JPH04259937A - Production of stamper for producing information recording medium - Google Patents

Abstract

PURPOSE:To allow the use of the substrate itself as a stamper by providing the thin film of a positive type photoresist on a silicon wafer which is the substrate and is subjected to mirror polishing and irradiating the parts exposed by recording light with UV rays, then subjecting the thin film to development processing then to dry etching, thereby forming the recessed parts corresponding to information signals. CONSTITUTION:The thin film 2 of the positive type photoresist is deposited on the wafer 1 formed by subjecting the surface to mirror polishing to impart excellent flatness thereto in order to use the resist as a substrate, by which the master disk for information recording media is obtd. This master disk is rotated and the thin film 2 is irradiated with an argon laser beam modulated in intensity by the information signals as microspots via a recording optical system 3. The master disk is heated in a gaseous atmosphere contg. gaseous ammonia or amine and the entire surface of the thin film 2 is irradiated with UV rays when the temp. of the master disk restores ordinary temp. The master disk is thereafter heated again in the same atmosphere to change the exposed parts 2a to a material stable to UV rays and alkalis. The thin film is etched with these parts as a mask, by which the recessed parts 1b and projections 1a are generated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a stamper for producing information recording media.

0002

[Background Art] Recesses (pits) corresponding to the information signal to be recorded and reproduced are formed on the signal surface, and the information signal is read by illuminating the signal surface with a light spot with a minute diameter. Such recorded information recording media have conventionally been put to practical use as compact discs, video discs, digital audio discs, recordable discs, and other optical discs. When mass producing the various types of recorded information recording media described above, a stamper for producing information recording media is used, the surface of which is formed with uneven portions corresponding to the information signals to be recorded and reproduced. This is done by transferring the uneven shape on the surface of the stamper for producing information recording media to the surface of the disk made of synthetic resin. , the surface unevenness of a recorded information recording medium is, of course, an opposite unevenness {the protrusions (or recesses) of one correspond to the recesses (or convexes) of the other The correspondence relationship between the concave and convex shapes is as follows.

By the way, the most common conventional manufacturing method for a stamper for manufacturing an information recording medium is to record information using a thin film of positive photoresist formed on a mirror-polished glass master disk. After being exposed to recording light whose intensity is modulated by a signal, it is developed, and after the development, electroforming is performed on the metal thin film formed by means such as electroless plating, and then peeled off to create a master disc. ,
After performing a peeling treatment on the master disk surface, electroforming is performed, and then it is peeled off from the master disk to obtain a mother disk,
Next, the production of a stamper for producing information recording media consists of various steps such as applying a peeling treatment to the mother disc surface, electroforming is performed, and then peeling it off from the mother disc to obtain a stamper for producing information recording media. It is the law.

0004

[Problem to be Solved by the Invention] The problem is to solve the problem of the inside of various types of disks whose surface unevenness is opposite to each other obtained in each successive process in the conventional manufacturing method of a stamper for manufacturing an information recording medium. A disk having an uneven surface shape opposite to that of a recorded recording medium can also be used as a stamper for producing information recording media, but if the number of transfers increases, the recorded signal waveform may be deformed or foreign particles may There is a risk that defects may occur due to the adhesion of particles, resulting in an information recording medium with deteriorated recording and playback characteristics.In addition, a large amount of electrical energy and pure water are consumed due to the large number of electroforming processes. Another problem was that it required a lot of time to produce. In order to solve the above-mentioned problem that multiple transfer operations are required to produce a stamper for producing an information recording medium, conventionally, a stamper for producing an information recording medium can be produced by a single transfer operation. As a method for manufacturing a stamper for producing an information recording medium, a thin metal film is deposited on a glass substrate, and pits are formed by subjecting the thin metal film to dry etching or wet etching. A manufacturing method has been proposed in which pits are formed by dry etching or wet etching on the substrate itself, but the conventional manufacturing method proposed in (ii) above uses a glass master disk. There is a problem that the thickness of the board is large, which requires a large space for the stock, and the conventionally proposed manufacturing method of (2) has the problem of the surface roughness of the metal plate such as nickel, aluminum, or copper used as the substrate. In addition to the problem of not being able to obtain a satisfactory flatness, in the conventional methods (2) and (3) mentioned above, even if the substrate is etched using, for example, a photoresist as an etching mask. Since the surface shape of the stamper has an uneven shape that is opposite to that of the stamper, at least one transfer process is required to produce a stamper for producing an information recording medium from the substrate. It was.

