JP2002230784A - Method of making stamper for optical recording medium and optical recording medium made by using the stamper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form rugged patterns of a header region which is good in detection with a proximity field optical recording device and with which track number reading during seeking can be carried out with high accuracy. SOLUTION: The resist on a glass master disk is exposed by using >=2 laser beam spots in making the stamper for an optical recording medium, by which the marks and/or bits formed in the segments where the positions equivalent to each other between the adjacent two tracks are the marks with each other or the bits with each other are formed to a continuous shape no having a bounding between the tracks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rewritable optical recording medium, and more particularly, to a method of manufacturing a stamper for an optical recording medium which irradiates light from a recording film formed on a substrate to perform recording and reproduction, and uses the stamper. The present invention relates to an optical recording medium manufactured by the above method.

[0002]

2. Description of the Related Art At present, optical recording media capable of recording information at a high density are used for voices, images, computer memories, and the like. In recent years, a higher-density optical recording medium compatible with multimedia has been demanded.

In general, an optical recording medium is formed by forming a multilayer film including a recording layer on a transparent disk-shaped substrate such as plastic, irradiating a laser beam to perform recording or erasing, and reproducing by reflected laser light. At present, optical recording media that are put into practical use include read-only media such as CDs, CD-ROMs, and DVD-ROMs, media that can be recorded only once such as CD-Rs, magneto-optical disks, and phase-change disks. Some can be recorded repeatedly. In these optical recording media, recording / reproducing is performed using a laser beam spot obtained by narrowing a laser beam having a wavelength of 780 to 650 nm with a lens having a numerical aperture of about 0.5. To increase the recording density, the diameter of the laser beam spot is increased. Needs to be smaller. The laser beam spot diameter d is expressed as d = λ / NA, where λ is the wavelength of the laser and NA is the numerical aperture of the lens. To reduce the diameter of the laser beam spot, shorten the laser wavelength or use a lens. May be increased. However, short-wavelength lasers that can be used for recording and reproduction of optical recording media have not yet been put to practical use, and increasing the numerical aperture of the lens reduces the depth of focus of the lens system.
Since a control system for keeping the focal point constant on the recording surface becomes complicated, a lens having an NA of about 0.6 is the largest in practical use.

On the other hand, as a method for reducing the diameter of a laser beam spot, Solid Dimension is used.
A method using a Lens (hereinafter abbreviated as SIL) head has been proposed (Appl. Phys. Lett. 6).
8, p. 144 (1996)). In this method, the diameter of the laser beam spot can be reduced more than before, and the mark at a mark shorter than the conventional recording limit (決 ま る λ / 2NA: NA is the numerical aperture of the objective lens) determined by the laser wavelength (λ) of the light source. Reproduction is possible, and recording and reproduction at an ultra-high recording density are possible. However, the diameter of the laser beam spot becomes such a small size only in the near field of the SIL head, and when it is used for recording / reproducing of an optical recording medium, it is necessary to bring the head closer to the recording film at a distance of 200 nm or less. There is. Therefore, instead of irradiating the recording film with the laser beam through the substrate as in the conventional optical recording medium, a method of directly irradiating the recording film with the laser beam without passing through the substrate is used.

[0005] The optical recording medium is generally formed with concentric or spiral tracks, and the tracks are divided into several tens to several hundred sectors per round. Each sector has a data area for the user to record his / her own data and a header area for recording information for reproducing the address of each sector and the like. Has a concavo-convex structure for tracking, which follows a target track, that is, a continuous guide groove or a discrete point-shaped concave portion. In general, header information such as addresses recorded in the header area is recorded as irregularities on a master master by controlling the irradiation of a laser beam by an electro-optical element or the like in a mastering process in advance, and this is transferred to a substrate in a molding process. It is formed. Pits for the concave and convex parts that make up the header information
The convex portion is called a mark. The guide groove of the data area is called a groove, and the area sandwiched between the two grooves is called a land. In the case where a concave / convex structure or the like is provided as a concave / convex structure for tracking the laser beam spot for reproduction / recording to a target track, a portion equivalent to the region sandwiched between the two grooves is also landed. It is called.

