WO2004025641A1

WO2004025641A1 - Method of producing optical recording medium-use original and method of producing optical recording medium

Info

Publication number: WO2004025641A1
Application number: PCT/JP2003/011668
Authority: WO
Inventors: Syuji Tsukamoto
Original assignee: Tdk Corporation
Priority date: 2002-09-13
Filing date: 2003-09-11
Publication date: 2004-03-25
Also published as: AU2003266510A1; TW200407884A; JP2004110889A

Abstract

A method of producing an optical recording medium-use original, capable of assigning 2N kinds of pits different in size to the virtual recording cells of an optical recording medium to change the light reflectance of the virtual recording cells in 2N steps. The method comprises the step of applying a laser beam to expose a photoresist original and form patterns on the photoresist original, and the step of transferring the patterns formed on the photoresist original to produce an optical recording medium-use original, wherein the exposure power of a laser beam to be applied to the photoresist original is set according to a maximum light reflectance and/or a minimum light reflectance assigned to the virtual recording cells of the optical recording medium.

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing an optical recording medium master and a method for manufacturing an optical recording medium.

The present invention relates to a method for manufacturing a master for an optical recording medium and a method for manufacturing an optical recording medium. More specifically, ^2N types of pits having different sizes are provided in a virtual recording cell of the optical recording medium. Assignment, ^2N types of pits with different sizes are assigned to the manufacturing method of the master for the optical recording medium and the virtual recording cell that can change the light reflectance of the virtual recording cell to ^2N steps, The present invention relates to a method for manufacturing an optical recording medium in which the light reflectance of a cell is changed in ^2N steps. Conventional technology

Conventionally, optical recording media such as CDs and DVDs have been widely used as recording media for recording digital data. These optical recording media include CD-ROMs, DVD-ROMs, and other types of optical recording media (ROM-type optical recording media) that cannot write or rewrite data, and CD-R and DVD-R. Optical recording media that can write data but cannot rewrite data (write-once optical recording media), and optical recording media that can rewrite data, such as CD-RW and DVD-RW ( Rewritable optical recording medium). In these optical recording media, as a data recording method, a method of modulating data to be recorded to the length of a pit and a blank area along a track is widely used.

In recent years, in response to the demand for high-density data recording, tracks on optical recording media are virtually divided into virtual recording cells having a predetermined length, and 2 ^N types of virtual recording cells (N is 2 A so-called “multi-level recording method” has been proposed in which one of the recording marks having different numbers is formed and N-bit data is recorded. In the multi-level recording method, one of ^2N types of pits is formed in a virtual recording cell to record N-bit data. As a result, the virtual recording cell has a light reflectivity according to the type of the formed pit, and therefore, the virtual recording cell formed with a different pit has a different light reflection with respect to the laser beam. Therefore, the data can be reproduced by irradiating the laser beam along the track of the optical recording medium and detecting the light amount of the laser beam reflected by the virtual recording cell.

In order to manufacture a ROM-type optical recording medium in which N-bit data is recorded in each virtual recording cell using such a multi-level recording method, 2 ^N types of sizes are required for the virtual recording cell. different allocation of pit, is required to alter the light reflectance of the virtual recording cell 2 ^N stages, the but connexion, the virtual recording cell having an optical recording medium, allocated 2 ^N kinds of different sizes pit the However, it is required to fabricate an optical recording medium master so that the light reflectance of the virtual recording cell can be changed in ^2N steps. Disclosure of the invention

Therefore, the present invention provides ^2N kinds of pits having different sizes to the virtual recording cells of the optical recording medium, and can change the light reflectance of the virtual recording cells to ^2N steps. The purpose is to provide a method for manufacturing a master.

Another object of the present invention is to provide a method for manufacturing an optical recording medium in which 2 ^N kinds of different-sized pits are assigned to virtual recording cells, and the light reflectance of the virtual recording cells is changed in ^2N steps. To provide.

The inventor of the present invention has conducted intensive studies in order to achieve the object of the present invention. As a result, when the exposure power of the laser beam irradiated for exposing the photoresist master is changed, the laser to the photoresist master is changed. The relationship between the irradiation time of the beam and the light reflectance of the virtual recording cell of the optical recording medium changes, and the higher the level of the exposure power of the laser beam irradiated to expose the photoresist master, the higher the optical recording medium Highest virtual recording cell Even if a large reflectivity is assigned, pits of different sizes are formed in the virtual recording cell without significantly changing the irradiation time of the laser beam onto the photoresist master, and data with different recording levels are formed. On the other hand, the lower the level of the exposure power of the laser beam emitted to expose the photoresist master, the lower the minimum reflectivity assigned to the virtual recording cell. It is now possible to record data of different recording levels by forming pits of different sizes in the virtual recording cell without significantly changing the irradiation time of the laser beam onto the photoresist master. I found out.

The present invention is based on such findings, and according to the present invention, the object of the present invention is to form ^2N kinds of pits in a plurality of virtually set virtual recording cells, A method for producing an optical recording medium master for producing an optical recording medium on which the above data is recorded, comprising irradiating a laser beam, exposing the photoresist master, and forming a pattern on the photoresist master. Forming an optical recording medium master by transferring the pattern formed on the photoresist master, and forming a maximum optical reflection allocated to the virtual recording cell of the optical recording medium. An exposure power of the laser beam for irradiating the photoresist master according to the reflectance and / or the minimum reflectance. It is.

In a preferred embodiment of the present invention, the exposure power of the laser beam applied to the photoresist master is set to a higher level as the maximum reflectance assigned to the virtual recording cell of the optical recording medium is higher.

In another preferred embodiment of the present invention, as the minimum reflectance assigned to the virtual recording cell of the optical recording medium is lower, the exposure power of the laser beam for irradiating the photoresist master is set to a lower level. .

In a further preferred aspect of the present invention, as the maximum relative reflectance assigned to the virtual recording cell of the optical recording medium is higher, the photo height is higher. The exposure power of the laser beam irradiating the resist master is set to a high level, and satisfies the maximum relative light reflectance RR a H and the minimum relative light reflectance RR h H 1S 100-RR a H and RR h H It is set as follows.

In another preferred embodiment of the present invention, as the minimum reflectance assigned to the virtual recording cell of the optical recording medium is lower, the exposure power of the laser beam for irradiating the photoresist master is set to a lower level. The maximum relative light reflectance RRaH and the minimum relative light reflectance RRhH are set so as to satisfy 100—RRaL> RRhL.

Further, as a result of intensive studies to achieve the above object of the present invention, the inventor formed pits of the same size in virtual recording cells of an optical recording medium and recorded data of the same recording level. The exposure power and / or the pulse width of the exposure power of the laser beam applied to the photoresist master, regardless of the linear velocity of the laser beam applied to the photoresist master. It has been found that two or more bits of data in each virtual recording cell can be recorded.

