JPH0326527A - Manufacture of roll die for optical recording medium - Google Patents

Abstract

PURPOSE:To enable a roll die for an optical recording medium to be manufactured by a simple mechanism and with high accuracy, by a method wherein working of a stamper and fixing of the stamper to a forming roll are carried out through a jig having a recessed surface with a diameter matched to the forming roll. CONSTITUTION:A protective layer 2 is formed in a predetermined thickness on a surface of a stamper 1 provided with a rugged pattern 3 such as a pre- format pattern on the surface thereof. The stamper 1 is attached through the protective layer 2 to a jig 4 having a cylindrically recessed surface with a diameter matched to a forming roll, and the back surface of the stamper 1 is worked so as to provide the stamper 1 with a fixed thickness over the entire surface thereof. Then, the stamper 1 on the jig 4 is fixed onto the surface of the forming roll 7 or a die set 8 thereof, leaving no gap therebetween, and the stamper 1 and the protective layer 2 are exfoliated from each other at the interface therebetween to obtain a roll die for an optical recording medium. It is thus possible to fix the stamper 1 provided with the rugged pattern 3 to the surface of the forming roll with high accuracy and by a simple mechanism.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a roll mold for an optical recording medium, and more specifically, a method for manufacturing a roll-shaped mold or a stamper for forming a concavo-convex pattern on a transparent substrate of an optical recording medium. Regarding the method. [Prior Art] Conventionally, magnetic materials such as magnetic tapes and magnetic disks, various semiconductor memories, etc. have been mainly used for recording various information. Does this kind of magnetic memory semiconductor memory have the advantage of being able to easily write and read information? On the other hand, do they have problems such as the information content being easily tampered with and not being able to record at high density? there were. In order to solve these problems, an optical information recording method using an optical recording medium has been proposed as a means to efficiently handle a wide variety of information, and an optical information recording carrier,
Recording/reproducing methods, recording/reproducing devices, etc. have been proposed.

Such an optical recording medium as an information recording carrier is generally prepared by using a laser beam to evaporate a part of the optical recording layer on the information recording carrier, to cause a change in reflectance, or to cause deformation. Information is recorded or reproduced based on differences in optical reflectance and transmittance. In this case, the optical recording layer does not require any development treatment after information is written, and can be read directly after writing, so-called DR.
AW (Direct read after write: di
It is an effective medium for recording and storing information because it is capable of high-density recording and additional writing is possible.

FIG. 7 is a schematic cross-sectional view of a conventional optical recording medium. In FIG. 7, 41 is a transparent substrate, 42 is a track groove, 43 is an optical recording layer, 44 is a substrate/pickup waste, and 45 is a protective substrate. In FIG. 7, information is recorded and read out optically through a transparent substrate 41 and track grooves 42. At this time, the structure is such that tracking can be performed by utilizing the fine irregularities of the track groove portion 42 and the phase difference of the laser beam. [Problems to be Solved by the Invention] As mentioned above, conventional video discs and audio discs are generally produced using a stamper on which uneven shapes have been formed in advance, using a press method, an injection molding method, or an ultraviolet curing degreasing method. The uneven shape of the stamper is transferred onto the transparent resin substrate using the 2P method using The above-mentioned method is generally a single-wafer process, but in contrast, for example,
As disclosed in Japanese Patent Application Laid-open No. 87203, Japanese Unexamined Patent Publication No. 86721/1987, etc., FIG. 8(a). As shown in (b), a method of continuously forming a concavo-convex pattern on a transparent resin sheet 51 using a roll-shaped stamper or a molding roll 52 provided with a mold is also widely used.

In the above prior art, as shown in FIG.
The stamper 12 is fixed to the stamper 12 with screws, or by pasting it with adhesive or double-sided tape. In this method, in order to obtain the roundness of the roll, the roll surface, which has been processed with high precision, is bent to the same radius of curvature as the roll so that it has a uniform thickness and adheres well to the roll. A problem has arisen in that the stamper must be fixed using an adhesive or double-sided tape under severe conditions such as when the thickness of the adhesive or double-sided tape is extremely small and where air is not trapped. . In addition, in the conventional method, the stamper is polished on a flat surface to make the thickness uniform, and then fixed to the roll surface while being bent. Another problem is that it requires a high level of skill to bend the stamper while pasting it together.