[0006] In the header of the optical recording medium, address information and the like are recorded at the position and length of the pit as in the case of data recording on a CD, and the amount of reflected light generated when a reproduced laser beam spot passes over the pit. Information is reproduced by the change of In this method, since the change in the amount of reflected light is caused by diffraction on the side surface of the pit, a pit having an opening width smaller than the track width is used.

[0007]

In an optical recording apparatus using an SIL, the distance between the surface of the optical recording medium and the SIL head needs to be short, so that the SIL head performs recording and reproduction while floating above the surface of the medium. . At this time, the distance from the medium surface to the lower surface of the SIL head is the flying height of the head on the mark in the header area, but is the sum of the flying height and the pit depth on the pit. The reflected light intensity on the mark changes depending on the flying height. Further, the reflected light intensity on the pit may exceed the effect of diffraction on the side surface of the pit, and may change due to the effect of a change in the distance from the bottom surface of the pit to the lower surface of the SIL head. The influence of the flying height of the reflected light intensity and the distance from the bottom surface of the pit to the lower surface of the SIL head is mainly due to optical interference due to multiple reflection between the lower surface of the SIL head and the medium surface and a change in the reflectance of light at a high incident angle.

When a signal is detected based on a difference in reflected light intensity from a mark and a pit, in a header region in which pits having an opening width smaller than the track width are arranged, a diffraction signal due to the pit, a flying height, and a distance from the pit bottom surface to the lower surface of the SIL head. If the signals due to the change in the distance are not in phase, the signal strength becomes weak and detection becomes difficult.

Moving an optical head to a target track on a recording / reproducing medium in an optical recording apparatus is called a seek. In a seek in a conventional optical recording apparatus, a target track radius value is calculated, an optical head is roughly moved, tracking is performed at that location, a track number is detected, and a difference from a target track is detected. After moving the optical head finely, tracking is performed again to detect a track number, and the operation is repeated to reach a target track.

Efforts have been made to reduce the seek time, such as counting the number of tracks moved during the seek and increasing the number of rotations of the medium to reduce the rotation waiting time. Attempts have been made to reduce the seek time by reading a track number during a seek. When a gray code is used for the header, most of the pit arrangement indicating the upper digit of the track number has the same pattern in each track, and the difference in the pit arrangement between adjacent tracks is always one minimum recording unit. Even in this case, the track position can be detected with an accuracy of ± 1 track, and a high-speed seek with high accuracy can be achieved. Here, the minimum recording unit is a signal recorded in a header area by a mark and a pit, the length of which is the shortest in a direction parallel to a track. Generally, all marks and pits are an integral multiple of this length. Length.

When a conventional pit having an opening width smaller than the track width is reproduced during a seek, a signal is detected when a laser beam spot passes over the pit. However, since no signal is detected when the laser beam spot passes over the mark, it is difficult to accurately read the track number.

The present invention is suitable for a header of a near-field optical recording medium using an SIL head, and is a method for manufacturing a stamper having pits and marks capable of high-accuracy and high-speed seek, and manufactured using the stamper. It is an object to provide an optical recording medium.

[0013]

Means for Solving the Problems In view of the above-mentioned current situation, the present inventors have made intensive studies and as a result, when manufacturing a stamper, devised a shape of a laser beam spot for exposing a resist on a glass master. As a result, it has been found that marks and pits in a header area that can be detected with a near-field optical recording device and that can read a track number during a seek with high accuracy can be formed, and the present invention has been completed. .

That is, the present invention relates to a method for manufacturing a stamper for an optical recording medium, comprising a step of manufacturing a master master for forming marks and / or pits by exposing a resist applied on a glass master to laser light. When producing a master master, two or more laser beams are used to form marks and / or pits in the header area where signals for address reproduction are recorded, and the center of the spot on the resist surface is separated. A method for manufacturing a stamper for an optical recording medium, characterized by using a laser beam spot having an effective width in a direction perpendicular to the track wider than the track width, and a light characterized by using the stamper manufactured by this method. It is a recording medium. Here, the effective width of the laser beam spot refers to the width of a pit formed at a depth of 1/2 formed by exposing the resist applied on the glass master to the laser beam and developing the resist.

