perform the lift-off.

This problem is particularly remarkable when a large-area field emission type microcathode array is formed. That is, in the field emission type micro-cathode array, the pitch of the cathode 107 is, for example, about 10 μm, whereas the diameter of the opening 105 a of the gate electrode 105 formed right above the cathode 107 is about 1 μm. , Is much smaller than the pitch of the cathode 107. Then, the opening 105 of the gate electrode 105 in this case
The arrangement of “a” is as shown in FIG. 13, and it can be seen that there is almost no place where the lift-off etchant can enter the lower side of the Mo film 108. As a result, lift-off cannot be performed partially, or the release layer 106
Lift-off could not be performed completely, for example, the Mo film 108 remained thin on top. Furthermore, even if lift-off could be performed completely, the time required for lift-off was quite long and unproductive. Accordingly, it is an object of the present invention to provide a method of manufacturing a field emission type microcathode which can completely lift off a film formed on a peeling layer at the time of forming a cathode in a short time.

[0008]

In order to achieve the above object, the present invention provides a substrate (1), an insulating film (2) formed on the substrate (1), and an insulating film (2) formed on the substrate (1). Cavity (2a), a cathode (5) formed on a substrate (1) inside the cavity (2a), and an insulating film (2)
In a method for manufacturing a field emission type microcathode including a gate electrode (3) formed thereon, an insulating film (2) having a cavity (2a) and a gate electrode (3) are formed on a substrate (1). Thereafter, a step of forming a release layer (4) made of metal on the gate electrode (3) by performing first vapor deposition from a direction inclined with respect to the surface of the substrate (1); From a direction almost perpendicular to
Forming a cathode (5) by vapor deposition, and partially removing the film (6) formed on the release layer (4) by the second vapor deposition to remove the release layer (4). And a step of removing the release layer (4) together with the film (6) by a lift-off method. The removed portion of the film (6) formed on the peeling layer (4) by the second vapor deposition can be located at any place except directly above the cathode (5), and its shape is also optional. it can.
In this case, in order to facilitate the lift-off, the size of the removing portion is preferably made large as long as there is no problem.

[0009]

According to the method of manufacturing the field emission type microcathode of the present invention constructed as described above, the film (6) formed on the release layer (4) by the second evaporation is partially removed by etching. Then, the lift-off etchant easily reaches the exposed portion of the release layer (4) at the time of the lift-off that is performed thereafter, whereby the release layer (4) is partially exposed. Lift-off of the film (6) formed on the layer (4) can be performed completely and in a short time.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same portions are denoted by the same reference numerals. 1 to 4 are cross-sectional views illustrating a method of manufacturing a field emission type microcathode according to an embodiment of the present invention.

In this embodiment, first, FIGS.
The process is advanced to the state shown in FIG. 1 in the same manner as in the conventional method for manufacturing a field emission type microcathode shown in FIG. That is, for example, after forming an insulating film 2 such as a SiO ₂ film having a cavity 2 a and a gate electrode 3 made of Mo, for example, on a conductive Si substrate 1, the gate electrode 3 is inclined at a predetermined angle with respect to the substrate surface. By performing evaporation, for example, Al
Then, a cathode 5 is formed on the Si substrate 1 inside the cavity 2a by depositing, for example, Mo from a direction perpendicular to the substrate surface. Reference numeral 6 denotes the Mo formed on the release layer 4 during this vapor deposition.
3 shows a membrane.

Next, as shown in FIG. 2, a resist pattern 7 having a predetermined shape is formed on the Mo film 6 by lithography. Next, using the resist pattern 7 as a mask, Mo
By etching the film 6 in a direction perpendicular to the substrate surface by, for example, a reactive ion etching (RIE) method, a release groove 8 is formed in the Mo film 6 as shown in FIG. The release layer 4 is exposed in the release groove 8. FIG. 5 shows an example of the planar shape of the release groove 8. FIG. 3 corresponds to FIG.
Corresponding to the cross section along line -3.