The present invention is based on such findings, and according to the present invention, the object of the present invention is also to form ^2N kinds of pits in a plurality of virtual recording cells that are virtually set, and to provide two bits. A method for manufacturing an optical recording medium master for producing an optical recording medium on which data equal to or more than the data is recorded, comprising irradiating a laser beam to expose the photoresist master, and forming a pattern on the photoresist master. Forming an optical recording medium master by transferring the pattern formed on the photoresist master, and forming a virtual recording cell of the same size on the virtual recording cell of the optical recording medium. When forming a pit and recording data at the same recording level, regardless of the linear velocity of the laser beam applied to the photo-resist master, the laser beam applied to the photo-resist master is used. This is achieved by a method for manufacturing a master for an optical recording medium, wherein the exposure power of the beam and / or the pulse width of the exposure power are set to be substantially the same.

In a preferred embodiment of the present invention, a pit of the same size is formed in the virtual recording cell of the optical recording medium, and data of the same recording level is formed. When recording the laser beam, the exposure power and the pulse width of the exposure power of the laser beam applied to the photoresist master are substantially the same regardless of the linear velocity of the laser beam applied to the photoresist master. As described above, the power of the laser beam applied to the photoresist master is controlled.

In a preferred embodiment of the present invention, the linear velocity V of the laser beam irradiating the photoresist master, the length L of the virtual recording cell, and the photo necessary to substantially saturate the light reflectance of the virtual recording cell. The exposure power level of the laser beam irradiating the photoresist master and the length of the virtual recording cell so that the irradiation time T s of the laser beam irradiating the resist master satisfies T s ≤ L / V. L and the linear velocity V of the laser beam applied to the photoresist master are set.

Another object of the present invention is to manufacture an optical recording medium in which ^2N kinds of pits are formed in a plurality of virtual recording cells virtually set on a substrate, and data of 2 bits or more are recorded. Irradiating a laser beam to expose a photoresist master, forming a pattern on the photoresist master, and transferring the pattern formed on the photoresist master, A step of producing an optical recording medium master, and a step of transferring the pattern transferred to the optical recording medium master to produce the substrate, wherein the maximum allocated to the virtual recording cells of the optical recording medium is provided. A method for manufacturing an optical recording medium, comprising: setting an exposure power of the laser beam for irradiating the photoresist master according to a light reflectance and a Z or a minimum light reflectance. It is made.

In another preferred embodiment of the present invention, the higher the maximum reflectance assigned to the virtual recording cell of the optical recording medium, the higher the exposure power of the laser beam applied to the photoresist master is set to a higher level. Is done.

In a further preferred aspect of the present invention, the higher the maximum relative reflectance assigned to the virtual recording cell of the optical recording medium, the higher the exposure power of the laser beam applied to the photo resist master is set to a higher level. It is set to satisfy the maximum relative light reflectance RR a H and the minimum relative light reflectance RR h H 110 0-RR a H <RR h H.

In another preferred embodiment of the present invention, as the minimum reflectance assigned to the virtual recording cell of the optical recording medium is lower, the exposure power of the laser beam for irradiating the photoresist master is set to a lower level, The maximum relative light reflectance RRaH and the minimum relative light reflectance RRhH are set so as to satisfy 100—RRaL> RRhL.

The object of the present invention is also to manufacture an optical recording medium in which ^2N kinds of pits are formed in a plurality of virtual recording cells virtually set on a substrate and data of 2 bits or more is recorded. A method of irradiating a laser beam to expose a photoresist master to form a pattern on the photoresist master, and transferring the pattern formed on the photoresist master. Producing a master for an optical recording medium, and transferring the pattern transferred to the master for an optical recording medium to produce the substrate. When forming a pit of the same size and recording data of the same recording level, irradiate the photoresist master to the photo resist master regardless of the linear velocity of the laser beam to irradiate the photoresist master. The exposure power of the laser beam and / or the pulse width of the exposure power are set to be substantially the same.

In a preferred embodiment of the present invention, when a pit having the same size is formed in the virtual recording cell of the optical recording medium and data of the same recording level is recorded, a laser is applied to the photoresist master. Laser irradiating the photoresist master so that the exposure power of the laser beam and the pulse width of the exposure beam are substantially the same regardless of the linear velocity of the beam. Beam power Controlled.

In a preferred embodiment of the present invention, the linear velocity V of the laser beam irradiating the photoresist master, the length L of the virtual recording cell, and the light reflectance required to substantially saturate the light reflectance of the virtual recording cell. The exposure power level of the laser beam applied to the photoresist master and the length of the virtual recording cell so that the irradiation time T s of the laser beam applied to the photoresist master satisfies T s ≤ L / V. And the linear velocity V of the laser beam applied to the photoresist master are set.

The above and other objects and features of the present invention will be apparent from the following description and corresponding drawings.

A brief description of surface 0

FIG. 1 is a schematic perspective view of an optical recording medium according to a preferred embodiment of the present invention.

FIG. 2 is an enlarged schematic cross-sectional view of a portion surrounded by a circle of the optical recording medium shown in FIG.

FIG. 3 shows the pits P a, P b, P c, P d, P e, P f, and P h formed in the plurality of virtual recording cells S of the optical recording medium 1 and the respective virtual recording cells S. 4 is a diagram illustrating a relationship between light reflectances.

Figure 4 is preferably _t Figure 5 is a diagram showing a cutlet coating machine used in the method of manufacturing a master for optical recording medium according to embodiment (a) to FIG. 5 of the present invention (f), the optical recording FIG. 4 is a process chart showing a production process of a medium master.

6 (a) to 6 (c) are process diagrams showing a manufacturing process of the optical recording medium 1.

FIG. 7 is a diagram showing a modulation pattern of the power of a laser beam applied to a virtual region of a photosensitive material layer of a photoresist master corresponding to a virtual recording cell of an optical recording medium.

FIG. 8 is a process chart showing a method of forming a minimum pit Pa in a virtual recording cell of an optical recording medium. FIG. 9 is a process chart showing a method of forming a maximum pit Ph in a virtual recording cell of an optical recording medium.

Fig. 10 shows the time of irradiating the laser beam with the power set to the exposure power to the virtual area corresponding to the virtual recording cell of the photosensitive material layer of the photoresist master, and using the photoresist master. 7 is a graph showing a relationship between the optical reflectance of a virtual recording cell of the manufactured optical recording medium.

Fig. 11 shows the irradiation time of the laser beam when the exposure power w of the laser beam irradiating the virtual area corresponding to the virtual recording cell of the photosensitive material layer of the photoresist master was changed, and the photo resist 6 is a graph showing the relationship between the master disk and the optical reflectance of a virtual recording cell of an optical recording medium manufactured.

FIG. 12 is a view showing a virtual region of a photosensitive material layer of a photoresist master corresponding to a virtual recording cell of an optical recording medium used in a method of manufacturing an optical recording medium master according to another preferred embodiment of the present invention. 6 is a diagram showing a modulation pattern of the power of an irradiated laser beam.

Figure 13 shows the irradiation time of the laser beam when the exposure power w of the laser beam applied to the virtual area corresponding to the virtual recording cell of the photosensitive material layer of the photoresist master was changed, and the photoresist master 5 is a graph showing the relationship between the optical recording medium and the light reflectance of the virtual recording cell of the manufactured optical recording medium.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a partially cut-away schematic perspective view of an optical recording medium, and FIG. 2 is a substantially enlarged perspective view of a circled portion in FIG.