Hereinafter, the present invention will be described in more detail.

FIG. 1 shows an example of a master master disc exposure apparatus for an optical recording medium. The continuous beam from the laser oscillator is separated by a separation prism. Each laser beam is controlled by an electro-optical element or acousto-optical element for controlling the amount of light installed in the optical path, and an electro-optical element for modulation.
The light quantity is controlled and modulated. After the two laser beams are combined by the combining prism, the two laser beams are incident on an objective lens provided in a focus servo mechanism, are focused on the resist surface on the master, and form a laser beam spot. At this time, one objective lens is used by changing the incident direction of the beam to the combining prism or changing the position, direction, and the like of the combining prism so that the optical paths of the two combined beams are shifted. However, two spots can be formed at different positions on the resist surface.

The effective width of the laser beam spot on the resist surface is proportional to the wavelength (λ) of the laser and inversely proportional to the numerical aperture (NA) of the objective lens (ie, proportional to λ / NA). In the case of an optical recording medium using SIL, a laser beam spot for recording and reproduction can be reduced to about の of that in the related art, and a disk having a track width (track pitch) of 0.5 μm or less is being studied. In order to make the track width 0.5 μm or less, it is necessary to form a guide groove for tracking as narrow as possible, and a short wavelength laser and an objective lens having a large numerical aperture are used. As an apparatus currently in practical use, there is an apparatus using an Ar laser or a Kr laser having a wavelength of 351 nm and an objective lens having a practically maximum numerical aperture of 0.90.

The method for forming marks and / or pits in a header area according to the present invention uses two or more laser beams,
By arranging at least two or more centers of laser light spots formed on the resist surface by respective beams in a direction perpendicular to the tracks, equivalent positions between two adjacent tracks can be determined between marks or pits. Where the mark to be formed and / or
Alternatively, the pits are formed as a continuous shape without boundaries between tracks. Here, being at an equivalent position means being at a position along the trajectory of the head moving in and out on the medium between adjacent tracks.

Generally, to form a pattern on an optical recording medium having a guide groove in the data area and pits in the header area, continuous light from a laser oscillator is used for the guide groove as in the master master exposure apparatus shown in FIG. And a pit beam, and the light amount is controlled and modulated, respectively. Since the two or more laser beams used for forming the pits in the method of the present invention do not complicate the master master disc exposure apparatus, it is possible to use the light amount control and modulated pit beams separately for two or more. Preferably, at least one may be a laser beam for forming a guide groove for tracking.

The spots formed on the resist surface by two or more laser beams, respectively, need not be the same in size and shape, but the overall shape of the composite laser light spot consisting of a plurality of spots is formed. If the shape of the pit in the direction perpendicular to the track is symmetrical with respect to the track center, the mark or pit reading accuracy is improved, and therefore it is preferable that the shape be symmetrical with respect to the track center. Also, in order for the mark or pit to have a continuous shape between adjacent tracks, the effective width of the composite laser beam spot in the direction perpendicular to the track must be wider than the track width. Since the width of the mark becomes narrow in the adjacent portion and reading becomes impossible, it is preferable that the width be within 1.4 times the track width.

In the optical recording medium manufactured by using the stamper in which the pits in the header area are continuously formed between the adjacent tracks according to the present invention, the diffraction signal due to the pits can be ignored except at the edges of the pits. Good detection can be performed based on the difference in reflected light intensity from each of the mark and the pit, and the track number can be read during a seek because there is no boundary between the mark or the pit in the direction orthogonal to the track.

