JP2006338775A - Stamper for optical disk substrate and method for manufacturing stamper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a plurality of optical disk substrates from one master glass plate by solving problems of surface deterioration due to oxidation processing and squareness deterioration due to the transfer of 2P resin. <P>SOLUTION: A method for manufacturing a stamper for optical disk substrates comprises a process for exposing a master plate (quartz glass 10 or the like) coated with photoresist 2 through a pattern, a process for developing exposed patterns (4, 5) of the photoresist 2 and producing a master plate, a process for transferring a pattern shape formed on the surface of the master plate to a base material 91 by using photopolymer (2P) resin 80, and a process for forming a protection film 93 using a dielectric substance as a material on the pattern formed on the base material 91. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a replication stamper for an optical disk substrate, particularly an optical disk substrate for high density recording. More specifically, the present invention relates to a method capable of easily replicating a stamper in large quantities in place of the conventional stamper replication technique using an oxide film. The stamper manufactured according to the present invention is particularly effective for producing a magneto-optical recording medium of a domain wall motion detection type among optical disks.

  Conventionally, various attempts have been made to increase the density of optical disk recording. For example, Patent Document 1 proposes a high-density magneto-optical recording by a domain wall motion detection method. This domain wall motion detection method uses the domain wall motion phenomenon due to the temperature gradient of the readout light spot, and it is possible to obtain reproduction resolution exceeding the limit restricted by the light spot diameter in the line (track) direction.

  Hereinafter, the domain wall motion detection method will be briefly described with reference to the drawings. FIG. 2 is a schematic diagram for explaining the operation of the domain wall motion detection type magneto-optical recording medium and the reproducing method thereof.

  FIG. 2A is a schematic cross-sectional view of a magneto-optical recording medium. The magnetic layer of this medium is formed by sequentially laminating a first magnetic layer 111, a second magnetic layer 112, and a third magnetic layer 113. Arrows 114 in each layer indicate the direction of atomic spin. A domain wall 115 is formed at the boundary between regions where spin directions are opposite to each other. 116 is a light spot for reading, and an arrow 118 is a moving direction with respect to the light spot of the recording medium.

  FIG. 2B is a graph showing the temperature distribution formed on the magneto-optical recording medium. This temperature distribution is formed on the medium by the light spot irradiated for reproduction, the temperature rises from the front side of the light spot, and the temperature peak comes behind the light spot. Here, at the position Xs, the medium temperature is a temperature Ts near the Curie temperature of the second magnetic layer.

  FIG. 2C is a graph showing the distribution of the domain wall energy density σ1 of the first magnetic layer corresponding to the temperature distribution of FIG. Thus, when there is a gradient of the domain wall energy density σ1 in the X direction, the force F1 = ∂σ / ∂X acts on the domain wall of each layer existing at the position X. This force F1 acts to move the domain wall toward the lower domain wall energy. Since the first magnetic layer has a small domain wall coercive force and a large domain wall mobility, the domain wall easily moves by this force F1 alone. However, in the region before the position Xs (right side in the figure), the medium temperature is still lower than Ts and exchange-coupled with the third magnetic layer having a large domain wall coercivity, so that the domain wall in the third magnetic layer The domain wall in the first magnetic layer is also fixed at a position corresponding to this position.

  In the domain wall motion detection method, as shown in FIG. 2A, when the domain wall 115 is at the medium position Xs, the medium temperature rises to a temperature Ts near the Curie temperature of the second magnetic layer. The exchange coupling between the magnetic layer and the third magnetic layer is broken. As a result, the domain wall 115 in the first magnetic layer moves “instantaneously” to a region where the temperature is higher and the domain wall energy density is smaller, as indicated by the dashed arrow 117.

  When the domain wall 115 passes under the reproduction light spot 116, the atomic spins of the first magnetic layer in the light spot are all aligned in one direction. Then, whenever the domain wall 115 comes to the position Xs with the movement of the medium, the domain wall 115 instantaneously moves under the light spot, the direction of the atomic spin in the light spot is reversed, and all are aligned in one direction. As a result, as shown in FIG. 2A, the reproduction signal amplitude is always constant and maximum regardless of the interval between recorded domain walls (that is, the recording mark length), and is caused by the optical diffraction limit. Free from problems such as waveform interference. The occurrence of the domain wall motion can be detected by a conventional magneto-optical head as the rotation of the polarization plane of the reproducing laser beam accompanying the magnetization reversal of the domain wall motion region.