As shown in FIGS. 1 and 2, the optical recording medium 1 according to the present embodiment is configured as a CD-ROM type optical recording medium, and has a light transmitting substrate. It comprises a plate 11, a reflective layer 22 and a protective layer 23 provided on the light-transmitting substrate 11.

As shown in FIG. 1, the light-transmitting substrate 11 is formed in a disk shape using a light-transmitting resin.

The light-transmitting resin used for forming the light-transmitting substrate 11 is not particularly limited as long as it has a high transmittance with respect to a laser beam used for reproducing data. However, polycarbonate is preferably used.

In FIG. 2, the lower surface of the light-transmitting substrate 11 constitutes a light incident surface on which a laser beam is incident. As shown in FIG. 2, the upper surface of the light-transmitting substrate 11 has a central portion. A plurality of eight different sizes of pits P a, P b, P c, P d, P e, P f, P g, and P h are formed spirally from the vicinity to the outer edge. I have.

The reflective layer 22 is a thin film layer for reflecting a laser beam transmitted through the light-transmitting substrate 11 when reproducing data recorded on the optical recording medium 1, and mainly includes a metal such as gold or silver. It is formed by the sputtering method used as a component.

As shown in FIG. 2, in order to protect the reflective layer 22, a protective layer 23 is formed so as to cover the surface of the reflective layer 22.

In this embodiment, the light-transmitting substrates 11 each have a thickness of about 1.2 mm.

As shown in FIG. 2, the track of the optical recording medium 1 is virtually divided into a plurality of virtual recording cells S, S,... Having a predetermined length. Constitute a recording unit for recording.

FIG. 3 shows the pits Pa, Pb, Pc, Pd, Pe, Pf, Pg, Ph formed on the plurality of virtual recording cells S of the optical recording medium 1, and each virtual recording. 6 is a diagram illustrating a relationship between light reflectances of a cell S.

As shown in FIG. 3, the virtual recording cells S, S,... Are virtually set so that the length L in the direction along the track is smaller than the spot diameter D of the laser beam. ing. As shown in FIG. 3, the light reflectivity of the virtual recording cell S increases as the size of the pit P k (1 ^ = & Nana 11) formed in the virtual recording cell S decreases. In this embodiment, since eight types of pits having different sizes are formed in the virtual recording cell S, 3-bit data is recorded on the optical recording medium 1.

The optical recording medium 1 configured as described above is manufactured as follows.

First, an optical recording medium master, ie, a stamper, for producing the light-transmitting substrate 11 is produced.

Figure 4, as shown in the preferred is a diagram showing the force Tsu coating machine used in the method of manufacturing the master for such an optical recording medium to embodiment _c Figure 4 of the present invention, Chikara' according to this embodiment The scanning machine 100 includes a laser generator 102 for generating a laser beam 101, an optical modulator (EOM: Electro Optic Modulator) 103 using an electro-optic effect, and a beam splitter 104, 1 , A light modulation unit 105, an optical head 107, and a turntable 108. On the turntable 108, a photo resist master 110 is placed.

The photoresist master 110 is a disk-shaped master having a glass substrate 110a and a photosensitive material layer 110b laminated on the glass substrate 110a, and is used for an optical recording medium. Used as a mold for producing masters. Further, as shown in FIG. 4, the optical modulation unit 105 includes a lens 105a, an optical modulator 105b, and a lens 105c, and the optical head 107 includes: A mirror 107a and a lens 107b are provided. In the cutting machine 100 configured as described above, the laser beam 101 is focused on the photosensitive material layer 110 b of the photo resist master 110 as follows, and The master layer 110 is exposed to the light-sensitive material layer 110b, and as a result, the latent image corresponding to the pit Pk to be formed in the virtual recording cell S 110c force Photosensitive material layer 1 Formed as 10b. First, a pulse signal train 105 d corresponding to the pattern of the latent image 110 c to be formed on the photosensitive material layer 110 b of the photoresist master 110 is sent to the light modulation unit 105. While input to the optical modulator 105 b, the turntable 108 on which the photoresist master 110 is placed is rotated, and the optical head 107 is moved to the photoresist master 110. Move in the radial direction of.

The power of the laser beam 101 generated by the laser generator 102 was modulated by the optical modulator 103 to a predetermined power suitable for the exposure of the photosensitive material layer 110b. After that, it is reflected by the beam splitter 104, the beam splitter 106 and the mirror 107a, and is condensed on the photo resist master 110 by the lens 107b. . As a result, the pulsed laser beam 101 is irradiated onto the photosensitive material layer 110 b of the photo resist master 110, and a latent image corresponding to the pit P k to be formed in the virtual recording cell S is formed. 110c force formed on the photosensitive material layer 110b.

FIGS. 5 (a) to 5 (f) are process drawings showing the process of manufacturing an optical recording medium master.

First, as shown in FIG. 5 (a), a glass substrate 110a and a photosensitive material layer 1 having a thickness of 100 to 150 nm formed on the glass substrate 110a are formed. A photoresist master 110 having 10b is prepared. An adhesive layer for improving the adhesiveness may be formed between the glass substrate 110a and the photosensitive material layer 110b.

Next, as shown in FIG. 5 (b), the laser beam 101 whose power has been modulated by the optical modulator 105b, the power lens 107b, and the photo-resist master 1 The area of the photosensitive material layer 110 Ob irradiated with the laser beam 101 after being focused on the 10 photosensitive material layer 110 b is exposed by the laser beam 101. The width and depth of the exposed region of the photosensitive material layer 110b are determined according to the irradiation energy of the laser beam 101.

Thus, a virtual recording cell S is formed on the photosensitive material layer 110b. A latent image 110c corresponding to the power pit Pk is formed.

Further, a developing solution such as a sodium hydroxide solution is sprayed on the exposed area of the photosensitive material layer 110b of the photoresist master 110, as shown in FIG. 5 (c). The latent image 110c formed on the photosensitive material layer 110b is developed to form a concave portion 202 corresponding to the latent image 110c.

When a plurality of recesses 202 corresponding to the pits P k to be formed in the virtual recording cell S are formed in the photosensitive material layer 110 b in this way, FIG. As shown in (1), a thin metal film 203 such as nickel is formed on the developed photosensitive material layer 110b by electroless plating or vapor deposition.

Further, as shown in FIG. 5 (e), about 0.3 μm is formed on the metal thin film 203 by using a thick film with the surface of the metal thin film 203 as a cathode and nickel or the like as a cathode. A metal film 204 having a thickness of m is formed. Next, the photoresist master 110 is peeled off from the metal thin film 203, washed and subjected to necessary processing, and as shown in FIG. 5 (f), the optical recording medium master 210 is removed. 5 is produced.

As shown in FIG. 5 (f), the master for optical recording medium 205 produced in this manner has a pattern of a plurality of recesses 202 formed in the photosensitive material layer 110 b. Is transferred to form a plurality of convex portions 206. Further, using the optical recording medium master 205, the optical recording medium 1 in which the pit Pk is formed in each virtual recording cell S is manufactured as follows.

First, as shown in FIG. 6 (a), a light transmissive substrate 11 having a thickness of about 1.2 mm is injected by an injection molding method using an optical recording medium master 205. Molded.