However, if the undulation at the mark / pit boundary in the direction orthogonal to the track is large in the portion where the marks or pits are continuously formed, a timing shift occurs in the information reading of the header area between the adjacent tracks. , The reading accuracy during seeking is reduced. If the laser light spot used to form the mark and pit in the header area is circular, the undulation at the uneven boundary in the direction perpendicular to the track will be large, but a composite laser light spot consisting of multiple laser light spots In the method of the present invention used, ON / O of each laser beam was used.
By controlling the FF time, it is possible to reduce the undulation in the direction orthogonal to the track at the mark / pit boundary. At this time, if all of the plurality of laser light spots have the same size and are arranged symmetrically with respect to the track center, all the laser beams can be turned on / off at the same timing, thereby simplifying the control.

The stamper for the optical recording medium is manufactured by the following method. First, a resist layer is formed on a precisely polished glass substrate. Usually, a positive resist is used, but a negative resist can also be used. Next, the formed resist layer is exposed by irradiating a laser beam, and is developed to form grooves and marks / pits. Thereafter, the master on which the grooves and the marks / pits are formed is subjected to a heat treatment. After a conductive thin film made of nickel or the like is formed on the resist layer on the master, electroforming is performed to form an optical recording medium master made of nickel or the like on the resist layer. Thereafter, the optical recording medium master is peeled from the resist layer. Thereby, the stamper of the optical recording medium is completed.

Using this stamper, a resin substrate made of polycarbonate, polymethyl methacrylate, amorphous polyolefin or the like is produced by an injection molding method. In addition, the substrate can be manufactured by a 2P method using an ultraviolet curable resin. On this substrate, a reflective layer, a recording layer,
A protective layer and a liquid lubricating layer are formed. As the reflective layer, a material having a high reflectance at a laser wavelength used for recording and reproduction, such as a metal such as Al, Ag, Au, Cu, Ti, or Ni, or an alloy thereof is used. When the thickness of the recording layer is sufficiently large, the reflective layer may not be provided. Also, AlN, SiN, GeN, Ta ₂ O ₅ , ZnS
It may be a dielectric layer consisting of -SiO ₂ and the like is. In the case of magneto-optical recording, the recording layer is made of TbFeCo, GdFeCo, G
Amorphous rare earth transition metals having large perpendicular magnetic anisotropy, such as dTbFeCo, DyFeCo, etc .;
And the like. In the case of phase change recording, the recording layer is made of a material such as GeSbTe or AgInSbTe whose optical constant changes between a crystal and an amorphous.
In the case of the write-once type, the recording layer is composed of a dye such as cyanine, phthalocyanine or naphthalocyanine. AlN on the recording _{layer, SiN, GeN, Ta 2 O} 5, ZnS-
A transparent protective layer made of SiO ₂ or a resin having a high hardness is formed. This protective layer may be a multilayer, for example, a layer having excellent self-lubricating properties such as diamond-like carbon. The liquid lubricating layer is composed of a lubricant such as perfluoropolyether and silicone oil.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to examples. Note that the present invention is not limited to the following embodiments.

Embodiment 1 First, the used mastering device will be described. Wavelength 351 from Ar laser
nm continuous light is separated into two laser beams (main beam and sub-beam) by a separating prism, and after passing through a light quantity controlling electro-optical element and a modulating electro-optical element, respectively, is shaped by a collimator lens and a pinhole. You. The shaped laser beam is synthesized by the synthesizing prism, and is condensed on the resist surface on the master by an objective lens having a numerical aperture of 0.90 installed in a focus servo mechanism. Here, the master is set on a rotary table, and the objective lens is set on a slider. The pattern consisting of spiral guide grooves and pit rows is exposed on the rotating master while moving the objective lens toward the center of rotation. I do.