FIG. 3 is a schematic cross-sectional view illustrating the layer configuration of the magneto-optical recording medium. In this figure, a dielectric layer 123, a first magnetic layer 122, a second magnetic layer 121, a third magnetic layer 120, and a dielectric layer 119 are sequentially laminated on a transparent substrate 124. An arrow 125 is a direction in which a light beam for recording and reproduction is incident. For example, polycarbonate can be used as the transparent substrate 124, and Si ₃ N ₄ can be used as the dielectric layer 123.

  FIG. 4 is a schematic diagram showing a state in which the magneto-optical recording medium having the configuration described in FIG. 3 is formed on the land / groove substrate. The recording track 8 far from the incident direction of the light beam 125 is called a land portion, and the recording track 9 near the incident direction is called a groove portion. In land / groove recording, when recording / reproducing a land track, the groove portion becomes a guide groove for tracking, and when recording / reproducing a groove track, the land portion becomes a tracking guide groove and is adjacent. Since recording can be performed simultaneously on the land portion and the groove portion, it is effective in improving recording density in the track direction.

  As described above, by using the domain wall motion detection method, the linear recording density can be improved. By combining this with the land / groove recording, the surface recording density has been greatly increased compared with the conventional magneto-optical recording. Can be improved.

  Further, in the land / groove recording, as a device for facilitating the domain wall movement, it is effective to use a so-called deep groove substrate (see Patent Document 2) having a steep tapered portion as shown in FIG. If a magnetic film is formed on the substrate by a highly directional film forming method, the magnetic film can be substantially prevented from being deposited on the tapered portion (that is, the side wall portion between the land and the groove). As a result, it is possible to form a magnetic domain in which the domain wall does not substantially exist in the side wall part for each of the land part and the groove part, and the track is magnetically divided, and the domain wall movement is likely to occur. The mechanical distance between the land track 8 and the groove track 9 is preferably selected to be about 80 to 300 nm which exceeds at least the total thickness of the magnetic films.

  In addition, preventing the magnetic film from being deposited on the side wall portion is also effective in suppressing thermal interference with adjacent tracks and improving cross erase resistance. At the same time, the domain wall motion detection method can be expected to suppress crosstalk from adjacent tracks during reproduction. This is because it is possible to prevent the adjacent tracks from being heated above the domain wall motion start temperature Ts during reproduction. For this reason, in the magnetic domain recorded in the adjacent track, domain wall movement does not occur and normal magneto-optical reproduction is performed. However, if the recording mark length is selected to be equal to or less than the resolution of the light spot, large crosstalk occurs. There is nothing.

  The combination of the deep groove substrate and the domain wall motion detection method can drastically improve the surface recording density due to the synergistic effect of the magnetic track segmentation effect, the cross erase resistance improvement and the crosstalk suppression effect described above ( Non-patent document 1).

  Next, a conventional method for manufacturing an optical disk substrate stamper will be described with reference to FIG.

  First, as shown in FIG. 5A, a primer such as a silane coupling material is spin-coated on the polished master glass 1, and then a positive photoresist 2 is spin-coated and prebaked in a clean oven. Next, as shown in FIG. 5B, a predetermined region of the master glass 1 is exposed by an exposure apparatus using an Ar ion laser or the like as a light source. 3 is a light beam of the cutting machine, 4 is an exposed portion, and 5 is an unexposed portion. As the photoresist, a negative photoresist using an exposed portion and a positive photoresist using an unexposed portion can be properly used as necessary. Next, as shown in FIG. 5 (3), the exposed portion is removed by washing with a developer. Then, pure water washing and spin drying are performed, and post baking is performed in a clean oven. The photoresist removal portion becomes the groove 9 and the remaining portion becomes the land 8. Next, as shown in FIG. 5 (4), a conductive film 6 such as a Ni film is formed on the surface of the master glass by sputtering. Next, as shown in FIG. 5 (5), Ni electroforming is performed on the Ni conductive film 6. Reference numeral 15 denotes a Ni electroformed layer. Next, as shown in FIG. 5 (6), the Ni electroformed surface is polished on the back surface, and then the metal stamper is peeled off from the master glass to obtain a stamper 7 as shown in FIG. 5 (7).