By the way, if the substrate itself can be configured to be used as a stamper for producing information recording media, it is possible to eliminate the transfer process that was conventionally required to obtain a stamper for producing information recording media. can be done, but
For example, even if an attempt is made to use a negative photoresist to configure the substrate itself so that it can be used as a stamper for producing information recording media, the currently available negative photoresist cannot be used with the recording light used for exposure. A solution to this problem was sought, since it has only low sensitivity at the wavelengths of

[0006]

[Means for Solving the Problems] The present invention provides a process for obtaining a master disc for producing an information recording medium by coating and forming a thin film of positive photoresist on the surface of a mirror-polished silicon wafer used as a substrate; A step of exposing a thin film of a positive photoresist in the master disc for producing an information recording medium with recording light whose intensity is modulated by the targeted information signal; In order to change the exposed portion of the photoresist thin film into a substance that is stable to ultraviolet rays and alkalis, the master disk for producing information recording media is treated in a high temperature gas atmosphere of a specified type, and then the photoresist thin film is exposed to a predetermined wavelength. a step of irradiating the photoresist thin film with ultraviolet rays of a range and then developing the photoresist thin film to obtain a master disc for producing an information recording medium in which the portion of the photoresist thin film exposed to the recording light remains; A process of forming recesses on a silicon wafer by dry etching using the remaining photoresist thin film as a mask member, and forming a photoresist from the silicon wafer with recesses corresponding to the information signals to be recorded. A method of manufacturing a stamper for manufacturing an information recording medium is provided, which comprises a step of removing a thin film of the present invention.

[0007]

[Operation] A thin film of positive photoresist deposited on the mirror-polished surface of a silicon wafer used as a substrate is exposed to recording light whose intensity is modulated by the information signal to be recorded. In order to change the exposed portion of the thin film of the positive photoresist into a substance that is stable to ultraviolet rays and alkalis, the master disk for producing information recording media is treated in a high temperature gas atmosphere of a predetermined type, and then the photoresist is After the thin film is irradiated with ultraviolet rays in a predetermined wavelength range, the thin film of photoresist is developed to obtain a master disk for producing an information recording medium in which the portion of the thin film of photoresist exposed to the recording light remains. Using the remaining photoresist thin film as a mask member, a recess is formed on the silicon wafer by dry etching, and then the remaining photoresist is removed from the silicon wafer in which the recess corresponding to the information signal to be recorded is formed. A stamper for producing an information recording medium is obtained by removing the photoresist thin film.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific details of the method for manufacturing a stamper for manufacturing an information recording medium according to the present invention will be explained in detail with reference to the accompanying drawings. FIG. 1 is a side sectional view used to explain the sequential steps in manufacturing a stamper for manufacturing an information recording medium by the method of manufacturing a stamper for manufacturing an information recording medium of the present invention. (a) shows a silicon wafer 1 used as a substrate. This silicon wafer 1 is a single crystal silicon wafer that is widely used as a material for semiconductor integrated circuits, and has a thickness of, for example, 50 mm.
It is circular with a diameter of 0 to 800 microns and approximately 150 mm, and its surface is mirror-polished and has excellent flatness as a substrate for the master of information recording media. . Reference numeral 2 in FIG. 1B is a thin film of positive photoresist coated on the surface of the silicon wafer 1 described above. The thin film 2 of positive photoresist is formed by precisely cleaning and drying the single crystal silicon wafer 1, and then applying a thick layer of positive photoresist, for example, positive photoresist MP1400 manufactured by Shipley Far East Co., Ltd. Saga 1000 angstroms ~ 1
A thin film having a thickness of 500 angstroms is coated on the silicon wafer 1 by, for example, a spinner method. As the positive photoresist, positive photoresist MP1300 manufactured by Shipley Far East Co., Ltd. or AZ1350 and AZ1350J manufactured by Hoechst Japan Co., Ltd. may be used.