Furthermore, as shown in FIG. 4, when the stamper and the pressure roll are fixed with screws without adhesive, it is difficult to completely expel the air between the stamper and the roll to achieve close contact. When air enters between the stamper and the roll, the surface of the stamper becomes uneven, and the unevenness is transferred to the resin sheet, resulting in a problem of deteriorating the quality of the optical recording medium substrate. In order to solve this problem, the thickness of the stamper has been reduced to improve the adhesion between the stamper and the roll.If the stamper is thin, its strength is reduced, so the stamper may be torn during molding. In addition, problems arise in that the stamper becomes easily damaged, and that the stamper stretches when fixed to the surface of the roll, resulting in poor precision of the molded product. On the other hand, if the stamper is made thicker, its rigidity increases, and when it is fixed to a roll, it becomes difficult to bend it to the same radius of curvature as the roll.

In addition, stampers are generally manufactured by electroforming nickel after forming a pattern in a trilithography process, developing it and making it conductive, or nickel stampers made by this electroforming process have electrodes. It depends on how it is taken, but generally the thickness is uneven.For this reason, a protective layer is formed on the surface of the uneven pattern, and then the back surface is polished on a flat surface to make the thickness uniform, or it is polished. Since the material is then bent to the same radius of curvature as the roll and fixed to the surface of the roll, the bending process requires a large number of steps and is easily damaged.

Another known method is to form a pattern directly on a roll. For example, "Introduction to Printing Machines" (published by the Printing Society of Japan Publishing Department in 1986) and "New Photosensitive Resins" (published by the Printing Society of Japan Publishing Department in 1986) contain information such as those shown in Figures 5 and 6. General plate-making techniques are described. In FIG. 5, the pattern of the mask is transferred onto the plate-making roll by irradiating electron beams or electromagnetic waves from the pattern exposure beam 23 while rolling the plate-making roll 2l over the mask 22 on which a pattern has been formed in advance. Also, in the method shown in Figure 6,! ! A pattern is directly drawn by scanning a pattern exposure beam 32 in one direction while rotating a plate-making roll 31 coated with photoresin or the like around an axis. However, since the patterns on optical recording media are minute on the order of submicrons, it is currently impossible to transfer the line width of submicron patterns using the method shown in Figure 5 due to the optical resolution. . In addition, in the method shown in Figure 6, the spiral pattern must be precisely positioned and drawn with submicron precision while moving the roll and beam, making it difficult to control both mechanically. ．． Further, since precision is required for the roll bearings and the flatness of the roll surface, it is also difficult to process the rolls. As described above, it is difficult to manufacture roll molds for optical recording media by applying general plate-making techniques.

The present invention has been made in order to solve the above-mentioned problems, and provides a method for manufacturing roll molds for manufacturing optical recording media with high precision using a simple mechanism.

[Means for Solving the Problems] That is, the present invention provides an optical recording medium for recording and reproducing information by changing optical properties such as reflectance and refractive index by irradiation with a light beam such as a laser beam. In a roll-type manufacturing method used for manufacturing a substrate, a step of forming a protective layer on the uneven pattern of a stamper having an uneven shape such as a briformat pattern on the surface, and transferring the stamper to a forming roll through the protective layer. A process of fixing the stamper to a jig with a concave surface of the same diameter, a process of processing the back side of the stamper fixed to the jig to make the entire surface of the stamper a constant thickness, and a forming roll on the back side of the processed stamper. This is a method for manufacturing a roll mold for an optical recording medium, comprising the steps of fixing the stamper and peeling off the stamper fixed to the molding roll from the jig.

The present invention will be explained in detail below.