As a result, a plurality of convex portions 2 0 6 formed on the surface of the master for optical recording medium ² 0 5, are transferred to the light transmitting substrate 1 1 surface, the surface, a plurality of times 11668

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The light-transmitting substrate 11 on which a plurality of pits are formed is manufactured.

Next, as shown in FIG. 6 (b), a reflection layer 22 is formed on the surface of the light transmitting substrate 11 on which the pits Pk are formed. The reflective layer 22 can be formed, for example, by a vapor phase growth method using a chemical species containing the constituent element of the reflective layer 22. Examples of the vapor growth method include a vacuum evaporation method and a sputtering method.

Further, as shown in FIG. 6 (c), a protective layer 23 is formed on the surface of the reflective layer 22. The protective layer 23 is formed, for example, by dissolving an acrylic ultraviolet curable resin or an epoxy ultraviolet curable resin in a solvent to prepare a resin solution, and spin-coating or the like on the reflective layer 22. It can be formed by applying a resin solution.

As described above, the optical recording medium 1 in which the pit Pk is formed in each virtual recording cell S is manufactured.

As described above, in order to record 3-bit data in each virtual recording cell S of the optical recording medium 1, eight types of pits having different sizes are formed on the optical recording medium 1. It is necessary.

However, as described above, the pit pk to be formed in the virtual recording cell S of the optical recording medium 1 is obtained by transferring the plurality of convex portions 206 formed on the optical recording medium master 205, The plurality of projections 206 formed on the optical recording medium master 205 are formed on the photosensitive material layer 110b of the photoresist master 110. Since the recesses 202 are transferred and formed, in order to form eight kinds of pits having different sizes on the optical recording medium 1, the photo-resist master 110 can be used as a light-sensitive medium. In the conductive material layer 110b, a plurality of recesses 202 having sizes corresponding to the pits Pk having different sizes to be formed in the virtual recording cell S of the optical recording medium 1 may be formed. is necessary.

As described above, the width and depth of the exposed region of the photosensitive material layer 110b, that is, the size of the concave portion 202 is irradiated to the region of the photosensitive material layer 110b. Determined by the energy of the laser beam 101 8

14

In order to record 3-bit data in each virtual recording cell S of the optical recording medium 1, the photosensitive material of the photoresist master 110 corresponding to the virtual recording cell S of the optical recording medium 1 must be used. It is necessary to control the energy of the laser beam 101 applied to the virtual area 3 ′ of the layer 1 1 1 1) in eight steps. FIG. 7 shows the power of the laser beam 101 applied to the virtual area 3 'of the photosensitive material layer 11013 of the photoresist master 110 corresponding to the virtual recording cell S of the optical recording medium 1. 6 is a diagram illustrating a modulation pattern. As shown in FIG. 7, the laser beam 1 applied to the virtual area S ′ of the photosensitive material layer 110 b of the photoresist master 110 corresponding to the virtual recording cell S of the optical recording medium 1 The power of 0 1 is selectively modulated into the exposure power and the base power P b, and corresponds to the size of the concave portion 202 to be formed in the virtual region S ′ of the photosensitive material layer 110 b. The time Ta, Tb, Tc, Td, Te, Tf, Tg, Th in which the power of the laser beam is set to the exposure power ^ PH is set. Here, the modulation pattern of the power of the laser beam 101 corresponds to the waveform of the pulse signal train 105 d input to the optical modulator 105 b.

FIG. 8 is a process chart showing a method of forming the minimum pit Pa in the virtual recording cell S of the optical recording medium 1.

First, as shown in FIG. 8 (a), the pulse width of the laser beam 101 to be irradiated on the photosensitive material layer 110b is set to the minimum width Ta.

Next, the laser beam 101 is irradiated onto the virtual region s ′ of the photosensitive material layer 110 b of the photo resist master 110. Here, since the pulse width of the laser beam 101 is set to the minimum width Ta, the virtual area S ′ of the photosensitive material layer 110 b of the photoresist master 110 is irradiated. The energy of the laser beam 101 is minimum, and therefore the size of the latent image 110c formed on the photosensitive material layer 110b is also minimum. ·

Further, the latent image 110 c formed in the virtual area S ′ of the photosensitive material layer 110 b of the photo resist master 110 is developed, and the photosensitive material In the virtual region S ′ of the material layer 110 b, the smallest concave portion 202 is formed. Next, a metal thin film (not shown) of nickel or the like is formed on the developed photosensitive material layer 110b by an electroless plating or a vapor deposition method, and the metal film is further formed on the metal thin film. After the formation, the photoresist master 110 is peeled off from the metal thin film, washed and subjected to necessary processing, and as shown in FIG. 8 (d), the optical recording medium master 205 is formed. It is made.

Further, the optically transparent substrate 11 having a thickness of about 1.2 mm is injection-molded by injection molding using the optical recording medium master 205, as shown in FIG. 8 (e). Then, the light-transmitting substrate 11 on which the minimum pit Pa is formed is manufactured.

Thus, by setting the pulse width of the laser beam 101 irradiating the virtual area S ′ of the photosensitive material layer 110 b of the photoresist master 110 to the minimum width Ta, The minimum pit Pa can be formed in the virtual recording cell S of the optical recording medium 1, and the maximum light reflectance can be assigned to the virtual recording cell S.

FIG. 9 is a process chart showing a method of forming a maximum pit Ph in a virtual recording cell of an optical recording medium.

First, as shown in FIG. 9 (a), the pulse width of the laser beam 101 to be irradiated on the photosensitive material layer 110b is set to the maximum width Th.

Next, the laser beam is applied to the virtual region S ′ of the photosensitive material layer 110 b of the photo resist master 110. Here, the pulse width of the laser beam 101 is set to the maximum width Th, so that the virtual region S ′ of the photosensitive material layer 110 b of the photoresist master 110 is irradiated. The energy of the laser beam 101 is maximum, and therefore, the size of the latent image 110c formed on the photosensitive material layer 110b is also maximum.

Further, the latent image 110 c formed in the virtual region S ′ of the photosensitive material layer 110 b of the photoresist master 110 is developed, and the photosensitive material TJP2003 / 011668

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In the virtual region S ′ of the material layer 110 b, the smallest concave portion 202 is formed.

Next, a metal thin film (not shown) of nickel or the like is formed on the developed photosensitive material layer 11 Ob by an electroless plating or a vapor deposition method, and a metal film is further formed on the metal thin film. After the formation, the photoresist master 110 is peeled off from the metal thin film, washed and subjected to necessary processing, and as shown in FIG. 8 (d), the master for optical recording medium 205 is formed. Is produced.

Further, a light-transmitting substrate 11 having a thickness of about 1.2 mm is injection-molded by an injection molding method using the optical recording medium master 205, as shown in FIG. 8 (e). Then, the light-transmitting substrate 11 on which the maximum pit Ph is formed is produced.

As described above, by setting the pulse width of the laser beam 01 irradiating the virtual region S ′ of the photosensitive material layer 110 b of the photo resist master 110 to the maximum width Th, the light width can be increased. The maximum pit Ph can be formed in the virtual recording cell S of the recording medium 1, and the minimum light reflectance can be assigned to the virtual recording cell S.

