JP2000073187A - Metallic thin film for pattern formation and production of patterned metallic thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the productivity in the patterning of a metallic thin film and to form the edge part of an orderly taper by subjecting a metallic thin film formed on a substrate to ozone exposure or cleaning with an aq. soln. of potassium hydroxide and converting it to the hydrophilic one in such a manner that the surface thereof and water make a specified contact angle. SOLUTION: On a substrate 11 such as glass or the like, a metallic thin film 12 of aluminum, chromium or the like is formed to a thickness of about 1500 to 4000 Åby a vapor deposition method or the like. This metallic thin film 12 is subjected to ozone exposure and/or cleaning with an aq. soln. of potassium hydroxide and is made into the hydrophilic one in such a manner that the contact angle between the surface thereof and water is controlled to <35 degrees, preferably about <=30 degrees. The surface of this hydrophilic metallic thin film 12 is applied with a photoresist composed of a resin to a thickness of about 0.05 to 15 μm to form a resist pattern 13 by photomechanical processing technology. Then, this is etched with an etching soln. In this way, the etching soln. infiltrates from the end part of the resist pattern 13 to make the edge part of the metallic thin film 12 to an orderly taper to prevent the cutting of the difference in level (edge) in the film 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal thin film for forming a pattern and a method for producing a patterned metal thin film. More specifically, the present invention relates to a metal thin film in which, when a resist is formed on a metal thin film to form a pattern, an end of the metal thin film is formed to have a forward taper, and a method of manufacturing a patterned metal thin film.

[0002]

2. Description of the Related Art Conventionally, when forming a pattern on a thin metal film such as chromium formed on a glass substrate, the composition of an etching solution is 100 cc of water, 17 g of ceric ammonium nitrate and 5 cc of perchloric acid. It is dissolved (Narazaki Nihei, "Photoetching and Fine Processing", Sogo Denshi Shuppansha, May 10, 1977, hereinafter, the etching solution of this composition is abbreviated as "Narazaki Nihei"). A procedure for forming a pattern on a metal thin film according to a conventional procedure will be described with reference to FIG.
22 is a metal thin film and 23 is a resist pattern. After a resist pattern as shown in FIG. 2B is formed on the metal thin film 21 by a normal photolithography technique, the metal thin film 21 is oxidized by an oxidizing agent of the etching solution when the etching is performed by the above-mentioned etching solution. It elutes as ions in the etching solution.

[0003] At this time, the portion covered with the resist pattern 23 does not come into contact with the etching solution, and thus does not dissolve.
The portion of the metal thin film 21 that is not covered with the resist pattern 23 is dissolved by contacting the etching solution. After the elution with the etching solution, the pattern is washed with water and then the resist pattern 23 is removed to obtain the pattern of the metal thin film 22 shown in FIG. 2D. When the metal thin film formed on the glass substrate is etched with the chromium etchant, the edge of the metal thin film may have a vertical taper of 70 to 90 degrees as shown in the cross-sectional view of FIG. There were many.

However, when the edge of the metal thin film has a vertical taper of 70 to 90 degrees, depending on the application, FIG.
If a coating 24 is further formed on the metal thin film 22 as shown in the cross-sectional view of FIG. 5E, there is a problem that a step (edge) break occurs at a step (edge) portion 25. In order to solve the problem of disconnection of the step (edge), a chromium film patterning method described in JP-A-64-86524 has been proposed.

According to this proposed method, an etching solution containing 17 g of ceric ammonium nitrate and 13 cc of nitric acid dissolved in 87 cc of water and containing at least 2 mol / l (hereinafter, the etching solution of this composition is abbreviated as "86524 solution") To use). The operation procedure will be described with reference to FIG. 3. In FIG. 3, 31 is a substrate, 32 is a metal thin film, and 33 is a resist pattern. After a resist pattern as shown in FIG. 3 (B) is formed on the metal thin film 31 by a normal photolithography technique and then etched with the above-mentioned etching solution, the metal thin film 31 is oxidized by an oxidizing agent of the etching solution, It elutes as ions in the etching solution. At this time, the portion covered with the resist pattern 33 does not come into contact with the etching solution and thus does not dissolve.