The present invention is a roll-type manufacturing method used in a method for manufacturing an optical recording medium substrate on which a pattern such as a preformat is continuously formed using a roll-shaped stamper or original plate, and the method includes a roll-shaped manufacturing method that uses a roll-shaped stamper or an original plate to continuously form a pattern such as a preformat. A process of forming a protective layer on the uneven pattern of a stamper on which an uneven shape such as a matte pattern is formed, and fixing the stamper from the uneven pattern side to a jig having a cylindrical concave surface with a diameter matching the stamping roll. a process of processing the back side of the stamper until the entire surface of the stamper has a certain thickness; a process of fixing the back side of the stamper to the surface of the mold roll on a jig having a concave surface; This is a method for manufacturing a roll type optical recording medium, which comprises a step of peeling off a stamper.

1 to 3 are schematic cross-sectional views showing one implementation of the method for manufacturing a roll type for optical recording media of the present invention. In FIG. 1, the manufacturing method of the roll type for optical recording media of the present invention is as follows:
Concave and convex patterns such as Buriformat pattern on the surface 3
A protective layer 2 is applied to a certain thickness on the surface of the stub bar 1 formed by the process. In the next step, as shown in FIG. 2, the stamper l with the protective layer 2 formed thereon is fixed via the protective layer 2 to a jig 4 having a cylindrical concave surface with a diameter matching the forming roll. At this time,! f3 Press the stamper l onto the concave surface of the jig 4 from one end or the center and fix the stamper l so that there is no gap between the concave surface of the jig 4 and the stamper l without bending the stamper l. Any method can be used for fixing as long as it does not shift during subsequent steps; for example, bonding, screwing, etc. can be used.

After fixing the stamper ■ to the jig 4 in this way, place the stamper 1 so that the entire surface of the stamper 1 has a constant thickness.
Process the back side of. The method is to polish it with a polishing jig 6 such as a grinding stone having the same diameter as a certain type of roll, or to cut it with a lathe or the like. Next, as shown in FIG.
Alternatively, fix the stamper to the surface of the die set 8 so that there are no gaps. Thereafter, the stamper 1 and the protective layer 2 are peeled off at the interface to obtain a roll mold for an optical recording medium. At this time, the protective layer 2 remaining on the jig 4 can be peeled off from the jig 4 using a peeling agent or the like.

In the present invention, the stamper l may be obtained by any material or manufacturing method as long as it has the strength and durability necessary for resin molding and can form a stamper with the necessary precision of unevenness. An example of this is a stamper commonly used for CDs (compact discs). It can be manufactured by a manufacturing method generally used for CDs (compact discs) and the like. Specifically, a resist is applied to a glass master disk, a pattern is exposed and developed, a nickel film is formed by sputtering, and nickel is deposited to a predetermined thickness by electroforming. You may use the second master obtained in this way as the father to create a third master (mother) and grandchild stamper. Alternatively, the irregularities may be formed by forming a pattern on a metal plate or the like and then performing dry or wet etching. In addition to the above materials, metal compounds, glass, ceramics, etc. may also be used. The thickness of the stamper l depends on the material of the stamper l, since the obtained roll mold for optical recording media has a certain degree of rigidity, which is desirable in terms of strength and durability, or it is processed to a certain thickness. Generally, it is sufficient that the thickness is 100 μm or more, and the more preferable thickness is 400 to 5000 JLm.

