JP2002251799A - Manufacturing method for stamper for optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stamper having high wear resistance and durability and formed with low defect without damaging a fine groove formed by a resist mask method, when the stamper is formed from a glass master disk wherein a fine pattern is formed by the resist mask method using water soluble resin. SOLUTION: A manufacturing method for the stamper has a stage for performing exposure and etching of a photoresist layer to form an information fine pattern at a lower layer, a stage for forming a chromium film by chromium sputtering using an argon ion after the photoresist layer is removed and forming a nickel conductive film by nickel sputtering using an argon ion or by nonelectrolytic nickel plating, a stage for performing nickel electroforming to laminate a nickel layer having a fine pattern having ruggedness reverse to the information fine pattern and a stage for peeling the nickel layer together with the chromium film from the glass master disk to form the stamper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a stamper for an optical information recording medium, which can improve the quality and durability of the stamper for an optical information recording medium, and which can improve the fine pattern in a semiconductor process. It is also applicable to a forming method.

[0002]

2. Description of the Related Art A guide groove for tracking and concave and convex pits representing address data are previously formed in a spiral or concentric circle on an optical disk master. Such a guide groove or pit pattern is formed by forming a photoresist layer on a glass substrate serving as a master, converging a light beam whose intensity is modulated according to a pattern to be formed by an objective lens of a master exposure apparatus, and forming a photo-resist. It is obtained by exposing the resist layer and then developing it. Generally, in a photoresist, a latent image is formed by a photo-crosslinking reaction and a thermal cross-linking reaction by exposure, so that the groove width of the pattern opening is about 10 to 20% larger than the beam spot diameter. Further, since the light intensity distribution of the focused beam is a Gaussian distribution, the groove of the pattern formed in the photoresist has a trapezoidal shape (the long side of the trapezoidal shape: Wtop, see development in FIG. 1D). The problem with the trapezoidal pattern is that when the track pitch becomes narrower, the openings of the grooves interfere with each other between adjacent tracks, the height of the flat portion (land) between the grooves decreases, and the depth of the grooves is The point is that it cannot be controlled by the thickness of the resist. In addition, there is a problem that the recording characteristics of an optical information recording medium manufactured from a stamper whose lands are not flat are deteriorated (a crosstalk signal from an adjacent track is increased, and jitter characteristics are particularly deteriorated). For this reason, in a large-capacity optical information recording medium stamper having a narrow track pitch, it is necessary that the groove width of the pattern is narrow and the groove cross section is rectangular. In order to narrow the groove formed in the photoresist, the wavelength of the exposure beam may be shortened and the numerical aperture NA of the objective lens may be increased. However, since the depth of focus at the time of exposure is reduced, the groove shape may be fluctuated. . Therefore, a water-soluble resin layer (lower layer) is formed on the glass master,
A photoresist layer is formed thereon, and then exposed and developed. At the same time, the lower layer is etched using the photoresist layer as a mask layer, and then the photoresist layer is removed, so that exposure can be performed without short wavelength and high NA. There is a technique called a so-called resist mask method in which a thin groove cross section smaller than a beam spot can be obtained.

[0003] In a stamper making technique using a general photoresist, it is necessary to form a conductive film on the surface of a glass master before nickel electroforming. For this purpose, there are techniques such as the following examples. (1) Japanese Unexamined Patent Publication No. 5-205321 discloses a method for forming a stamper for forming an optical (magnetic) disk by electroforming in order to prevent a peeling defect of a conductive film which occurs at an early stage of electroforming. Argon gas pressure 8 mtorr on master
(1.1 Pa), nickel was sputtered at an incident power of 1 kW, and the nickel film thickness was 200 to 350 Å,
The internal stress of the tension is 7 × 10 ⁹ dyn / cm ² (7 × 10 ⁹ dyn / cm ²
10 ² N / cm ² ) or more. (2) Japanese Unexamined Patent Application Publication No. 11-7662 discloses that a high-density, large-capacity optical disk stamper is manufactured with high yield. After a chemical amplification type photoresist is spin-coated on the glass master and subjected to pattern exposure with far ultraviolet laser light, the glass master is baked and then a pattern is formed with an alkali developing solution. Further, a 30-100 nm nickel thin film is laminated on the resist surface by a sputtering method under a film forming condition of a sputtering pressure of 0.5-2.0 Pa, and then nickel electrolytic plating is performed to produce a stamper. (3) Japanese Patent Publication No. 6-78590 discloses a method in which first (silver) and second (nickel) metal conductive layers which are easily peelable are formed on a master by sputtering or vacuum evaporation. The stamper was manufactured by nickel electroforming. The first layer thickness is 50 to 200.
The thickness of the second layer is 300 to 1000 angstroms, and chromium is also acceptable for the first layer.