  Furthermore, as another conventional technique, a method for manufacturing a stamper for an optical disk substrate using anisotropic etching has been proposed for manufacturing a substrate for a deep groove substrate that requires a cross-sectional shape close to a rectangle. For example, Patent Document 3 describes a method for manufacturing a stamper for a land / groove recording substrate using reactive ion etching (hereinafter referred to as “RIE”). Hereinafter, such a manufacturing method of the RIE method will be described with reference to FIG.

  First, as shown in FIG. 6 (1), the polished synthetic quartz master 10 is sufficiently washed, a primer is spin-coated on the surface of the synthetic quartz master 10, and then a positive photoresist 2 is spin-coated. Thereafter, the master is pre-baked in a clean oven. Next, as shown in FIG. 6B, a predetermined region of the synthetic quartz master 10 is exposed by an exposure apparatus using an Ar ion laser or the like as a light source. Next, as shown in FIG. 6 (3), the exposed portion 4 is removed by spin development with a developer. Then, pure water washing and spin drying are performed, and post baking is performed in a clean oven. Next, as shown in FIG. 6 (4), reactive ion etching (RIE14) is performed. By adjusting the RIE time, etching can be performed until a predetermined groove depth is reached. Next, as shown in FIG. 6 (5), the glass master 13 is obtained by immersing in a stripping solution and stripping the remaining resist. 8 is a land portion, and 9 is a groove portion. Next, as shown in FIG. 6 (6), a conductive film 6 such as a Ni film is formed on the surface of the glass master 13 by sputtering. Next, as shown in FIG. 6 (7), Ni electroforming is further performed on the conductive film 6. Reference numeral 15 denotes a Ni electroformed layer. Next, as shown in FIG. 6 (8), after the Ni electroformed surface is polished, the Ni electroformed layer 15 is peeled off from the glass master 13, and the stamper 7 as shown in FIG. 6 (9) is obtained.

  Note that the above-described stamper production requires a long process, and only one stamper can be produced from one master glass, resulting in high cost. Therefore, in order to reduce the cost per stamper, a metal stamper peeled from the master glass is used as a master stamper, and the surface is oxidized to produce a stamper family called a mother stamper / sun stamper. The cost per hit is being reduced.

  Hereinafter, the oxidation treatment for producing such a family stamper will be described with reference to FIG. In this method, when the mother stamper 72 is produced from the master stamper 71, if Ni electroforming is performed directly on the surface of the master stamper 71, peeling becomes impossible due to the same metals. Therefore, the surface of the master stamper 71 / the mother stamper 72 is oxidized so that the master stamper 71 and the mother stamper 72 and the mother stamper 72 and the sun stamper 73 can be peeled off.

  First, as shown in FIG. 7A, the master stamper 71 is immersed in the dichromic acid solution 70 for a predetermined time to form an oxide film 74 on the surface. Next, as illustrated in FIG. 7B, a conductive film 6 such as a Ni film is formed on the oxide film 74 of the master stamper 71. Next, as shown in FIG. 7 (3), Ni electroforming is performed to obtain a Ni electroforming layer 15 having a desired film thickness. Next, as shown in FIG. 7 (4), the master stamper 71 and the Ni electroformed layer 15 are peeled off to obtain a mother stamper 72. Furthermore, by performing the same steps (1) to (4) on the mother stamper 72, the sun stamper 73 can be obtained. In addition, it is possible to obtain a large number of sun stampers 73 by subjecting the master stamper 71 and the mother stamper 72 once used for manufacturing the family to surface treatment, and again using them for manufacturing the family stamper, and performing the same process a plurality of times. It becomes.