The material for the protective layer 2 formed on the surface of the stamper 1 should be one that can be formed to a uniform thickness on the stamper 1, can prevent scratches on the uneven pattern 3, and has good removability. Although any material can be used, for example, a resin such as an acrylic resin is preferred. The forming force method for forming the protective layer 2 may be such that the material is uniformly applied onto the uneven pattern of the stand bar 1 and then cured. Any coating method that is generally used for resin coating can be used; for example, spray coating, dipping, roll coater, etc. can be used. The curing method may be an ultraviolet curing method, a radiation curing method, a thermosetting method, or the like depending on the material used. Alternatively, the protective layer 2 can also be formed by coating vinyl chloride resin or the like with a solvent and then volatilizing the solvent. The protective layer 2 may have any thickness as long as it can protect the concavo-convex pattern 3, but preferably has a thickness of 0.05 to 10. The jig 4 in the present invention can be made of any material as long as it has a certain degree of hardness and a certain degree of rigidity. For example, metals such as iron and chrome steel, metal compound ceramics,
Hard resin, glass, etc. can be used. It is necessary that the concave surface of the jig be formed into a mirror surface. The surface accuracy must be approximately the same as or better than the surface accuracy of the optical recording medium substrate to be molded. In particular, it is preferable that the surface unevenness be 501 L1 or less in pp. Also,
If necessary, a hardened film of titanium nitride or the like may be formed on the surface of the jig, or it may be plated with chromium or the like.

As the adhesive for bonding the protective layer 2 of the stamper 1 and the jig 4, any adhesive can be used as long as it does not peel off in the subsequent process, but for example, heat-resistant adhesives such as epoxy resin can be used. Cured adhesives, hot melt adhesives, etc. can be used.

In addition, the stamper fixed to the jig 4 as shown in FIG.
The back surface of the stamper 1 is processed to make the entire surface of the stamper 1 have a constant thickness, and this processing can be easily carried out using a polishing device 6 having the same radius of curvature as the diameter of the outer periphery or the die roll 7. It's coming. Alternatively, mechanical cutting using a precision lathe or the like may be used.

In addition, as shown in Fig. 3, the method of fixing the stamper 1 processed to a certain thickness to the die roll 7 or die set 8 while attached to the jig 4 without leaving any gaps is not suitable for stamping. Any method can be used as long as the necessary strength is maintained, and for example, methods such as adhesion and screwing can be used. It is best to use an adhesive that has strong adhesive strength and is durable. Preferred adhesives include heat-resistant epoxy adhesives. The forming roll 7 in the present invention can be made of any material as long as it has a certain degree of hardness and a certain degree of rigidity. For example, metals such as iron, chrome steel, metal compounds, hard vinyl chloride, etc. resin can be used. The surface of the forming roll is polished to a mirror finish. The surface accuracy must be approximately the same as or better than that of the optical recording medium to be molded. Surface unevenness is pp 5
It is preferable that the river weight is 0 or less. Also, if necessary, a hardened film such as titanium nitride or a protective layer such as silicon can be formed on the surface of the forming roll. It is also possible to plate with nickel or chromium. Furthermore, depending on the diameter of the roll, it is possible to incorporate a die set 8 to simplify handling. The die set 8 can be made in the same way as the die roll 7.

When the die set 8 is assembled into the die roll 7-, it is desirable that no steps are formed on the surfaces of the die roll and the die set.

After fixing the stamper 1 to the molding roll 7 or the die set 8, the interface between the stamper 1 and the protective layer 2 is peeled off, and the stamper 1 is peeled off from the jig 4.

Any method can be used for peeling.
For example, you can use a wedge-like tool to peel it off from the edge. Stand bar 1! After the protective layer 2 has been released, it is peeled off from the jig 4 using, for example, a release agent, and the jig 4 can be used for processing and fixing the next stamper. [Function] The method of manufacturing a roll mold for optical recording media of the present invention manufactures a roll-shaped stamper or mold used in the process of continuously manufacturing a transparent substrate for an optical recording medium on which a pattern such as a preformat is formed. In the step of forming a protective layer on the uneven pattern of the stamper having an uneven shape such as a briformat pattern on the surface, the stamper is passed through the protective layer to form a concave surface with a diameter matching the die roll. A process of fixing to a jig, a process of processing the back side of the stamper fixed to the jig to make the entire surface of the stamper a constant thickness, a process of fixing a forming roll to the back side of the processed stamper, a process of fixing the stamper to the jig, Through a series of steps consisting of peeling off the stamper fixed to the mold roll from the jig, it becomes possible to fix the stamper with the uneven pattern on the surface of the mold roll with high precision and with a simple mechanism. [Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. Example l As shown in Fig. 1, 1.6 end pitch, 0.6 zaho width,
A continuous groove with a depth of 700mm or a thickness of 0.3llI1
A protective agent (Silitechto ■, Trilaner Technology) was spray coated onto a nickel stamper (manufactured by Seiko Epson) to a thickness of 50 gm.