[0004]

Problems in the prior art In the case of the resist mask method,
Because a fine pattern is formed using a water-soluble resin,
When the conductive film is water-permeable, there is a major problem that the water-soluble resin layer (lower layer) is eroded by moisture in the electroforming solution during nickel electroforming, and the conductive film peels off. JP-A-5
The conductive film formed by the sputtering method disclosed in JP-A-20553212 and JP-A-11-7662 does not have sufficient barrier properties against water, and there is a great risk that the conductive film peels off during electroforming. However, the above publication does not disclose a specific method for electroforming for preventing the conductive film from peeling. The use of the two-layer coating described in Japanese Patent Publication No. 6-78590 has the disadvantage that the abrasion resistance of the stamper surface is poor because the first layer is silver. This publication describes that chromium can be used instead of silver. However, chromium has a problem that cracks are easily generated depending on sputtering conditions, but there is no specific description of sputtering conditions in this publication. The publication also discloses the above-mentioned JP-A-5-2053212 and JP-A-11-766.
As in JP-A No. 2, there is no specific description about the electroforming method.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to form a stamper from a glass master on which a fine pattern is formed by a resist mask method using a water-soluble resin. That is, a stamper can be formed without any defect and at a low cost. The subject of the invention according to each claim is as follows. (1) Problem 1 Problem 1 is to provide a stamper that has a low defect and does not damage fine grooves formed by a resist mask method using a water-soluble resin, and has high abrasion resistance and durability. (Corresponding to claim 1). (2) Problem 2 Problem 2 is to prevent cracks from occurring in the first layer film,
An object of the present invention is to provide a stamper having a low defect (corresponding to claims 2, 3 and 4). (3) Problem 3 Problem 3 is to prevent the conductive film from peeling at the beginning of nickel electroforming (corresponding to claims 5 and 6). (4) Problem 4 Problem 4 is to provide a stamper having high durability (corresponding to claim 7).

[0006]

[Measures taken to solve the problem]

Solution 1 (corresponding to claim 1) Solution 1 is for the above-mentioned problem 1, and is as follows. A water-soluble resin, which does not react by exposure selected from polyvinyl alcohol, methylcellulose, or polyvinylpyrrolidone, is coated on a glass master to form a water-soluble resin layer having a film thickness equal to a groove depth formed on a stamper surface (hereinafter, referred to as a water-soluble resin layer). ,
Forming a lower layer), a step of heat-treating the lower layer, a step of applying a photoresist on the lower layer, a step of heat-treating the photoresist layer, and forming a predetermined information pattern by a light beam. Exposing the photoresist layer to light, developing the exposed photoresist layer with an alkaline developer, washing with pure water after the development, and simultaneously etching the lower layer to form an information fine pattern in the lower layer; After the formation of the fine pattern, a step of removing the photoresist layer, a step of forming a chromium film on the lower layer surface by chromium sputtering with argon ions, and a step of nickel sputtering or electroless plating with argon ions on the first chromium film. Forming a second layer of nickel conductive film by nickel plating; A step of applying nickel electroforming on the film and laminating a nickel layer having a fine pattern in which the information fine pattern of the lower layer and the concavo-convex are reversed, and after laminating the nickel layer, peeling off the first chromium film together with the first layer of chromium film from the glass master. A stamper, a step of cleaning and removing adhesion residues on the fine pattern surface side of the stamper, and a step of manufacturing a master stamper board by polishing the back surface and processing the inner and outer diameters of the stamper.