  As a method for forming the oxide film 74 on the surface of the stamper, in addition to the method using the dichromic acid solution 70 described above, the surface corresponding to the Ni film of the conductive film 6 as described in Patent Document 4, for example, is sublimed. There are proposed a method of oxidizing with a halogen acid, a method of performing oxygen plasma treatment on the surface corresponding to the Ni film of the conductive film 6 as described in Patent Document 5, and the like. As described above, the family stamper can be manufactured by performing the oxidation treatment on the Ni conductive film or the conductive film 6 corresponding to the Ni film.

  The stamper obtained by each method described above is further subjected to press punching or back surface polishing to obtain a desired shape, thereby completing the stamper. Using this stamper, an optical disk substrate having a recording signal such as a land / groove shape is duplicated by an injection molding method or a 2P method. Thereafter, a metal reflective film such as aluminum or a magnetic film is formed on the optical disk substrate to obtain an optical disk (optical recording medium).

  In the production of such a family stamper, a large amount of a sun stamper can be produced by oxidation treatment on the master stamper surface and the mother stamper surface. However, if the oxidation treatment is repeated several times, the surface roughness of the stamper deteriorates, and the surface of the first stamper and the one obtained from the master stamper or mother stamper that has been subjected to multiple oxidation treatments There is a big difference in roughness, resulting in a difference in quality as a stamper. In the domain wall motion detection method, the signal quality is deteriorated because the domain wall motion is inhibited as the surface roughness deteriorates. In addition, there is a problem that the conditions for each stamper are different for molding, and it takes time to extract optimum conditions for production. Further, when the oxidation treatment is performed, an oxide film adheres to the surfaces of the master stamper and the mother stamper, so that it cannot be used as a molding stamper for the magneto-optical recording medium of the domain wall motion detection type.

Therefore, Patent Document 6 proposes a method for producing a stamper family that does not require oxidation treatment to the stamper surface and prevents deterioration of the surface roughness. This method will be described with reference to FIG. First, as shown in FIG. 8A, a primer is spin-coated on the polished and cleaned master glass 1, a photoresist 2 is spin-coated, and prebaked in a clean oven. Next, as shown in FIG. 8B, a predetermined region of the master glass 1 is exposed by an exposure apparatus using an Ar ion laser or the like as a light source. 3 is a light beam of the cutting machine, 4 is an exposed portion, and 5 is an unexposed portion. As the photoresist, a negative photoresist using an exposed portion and a positive photoresist using an unexposed portion can be properly used as necessary. Next, as shown in FIG. 8 (3), the exposed portion is removed by washing with a developer. Then, pure water washing and spin drying are performed, and post baking is performed in a clean oven. The photoresist removal portion becomes the groove 9 and the remaining portion becomes the land 8. Next, as shown in FIG. 8 (4), an appropriate amount of photopolymer (hereinafter referred to as “2P resin”) 80 is dropped onto the prepared resist pattern so that air and dust do not enter the other master glass 1. Laminate carefully and cure thoroughly with ultraviolet light. By peeling the cured 2P resin from the resist pattern, the 2P master master 81 is completed as shown in FIG. Here, the 2P master master was produced from the resist pattern. However, the pattern on the glass master from which the resist is removed by performing RIE using the resist pattern as a mask can be used, and is not particularly limited. Next, as shown in FIG. 8 (6), a release layer 83 such as a Ti thin film is formed on the 2P master master. Next, as shown in FIGS. 8 (7) and 8 (8), the 2P mother master 82 is completed by further transferring the pattern from the 2P master master on which the release layer 83 is formed using 2P resin. Next, as shown in FIGS. 8 (9) to (11), the conductive layer 6 is formed on the 2P mother master, the electroformed layer 15 is further formed, and the stamper 7 is completed by peeling it off. In this manner, by repeating the steps after the production of the 2P master master, a large amount of 2P stamper family can be produced without performing oxidation treatment.
Japanese Patent Application Laid-Open No. 6-290496 JP-A-9-161321 Japanese Patent Laid-Open No. 7-161080 JP 54-40239 A JP 59-173288 A JP 2003-203395 A Journal of Japan Society of Applied Magnetics Vol.23, No.2, 1999, p764-769, Shiratori "High-density magneto-optical disk by domain wall motion detection method"