A collimator lens having the same laser beam diameter before and after the main beam of the mastering device is installed so that the diameter of the laser beam is doubled before and after in the optical path of the sub beam. A collimator lens was installed. The main beam, so that the center of the laser beam spot formed on the resist surface by each laser beam is separated in the direction perpendicular to the track,
The incident position of the sub-beam on the objective lens was adjusted. With this apparatus, control is performed so that only guide grooves are formed in the data area and only marks and pits are formed in the header area, and a 70 nm-thick resist film formed on the glass master is rotated at a rotation speed of 600 rpm and a track pitch of 400 nm. With radius 3
Exposure was performed from 0 mm to 60 mm. The sub-beam was used for exposing the guide groove, and both the main beam and the sub-beam were used for exposing the pit. Since the laser beam spot formed by the sub beam is smaller than that formed by the main beam, the ON / OFF time at the time of pit formation is controlled so that the undulation in the direction orthogonal to the track at the mark / pit boundary is reduced. did. The output of the laser beam was set on the basis of the value (P30) at a radius of 30 mm, and was controlled so as to change in proportion to the radius (R) (output at a radius Rmm = P30 × R / 30). With this control, the opening width of the guide groove and the pit formed by developing with an alkali developing solution after exposure is adjusted by an atomic force microscope (AFM).
As a result, it was constant in all areas. In addition, the pit depth 1 / corresponding to the effective width of the mark / pit formation laser beam spot in the direction orthogonal to the track.
The width at 2 was 495 nm.

FIG. 2 is a plan view schematically showing the formed resist pattern. In this plan view, only three tracks, a track N, a track N-1 one track inner circumference from the track N, and a track N + 1 one track outer circumference from the track N are shown. Here, a pit formed in a concave shape by removing a black portion by exposure / development is shown. The formed marks or pits are portions where the positions equivalent to each other between two adjacent tracks are marks or pits, and are continuously formed without boundaries between tracks. The undulation in the direction perpendicular to the track at the mark / pit boundary was small.

A stamper was prepared from the master master thus formed by the above-described method, and a polycarbonate substrate was formed by injection molding. A is formed on the mark / pit and guide groove forming surface of this substrate by sputtering.
1 alloy reflection film, SiN dielectric film, TbFeCo recording film,
An SiN dielectric film and a diamond-like carbon film were formed. Further, a perfluoroether liquid lubricant was applied by a pull-up method to produce an optical recording medium.

The optical recording medium of the near-field optical recording type manufactured by the above process was applied to a laser wavelength of 650 nm and an effective NA.
The pit signal reproduction characteristics were evaluated using an SIL tester equipped with a 1.3 SIL on a flying slider. The rotation speed of the optical recording medium is 2400 rpm, and the flying height of the SIL head is 1
When the header reading error rate during seek operation and tracking was measured with the laser power set to 00 nm and the laser power set to 1.3 mW, the seek operation was possible and the header reproduction signal during tracking was good. The error rate of header reproduction was 7 × 10 ⁻⁵ .

(Embodiment 2) After the collimator lens of the main beam, a prism for separating the laser beam into two and a prism for synthesizing the laser beam are installed, and the center of the laser beam spot formed on the resist surface by each laser beam is tracked. The positions of incidence of the two main beams on the objective lens were adjusted so as to be separated in a direction perpendicular to.
Thereby, the shape of the composite laser beam spot in the direction orthogonal to the track became symmetric with respect to the track center. In addition, since the prism for separating the main beam is provided after the electro-optic element for modulation, the ON / OFF timing of each laser beam spot formed by the two main beams at the time of pit formation is the same. A guide groove, marks and pits are formed at a track pitch of 450 nm on a 70 nm-thick resist film formed on a glass master in the same manner as in Example 1 except that the main beam separated into two is used for pit exposure. Formed.
At this time, the width at a pit depth of 1/2 corresponding to the effective width of the mark / pit forming laser beam in the direction orthogonal to the track on the resist surface was 545 nm.
FIG. 4 is a plan view schematically illustrating the formed resist pattern. The formed marks or pits are portions where the positions equivalent to each other between two adjacent tracks are marks or pits, and are continuously formed without boundaries between tracks. The undulation in the direction perpendicular to the track at the mark / pit boundary was small.