[0007]

A lower water-soluble resin layer is provided between the master and the photoresist layer. The groove pattern formed in the photoresist layer is used as a mask layer, and the lower groove pattern formed by etching is used as a stamper. I do. As a result, the bottom width of the groove of the mask layer becomes the groove width of the lower layer, so that a groove smaller than the groove cross section formed in the photoresist layer, that is, a fine groove smaller than the exposure beam spot diameter can be formed in the lower layer. In addition, a groove pattern having a rectangular cross section can be formed instead of a trapezoid. Further, since the chromium film having high hardness is formed on the outermost surface of the stamper, the durability of the stamper is significantly improved.

[0008]

A second aspect of the present invention is to solve the above-mentioned problem 2. In the chromium sputtering using argon ions in the first aspect, the sputtering power is less than 1 kW. The argon current is 1.5 Pa or more, and the thickness of the chromium film formed by chromium sputtering with argon ions is 50 nm or more.
This is within the range of 150 nm.

[0009]

In the chromium sputtering using argon ions in the solution 1, the sputtering power is less than 1 kW and the argon current is 1.5 Pa or more. The film forming conditions are defined so that the internal stress does not increase and cracks do not occur while the state is maintained. In addition, since the thickness of the chromium film formed by chromium sputtering using argon ions is in the range of 50 nm to 150 nm, the film is too thick while maintaining the water permeation resistance (water resistance). Does not increase and cracks do not occur, and therefore, occurrence of defects in the stamper is suppressed as much as possible.

[0010]

[Solution 5] (Solution 5) The solution 5 is for the above-mentioned problem 3, and in the nickel electroforming process of the solution 1, a time period from 15 seconds to 30 seconds after entering the electroforming tank. Maintains a non-energized state for 2 seconds, and thereafter, a current density of 0.1 A / d
This means that a weak current is applied within a range of m ^{2 to} 0.4 A / dm ² for 1 minute to 3 minutes.

[0011]

Function: After entering the electroforming tank, passing a non-energized state and then performing a weak current density state for several minutes, it is possible to sufficiently impart the wettability of the surface of the nickel conductive film to the nickel electroforming liquid. As a result, it is possible to prevent the nickel film from peeling due to insufficient adhesion during electroforming.

[0012]

[Solution 6] (Solution 6) The solution 6 is for the above-mentioned problem 3, and after the solution 5 is weakly energized,
Per minute rising slope of the supply current value when increasing the current ^value, is that in the range of ^{0.4A / dm 2 ~0.8A / dm 2} .

[0013]

The shock applied to the nickel sputtered film is suppressed to an allowable limit when the current supply current rises steeply, and the shock causes local fine peeling of the nickel sputtered film. Can be reliably avoided.

[0014]

[Solution 7] (Solution 7) A solution 7 is for the above-mentioned problem 4. After the current value of the solution 6 increases, the current density is set to 2 A / dm ^{2 to} 4 A / dm ² . 3
After laminating nickel to a thickness of 6 μm to 6 μm, the energizing current value is again increased to a predetermined current density, and then kept constant, and nickel is laminated to a desired thickness.

[0015]