  According to the method described above, it is possible to prevent the surface roughness from being deteriorated due to the production of the stamper family. However, by repeating the transfer from the glass master to the 2P master, the 2P master to the 2P mother, and the 2P resin, transferability can be improved. Due to the problem, the rectangular shape of the pattern shape may be deteriorated. When this shape deterioration occurs, the film adherence is improved when the magnetic film is formed, so that the above-described division between tracks is lost, and the magneto-optical disk characteristics of the domain wall motion detection method such as cross light resistance are deteriorated. To do.

  SUMMARY OF THE INVENTION Accordingly, the present invention has an object to produce a plurality of optical disk substrate stampers from a single glass master disk by solving the problem of deterioration of surface properties due to the transfer of 2P resin, without deterioration of surface properties due to oxidation treatment. To do.

  It is another object of the present invention to reduce the number of steps required for manufacturing a stamper and dramatically shorten the trial production time from mastering to substrate manufacturing.

  The present invention includes a step of exposing a pattern on a master coated with a photoresist, a step of developing an exposure pattern of the photoresist to produce a master master, and a pattern shape formed on the surface of the master master, For an optical disk substrate comprising: a step of transferring to a base material (for example, the surface of a metal plate) using a photopolymer (2P) resin; and a step of forming a protective film made of a dielectric material on a pattern on the base material This is a stamper manufacturing method.

  Furthermore, the present invention is a stamper for an optical disk substrate (hereinafter referred to as “simple stamper”) obtained by such a method.

  In the present invention, since there is no deterioration in surface properties due to oxidation treatment, and since rectangular deterioration due to repeated transfer of 2P resin can be suppressed, a plurality of stampers with good signal quality can be produced from a single glass master. . In addition, since the number of steps required for producing the stamper can be reduced, the trial production time from mastering to production of the substrate can be drastically reduced as compared with the conventional example.

  Such an optical disk substrate stamper is particularly useful as a stamper for producing a magneto-optical recording medium.

The main steps of the method of the invention are:
(1) forming a pattern shape on a master such as a quartz substrate;
(2) A step of transferring the pattern shape on the master to a base material such as a metal plate using 2P resin,
(3) a step of forming a protective film in a pattern shape on the substrate;
It can be roughly divided into three processes.

The step (1) includes, for example, a step of exposing a photoresist coated on a master such as a quartz substrate with a light beam, a step of producing a resist pattern by developing by spin development, and the like. It is preferable to carry out by a step of etching a master such as a quartz substrate by reactive ion etching using a gas such as CHF ₃ as a mask and a step of removing the remaining resist by oxygen ashing or the like.

In the step (2), it is preferable to carry out a step of transferring a pattern using a 2P resin after the step of applying a silane coupling agent on the substrate. Here, the material of the base material is not particularly limited as long as it can transfer the 2P resin pattern. However, when the substrate is manufactured by the 2P method, it is preferable that the following conditions (a) to (c) are satisfied.
(A) Considering handling and processing steps, it should be thin and lightweight, and should have impact resistance and heat resistance.
(B) Since the pattern is centered by a microscope, it has an appropriate reflectivity from the visibility problem and has a contrast with the 2P pattern.
(C) In peeling after hardening 2P resin, it has moderate softness | flexibility in order to improve the workability | operativity.

  From these conditions (a) to (c), it is preferable to use a metal plate as the base material of the simple stamper.

In the step (3), a protective film made of a dielectric material is formed in the present invention. According to the knowledge of the present inventors, when a metal film such as Al or Ti is formed as a protective film, the 2P resin pattern is damaged at the time of film formation, and unevenness occurs in the flat portion of the land / groove, -Change in groove shape, such as change in the angle of the boundary of the groove, and accompanying deterioration in surface properties occur. These changes in shape and surface property are very important problems in the domain wall motion detection method. Although it is possible to suppress the change to some extent by changing the film forming conditions such as reducing the power during discharge, it is difficult to achieve both stable film quality. On the other hand, in the present invention, the 2P resin is not deformed as described above by forming a protective film made of a dielectric material. Examples of such a protective film include dielectrics such as SiN, Ta ₂ O ₅ , SiO ₂ , SiC, ZnS, ZnS · SiO ₂ , AlN, MgF, and a dielectric film containing Si as required.

