JPS61163342A - Method for removing photoresist - Google Patents

Abstract

PURPOSE:To enable a photoresist film to be removed down to a desired thickness without damaging an attached face by immersing an intermediate work into a photoresist-removing soln. and irradiating it with UV rays in a chamber filled with O2. CONSTITUTION:The intermediate work II composed of the photoresist film 2, a thin metal film 4, and an electroformed plate 5 is formed in a step for forming a stamper III. The photoresist film 2 of this work II is implanted with the metal of the film 4 by the sputtering method to make it difficult to remove the film 2 by the usual method. To solve this problem, the work II is immersed into the photoresist-removing soln. to remove most of the film 2, and it is placed in this state into the chamber filled with O2 to irradiate it with UV rays for about 15min, thus permitting the photoresist film 2 to be removed down to an intended film thickness of <=10Angstrom without damaging the attached face.

Description

[Detailed Description of the Invention] 11i! The present invention relates to a photoresist removal method, and more particularly to a photoresist removal method that can be applied to all fields using photolithography technology, such as the production of optical information recording disks, ICs, and LSIs.

Normally, when removing a photoresist, a method of immersing it in a conventionally used photoresist removal solution or a solvent such as acetone is usually adopted.

However, when the photoresist is removed from a metal film formed by sputtering on the photoresist, such as in the process of manufacturing a stamper for an optical disk.

Approximately 30 to 150 portions of the photoresist film remain unremoved, probably because the metal film is implanted into the surface layer of the photoresist using a sputtering method. If a photoresist film of this thickness remains on the stamper, it will be difficult to separate the remaining photoresist film from the optical disc material when molding an optical disc, resulting in the inconvenience that the part will be missing when the mold is released.

One of the removal methods that does not cause the photoresist residual film described above is the plasma asher method, but with this method, it is difficult to stabilize the plasma, and if the processing time is exceeded, there is a risk of deteriorating the stamper surface. be. In addition, methods that use the above-mentioned immersion method and scrubber treatment in combination, and methods that use the above-mentioned immersion method and ultrasonic treatment in combination are also effective, but the former method has the risk of deforming the stamper in order to press the brush, and the latter method In the method described above, if the ultrasonic output is increased to avoid leaving a photoresist film, the stamper surface is likely to be damaged.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a photoresist removal method that can easily remove adhering photoresist to a harmless extent without adversely affecting the adhering surface. purpose.

In order to achieve the above object, the present invention provides a method for removing unnecessary photoresist in the process of manufacturing a stamper from a prototype, etc. by removing a workpiece to which the photoresist is strongly adhered, using a solvent to remove the photoresist. irradiating the workpiece with ultraviolet rays for an appropriate period of time while the workpiece is immersed in a photoresist removal solution consisting of a liquid that acts as a photoresist removal solution and pulled out of the photoresist removal solution and placed in a chamber filled with oxygen gas; It is characterized by

A detailed description will be given below based on one embodiment of the present invention. FIGS. 1 to 8 are schematic explanatory diagrams showing each main stage of an optical disk manufacturing process according to an embodiment of the present invention.

First, as shown in FIG. 1, a predetermined substrate 1 made of glass or the like formed into a disk shape is prepared, and a photosensitive photoresist is applied onto its highly flat surface using a spinner method in this example. Then, a photoresist film 2 having a uniform layer thickness of approximately 1000 layers is laminated.

Next, as shown in FIG. 2, a signal medium S such as a laser beam whose intensity is modulated according to information is placed on the photoresist film 2.
and record information. Thereafter, the photoresist film 2 on which information has been exposed and recorded is developed to form signal grooves (pits) 3 consisting of preformats and pregrooves corresponding to the information as shown in FIG.
get.

Next, in this example, a thin film 4 made of a metal material is deposited on the surface of the resist master I. Nickel is used as the metal material, and the thin metal film 4 is coated with a thickness of about 500 to 1000 by sputtering. Next, as shown in FIG. 5, an electroformed plate 5 is deposited on the surface of the thin metal film 4 by electroforming using the metal thin film 4 as a cathode.

After this, the electroformed plate 5, the metal thin film 4 and the photoresist film 2
are peeled off from the glass substrate 1 described above as one body, and the sixth
The intermediate workpiece ① shown in the figure is obtained.

Then, by removing the photoresist film 2 from the intermediate workpiece (1), a stamper (2) for forming an optical disk as shown in FIG. 7 is completed. By the way, as in this example, the glass substrate 1
In the case of a photoresist film 2 deposited on top by a spinner method or the like, the film thickness can be reduced to approximately 10 mm by immersing it in a removal solution made of a conventionally used photoresist solvent for an appropriate time.
The photoresist film 2 can be removed until the thickness becomes less than .ANG. However, in the case of this example in which the metal thin film 4 was deposited on the photoresist film by the sputtering method as described above, it could not be removed sufficiently even when immersed in the photoresist removal solution, and about 30 to 100 people removed the photoresist film. 2 will remain. This is considered to be because the metal material of the thin film 4 is implanted into the surface layer of the photoresist film 2 by the sputtering method.