After the current value of the above-mentioned means 6 rises, the current density is raised to 2
As ^{A / dm 2 ~4A / dm 2} , after a laminate of nickel to a thickness of 3Myuemu～6myuemu, kept constant from raising the electric current value to a predetermined current density again, the nickel to the desired thickness Two-stage electroforming is performed by laminating,
In addition to completely preventing peeling of the conductive film during electroforming, the first
Since the nickel layers stacked in the step have a low current density and a dense structure, the hardness is high, and the durability of the stamper is improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A stamper is manufactured from a master according to the present invention by the procedure shown in FIG. Each of the steps is as follows. (1) Master disk cleaning In order to improve the applicability of a water-soluble resin to a polished glass disk (disk shape), organic substances on the surface of the glass disk are treated by an ultraviolet ozone treatment device called UV / O3 for about 2 minutes. While removing, an oxide film is formed on the surface (not shown in FIG. 1). By this effect, the wettability (hydrophilicity) of the water-soluble resin on the glass master is improved,
The thickness of the water-soluble resin can be made uniform, and the adhesion between the water-soluble resin and the glass master is enhanced. However, a method other than the ozone treatment can be used as long as the method improves the wettability to water. For example, if the surface is washed with a solvent such as isopropyl alcohol (removal of organic substances) and then sufficiently washed with pure water, the glass surface can be replaced with a hydrophilic one. However, ultraviolet ozone treatment is the most excellent method in terms of environmental impact, cost, and workability, such as excellent removal of organic substances and no use of chemicals. Then, the impurities floating on the surface of the glass master disk are completely washed and removed by a high-pressure pure water shower or a pure water shower to which ultrasonic waves are applied, and then dried by high-speed spin-off and N2 blow (not shown in FIG. 1). If the thickness of the glass master is too small, the glass master will warp due to the internal stress of the nickel laminated at the time of subsequent nickel electroforming, and if it is too thick, it will become heavy and hinder workability. , 5 mm to 10 mm.

(2) Coating of lower layer A water-soluble resin is spin-coated on the surface-treated glass master disk of the above (1), and is dried by heating and cooling.
A water-soluble resin layer (lower layer) is formed. Since the water resistance of the water-soluble resin is increased to some extent by this heat treatment, it is possible to prevent the lower layer from being peeled off by side etching in the later-described development / rinsing step. At this time, the thickness of the applied lower layer needs to be set to the same value as the groove depth of the pattern formed on the surface of the stamper (see the lower layer formation in FIG. 1A). As the water-soluble resin, any one of polyvinyl alcohol, methylcellulose, and polyvinylpyrrolidone is used. In particular, polyvinyl alcohol (hereinafter abbreviated as PVA)
It is also possible to control the rate of dissolution in water in the later-described development / rinsing step, utilizing the property that the higher the saponification degree, the higher the water resistance. Further, these water-soluble resins can control the dissolution rate in water by adjusting the heat treatment conditions (temperature and time), so that the quality of the groove shape formed in the lower layer can be stabilized. Usually, heat treatment may be performed in an oven at 160 ° C. to 240 ° C. for 30 minutes.

(3) Application of Photoresist Layer A photoresist is spin-coated on the surface of the glass master formed as a lower layer in the above (2), and is heated, dried and cooled to form a photoresist layer (FIG. 1 (b)). ))). The heating conditions are 90 ° C. to 130 ° C. for 30 minutes in an oven. As the photoresist material, for example, a high resolution type such as a positive type i-line type photoresist made by Tokyo Ohka is suitable. If the thickness of the photoresist layer is too large, a large exposure power is required. On the other hand, if the thickness is too small, the photoresist layer does not serve as a mask.

(4) Exposure The glass master produced in the above (3) is exposed by a Kr gas laser. By exposing the glass master while rotating and feeding the glass master, a spiral latent image is formed on the photoresist layer (see the exposure in FIG. 1C). As shown in FIG. 1D, the bottom width (Wbot) of the groove formed in the photoresist layer can be controlled by adjusting the exposure light amount. In addition,
FIG. 2 is a schematic diagram of the optical system of the exposure apparatus.

(5) Development and washing The exposed glass master is developed with an alkaline developer.
Wash with pure water and spin off at high speed to dry. First, the exposed portion (the portion where the latent image is formed) of the photoresist layer is removed by a development process, and a mask layer is formed (see the development in FIG. 1D). Further, as the development and pure water washing progress, etching of the lower layer is started, and Wbo is added to the lower layer.
A rectangular groove having the same groove width as t is formed (FIG. 1E).
See pure water cleaning.) Finally, shake off and dry at high speed. Since the dissolution rate of the water-soluble resin decreases as the temperature of the pure water decreases, it is possible to control the dissolution rate in water by adjusting the temperature of the pure water used for cleaning by using this characteristic. . As described above, when the dissolution rate in water is high, a problem arises in that the lower layer is separated from the glass master by side etching of the lower layer. Therefore, if the temperature of the pure water is set at about room temperature (maintained at a constant temperature of 15 ° C. to 25 ° C.), the rate of change of the groove shape relative to the cleaning time can be reduced. As a result, the variation in the shape of the groove formed in the lower layer (difference within the same sample or difference between samples) can be reduced, and the quality of the groove shape can be stabilized.