However, when this "86524 liquid" is used, the edge of the resist pattern 33 is peeled off from the metal thin film 31 by nitric acid contained in the etching solution, and the peeled lower metal thin film 32 is etched. Done. As a result, the edge of the metal thin film 32 is formed in a forward tapered shape with an angle of less than 70 degrees with respect to the substrate. The portion of the metal thin film 32 not covered by the resist pattern 33
After dissolving, the resist pattern 33 is removed and the pattern of the metal thin film 32 shown in FIG. 3D is obtained. However, the etching rate at this time is
There is a problem in that the productivity is inferior to the case where the above-mentioned "Narasaki-two bottle liquid" is used.

[0007]

Under such circumstances, the inventor of the present invention completed the present invention as a result of intensive studies in order to provide a technique which can solve the above-mentioned disadvantages of the prior art at once. The objects of the present invention are as follows. 1. An object of the present invention is to provide a patterning method in which an etching rate when removing a resist pattern formed on a metal thin film does not decrease and productivity does not deteriorate. 2. The edge of the metal thin film formed on the substrate is not formed into a vertical taper, but is formed in a forward taper shape, and the thin film formed on the metal thin film is less likely to have a step (edge) cut. Providing sheets. 3. The edge of the metal thin film formed on the substrate has a forward taper, and when a thin film is further formed on this metal thin film, the production of a patterned metal thin film in which a step (edge) is hardly cut at a step (edge) portion. Providing a way.

[0008]

According to the present invention, there is provided a metal sheet for forming a pattern for forming a resist film on a surface thereof, wherein a contact angle between the surface of the metal sheet and water is less than 35 degrees. It is intended to provide a metal sheet for pattern formation, characterized in that:

In the present invention, further, in manufacturing a patterned metal sheet, first, the contact angle between the surface of the metal sheet and water is set to less than 35 degrees, and then, a resist pattern is formed on the surface of the metal sheet. An object of the present invention is to provide a method for producing a patterned metal sheet, characterized by etching the metal sheet.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The thin metal sheet for patterning according to the present invention is a thin sheet formed on a glass substrate by a vapor deposition method, the type of metal is aluminum or chromium, and the thickness is 1.
It is selected in the range of 500 to 4000 Å.

According to experiments performed by the present inventors, the metal sheet for forming a pattern according to the present invention is required to have a contact angle between water and a metal sheet on which a resist pattern is formed is less than 35 degrees. , When the contact angle with water exceeds 35 degrees,
The edge of the metal thin film formed on the substrate does not have a forward taper but a vertical taper, which is not preferable. The contact angle with water is particularly preferably 30 degrees or less. In the present invention, the contact angle with water is measured by a droplet method (see “Glass Surface Design”, Modern Editing Co., Ltd., pp. 130-131) after a lapse of 30 seconds after a water droplet is dropped on a substrate. Say.

In order to make the contact angle between the metal thin film surface and water less than 35 degrees, for example, (1) a method of hydrophilizing the surface of the metal thin plate by exposing the metal thin plate to ozone; Any of a method of washing with a potassium oxide solution to make it hydrophilic and (3) a method of washing with a potassium hydroxide solution and subsequently exposing the metal sheet to ozone to make the surface of the metal sheet hydrophilic. The method of (1) exposing to ozone is a method of subjecting a metal sheet surface to UV / O3 surface treatment.
The method of washing with a potassium hydroxide solution in the above (2) includes a method of spraying a potassium hydroxide solution and a method of dipping (see FIG. 1 (A) described later).

In order to manufacture a thin metal sheet patterned according to the method of the present invention, first, the contact angle between the thin metal sheet and water is reduced to less than 35 degrees by any one of the above methods (1) to (3). A resist film is formed on a thin metal plate (see FIG. 1B described later). When the resin used to form the resist film is a photoresist whose solubility in a solvent is changed by irradiation with ultraviolet light, a positive resist in which a portion irradiated with light is soluble in the solvent, and conversely, Irradiation may be any negative resist which becomes insoluble in the solvent, but a positive resist is preferable.