If the above-mentioned photoresist film 2 of about 30 to 100 layers remains on the molding surface 4a of the stamper (2), when molding an optical disc with this stamper (2), it will not be possible to mix it with the optical disc material such as ultraviolet curing resin (2P) etc. Mold releasability deteriorates. Therefore, as shown in FIG. 8, when molding an optical disc (2) formed by laminating an ultraviolet curable resin layer 7 as a surface layer on an acrylic substrate 6 with a stamper (2), the mold releasability is deteriorated. If an attempt is made to forcefully release the mold, a missing portion will be created in the ultraviolet curable resin layer 7 corresponding to the molding surface 4a where the photoresist film 2' of the stamper 2 remains.

The inventor of the present application has experimentally determined that the mold release between the stamper ① and the ultraviolet curable resin layer 7 does not cause any missing parts, etc., and there is no problem. is about 1
．． It was found that it was necessary to remove the photoresist film 2 until the thickness became 0 Å or less. Therefore, using the method shown below, the photoresist film 2 (FIG. 6) on the intermediate workpiece (1) is reliably removed until the remaining film thickness becomes 10 Å or less.

First, the above-mentioned intermediate workpiece (2) is immersed in a normal photoresist removal solution such as diethylene glycol monobutyl ether or acetone, and a rough photoresist film 2 is removed.
is removed to reduce the remaining film thickness to about 200 Å or less. In this case, immersion for about 5 minutes is enough to reduce the remaining film thickness by 2
00 Å or less First, the thus obtained unfinished stamper with a remaining photoresist film of 200 Å or less is placed in a chamber filled with oxygen gas (O2), and exposed to ultraviolet rays using a mercury lamp or the like. Irradiate for about 15 minutes. As a result, the photoresist film is removed to the target thickness of 10 Å or less without causing any damage or deterioration to the molding surface of the stamper (2), which is made of the metal thin film 4. This is thought to be because the oxygen gas in the chamber is converted into ozone by ultraviolet rays, and this ozone removes the photoresist film until the remaining film becomes less than 10 Å thick.

In this case, if an attempt is made to remove an O7 photoresist film of, for example, 1000 people to a thickness of 10 Å or less using only the ultraviolet irradiation process, it will require an irradiation time of about 10 hours or more, which is not practical.

By using the stamper (2) obtained as described above, it is possible to easily mold a desired optical disc on which information is accurately recorded without causing any missing parts or the like.

Note that all the film thicknesses of the photoresist in the above description are values measured using an ellipsometer.

As detailed above, according to the present invention, the surface to which the photoresist is attached is damaged by irradiating it with ultraviolet rays for an appropriate period of time in a chamber filled with oxygen gas after being immersed in a photoresist removal solution. It becomes possible to easily remove the photoresist to a desired extent without any problems. Therefore, by applying the present invention to the manufacturing process of optical discs, it is possible to easily obtain high-performance stampers from which photoresist has been removed to a harmless extent, and to produce high-quality optical discs on which information is accurately recorded at low cost. It can be manufactured. It should be noted that the present invention is not limited to the above specific embodiments,
Of course, various modifications are possible within the technical scope of the present invention. For example, the present invention can be applied to photoresist removal in the manufacturing process of not only optical discs but also ICs, LSIs, and the like.

[Brief explanation of the drawing]

1 to 8 are schematic explanatory diagrams showing each main stage of an optical disk manufacturing process as an embodiment of the present invention. (Explanation of symbols) 1: Substrate 2: Photoresist film 4: Metal thin film ■=, resist master ■: Intermediate workpiece ■: Stamper ■: Optical disk

Claims (1)

[Scope of Claims] 1. In a method for removing unnecessary photoresist in the process of manufacturing a stamper from a master model, a workpiece to which photoresist is attached is removed from a photoresist consisting of a liquid that acts as a solvent for the photoresist. immersed in removal solution,
A method for removing photoresist, which comprises irradiating the workpiece with ultraviolet rays for an appropriate period of time while the workpiece has been pulled out of the photoresist removal solution and is housed in a chamber filled with oxygen gas. 2. The photoresist removal method according to item 1 above, wherein the photoresist removal liquid is diethylene glycol monobutyl ether. 3. The photoresist removal method according to item 1 above, wherein the photoresist removal liquid is acetone.