The master disc of the information recording medium, in which a thin film 2 of positive photoresist of a predetermined thickness is coated on a substrate made of a silicon wafer 1, is mounted on a turntable in a recording device and driven to rotate at a predetermined number of rotations. In this state, the positive photoresist thin film 2 is exposed to the recording optical system 3 illustrated in FIG.
Exposure is performed using a minute spot of argon laser light whose intensity is modulated depending on the information signal to be recorded. In FIG. 1(c), 2a exemplifies the unexposed portion of the thin film 2 of positive photoresist;
2b in (c) exemplifies the exposed portion of the thin film 2 of positive photoresist.

[0010] As described above, the master disc of the information recording medium is exposed to a minute spot of laser light whose intensity is modulated by the information signal to be recorded, in a gas atmosphere containing ammonia gas or amine. It is heated at 80 degrees Celsius to 110 degrees Celsius for 30 minutes to 90 minutes. When the temperature of the master of the information recording medium returns to room temperature, a film of 300 nm to
The exposure amount of ultraviolet rays with a wavelength of 435 nm is 200 to 30
After irradiating to 0 mj, it is developed with an alkaline developer. As mentioned above, the exposed positive photoresist film 2 is heated at 80 degrees Celsius to 110 degrees Celsius for 30 degrees in a gas atmosphere containing ammonia gas or amine.
When heated for 90 minutes to 90 minutes, the exposed portions 2b, 2b... of the photoresist change into a substance stable to ultraviolet rays and alkalis, so that the exposed portions 2b, 2b... of the photoresist will be It is made to remain undissolved during development processing. Therefore, as mentioned above, the photoresist film 2 is coated in a gas atmosphere containing ammonia gas or amine at a temperature of 80 degrees Celsius or more.
After heating at 110 degrees Celsius for 30 to 90 minutes, and after the temperature of the information recording medium master returns to room temperature, a 300 nm thick film of photoresist is applied to the entire surface of the photoresist thin film 2 of the information recording medium master.
After irradiation with ultraviolet rays having a wavelength of ~435 nm, development processing is performed. The development process described above is carried out for 30 seconds using a 0.2N alkaline developer, and as a result of the development process, the unexposed portion 2a of the photoresist thin film 2 shown in FIG. 1(c) is dissolved in the developer. Along with (
c) Exposed portion 2b of thin film 2 of photoresist in
2br, 2br... in (d) of Figure 1 without dissolving.
It is left on a silicon wafer 1 used as a substrate as shown in FIG.

2b in FIG. 1(d) remaining on the photoresist thin film 2 on the master of the information recording medium.
Using the unexposed parts indicated by r, 2br... as a mask member,
The substrate of the silicon wafer 1, which is the master of the information recording medium, is etched by a dry etching method. The dry etching performed on the substrate of the silicon wafer 1 which is the master of the information recording medium described above uses, for example, CF4 gas as the etching gas, and the CF4 gas is heated at 5 mT.
5SCCM~30SC at pressure of orr~30mTorr
The process is carried out for a period of 2 to 15 minutes at a flow rate of CM, and then the CF4 gas described above is converted to oxygen to remove the unexposed portion 2 of the photoresist remaining on the silicon wafer.
When br, 2br... are ashed and cleaned in oxygen plasma, recesses 1b, 1b are formed on the surface of the silicon wafer 1 used as a substrate, as shown in FIG. 1(f).
... are formed, thereby making the protrusions 1a, 1a...
A stamper for producing an information recording medium having a configuration in which a portion is formed is obtained.