(6) Removal of Photoresist Layer The photoresist layer is removed using an organic solvent. As the removal method, (a) the glass master is immersed in an organic solvent, and ultrasonic waves are applied for 1 to 5 minutes (refer to the removal of the photoresist layer in FIG. 1 (f)).
A method in which a new organic solvent is sprinkled from the top of the glass master and rotated at a low speed to wash away the dirty organic solvent mixed with the photoresist, and finally dried by high-speed spin-off (Fig. 1)
(See (g) high-speed shake-off drying), (b) a method of drying by high-speed shake-off after a shower of an organic solvent to which ultrasonic waves are applied for 1 to 5 minutes (not shown in FIG. 1). is there. The output of the applied ultrasonic wave is in the range of 100 W to 500 W. The organic solvent is ethyl lactate or N
By using -methyl-2-pyrrolidone, only the photoresist layer can be completely removed without attacking the lower water-soluble resin. Further, since these organic solvents have low harmfulness, the influence on the environment can be minimized.

(7) Chromium film formation A chromium film is formed on the surface of the glass master disk of the above (6) by chromium sputtering using argon ions (FIG. 1).
(See chromium film formation in (h)). As a result, the chromium film is formed on the outermost surface of the stamper, so that the abrasion resistance of the stamper is increased, and the life can be extended as compared with the stamper on the nickel outermost surface. However, when chromium is sputtered, attention must be paid to the generation of cracks. As a film forming condition for this purpose, the sputtering power at the time of sputtering is 1
It is set so that it is less than kW and the flow rate of argon gas is 1.5 Pa or more. This can prevent the chromium film from cracking. In order to form a chromium film, a means of electroless chromium plating is not inconceivable, but this method cannot be used because the water-soluble resin is attacked in the plating pretreatment step. If the chromium film is too thin, the abrasion resistance is not sufficient, and if it is too thick, cracks occur due to internal stress. Therefore, the thickness of the chromium film is in the range of 50 nm to 150 nm.

The dummy disk coated with the resist on the glass master disk was sputtered under different film-forming conditions (sputtering power, argon flow rate, substrate moving speed), and observed under a microscope of 1000 times to confirm the presence or absence of cracks. The results of the experiment are shown in the following table.

(8) Formation of Nickel Conductive Film In order to prevent the chromium film from being attacked by the nickel electroforming solution during electroforming and to secure conductivity during electroforming, a nickel conductive film is successively formed on the chromium film. (Fig. 1
(Refer to (i) Formation of nickel conductive film). As a method of forming a film, the use of nickel sputtering using argon ions is efficient because a nickel conductive film can be continuously formed after chromium sputtering. Of course, a nickel conductive film may be formed by electroless nickel plating. The film thickness is 50 nm to 150 nm to protect the chromium film at the time of nickel electroforming and to prevent the occurrence of warpage due to internal stress.
nm.