  FIG. 1 is a process diagram for producing a stamper family for an optical disk substrate according to an embodiment of the present invention. First, as shown in FIG. 1A, a photoresist 2 is coated on a quartz glass 10 (master) so as to have a desired film thickness by a method such as spin coating. Next, as shown in FIG. 1B, a desired pattern is exposed to the quartz glass 10 on which the resist film is formed using a light beam 3 or the like. In the figure, 4 is an exposed portion. Next, as shown in FIG. 1 (3), a master master is produced by removing the exposed portion 4 using a developer and leaving the unexposed portion 5. In the figure, 8 is a land and 9 is a groove. It is also preferable to etch the quartz glass 10 by further performing reactive ion etching using the resist pattern thus formed as a mask. Next, as shown in FIG. 1 (4), the simple stamper 92 is produced by transferring the pattern shape to the substrate 91 using the 2P resin 80. Next, as shown in FIG. 1 (5), the simple stamper 92 is peeled from the master master. Next, as shown in FIG. 1 (6), a simple stamper is completed by forming a protective film 93 made of a dielectric material on the pattern.

  An optical disk substrate can be produced by the 2P method using the simple stamper thus obtained. This simple stamper is useful for any type of optical disk substrate, but is particularly useful for the magneto-optical recording medium substrate described above with reference to FIGS.

  Next, the present invention will be described in detail using examples.

<Example>
In accordance with the optical disk substrate stamper manufacturing process according to the present invention shown in FIG. 1, a simple stamper for forming an optical disk substrate (land / groove recording substrate) was manufactured by the following method.

  For surface observation, a tapping mode AFM of a scanning probe microscope (manufactured by Digital Instruments Inc., NanoScope-IIIa) is used, and the probe has an angle of ± 5 ° and a probe with excellent measurement accuracy (NCH -AR5) was used.

  First, a quartz master disk 1 having an outer diameter of 200 mm and a thickness of 6 mm and polished to a surface roughness Ra of 5 nm or less was prepared and thoroughly cleaned. This quartz master 1 was spin-coated with hexamethyldisilazane (hereinafter referred to as “HMDS”) as a silane coupling material. This has the effect of improving the adhesion between the resist to be applied later and the quartz master. After application of HMDS, it was dried in a clean oven at 50 ° C. for 1 hour. Thereafter, positive photoresist 2 (manufactured by Tokyo Ohka Kogyo Co., Ltd., TSMR-8900) was similarly spin-coated so that the photoresist film thickness was 100 nm. In addition, although HMDS was used as a silane coupling material here, it is not limited to this. The quartz master 1 was pre-baked in a clean oven at 90 ° C. for 30 minutes, and then an area from the radius 16 mm to 30 mm of the quartz master was exposed with the light beam 3 using an exposure apparatus equipped with an Ar ion laser as a light source. In this exposure, the track pitch was 0.64 μm, and exposure was performed intermittently while changing the laser power depending on the radial position so that a zone where the land width and groove width had a constant duty ratio after development was formed. . The rotation speed of the master glass during exposure was 600 rpm, and the spot diameter of the laser beam was about 0.45 μm. Here, an Ar ion laser is used as the light source, but there is no particular limitation, and an exposure apparatus using another light source such as a He—Cd ion laser, an electron beam, or ultraviolet light can also be used. Thereafter, an organic alkaline solution (NMD-3, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and ultrapure water were mixed in a ratio of 1.375: 1 by weight and spin-developed with a developing solution to prepare a resist pattern. The development conditions at this time were a pre-pure water cleaning time of 300 seconds, a development time of 30 seconds, a post-pure water cleaning time of 300 seconds, and a spin drying time of 60 seconds, and then post-baking in a clean oven at 90 ° C. for 30 minutes.