The operation of applying the photoresist can be performed by a conventionally known method such as a spin coating method, a roll coating method, a curtain coating method, and a screen printing method. After forming the resist film, pre-baking can be performed at a temperature of 50 to 150 ° C. for a period of 30 to 10 minutes. The thickness of the applied film at the time of application varies depending on the type of the resist, but is selected in the range of 0.05 to 15 μm.

In order to form a resist pattern on a metal thin film using a positive resist, a filter provided with a patterning hole for patterning is arranged between a light source and a photoresist film and irradiated with ultraviolet rays. A latent image is formed on the resist film. The type of resist pattern formed on the metal thin film can be selected according to the pattern of the holes formed in the filter. Generally, as a light source,
A high-pressure or low-pressure mercury lamp is used.

The resist film on which the latent image has been formed is etched with an etchant to dissolve the remaining portions except for the insoluble portion where the solubility changes due to ultraviolet rays, and the metal thin film is also oxidized by the oxidizing agent of the etchant. The ions are eluted as ions into the etching solution. At this time, since the portion covered with the resist film does not come into contact with the etching solution, it does not come into contact with the etching solution and thus does not dissolve, leaving a metal thin film pattern (see FIG. 1 (C) described later). As an etchant,
The above-mentioned "Narasaki-two bottle solution" can be used. There is no particular limitation on the etching method, and a conventionally known method such as a paddle method, a dipping method, or a spray method can be used. Finally, by washing with water and removing the resist, a patterned metal sheet is obtained (see FIG. 1 (D) described later).

A procedure for manufacturing a metal sheet patterned according to the method of the present invention will be described with reference to FIG. FIG. 1A is a cross-sectional view of a state in which a thin metal plate is formed on a surface of a glass substrate by a vapor deposition method, and FIG.
FIG. 4 is a cross-sectional view showing a state where a resist pattern 13 is formed on the surface of an upper metal thin film 12 by photolithography. FIG. 1 (C) is a cross-sectional view showing a state after the metal thin plate is etched with an etching solution, FIG. 1 (D) is a cross-sectional view showing a state in which the resist is removed, and FIG. FIG. 3 is a cross-sectional view showing a state where the surface of the metal thin film 12 is protected by a coating 14.

Before the resist pattern is formed on the metal thin film according to the method of the present invention, if the contact angle between the metal thin film and water is made hydrophilic so as to be less than 30 degrees, an etching solution is applied between the surface of the metal thin film and the resist film in the etching step. And the edge of the metal thin film is etched by the etchant that has entered the interface with the edge of the metal thin film. As a result, the edge of the metal thin film is tapered forward. “865” as an etchant
Solution 24 has a higher nitric acid concentration, so the etching rate is lower than in the case of using "Narasaki / Nibe", but when using a metal thin film having a contact angle with water of less than 35 degrees, It is not necessary to increase the nitric acid concentration, and the etching rate does not decrease, so that etching can be performed at a high rate. The taper angle at the edge of the metal thin film can be easily confirmed by a scanning electron microscope.

[0019]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to the following description unless it exceeds the gist.

[Example 1] A chromium thin film having a thickness of 2000 angstroms was formed on the surface of a glass substrate by a vacuum evaporation method. The contact angle of the obtained chromium thin film surface with water was measured by a water drop method and found to be 79 degrees.
This chromium thin film surface was immersed and washed in a 5% aqueous solution of potassium hydroxide for 8 minutes. The contact angle of the chromium thin film surface after washing with water was 33 degrees. A positive resist (manufactured by Mitsubishi Chemical Corporation, i5040) was applied to the surface of the chromium thin film by spin coating, and prebaked at a temperature of 90 ° C. for 60 seconds. Subsequently, an exposure machine (manufactured by Oak Manufacturing Co., Ltd., model:
EXM-1066-C-00), mercury lamp ｛light source lamp: 5kw mercury short arc lamp, illuminance: 10mW / cm2, wavelength 24
Irradiation was performed at 90 mJ according to 0 to 450 nm (wavelength center: 365 nm). Thereafter, development was performed at 23 ° C. for 40 seconds with a 0.5% aqueous solution of potassium hydroxide, and etching was performed for 40 seconds by a shower method using “Narasaki / Nibotsu liquid”. The taper angle of the edge of the obtained patterned metal thin film was measured with a scanning electron microscope, and was found to be 25 degrees.