Similarly, the pulse widths of the laser beam 101 irradiating the virtual region S ′ of the photosensitive material layer 110 b of the photo resist master 110 are represented by T b, T c, and T b, respectively. By setting d, T e, T f, and T g, the pits P b, P c, P d, P e, P f, and P g having corresponding sizes are respectively stored in the virtual recording cell S. Once formed, a corresponding light reflectance can be assigned to the virtual recording cell S.

FIG. 10 shows a laser beam 1 1 having a power set to the exposure power w in a virtual area S ′ corresponding to the virtual recording cell S of the photosensitive material layer 110 b of the photo resist master 110. 5 is a graph showing the relationship between the time of irradiating 0 and the light reflectance of the virtual recording cell S of the optical recording medium 1 manufactured using the photoresist master 11.

As described above, in the virtual area S ′ corresponding to the virtual recording cell S of the photosensitive material layer 110 b of the photo resist master 110, the laser beam 110 whose power is set to the exposure power P w Irradiation time was increased Accordingly, that is, as the pulse width of the laser beam 110 increases, the pit P k formed in the virtual recording cell s of the optical recording medium 1 increases, and the light reflectance of the virtual recording cell s Drops.

Therefore, the time during which the laser beam 101 set to the exposure power is applied to the virtual area S ′ corresponding to the virtual recording cell S of the photosensitive material layer 110 b of the photo resist master 110 is set. At Ta, the light reflectance Ra of the virtual recording cell S at the shortest time is assigned as the light reflectance of the virtual recording cell S having the maximum light reflectance, and the laser beam 1 set to the exposure power 1 0 1 irradiates the virtual area S ′ corresponding to the virtual recording cell S of the photosensitive material layer 110 b of the photo resist master 110, and the time when it is Th is the longest. The reflectance R h is assigned as the light reflectance of the virtual recording cell S having the minimum light reflectance, and the light reflectance between the maximum light reflectance Ra and the minimum light reflectance R h is set to seven. And determine the six different types of light reflectance R b, R c, R d, R e, R i, and R g, and determine the pit P k Are assigned as the light reflectances of the virtual recording cells S having different sizes, and the light reflectances of the virtual recording cells S are defined as Ra, Rb, Rc, Rd, Re, Rf, Rg, and R. h, the irradiation time of the laser beam 101 with the exposure power to the virtual area S ′ of the photosensitive material layer 110 b is determined, and the virtual recording cell of the optical recording medium 1 is determined. Depending on the size of the pit P k to be formed on S, the laser beam 10 1 is applied to the virtual area S ′ corresponding to the virtual recording cell S of the photosensitive material layer 110 b of the photo resist master 110. Irradiation makes it possible to record 3-bit data in each virtual recording cell S of the optical recording medium 1.

However, the maximum irradiation time Tma X of the laser beam 101 to the virtual region S of the photosensitive material layer 110 of the photoresist master 110, and Tma X is LZV (where L is the photosensitive material layer). The length of the virtual area S ′ corresponding to the virtual recording cell S of 110b, that is, the length of the virtual recording cell S, and V is the linear velocity of the force-setting machine 100.) Thus, the irradiation time T h of the laser beam 101 for forming the maximum pit P h on the virtual recording cell S is set so that the virtual recording cell S has the minimum light reflectance R h. It must be set below T max.

As shown in FIG. 10, the light reflectance of the virtual recording cell S of the optical recording medium 1 is determined by the laser beam set to the exposure power to the virtual area 3 ′ of the photosensitive material layer 111). When the irradiation time of 101 was within the area A shorter than the first predetermined time, the irradiation power of i ⁷ was not changed much even if the irradiation time of the laser beam 101 was increased. When the irradiation time of the laser beam 101 is within the region B that is equal to or longer than the first predetermined time and shorter than the second predetermined time, the irradiation time of the laser beam 101 increases substantially as the irradiation time of the laser beam 101 increases. When the irradiation time of the laser beam 101 set to the exposure power falls within the region C for the second predetermined time or more, even if the irradiation time of the laser beam 101 increases, The light reflectivity reaches R s without much change. This is because the photosensitive material layer 110b of the photo-resist master 110 changes little by little immediately after being irradiated with the laser beam 101 set at the exposure power, and the exposure power After the first predetermined time has elapsed from the start of the irradiation of the laser beam 101, the degree of deterioration of the photosensitive material layer 110b is increased according to the increase in the irradiation time of the laser beam 101. After the second predetermined time has elapsed, the irradiation time of the laser beam 101 is increased, and the degree of deterioration of the photosensitive material layer 110b hardly increases even after the second predetermined time has elapsed. This is because it has the property of:

Therefore, when the light reflectance in the area A and the area C as well as the light reflectance in the area B are assigned as the light reflectance of the virtual recording cell S, the light reflectance in the area B becomes By using the light reflectance in the area A and the area C as compared with the case where pits having different sizes are formed in the virtual recording cell S and data of different recording levels are recorded, the virtual recording cell S is used. When pits having different sizes are formed on S and data of different recording levels are to be recorded, the laser beam set to the exposure area to the virtual area S ′ of the photosensitive material layer 11 Ob is used. Since it is necessary to greatly change the irradiation time of 101, the light reflectance in the area B shown in FIG. 10 is assigned as the light reflectance of the virtual recording cell S, and the virtual recording cell S Light reflection The optical recording time is controlled by controlling the irradiation time of the laser beam 101 set to the exposure power to the virtual area S of the photosensitive material layer 110b so that the rate becomes the assigned value. It is preferable that pits having different sizes are formed in the virtual recording cell s of the medium 1 to record data having different recording levels.

However, the light reflectance in the area B shown in FIG. 10 is assigned as the light reflectance of the virtual recording cell S, and the light reflectance of the virtual recording cell S becomes the assigned value. In addition, by controlling the irradiation time of the laser beam 101 set to the exposure power w to the virtual area S ′ of the photosensitive material layer 110 b, the virtual recording cell s of the optical recording medium 1 is When pits with different sizes are formed and data with different recording levels are recorded, the difference between the maximum reflectance Ra and the minimum reflectance Rh cannot be made sufficiently large, and as a result, However, it becomes difficult to obtain a reproduced signal having a sufficiently wide dynamic range.

Therefore, even if the irradiation time of the laser beam 101 set to the exposure power is not largely changed, pits having different sizes are formed in the virtual recording cell s of the optical recording medium 1 to reduce the recording level. Within the range where different data can be recorded, the maximum light reflectance Ra of the virtual recording cell S is as close as possible to the light reflectance Ro of the virtual recording cell S where no recording mark is formed, and The light reflectance of each virtual recording cell S is assigned so that the minimum light reflectance R h is as close as possible to the saturated light reflectance R s, and the laser beam 101 set to the exposure power w is exposed to light. It is preferable to determine the minimum value and the maximum value of the time for irradiating the virtual region 3 ′ of the conductive material layer 111> in reproducing a signal having a wide dynamic range.