Next, the release layer 4 and the Mo film 6 formed thereon are removed by a lift-off method. The lift-off etchant has an etching effect on the release layer 4 but has almost no etching effect on the Mo film 6, the gate electrode 3, the insulating film 2, the Si substrate 1, and the like. Can be At the time of this lift-off, the lift-off etchant easily reaches the release layer 4 through the release groove 8, so that lift-off is easily and completely performed in a short time, and the release layer 4 and the Mo film 6 are completely removed. . Thereby, as shown in FIG. 4, the intended field emission microcathode is completed. In addition,
Since it is necessary to emit electrons from the cathode 5 in a vacuum of about 10 ^-6 Torr or less, the electron is actually vacuum-sealed by an opposing plate or other members not shown later. As described above, according to this embodiment, the release groove 8 is formed on the Mo film 6 formed on the release layer 4 when the cathode 5 is formed.
Is formed, and then lift-off is performed. Therefore, the etching solution for lift-off easily reaches the release layer 4 through the release groove 8, whereby the release layer 4 is removed.
It can be removed completely and in a short time together with the Mo film 6 by the lift-off method.

Next, an embodiment in which the present invention is applied to the manufacture of a field emission type flat CRT using a field emission type micro cathode array will be described. FIG. 6 is a plan view of the field emission type flat CRT according to this embodiment in which the cathode is formed, and FIG. 7 is a partially enlarged cross-sectional view along the cathode line of the field emission type flat CRT shown in FIG. . As shown in FIGS. 6 and 7, in this embodiment, a desired number of cathode lines 12 are formed on a glass substrate 11 in parallel with each other. Here, in order to solve the problem of indeterminate potential on the glass surface, an insulating film (not shown) such as an SiO ₂ film is preferably formed on the glass substrate 11, and a cathode line is formed on the insulating film. 12
Is formed.

Next, the process proceeds in the same manner as shown in FIGS. That is, after first forming the insulating film 2 on the entire surface,
For example, a Mo film is formed on the insulating film 2 as a material for forming a gate line. Next, after a resist pattern having a shape corresponding to the gate line is formed on the Mo film, the Mo film is etched using the resist pattern as a mask. As a result, a desired number of gate lines 13 constituting the gate electrode are formed perpendicular to the cathode lines 12 and parallel to each other. In this case, for example, a desired number of circular openings 13a are formed in a matrix at the gate line 13 at the intersection with the cathode line 12. Next, the gate line 1 in which the opening 13a is formed
By etching the insulating film 2 using the mask 3 as a mask, a cavity 2a is formed in a lower portion of each opening 13a.

Next, the release layer 4 is formed on the gate line 13 by performing oblique vapor deposition from a direction inclined at a predetermined angle with respect to the substrate surface, and then by performing vapor deposition from a direction perpendicular to the substrate surface. The cathode 5 is formed on the cathode line 12 inside each cavity 2a. In this way, a micro-cathode array including a large number of cathodes 5 arranged in a matrix is formed on the cathode line 12 at the intersection with the gate line 13.
Next, a release groove 8 is formed by etching and removing a predetermined portion of the Mo film 6 formed on the release layer 4 using, for example, a resist pattern as a mask. Next, the release layer 4 and the Mo film 6 are removed by a lift-off method.
At the time of this lift-off, the lift-off etching liquid easily reaches the peeling layer 4 through the release groove 8 in the same manner as in the above-described embodiment, so that the lift-off is completely performed. Thereafter, vacuum sealing is performed with a glass plate (not shown) having a phosphor formed on the surface on the side of the cathode 5 to complete the intended field emission flat CRT.

According to this embodiment, a release groove 8 is formed by etching and removing most of the release layer 4 except for a portion immediately above a microcathode array composed of a large number of cathodes 4 arranged in a matrix. Since the lift-off is performed later, the lift-off etchant easily reaches the release layer 4, and the lift-off can be completed completely in a short time. Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible.