Next, as shown in Figure 2, adhesive (Adfix H, manufactured by Nikka Seiko Co., Ltd.) was evenly applied to a thickness of 30 mm on the jig in which a concave surface with a radius of curvature of 300 mm was formed. The stamper was attached from the protective layer side. Using a polishing jig (material: SiC) having a convex outer shape with the same radius of curvature as the concave surface of the back surface of the stamper attached to the jig, alumina powder with a 10-square diameter was used as the abrasive to polish the entire surface of the stamper to 0. 3m+a
Polished to a uniform thickness. After polishing, an adhesive (W-bond: AL manufactured by Nikka Seiko Co., Ltd.) was uniformly applied to a thickness of 50 μm on the surface of the die roll having the same radius of curvature as the concave surface of the jig. The forming roll was placed on top of the polished stamper, and the stamper and stamping roll were adhered. After adhesion, a wedge was inserted into the interface between the stamper and the protective layer and the stamper was peeled off to obtain a stamp roll. The protective layer remaining on the ridge was removed using acetone. When the obtained power roll was measured,
The unevenness on the surface of the roller was sufficiently small at less than 50 river weight pp. The eccentricity of the roller surface is sufficiently small, 307t.
It was less than m. This forming roll was attached to an extrusion molding machine (Hitachi Zosen, SHT90-32DVG), and
．． Polycarbonate (Teijin Kawei, K
-1285) was extruded to a thickness of 1.2 mm. Even when 10,000 optical disk substrates were molded using this molded roll, there was no change in the shape of the roller surface. When the extruded board was measured, the amount of surface runout was sufficiently small at less than 50 rou in pp. This substrate was cut into a size of 861●φ, and an optical recording material represented by the following structural formula [I] was coated with a solvent.

((:2HS)2Nl < N(CJs)zC
204° [I] For the protective substrate, cut 0.3cm thick polycarbonate (Teijin Kasei, Panlite 251) into 86 mm diameter.
It was glued so that there was an air gap of mm. When recording and playing back, the disc rotation speed was 1800 rpm. Write frequency 3Mllz. The C/N ratio was 50 dB with a write power of 6.5 W and a read power of 0.5 W. Example 2 In the same way as in Example 1, an ultraviolet curing resin (manufactured by Mitsubishi Rayon ■,
After uniformly applying MRA50Lm to a thickness of 501Lm, it was covered with a 21mm thick glass plate and sealed. Using two 3kW ultraviolet lamps (manufactured by Ushio Electric Co., Ltd.), they are air-cooled to prevent heat from the ultraviolet rays, and generate 200mW/a.
The resin was cured by irradiation with ultraviolet light at an intensity of 1 for 30 seconds. After removing the glass plate, the same UV lamp was used to irradiate the resin with UV light for 3 minutes to completely cure the resin. Next, as in Example 1, the stamper was bonded onto a jig having a concave surface with the same radius of curvature as in Example 1. As in Example 1, the back surface was polished to a thickness of 0.1
mm, a die set that accommodates a convex surface with the same radius of curvature as the concave surface of the jig was glued to the stamper. The glued die set was fixed to a roll with the same diameter as in Example 1 by screwing it. The protective layer remaining on the jig was removed in the same manner as in Example 1.

When the obtained molded roll was measured, the unevenness on the surface of the roller was 501 Lm or less in pp, which was sufficiently small.

The eccentricity of the die roll surface was sufficiently small at 301 Lm or less. Even after testing 10,000 optical disk substrates in the same manner as in Example 1, no change in surface shape was observed.