(9) Nickel Electroforming The glass master having the nickel conductive film of the above (8) is subjected to a nickel electroforming process, and nickel is laminated to form a stamper (see nickel electroforming in FIG. 1 (j)). The setting of the electroforming value in nickel electroforming is described below and shown in FIG. After maintaining the non-energized state (state 1 in FIG. 3) for 15 to 30 seconds after entering the glass master, 0.1 A / dm ² to
By applying a current at a weak current density of 0.4 A / dm ² for 1 minute to 3 minutes (state 2 in FIG. 3), the conductive film gradually adapts to the nickel electroforming solution to prevent peeling during electroforming. . Thereafter, the rising gradient of the energizing current value is set to 0.4 A / d per minute.
As m ^{2 to} 0.8 A / dm ² (state 3 in FIG. 3), the conductive film was increased while preventing the conductive film from peeling off due to a shock at the time of power increase, and the current density was increased to 2 A / dm ^{2 to} 4 A / dm ² . By the way, the ascent is stopped once, and nickel is laminated at 3 μm to 6 μm at the low current density (state 4 in FIG. 3). As a result, a nickel layer having a certain thickness is formed, so that peeling during electroforming can be completely prevented even if the amount of current is increased suddenly. After stacking nickel to the above thickness, the amount of current is increased again (state 5 in FIG. 3), the current density is increased until the current density becomes about 12 A / dm ^{2 to} 20 A / dm ² , and the current density is kept constant. Electroformed film thickness (300μ
m) (state 6 in FIG. 3). By performing the two-stage electroforming in this way, peeling of the conductive film at the time of electroforming can be completely prevented, and the nickel layer laminated in the first stage has a low current density and a dense structure, so that the hardness is low. It is high and helps to improve the durability of the stamper. The actual hardness is 350 or more in Vickers hardness, and can be about 50 to 100 higher than the hardness of a stamper made by nickel electroforming without using the above-mentioned method.

In the conventional program 11 (see a two-dot chain line in FIG. 3), after a nickel sputtered film is adapted to an electroformed film at a low current value of 1.5 A, abruptly with almost no nickel plating laminated. However, according to the program 1 of the present invention (see the solid line in FIG. 3), after the initial adaptation, the current value is set to a gentle slope such that the nickel sputtered film is not peeled off by the shock at the time of power increase. After nickel is laminated at about 6 μm at a low current density, the current value is increased to a normal value (to shorten the time required to reach a predetermined current value), and the current value is reduced to a predetermined current density. And continue electroforming until the desired plating thickness is achieved. As a result, the nickel protective film is temporarily laminated on the nickel sputtered film at a low current density, and the phenomenon that the nickel sputtered film locally causes fine peeling due to the shock caused by electroforming at the high current density is reliably avoided. The thickness of the nickel film formed by the first-stage nickel electroforming does not necessarily need to be about 6 μm or more, and it is sufficient that the above-mentioned protection function can be sufficiently ensured. It is also desirable from the viewpoint of work efficiency that the current rising gradient up to the current density at the time of the first stage electroforming be as steep as possible as long as the above protective function is not impaired.

According to the conventional electroforming program (program 11) shown in FIG. 3 and the electroforming program (program 1) according to the present invention in which the current gradient is gentle, a stamper is manufactured by performing nickel electroforming and each defect is formed. It was confirmed. The contents of the electroforming program (program 1) according to the present invention in this experiment are as follows. (A) Entering the tank and maintaining a non-energized state for 15 seconds. (B) Energized at 1.5 A (0.3 A / dm ² ) for about 2 minutes. (C) The current value is increased by 0.5 A in one step (15-second unit) to 10 A (2 A / dm ² ) in about 4 minutes. (D) Energize at 10 A (2 A / dm ² ) for about 9 minutes (about 6 μm of nickel is stacked during this time). (E) The current value is increased in steps of 1.6 A to 1.7 A, and is increased to 60 A (12.2 A / dm ² ) in about 8 minutes. (F) Energizing current value 60 A (current density: 12.2 A / dm
² ) In step ² ), energization is continued until the plating thickness becomes 300 to 305 μm. Three stampers were manufactured according to the conventional electroforming program 11 and the electroforming program 1 according to the present invention, respectively, and the results of confirming the presence or absence of defects were as follows. Program 11 (conventional method): 2 out of 3 defects
Sheet. Program 1 (method of the present invention): 0 out of 3 defects
Sheet. However, partial peeling of the nickel stamper was evaluated as a defect.

(10) Peeling off the stamper The stamper is peeled off from the glass master after nickel electroforming (see stamper peeling in FIG. 1 (k)). At this time, it is necessary to take care that the stamper is not bent by applying a stress to the stamper.