Thus, the inventor conducted intensive research and found that, when the level of the exposure power w of the laser beam 101 irradiating the virtual region S ′ of the photosensitive material layer 110 b changes, FIG. A virtual area S ′ corresponding to the virtual recording cell S of the photosensitive material layer 110 b of the indicated photo resist master 110 is irradiated with a laser beam 110 whose power is set to the exposure power w. The relationship between the time and the light reflectance of the virtual recording cell S of the optical recording medium 1 produced using the photoresist master 110 changes, and the level of the exposure power w of the laser beam 101 increases. As a result, even if a higher maximum reflectance is assigned to the virtual recording cell S, the virtual recording cell S has a different size without changing the irradiation time of the laser beam 101 set to the exposure power. Can be formed to record data having different recording levels. On the other hand, the lower the level of the exposure power w of the laser beam 101, the lower the minimum reflectivity assigned to the virtual recording cell S. Exposure power It is possible to record data of different recording levels by forming pits of different sizes in the virtual recording cell S without greatly changing the irradiation time of the set laser beam 101. Possible It was found that.

FIG. 11 shows that the exposure power 1 ^ of the laser beam 101 irradiating the virtual area S ′ corresponding to the virtual recording cell S of the photosensitive material layer 110 b of the photoresist master 110 is changed. FIG. 9 is a graph showing the relationship between the irradiation time of the laser beam 101 and the light reflectance of the virtual recording cell s of the optical recording medium 1 manufactured using the photoresist master 110. .

As shown in FIG. 11, according to the study of the present inventor, when the exposure power w of the laser beam 101 used for exposing the photosensitive material layer 110 b is set to a high level, The light reflectance of the virtual recording cell S of the recording medium 1 is reduced in a short time after starting the irradiation of the laser beam 101 set at the exposure power, in other words, at a stage where the light reflectance is high. As the irradiation time of the laser beam 101 increases, it decreases almost linearly, and at an early stage, in other words, at a stage where the light reflectance does not decrease so much, the irradiation time of the laser beam 101 It is recognized that the light reflectance does not change much even if the laser beam is increased, and eventually reaches the saturated light reflectance Rs. On the other hand, the laser beam used for exposing the photosensitive material layer 110b is exposed. When the exposure power w of 101 is set to a low level, optical recording The light reflectance of the virtual recording cell S of the medium 1 is set to a relatively long time after the irradiation of the set laser beam 101 is started. Even when the irradiation time of the laser beam 101 increased, the light reflection did not change much, and when the light reflectance became relatively low, the light reflection increased as the irradiation time of the laser beam 101 increased. Rate decreases almost linearly and the laser beam

Even if the irradiation time of 101 increases, it takes a long time until the light reflectance does not change much, and the irradiation time of the laser beam 101 is the first time when the light reflectance is considerably low. It is recognized that the light reflectivity does not change much even if increases.

Therefore, if the exposure power of the laser beam 101 used for exposing the photosensitive material layer 110b is set to a high level, even if the maximum light reflectance assigned to the virtual recording cell S is set to a high value, the exposure It is possible to record data with different recording levels by forming pits with different sizes in the virtual recording cell s without greatly changing the irradiation time of the laser beam 101 set in the power section. Therefore, when the exposure power w of the laser beam 101 used for exposure of the photosensitive material layer 110 b is, the maximum light reflectance R a H that can be assigned to the virtual recording cell S and When the maximum relative light reflectance R a H (%) and the exposure power w of the laser beam 101 used for exposing the photosensitive material layer 110 b are w (PwL <PwH), the virtual recording cell S The maximum light reflectance R a L and And the maximum relative light reflectance R R a L (%) satisfies the following equation.

R a L <R a H

R R a L <R R a H

Here, the relative light reflectance RR i (%) when the absolute light reflectance is R i is defined by the following equation.

RR i (%) = {(R i-R s) / (R o-R s)} X 100 Thus, the maximum light reflectance Ra and the maximum relative light reflectance RR a allocated to the virtual recording cell S By setting the level of the exposure power w of the laser beam 101 used for exposing the photosensitive material layer 110 b in accordance with (%), the maximum light reflectance Ra assigned to the virtual recording cell S And the maximum relative light reflectance RR a (%) is set to a high value, the exposure power P Without changing the irradiation time of the laser beam 101 set to w, the pits with different sizes can be formed in the virtual recording cell s, and data with different recording levels can be recorded. A reproduced signal having a wide dynamic range can be obtained.

On the other hand, if the exposure power w of the laser beam 101 used for exposing the photosensitive material layer 110 b is set to a low level, the minimum light reflectance assigned to the virtual recording cell S is set to a low value. However, the pits having different sizes are formed in the virtual recording cell S without largely changing the irradiation time of the laser beam 101 set to the exposure power W, so that data having different recording levels can be obtained. Since recording becomes possible, when the exposure power w of the laser beam 101 used for exposing the photosensitive material layer 110 b is w / J, it can be assigned to the virtual recording cell S. The minimum light reflectance R h L and the minimum relative light reflectance RR h L (%) and the exposure power w of the laser beam 101 used for exposing the photosensitive material layer 110 b are (P wL <PwH) In some cases, the minimum light reflectance R h L that can be assigned to virtual recording cell S Minimum relative reflectance and RR h L (%) would satisfy the following equation.

R h L <R h H

R R h L <RR hH

Thus, according to the minimum light reflectance R h and the minimum relative light reflectance RR h (%) assigned to the virtual recording cell S, the laser beam 101 used for exposing the photosensitive material layer 11 Ob By setting the level of the exposure power w, even if the minimum light reflectance R h and the minimum relative light reflectance RR h (%) assigned to the virtual recording cell S are set to low values, the exposure power is set. The pits having different sizes can be formed in the virtual recording cell S without greatly changing the irradiation time of the laser beam 101, so that data with different recording levels can be recorded. Thus, it is possible to obtain a reproduced signal having the edge.

Further, as shown in FIG. 11, when the exposure power P w of the laser beam 101 used for exposing the photosensitive material layer 110 b is high, The light reflectivity of the virtual recording cell S of the optical recording medium 1 decreases almost linearly as the irradiation time of the laser beam 101 increases at a relatively high light reflectivity level. Therefore, the light reflectance of the virtual recording cell s of the optical recording medium 1 hardly changes even if the irradiation time of the laser beam 101 is increased at a stage where the light reflectance level is not so low. When the exposure power i ^ w of the laser beam 101 used for exposing the photosensitive material layer 110b is set to a high level w / in order to increase the maximum light reflectance assigned to the virtual recording cell S, the virtual recording cell S The maximum relative light reflectance RRaH and the minimum relative light reflectance RRhH assigned to are determined so as to satisfy the following equation.

100-RR a H <RR h H

When the exposure power w of the laser beam 101 used for exposing the photosensitive material layer 110b is //, the maximum relative light reflectance RRaH and the minimum relative light reflectance assigned to the virtual recording cell S By determining RRhH in this manner, when the exposure power w of the laser beam 101 is wH, the irradiation time of the laser beam 101 set to the exposure power w does not need to be largely changed. In the virtual recording cell S, pits having different sizes are formed, and the maximum relative light reflectance RR aH and the minimum relative light reflectance of the virtual and recording cells S are respectively set within a range where data of different recording levels can be recorded. Relative light reflectance RR h H can be assigned. On the other hand, when the level of the exposure power ^ Pw of the laser beam 101 used for exposing the photosensitive material layer 110b is low, the light of the virtual recording cell s of the optical recording medium 1 is reduced as shown in FIG. The reflectivity does not decrease almost linearly with the increase in the irradiation time of the laser beam 101 until the level of the light reflectivity becomes relatively low, while the virtual recording cell of the optical recording medium 1 does not decrease. It is recognized that the light reflectance of S decreases almost linearly as the irradiation time of the laser beam 101 increases until the level of the light reflectance becomes considerably low. In order to increase the exposure power, the exposure power of the laser beam 101 used for exposure of the photosensitive material layer 110b is set to a low level! Set to ^ In this case, the maximum relative light reflectance RRaL and the minimum relative light reflectance RRhL assigned to the virtual recording cell S are determined so as to satisfy the following equation.