A stamper was manufactured from the master master thus formed by the above-described method, and a polycarbonate substrate was formed by injection molding. A is formed on the mark / pit and guide groove forming surface of this substrate by sputtering.
1 alloy reflection film, ZnS-SiO ₂ dielectric film, GeSbT
e recording film was formed ZnS-SiO ₂ dielectric layer. Further, a perfluoroether liquid lubricant was applied by a pull-up method to produce an optical recording medium.

The produced near-field optical recording type optical recording medium was
When the header reading error rate during seek operation and tracking was measured by the same device as in Example 1, the seek operation was possible and the header reproduction signal during tracking was good. The error rate of header reproduction was 3 × 10 ⁻⁵ .

(Embodiment 3) After the main beam collimator lens, a prism for splitting the beam into two and a prism for synthesizing are installed, and a prism for splitting the laser beam into two and a prism for synthesizing are installed on one of them. did. The incident positions of the three main beams on the objective lens were adjusted such that the centers of the laser light spots formed on the resist surface by the respective laser beams were separated in a direction orthogonal to the tracks. By arranging the prism for separating the main beam after the electro-optic element for modulation, the ON / OFF timing of the pits of the laser beam spots formed by the three main beams was the same. A guide groove, marks and pits are formed at a track pitch of 450 nm on a 70 nm-thick resist film formed on a glass master in the same manner as in Example 1 except that a main beam separated into three is used for pit exposure. Formed. At this time, the width at a pit depth of 1/2 corresponding to the effective width of the mark / pit forming laser light spot in the direction orthogonal to the track on the resist surface was 560 nm. FIG. 5 is a plan view schematically showing the formed resist pattern. The formed pits were portions where marks or pits at equivalent positions between two adjacent tracks became marks or pits, and were continuously formed without boundaries between the tracks. Also, there was almost no undulation in the direction perpendicular to the track at the mark / pit boundary.

A stamper was manufactured from the master master thus formed by the above-described method, and a polycarbonate substrate was formed by injection molding. A is formed on the mark / pit and guide groove forming surface of this substrate by sputtering.
1 alloy reflection film, SiN dielectric film, TbFeCo recording film,
An SiN dielectric film and a diamond-like carbon film were formed. Further, a perfluoroether liquid lubricant was applied by a pull-up method to produce an optical recording medium.

The produced near-field optical recording type optical recording medium is
When the header reading error rate during seek operation and tracking was measured by the same device as in Example 1, the seek operation was possible and the header reproduction signal during tracking was good. The error rate of header reproduction was 1 × 10 ⁻⁵ .

(Comparative Example 1) A mastering device was used in which the beam diameter of both the main beam and the sub beam was doubled before and after the collimator lens, and the sub beam was formed for forming the guide groove and the main beam was formed for forming the pit. Except that a beam was used, guide grooves and pits were formed on a glass master at a track pitch of 400 nm in the same manner as in Example 1. At this time, the width at a pit depth of 1/2 corresponding to the effective width of the mark / pit forming laser beam on the resist surface in the direction orthogonal to the track was 250 nm. FIG. 6 is a plan view schematically showing the formed resist pattern. The opening width of the formed pits is smaller than the track width, and the pits are not continuous with each other, but are separated from each other, even in the portion where the pits have equivalent positions between two adjacent tracks.

A stamper was prepared from the master master thus formed by the above-described method, and a polycarbonate substrate was formed by injection molding. An Al alloy reflective film, a SiN dielectric film, a TbFeCo recording film, a SiN dielectric film, and a diamond-like carbon film were formed on the pit and guide groove forming surfaces of this substrate by a sputtering method. Further, a perfluoroether liquid lubricant was applied by a pull-up method to produce an optical recording medium.

The manufactured near-field optical recording type optical recording medium was
When the header reading error rate during seek operation and tracking was measured by the same device as in Example 1, the header signal could not be reproduced during seek and the seek operation could not be performed. The header signal could be reproduced during tracking, but the error rate was 1 × 10 ^-2 .