(11) Washing of stamper The residue of the water-soluble resin adhering to the information pattern side of the stamper peeled off from the glass master is removed. The residue cannot be completely removed just by washing with water,
The ultraviolet / ozone treatment using UV / O3 described in the above (1) is performed (see the ultraviolet / ozone treatment in FIG. 1 (l)). At this time, in order to efficiently generate ozone, the inflow pressure of oxygen introduced into the processing chamber is set to 0.1 MPa or more, the irradiation intensity of ultraviolet rays is set to 3 mW / cm ² or more, and the integrated light amount is set to 1 J / cm ² or more. As a result, the bonds of the molecules of the water-soluble resin residue can be efficiently cut off and decomposed and released. After the completion of the ultraviolet ozone treatment, the residue is completely washed out within 5 minutes with pure water (see running water washing in FIG. 1 (m)). After some time after UV ozone treatment,
This is because the residue that has been decomposed and released is recombined and attached again. Since the water-soluble resin has high solubility in hot water, it seems at first glance that the use of warm water during washing seems to be efficient, but in practice the dissolved water-soluble resin becomes glue-like and firmly adheres to the stamper. Will not be removed. Therefore, the water temperature at the time of washing with running water is set to be in a range of 15 ° C to 25 ° C. After washing with running water is completed, shake off and dry at high speed.

(12) Use of master stamper A protective film is formed with a plastic coat on the information pattern side of the stamper of (11), and the back surface is polished. Here, the back surface may be polished before the stamper peeling step (10). In this case, there is no need to provide a protective film. Thereafter, the master stamper is completed by pressing the inner and outer diameters to desired dimensions (see the completion of the master stamper in FIG. 1 (n)). In the above manufacturing process of the present invention, the lower water-soluble resin layer is provided between the master and the photoresist layer, and the lower layer formed by etching using the groove pattern formed in the photoresist layer as a mask layer. The groove pattern is used as a stamper. As a result, the bottom width of the groove of the mask layer becomes the groove width of the lower layer, so that a groove smaller than the groove cross section formed in the photoresist layer, that is, a fine groove smaller than the exposure beam spot diameter can be formed in the lower layer. ,
Further, it is possible to obtain a groove pattern having a rectangular cross section instead of a trapezoid. In addition, since a Kr gas laser having a wavelength of about 400 nm can be used as an exposure light source, the optical system can be used not in an expensive ultraviolet region but in a normal visible region, which is extremely advantageous in terms of cost.

[0031]

The effects of the present invention can be summarized as follows according to each claim. 1. Effect of the Invention According to Claim 1 As a method for manufacturing a stamper for an optical information recording medium, claim 1
By adopting the process defined in (1), a stamper can be formed at a low defect and at a low cost without breaking a fine groove pattern below the diffraction limit.

2. Effects of the Invention According to Claims 2, 3, 4, and 8 Regarding the formation of a chromium film by chromium sputtering using argon ions, the sputtering power is set to less than 1 kW, the argon gas flow rate is set to less than 1.5 Pa, Since the thickness of the chromium film formed by chromium sputtering with argon ions is set in the range of 50 nm to 150 nm, a chromium film having excellent wear resistance can be formed without generating cracks. Despite having water permeation resistance (water resistance), the film is not too thick and the internal stress is not increased to cause cracks, so that a stamper with a low defect can be efficiently manufactured.

3. Advantageous Effect of the Invention According to Claim 5 At the time of nickel electroforming, 15 seconds to 3 seconds after the glass master on which the chromium film and the nickel conductive film are formed is placed in the electroforming tank.
Maintain the non-energized state for 0 second, and then set the current density to 0.1 A
Since the current is weakly applied for 1 minute to 3 minutes in the range of / dm ^{2 to} 0.4 A / dm ² , the film is sufficiently adapted to the nickel electroforming solution and the conductive film can be reliably prevented from peeling. it can.