1 00 -RR a L> RR h L

When the exposure power P w of the laser beam 101 used for exposing the photosensitive material layer 110 b is w, the maximum relative light reflectance RR a L and the minimum relative light reflectance assigned to the virtual recording cell S are By determining the relative light reflectance RR h L of the laser beam in this manner, the exposure power of the laser beam used to expose the photosensitive material layer 110 b is Even if the irradiation time of the laser beam 101 set at the time is not largely changed, pits having different sizes are formed in the virtual recording cell s so that data having different recording levels can be recorded within a range. Each is a virtual recording cell

It becomes possible to assign the maximum relative light reflectance RR a L and the minimum relative light reflectance RR h L of S.

According to the above basic idea, according to the maximum light reflectance R and the maximum relative light reflectance RRa and the minimum light reflectance Rh and the minimum relative light reflectance RRh assigned to the virtual recording cell S, The exposure power of the laser beam 101 used for exposing the photosensitive material layer 110 b of the photo resist master 110 is selected, and other characteristics, such as the error rate when data is reproduced, are selected. Accordingly, from among the selected laser beam 1 0 1 exposure power / ⁵ w, the optimum exposure power is determined. Further, the light reflectance between the maximum light reflectance R a and the minimum light reflectance R h is roughly divided into seven equal parts, and six different light reflectances R b, R c, R d, R e, R f and R g are determined, and the data recording levels are assigned as the light reflectivity of the virtual recording cell S, and the light reflectivity of the virtual recording cell S is calculated as Ra, R b, R c, and R d , R e, R f, R g, and R h, and the optimal level of the exposure power w of the laser beam 101 to be applied to the virtual area S ′ of the material layer 110 b. The irradiation time of the laser beam 101 set to the optimum exposure power to the virtual area S 'of the photosensitive material layer 110b is determined for each virtual recording cell S having a different pit size. The exposure condition setting data is generated.

According to this embodiment, the higher the maximum light reflectance R a and the maximum relative light reflectance RR a (%) assigned to the virtual recording cell S are, the more the photosensitive material layer 110 b of the photoresist master 110 Since the exposure power of the laser beam 101 used for the exposure is set to a high level, the maximum light reflectance Ra and the maximum relative light reflectance RRa (%) assigned to the virtual recording cell S are Even if it is set to a high value, the exposure power PT forms pits of different sizes in the virtual recording cell S without greatly changing the irradiation time of the set laser beam 101. out to record different data recording _level; come, it is possible to obtain a reproduced signal having a wide dynamic range.

Further, according to the present embodiment, the lower the minimum light reflectance R h and the minimum relative light reflectance RRh (%) assigned to the virtual recording cell S, the lower the photosensitive material layer 1 of the photo resist master 110. Since the exposure power of the laser beam 101 used for the exposure of 100 b is set to a low level, the minimum light reflectance R h and the minimum relative light reflectance RR h ( %) Is set to a low value, pits of different sizes are formed in the virtual recording cell S without greatly changing the irradiation time of the laser beam 101 set to the exposure power ^. In addition, data of different recording levels can be recorded, and a reproduced signal having a wide dynamic range can be obtained.

Further, according to the present embodiment, in order to increase the maximum light reflectance to be assigned to the virtual recording cell S, the laser beam 10 used for exposing the photosensitive material layer 110 b of the photo resist master 110 is used. When the exposure power of 1 is set to a high level wf, the maximum relative light reflectance RR a H and the minimum relative light reflectance RR h H assigned to the virtual recording cell S satisfy the following equation. Therefore, if the exposure power P w of the laser beam 101 used for exposing the photosensitive material layer 110 b of the photo resist master 110 is P w! I, the exposure power Even if the irradiation time of the set laser beam 101 is not largely changed, the virtual recording cell S The maximum relative light reflectance RR a H and the minimum relative light reflectance RR h H of the virtual recording cell S should be allocated to the extent that data of different recording levels can be recorded by forming pits of different sizes. Becomes possible.

1 0 0 -R R a H <R R h H

Further, according to the present embodiment, in order to lower the minimum light reflection rate assigned to the virtual recording cell S, the laser beam 1 used for exposing the photosensitive material layer 110 b of the photo resist master 110 is not used. 0 When the exposure power of 1 is set to a low level w L, the maximum relative light reflectance RR a L and the minimum relative light reflectance RR h L assigned to the virtual recording cell s satisfy the following formula: as such, since determined, the Photo Regis laser beam 1 0 1 exposure power / ⁵ used for preparative master 1 first photosensitive material layer 1 1 0 b exposure of 0

Laser beam set to exposure power W when W is wL

Even if the irradiation time of 101 is not largely changed, the pits having different sizes are formed in the virtual recording cell S, and each of the virtual recording cells is within a range where data of different recording levels can be recorded. It is possible to assign a maximum relative light reflectivity RR a L and a minimum relative light reflectivity RR h L of S.

1 0 0 -R R a L> R R h L

FIG. 12 shows a photoresist master 110 corresponding to a virtual recording cell S of an optical recording medium 1 used in a method of manufacturing an optical recording medium master 205 according to another preferred embodiment of the present invention. 4 is a diagram showing a modulation pattern of the power of the laser beam 101 applied to the virtual region S ′ of the photosensitive material layer 110 b of FIG.

In FIG. 12, the length of the virtual area S of the photosensitive material layer 110 b of the photoresist master 110 corresponding to the virtual recording cell S of the optical recording medium 1 is represented by the laser beam 10. The time required for 1 to pass through the virtual area S ′, that is, the maximum irradiation time Tmax, is represented.

As described above, the maximum irradiation time Tmax of the laser beam 101 to the virtual area S ′ of the photosensitive material layer 110b of the photoresist master 110 is L / V (where L Is the length of the virtual area S ′ corresponding to the virtual recording cell S of the photosensitive material layer 110b, that is, the length of the virtual recording cell S, V is the linear velocity of the force-setting machine 100. ), The irradiation time T h of the laser beam 101 for forming the maximum pit P h on the virtual recording cell S is set so that the virtual recording cell S has the minimum light reflectance R h. It must be set to TmaX or less.