(Comparative Example 2) The beam diameter of both the main beam and the sub beam was set to be doubled before and after the collimator lens, and the effective width of the main beam in the direction orthogonal to the track on the resist surface was set. In the same manner as in Example 1, except that a mastering device having a slit of 1.0 mm width in the optical path was used so as to reduce the width of the beam, and a sub beam was used to form the guide groove and a main beam was used to form the pit. Track pitch 450nm on glass master
Formed guide grooves and pits. At this time,
Pit depth 1 / corresponding to the effective width of the pit forming laser beam in the direction perpendicular to the track on the resist surface
The width at 2 was 700 nm. FIG. 7 is a plan view schematically showing the formed resist pattern. The formed pits are portions where marks or pits have equivalent positions between two adjacent tracks and are continuously formed without boundaries between tracks. Was formed narrow.

A stamper was manufactured from the master master thus formed by the above-described method, and a polycarbonate substrate was formed by injection molding. A is formed on the mark / pit and guide groove forming surface of this substrate by sputtering.
1 alloy reflection film, ZnS-SiO ₂ dielectric film, GeSbT
e recording film was formed ZnS-SiO ₂ dielectric layer. Further, a perfluoroether liquid lubricant was applied by a pull-up method to produce an optical recording medium.

The produced near-field optical recording type optical recording medium was
When the header reading error rate at the time of seek operation and tracking was measured by the same device as in Example 1, the seek operation was possible, but the error rate of header reproduction was 5 × 10 ⁻³ .

[0043]

According to the present invention, it is possible to provide a near-field optical recording medium capable of reproducing a header signal during both tracking servo and seek operations and having a high seek speed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a mastering device used in the present invention.

FIG. 2 is a schematic diagram showing a resist pattern formed in Example 1.

FIG. 3 is a schematic view showing a resist pattern formed in Example 2.

FIG. 4 is a schematic view showing a resist pattern formed in Example 3.

FIG. 5 is a schematic view showing a resist pattern formed in Comparative Example 1.

FIG. 6 is a schematic diagram showing a resist pattern formed in Comparative Example 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ar laser 2 Separation prism 3, 8 Light quantity control element 4, 9 Light modulation element 5, 10 Collimator 6, 7 Mirror 11 Cylindrical lens, slit or aperture 12 Synthetic prism 13 Objective lens 14 Resist master

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 7/24 565 G11B 7/24 565F 7/26 501 7/26 501 511 511 F-term (Reference) 5D029 KB03 WA30 WA31 5D090 AA01 BB01 CC01 CC14 DD01 FF22 GG02 GG10 GG16 GG28 KK12 KK14 LL02 5D119 AA29 BA01 BB09 DA01 EB13 EC10 EC40 EC44 EC46 JA02 5D121 AA02 BB21 BB26 BB38 CA03 CB03

Claims (5)

[Claims] 1. A method of manufacturing a stamper for an optical recording medium, comprising a step of manufacturing a master master for forming marks and / or pits by exposing a resist applied on a glass master to laser light. When manufacturing a laser beam, two or more laser light spots are used to form marks and / or pits constituting the signal in a header area where a signal for address reproduction is recorded, and two adjacent tracks are equivalent to each other. A stamper for an optical recording medium, characterized in that marks and / or pits formed in portions where marks and / or pits are continuous have no boundaries between tracks. 2. The method according to claim 1, wherein the center of at least two of the two or more laser light spots used for forming marks and / or pits in the header area is separated on the resist surface in a direction perpendicular to the tracks. The method for producing a stamper for an optical recording medium according to claim 1, wherein: 3. An effective width of a composite spot composed of two or more laser light spots used for forming a mark and / or a pit in a header area in a direction orthogonal to a track is at least one time and at least 1.4 times the track width. The method for manufacturing a stamper for an optical recording medium according to claim 1 or 2, wherein the method is as follows. 4. The overall shape of a composite spot comprising two or more laser light spots used for forming a mark and / or a pit in a header area is symmetric with respect to a track center. 4. The method of manufacturing a stamper for an optical recording medium according to any one of items 3 to 3. 5. An optical recording medium manufactured by using a stamper manufactured by the manufacturing method according to claim 1.