4. Effect of the invention according to claim 6 When increasing the current value after weak current application in claim 5, the increasing gradient of the current application value is 0.4 A / dm ² per minute.
Since it is within the range of 0.8 A / dm ² , it is possible to reliably prevent the occurrence of peeling during electroforming due to a shock during power rise.

5. The invention according to claim 7 After the current value rises in claim 6, the current density is increased to 2 A / dm.
^Since nickel is laminated to a thickness of 3 μm to 6 μm as ^{2 to} 4 A / dm ² , it is possible to reliably prevent peeling when the current value increases again, and to achieve higher hardness and high durability. An excellent stamper can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a manufacturing process of a stamper manufacturing method according to the present invention.

FIG. 2 is an outline view of a general master exposure optical system.

FIG. 3 is a current setting diagram in nickel electroforming.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // B29L 17:00 B29L 17:00

Claims (8)

[Claims] A water-soluble resin selected from polyvinyl alcohol, methylcellulose, and polyvinylpyrrolidone, which does not react upon exposure, is applied on a glass master to form a water-soluble resin having a thickness equal to a groove depth formed on the surface of the stamper. Forming a conductive resin layer (hereinafter referred to as “lower layer”), heat treating the lower layer, applying a photoresist on the lower layer, heat treating the photoresist layer, A step of exposing a predetermined information pattern to a photoresist layer, and developing the exposed photoresist layer with an alkaline developer, washing with pure water after development, and simultaneously etching the lower layer to form an information fine pattern in the lower layer. Removing the photoresist layer after the formation of the information fine pattern, and performing an algorithm on the lower layer surface. A step of forming a chromium film by chromium sputtering with ions, a step of forming a second nickel conductive film on the first chromium film by nickel sputtering or electroless nickel plating with argon ions, A step of subjecting the second nickel conductive film to nickel electroforming and laminating a nickel layer having a fine pattern in which concavities and convexities are inverted from the underlying information fine pattern, and after the nickel layer is laminated, a first chromium film A step of peeling the entire stamper from the glass master to form a stamper, a step of cleaning and removing the adhesion residue on the fine pattern surface side of the stamper, and a step of manufacturing a master stamper board by polishing the back surface of the stamper and processing the inner and outer diameters. A method for manufacturing a stamper for an optical information recording medium, comprising: 2. In the chromium sputtering using argon ions, the sputtering power is less than 1 kW, and the thickness of the chromium film formed by chromium sputtering using argon ions is in the range of 50 nm to 150 nm. The method for manufacturing a stamper for an optical information recording medium according to claim 1. 3. The method for manufacturing a stamper for an optical information recording medium according to claim 1, wherein in the chromium sputtering using argon ions, an argon flow rate is 1.5 Pa or more. 4. The chromium film formed by chromium sputtering using argon ions has a thickness of 50 nm to 1 nm.
2. The method for manufacturing a stamper for an optical information recording medium according to claim 1, wherein the thickness is within a range of 50 nm. 5. In the above nickel electroforming step, a non-energized state is maintained for 15 seconds to 30 seconds after entering the electroforming tank,
Then, a current density of 0.1 A / dm ^{2 to} 0.4 A / dm ²
2. The method for manufacturing a stamper for an optical information recording medium according to claim 1, wherein a weak current is applied for 1 minute to 3 minutes within the range described above. 6. The method of claim 5, after the weak current, the increase gradient of the electric current value when increasing the current value, in the range of 0.4A ^/ dm ² ~0.8A ^/ dm 2 per minute A method for manufacturing a stamper for an optical information recording medium, comprising: 7. The method according to claim 6, wherein after the current value increases, the current density is set to 2 A / dm ^{2 to} 4 A / dm ² , and
A stamper for an optical information recording medium, comprising: stacking nickel to a thickness of 6 μm, raising the current value again to a predetermined current density, keeping the current constant, and stacking nickel to a desired thickness. Production method. 8. The method of manufacturing a stamper for an optical information recording medium according to claim 1, wherein said chromium sputtering using argon ions has a sputtering power of less than 1 kW and an argon flow rate of 1.5 Pa or more.