Next, using the formed resist pattern as a mask, RIE was performed using a parallel plate RIE apparatus (DEA-506 manufactured by Nidec Anelva). The etching conditions at this time are: reactive gas species CHF ₃ , RF power 200 W, gas flow rate 80 sccm, pressure 3.0 Pa, and time 10 minutes. Here, CHF ₃ is used as the reaction gas, but CF ₄ or the like can also be used and is not particularly limited. Thereafter, the quartz master was placed in an oxygen ashing device (manufactured by Nidec Anelva, RH-20), evacuated to a vacuum degree of 4 × 10 ⁻³ , oxygen gas was introduced, plasma ashing was performed, and residual photoresist was removed.

  A SUS plate as a base material of a simple stamper was punched into a desired shape, a silane coupling agent was applied on the SUS plate, and baked in a clean oven at 90 ° C. for 30 minutes. Thereafter, the pattern on the quartz master was transferred onto the SUS plate using 2P resin. Here, a SUS plate is used as a base material, but other materials can be used and are not particularly limited.

  On the pattern transferred onto the metal plate, 5 nm of SiN was deposited as a protective film on the pattern to complete a simple stamper. Here, SiN is used as the protective film, but other dielectric films can be used and are not particularly limited.

  A substrate was produced by the 2P method using the completed simple stamper.

  On this substrate, a SiN layer, which is an interference layer of a domain wall motion detection type magneto-optical medium configuration, is formed with a thickness of 80 nm, and then a GdFeCo layer is formed as a first magnetic layer (domain wall motion layer) with a thickness of 30 nm. A DyFe layer having a thickness of 10 nm was formed as a magnetic layer (switching layer), and a TbFeCo layer was formed as a third magnetic layer (memory layer) by sputtering in a thickness of 80 nm. Finally, a SiN layer having a thickness of 80 nm was formed as a protective layer. After forming this laminated film, a hard coat was formed on the film surface with an ultraviolet curable resin (manufactured by Nippon Kayaku, OVD-327Z). In addition, although the said commercial item was used as an ultraviolet curable resin here, it is not specifically limited.

  Table 1 shows the results of signal evaluation using the produced magneto-optical disk. Here, Pwmax / Pwth in the table is an evaluation index representing crosslight resistance, and the larger the value, the less likely crosslight occurs, which is advantageous in the domain wall motion detection method. The contents will be described in detail by taking as an example the case of recording on track n of the magneto-optical disk. When the recording power is increased, recording starts from a certain power and the carrier starts up. The recording power when the CN ratio, which is the carrier-to-noise ratio, becomes 10 dB is Pwth. When the recording power is further increased, destruction of the magnetic domain recorded on the adjacent track n + 1 starts, and as a result, the jitter of the track n + 1 deteriorates. The recording power of track n when the jitter of track n + 1 deteriorates by 0.5 sec is Pwmax. As the value of Pwmax is larger, the cross light is less likely to occur. However, since the value varies depending on the film configuration, the value cannot be simply used as an evaluation index. Therefore, the Pwmax standardized by the recording start power Pwth was used as an evaluation index for cross light. Moreover, in order to re-verify the effect obtained in the simple stamper produced from the master 1, the master 2 and the simple stamper were produced in the same process, and the same evaluation was performed.

  A photograph of the completed magneto-optical disk observed with an SEM is shown in FIG. From FIG. 9, it can be seen that the substrate manufactured according to the present invention maintains the rectangular shape of the rising portion of the side wall, that is, the land / groove boundary, and the transfer is performed well.

  Next, Comparative Example 1 will be described in order to demonstrate the usefulness of the examples in comparison with the prior art.

<Comparative Example 1>
In accordance with the conventional method shown in FIGS. 6 and 8, a stamper for forming an optical disk substrate (land / groove recording substrate) was produced by the following method.

  The same process as shown in Example 1 was performed until the pattern was formed on the quartz master. Next, the pattern on the quartz master from which the resist was removed was transferred to a soda lime master having the same size as the quartz master using a 2P resin to produce a 2P master. Next, a release layer was formed on the 2P master and transferred with 2P resin again to produce a 2P mother.