[0012] A stamper for producing an information recording medium having the structure shown in FIG. A recorded information recording medium can be obtained by molding and transferring it onto a polycarbonate resin disk. Regarding optical discs obtained by molding and transferring onto polycarbonate resin discs using the stamper for producing information recording media produced by the production method of the stamper for producing information recording media of the present invention, it is specified in the Red Book of Compact Discs. When various characteristic values were investigated, it was found that compared to an optical disc obtained by molding and transferring onto a polycarbonate resin disc using a stamper for manufacturing information recording media made by a normal method of manufacturing a stamper for manufacturing information recording media, In addition to an improvement of 0.01dB to 0.06dB in amplitude modulation characteristics,
An improvement of 0 to 0.05 dB was observed in symmetry, and
0.1-0.3% for C1 error, 5% for crosstalk
A certain degree of improvement was obtained.

[0013]

[Effects of the Invention] As is clear from the above detailed explanation, the method for producing a stamper for producing an information recording medium of the present invention includes forming a stamper by adhering it to the mirror-polished surface of a silicon wafer used as a substrate. A thin film of positive photoresist is exposed to recording light whose intensity is modulated according to the information signal to be recorded, and then the exposed portion of the thin film of positive photoresist is exposed to ultraviolet light.
In order to change the material into an alkali-stable material, the master disk for producing information recording media is treated in a high-temperature, specified type of gas atmosphere, and then the positive photoresist thin film is irradiated with ultraviolet rays in a specified wavelength range. The photoresist thin film is developed to obtain a master disc for producing an information recording medium in which the portion of the photoresist thin film exposed to the recording light remains, and the remaining photoresist thin film portion is Using this as a mask member, recesses are formed on the silicon wafer by dry etching, and then the remaining thin film of photoresist is removed from the silicon wafer on which the recesses corresponding to the information signals to be recorded are formed. A stamper for producing an information recording medium is obtained, and in the method for producing a stamper for producing an information recording medium of the present invention, transfer is not performed even once from a substrate when producing a stamper for producing an information recording medium. Since the substrate itself can be used as a stamper for producing an information recording medium without using a stamper, the method for producing a stamper for producing an information recording medium according to the present invention solves the above-mentioned conventional problems, namely, 1.
In the conventional production method of a stamper for producing information recording media, in which a stamper for producing information recording media can be produced by only one transfer operation, a thin metal film is deposited on a glass substrate. Glass master disks are used in manufacturing methods in which pits are formed by dry etching or wet etching on the substrate, or pits are formed by dry etching or wet etching on the substrate itself. There are problems in that the thickness is large and therefore a large space is required for the stock, and the surface roughness and flatness of the metal plates such as nickel, aluminum, and copper used as substrates are not satisfactory. All problems such as not being able to get things can be resolved successfully.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view used to explain the sequential steps in manufacturing a stamper for manufacturing an information recording medium by the method for manufacturing a stamper for manufacturing an information recording medium according to the present invention.

[Explanation of symbols]

Claims (1)

[Claims] 1. A process for obtaining a master disc for producing an information recording medium by coating and forming a thin film of positive photoresist on the surface of a mirror-polished silicon wafer used as a substrate, and an information signal to be recorded. A step of exposing a thin film of positive photoresist in the master disc for producing an information recording medium with recording light whose intensity is modulated by In order to change the material into a substance that is stable to ultraviolet rays and alkalis, the master disc for producing information recording media is treated in a high-temperature, specified type of gas atmosphere, and then the photoresist thin film is irradiated with ultraviolet rays in a specified wavelength range. developing a photoresist thin film to obtain a master for producing an information recording medium in which the portion of the photoresist thin film exposed by the recording light remains; and the remaining photoresist thin film. A step of forming a recess on a silicon wafer by dry etching using the part as a mask member, and a step of removing a thin film of photoresist from the silicon wafer in which a recess corresponding to an information signal to be recorded is formed. A method for producing a stamper for producing an information recording medium.