Example 2 A chromium thin film on the surface of a glass substrate prepared by the method described in Example 1 was washed by immersing it in a 5% aqueous solution of potassium hydroxide for 2 minutes, and then a low-pressure mercury lamp (manufactured by Nippo Electric Co., Ltd.) , Model: SGL-1000T-4UZ-4P), and after exposure to ozone by irradiation for 2 minutes, the contact angle with water was measured to be 7 degrees. A positive resist was formed on the surface of the chromium thin film according to the procedure described in Example 1, exposed, and etched. The taper angle of the edge of the obtained patterned metal thin film was measured with a scanning electron microscope, and it was 15 degrees.

Comparative Example A chromium thin film on a glass substrate on which a chromium thin film prepared by the method described in Example 1 was deposited was washed with ion-exchanged water for 10 minutes. The contact angle of the chromium thin film surface with water was 58 degrees. A positive resist was formed on the surface of the chromium thin film according to the procedure described in Example 1, and exposed,
Etched. When the taper angle of the edge of the obtained patterned metal thin film was measured with a scanning electron microscope, it was 80 degrees.

[0023]

The present invention has the following particularly advantageous effects, and its industrial value is extremely large. 1. According to the method of the present invention, the etching rate at the time of removing the resist pattern formed on the metal thin film does not decrease, so that the productivity when manufacturing the patterned metal thin film can be maintained at a high level. 2. Since the surface of the metal thin film for patterning according to the present invention is hydrophilic, it is easy to penetrate into the interface between the surface of the metal thin film and the edge of the resist when etching with an etchant, Gradually peels off from the metal thin film, the metal thin film gradually elutes during the dissolution of the etching solution, and the edge of the metal thin film becomes forward tapered. 3. According to the method of the present invention, it is possible to obtain a patterned metal thin film having a shape in which the edge is forward tapered. If a further thin film is formed on this metal thin film, a step (edge) is formed at the step (edge) portion. ) The problem of disconnection can be solved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a procedure for manufacturing a metal sheet patterned according to the method of the present invention.

FIG. 2 is a sectional view showing an example of a procedure for manufacturing a metal sheet patterned by a conventional technique.

FIG. 3 is a cross-sectional view showing another example of a procedure for manufacturing a metal sheet patterned by a conventional technique.

[Explanation of symbols]

 11, 21, 31: Substrate 12, 22, 32: Metal thin film 13, 23, 33: Resist pattern 14, 24, 34: Coating 25: Step (edge) portion

Claims (8)

[Claims] 1. A metal thin film for pattern formation which forms a resist film on its surface, wherein the contact angle between the surface of the metal thin film and water is less than 35 degrees. 2. The metal thin film for pattern formation according to claim 1, wherein the metal thin film has been exposed to ozone. 3. The metal thin film for forming a pattern according to claim 1, wherein the metal thin film has been washed with a potassium hydroxide solution. 4. The metal thin film for pattern formation according to claim 1, wherein the metal thin film is exposed to ozone and washed with a potassium hydroxide solution. 5. When manufacturing a patterned metal thin film, first, a contact angle between the surface of the metal thin film and water is set to less than 35 degrees, a resist pattern is formed on the surface of the metal thin film, and then the metal thin film is etched. A method for producing a patterned metal thin film, characterized in that the edge of the metal thin film is forward tapered by etching with a liquid. 6. The method for producing a patterned metal thin film according to claim 5, wherein the method of setting the contact angle of the metal thin film with water to less than 35 degrees is a method of exposing the metal thin film to ozone. 7. The method for producing a patterned metal thin film according to claim 5, wherein the method of reducing the contact angle of the metal thin film with water to less than 35 degrees is a method of cleaning the metal thin film with a potassium hydroxide solution. 8. The patterned film according to claim 5, wherein the method of setting the contact angle of the metal thin film with water to less than 35 degrees is a method of exposing the metal thin film to ozone and washing with a potassium hydroxide solution. Manufacturing method of metal thin film.