For example, in the above-described embodiment, the linear release groove 8 is formed, but the release groove 8 can have any shape. For example, when the cathodes 5 are densely formed, a large number of small holes can be formed in the Mo film 6 where the cathodes 5 are not formed, and these holes can be used as the release grooves 8. is there. The release layer 4 can be formed on the resist pattern while leaving the resist pattern used as a mask during etching for forming the gate electrode 3 or the gate line 13. In this case, predetermined portions of the Mo film 6 and the release layer 4 are removed by etching to form a release groove 8, and after exposing a resist pattern in the release groove 8, an organic solvent or a resist release liquid ( An organic base) may be used for lift-off. Further, in the above-described embodiment, Mo is used as a material for forming the cathode. However, as a material for forming the cathode, tungsten (W), titanium (Ti), lanthanum boride (LaB
₆ ), tungsten silicide (WSi _x ),
Titanium silicide (TiSi _x ), platinum silicide (PtS
It is possible to use a metal silicide such as i _x ). Also, as the material of the release layer 4, it is possible to use a material other than Al, for example, nickel (Ni) or zinc (Zn).

[0019]

As described above, according to the present invention, the film formed on the peeling layer at the time of forming the cathode is partially removed by etching to partially expose the peeling layer. The lift-off etchant easily reaches the peeling layer at the time of the lift-off performed in this manner, whereby the film formed on the peeling layer at the time of forming the cathode can be completely lifted off in a short time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a method of manufacturing a field emission microcathode according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a method of manufacturing a field emission microcathode according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a method of manufacturing a field emission microcathode according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a method of manufacturing a field emission microcathode according to one embodiment of the present invention.

FIG. 5 is a plan view showing an example of a planar shape of a release groove formed on a Mo film formed on a release layer in the method for manufacturing a field emission microcathode according to one embodiment of the present invention.

FIG. 6 is a plan view for explaining a method of manufacturing a field emission flat CRT according to another embodiment of the present invention.

7 is a partially enlarged cross-sectional view of the field emission flat CRT shown in FIG. 6, taken along a cathode line.

FIG. 8 is a cross-sectional view illustrating an example of a conventional method for manufacturing a field emission microcathode.

FIG. 9 is a cross-sectional view illustrating an example of a conventional method for manufacturing a field emission microcathode.

FIG. 10 is a cross-sectional view illustrating an example of a conventional method for manufacturing a field emission microcathode.

FIG. 11 is a cross-sectional view illustrating an example of a conventional method for manufacturing a field emission microcathode.

FIG. 12 is a cross-sectional view illustrating an example of a conventional method for manufacturing a field emission microcathode.

FIG. 13 is a cross-sectional view illustrating an example of a conventional method for manufacturing a field emission microcathode.

FIG. 14 is a plan view for explaining a problem of a conventional method of manufacturing a field emission microcathode.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Si substrate 2 insulating film 2 a cavity 3 gate electrode 4 release layer 5 cathode 6 Mo film 7 resist pattern 8 release groove

Claims (1)

(57) [Claims] A substrate, an insulating film formed on the substrate, a cavity formed in the insulating film, a cathode formed on the substrate inside the cavity, and formed on the insulating film. A method of manufacturing a field emission microcathode comprising: a gate electrode; and forming the insulating film and the gate electrode having the cavity on the substrate, and then forming the gate electrode from a direction inclined with respect to the surface of the substrate. Forming a release layer made of a metal on the gate electrode by performing the first vapor deposition; and forming the cathode by performing a second vapor deposition in a direction substantially perpendicular to the surface of the substrate. A step of partially etching away a film formed on the release layer by the second vapor deposition to partially expose the release layer; and forming the release layer together with the film. Field emission micro-cathode manufacturing method characterized by comprising the step of removing by lift-off.