The characteristics of the tested board were that the amount of surface runout was sufficiently small at less than 50 Kawaguchi in terms of pp. An optical recording layer was formed on this optical disk substrate in the same manner as in Example 1, and recording and reproduction were performed.
/N ratio was 52 dB. Example 3 A protective layer similar to Example 1 was formed on the concavo-convex pattern of a glass substrate (manufactured by Asahi Glass) with C and a thickness of 1.2 cm as in Example 1 in the same manner as in Example 1. did. Next, Example l
In the same manner as above, it was pasted on a jig with a concave surface with a radius of curvature of 500 cm, and the back surface was polished to a thickness of 50 JLm. After bonding the stamper to a glass roll (Corning) that has the same radius of curvature as the jig, the stamper was peeled off from the interface between the stamper and the protective layer to create a molded roll. The protective layer remaining on the jig was removed in the same manner as in Example 1. As a result of measuring the resulting rough roll, it was found that the unevenness on the surface of the roller was sufficiently small, being less than 40 mm in pp. Two 3kW ultraviolet lamps (Ushio Electric) were placed inside the forming roll. 1.211 thick polycarbonate (Teijin Kasei,
An ultraviolet curable resin (Mitsubishi Rayon, MRA500) was applied to a thickness of 10 JLs on top of Panrayon-202), and using this Kai type roll, the feed rate was 3 m/min and the roll pressure was 1.5 kg/c. 2, Irradiation ultraviolet intensity 1'80mW
/cm" to obtain an optical disc substrate by curing the pattern while transferring it. Thereafter, a disc was prepared in the same manner as in Example 1. Recording and reproduction were performed on this optical disc under the same conditions as in Example 1. The C/N ratio was 53 dB.

[Effects of the Invention] As explained above, according to the present invention, a stamper is fixed on a jig in which a concave surface is formed, back surface processing and bending processing are performed simultaneously, and a forming roll or a die set is formed on the jig. In order to fix the stamper on the surface of the stamper, it is possible to manufacture roll molds for manufacturing substrates for optical recording media with high precision using a simple mechanism.

[Brief explanation of drawings]

1 to 3 are schematic cross-sectional views showing an embodiment of the method for manufacturing a roll-type optical recording medium of the present invention, and FIG. 4 shows a conventional method for pasting a stamper for manufacturing an optical recording medium. 5 and 6 are explanatory diagrams showing a method of transferring a pattern onto a roll using a conventional plate-making method. FIG. 7 is a partial sectional view of a conventional optical recording medium, and FIG. 8(a). (b) is a schematic diagram showing a conventional continuous manufacturing method for substrates for optical recording media. 1. 12--Stambar 2--Protective layer 3--Irregular pattern 4--Jig 5--Adhesive layer 6--Polishing jig 7--Forming roll
8...Die set 1l...Pressure roller
21. 31... Roll for plate making 22... Mask 23. 32...Light beam for pattern exposure 4l...
Transparent substrate 42...Track groove portion 43...
Optical recording layer 44... baser/adhesive layer 45... protective substrate 51... resin sheet 5
2-... Roll for pressure 53... Roll for pressure or tension 54... Roll for unwinding 55... Roll for winding

Claims (1)

[Claims] In the roll-type manufacturing method used to manufacture substrates for optical recording media, which record and reproduce information by changing optical properties such as reflectance and refractive index by irradiation with a light beam such as a laser beam, the surface is pre-printed. A step of forming a protective layer on the uneven pattern of a stamper on which an uneven shape such as a format pattern is formed, a step of fixing the stamper to a jig having a concave surface with a diameter matching the forming roll via the protective layer, Processing the back side of the stamper fixed to the jig so that the entire surface of the stamper has a constant thickness, Fixing a forming roll to the back side of the processed stamper, Fixing the stamper fixed to the forming roll 1. A method for manufacturing a roll type optical recording medium, comprising a step of peeling it off from a material.