  A 100 nm Ni conductive film was formed on the 2P mother by sputtering. Ni electroforming was performed on this Ni conductive film to produce a metal stamper having a thickness of 0.3 mm. Next, the metal stamper was peeled off from the 2P mother and punched into a desired shape to complete a metal stamper.

  Thereafter, using this stamper, a land groove recording optical disk substrate was produced by the 2P method. On the completed disk, the same recording magnetic film as in the example and a protective coating were applied, and a magneto-optical disk was completed.

  Table 2 shows the results of signal evaluation using the produced magneto-optical disk. A photograph of the completed magneto-optical disk observed with an SEM is shown in FIG. In Tables 1 and 2, those with the same master number represent stampers made from the same master.

  From FIG. 10, it can be seen that the substrate manufactured according to the conventional manufacturing method has the rectangularity of the land / groove boundary impaired, and the rectangularity is deteriorated due to a plurality of times of transfer. Further, from the results of Example 1 and Comparative Example 1 shown in Tables 1 and 2, it can be seen that the magneto-optical disk using the simple stamper produced according to the present invention is superior in cross-write resistance.

Manufacturing process diagram of stamper family for optical disk substrate according to one embodiment of the present invention Schematic diagram of domain wall motion detection type magneto-optical disk medium and its reproduction principle Cross-sectional view of layer structure of magneto-optical recording medium of domain wall motion detection method Schematic diagram showing how the layer structure shown in FIG. 5 is formed on the land / groove substrate. Conventional optical disk substrate stamper manufacturing process diagram Process diagram for manufacturing optical disk substrate stamper using conventional RIE Manufacturing process diagram of stamper family for optical disc substrate by conventional surface oxidation treatment Manufacturing process diagram of stamper family for optical disk substrate by conventional 2P master SEM observation image of magneto-optical disk manufactured by the optical disk substrate stamper family manufacturing process according to the present invention. SEM observation image of magneto-optical disk produced by optical disk substrate stamper production process using conventional conventional RIE

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Master glass 2 Photoresist 3 Light beam 4 Exposed part 5 Unexposed part 6 Ni electrically conductive film 7 Stamper 8 Land 9 Groove 10 Quartz glass 13 Glass master 14 Reactive ion etching (RIE)
15 Ni electroformed layer 21 Al ₂ O ₃ film 22 SiO ₂ film 70 Dichromic acid solution 71 Master stamper 72 Mother stamper 73 Sun stamper 74 Oxide film 80 2P resin 81 2P master master 82 2P mother master 83 Release layer 91 Base 92 Simplified stamper 93 Protective film 111 First magnetic layer 112 Second magnetic layer 113 Third magnetic layer 114 Atomic spin 115 Domain wall 116 Reading light spot 117 Domain wall movement direction 118 Substrate movement direction 119 Dielectric layer 120 Third Magnetic layer 121 Second magnetic layer 122 First magnetic layer 123 Dielectric layer 124 Transparent substrate 125 Light beam incident direction

Claims (5)

Exposing the pattern to a master coated with a photoresist;
Developing an exposure pattern of the photoresist, producing a master master, and
Transferring the pattern shape formed on the surface of the master master to a substrate using a photopolymer (2P) resin;
Forming a protective film made of a dielectric material on the pattern on the substrate;
Manufacturing method of optical disk substrate stamper having   2. The method for manufacturing a stamper for an optical disk substrate according to claim 1, wherein the exposure pattern of the photoresist is developed, and reactive ion etching is performed using the resist pattern formed by the development as a mask to produce a master master.   2. The method for manufacturing a stamper for an optical disk substrate according to claim 1, wherein the master on which the photoresist is applied is quartz.   The method for producing a stamper for an optical disk substrate according to claim 1, wherein the base material on which the pattern shape formed on the surface of the master master is transferred using a photopolymer (2P) resin is a metal. An optical disk substrate stamper obtained by the method according to any one of claims 1 to 4.