For example, when the length L of the virtual recording cell S is 600 nm and the linear velocity V of the cutting machine 100 is 1.2 / sec, which is the reference linear velocity X1, as shown in Fig. 12 The irradiation time T h of the laser beam 101 for forming the latent image 110 c corresponding to the maximum pit P h in the virtual area S ′ is set to 500 nsec or less. When the linear velocity V of the cutting machine 100 is double speed X 2 and the speed is 2.4 m / sec, as shown in Fig. 12, the maximum area is The irradiation time Th of the laser beam 101 for forming the latent image 110 c corresponding to the pit P h is set to 250 nse _C or less, and the linear velocity V of the cutting machine 100 is In the case of 4.8 mZ sec, which is 4 × speed 4, as shown in FIG. 12, a latent image 110c corresponding to the maximum pit Ph is formed in the virtual area S 'as shown in FIG. Laser bee for 1 0 1 irradiation morphism time T h, it is necessary to set the following 1 2 5 nsec. Further, as is apparent from FIG. 10, the maximum light reflectance Ra of the virtual recording cell S is as close as possible to the light reflectance Ro of the virtual recording cell S where no recording mark is formed, and The light reflectance of each virtual recording cell S is assigned so that the minimum light reflectance R h of the recording cell S is as close as possible to the saturated light reflectance R s at which the light reflectance is substantially saturated, and Determining the minimum value and the maximum value of the laser beam irradiation time set to the exposure power w used for exposure of the photosensitive material layer 110b of the storage master 110 is a signal having a wide dynamic range. It is preferable to reproduce.

Therefore, Tmax at the time when the linear velocity V of the cutting machine 100 is the maximum, that is, LZV, is a virtual recording of a pit whose size is such that the light reflectance of the virtual recording cell S becomes the saturated light reflectance Rs. In order to form a cell S, a virtual area S of the photosensitive material layer 110 b of the photo resist master 110 is The photosensitive material layer 111 of the photo resist master 110 should be set so that the irradiation time Ts of the laser beam required to irradiate the laser beam 101 is shorter than the time Ts, that is, the following equation is satisfied. It is preferable that the level of the exposure power of the laser beam used for the exposure of 0b, the length L of the virtual recording cell, and the linear velocity V of the power cutting machine 100 are set.

丄 's≤Tm a X = / V m a x

As shown in FIG. 12, the laser beam 101 irradiated onto the virtual area S ′ of the photosensitive material layer 110 b of the photoresist master 110 has an exposure power And the base powers, which are selectively modulated to form the virtual recording cells S corresponding to the pitches Pa, Pb, Pc, Pd, Pe, Pf, Pg, and Ph. The time during which the power of the laser beam 101 is set to the exposure power, that is, the pulse width Ta, Tb, Tc, Td, Te, Tf, Tg, Th of the exposure power Pw is Is set.

As shown in Fig. 12, the maximum irradiation time TmaX of the laser beam 101 to the virtual area S 'of the photosensitive material layer 110b of the photoresist master 110 is The linear velocity V of the machine 100 becomes shorter as the linear velocity V becomes higher.However, in the present embodiment, even in the case of the quadruple-speed X4 where the recording linear velocity is the maximum, the Tmax becomes the virtual recording velocity. The irradiation time T h of the laser beam 101 to the virtual area S ′ necessary for forming the maximum pit P h in the cell S, that is, the light reflectance of the virtual recording cell S is minimized. The exposure of the photo-resist master 110 so that it is longer than the irradiation time T h of the laser beam 101 to the virtual area S Power w of the laser beam for exposing the conductive material layer 110b and the length L of the virtual recording cell S are set. There.

Therefore, as shown in FIG. 12, regardless of the linear velocity V of the cutting machine 100, the photosensitive material layer 110b of the photo resist master 110 is used using a constant modulation pattern. By modulating the power of the laser beam for exposing the laser beam, different sizes of pits P a, P b, P c, P d, P e, and P f can be stored in the virtual recording cell S as desired. , P g and P h can be formed.

FIG. 13 shows that the exposure power ⁵ ^ of the laser beam 101 for irradiating the virtual region S ′ corresponding to the virtual recording cell S of the photosensitive material layer 110b of the photoresist master 110 is changed. 4 is a graph showing the relationship between the irradiation time of the laser beam 101 and the optical reflectivity of the virtual recording cell s of the optical recording medium 1 manufactured using the photoresist master 110.

As described above, when the exposure power w of the laser beam 101 used for exposing the photosensitive material layer 110 b is set to a high level, the light reflectance of the virtual recording cell S of the optical recording medium 1 becomes Power P In a short time after the irradiation of the set laser beam 101 is started, in other words, at a stage where the light reflectance is high, the irradiation time of the laser beam 101 is almost increased as the irradiation time increases. Even if the irradiation time of the laser beam 101 is increased at an early stage, in other words, at a stage where the light reflectivity does not decrease so much, the light reflectivity changes too much. When the exposure power w of the laser beam 101 used for exposing the photosensitive material layer 110 b is set to a low level, optical recording is started. The light reflectance of the virtual recording cell s of medium 1 is Even if the irradiation time of the laser beam 101 is increased for a relatively long time after the irradiation of the laser beam 101 set in the exposure paper is started, the light reflectance does not change much, and the light reflectance does not change. At a relatively low stage, as the irradiation time of the laser beam 101 increases, the light reflectance decreases almost linearly, and even if the irradiation time of the laser beam 101 increases, It takes a long time for the light reflectance to change little, and for the first time, even when the irradiation time of the laser beam 101 is increased, the light reflectance is not very high, even if the light reflectance is significantly reduced. It is acknowledged that it will not change.

Therefore, as shown in FIG. 13, the photosensitive material layer 110b required for the light reflectance of the virtual recording cell S of the optical recording medium 1 to substantially reach the saturation reflectance Rs is obtained. The irradiation time Ts of the laser beam 101 becomes shorter as the level of the exposure power w of the laser beam 101 used for exposing the photosensitive material layer 110b becomes higher, and the virtual recording of the optical recording medium 1 is performed. Light of cell S 68

30

The irradiation time T h of the laser beam 101 to the photosensitive material layer 110 b necessary for the reflectance to reach the minimum reflectance also depends on the laser beam 1 used to expose the photosensitive material layer 110 b. The higher the level of the exposure power w is, the shorter the exposure power is. On the other hand, the maximum of the laser beam 101 to the virtual area S ′ of the photosensitive material layer 110 b corresponding to the virtual recording cell S Since the irradiation time Tmax depends on the length L of the virtual recording cell S and the linear velocity V of the force-setting machine 100, the photosensitive material is set so that Th≤Tmax = L / Vmax. It is necessary to set the level of the exposure beam w of the laser beam 101 used for the exposure of the layer 110b, the length L of the virtual recording cell S, and the linear velocity V of the force setting machine 100. , Ts Tmax = L / Vmax, so that the exposure power of the laser beam 101 used for exposure of the photosensitive material layer 110 b is Leveled Honoré, it is preferable to set the length L and force Tsu computing machine 1 0 0 linear velocity V of the virtual recording cells S.

According to this embodiment, the photosensitive material layer 11 of the photoresist master 1 10 satisfies T ≤ Tmax X = L / Vmax or Ts ≤ Tmax = L / Vmax. By setting the level of the laser beam 100 used for the exposure of the exposure b, the level of the exposure power /, the length L of the virtual recording sensor S, and the linear velocity V of the cutting machine 100, the cutting machine 100 Regardless of the linear velocity V of the laser beam, the pulse width of the exposure power w and the exposure power w of the laser beam 101 used for exposure of the photosensitive material layer 110 b of the photoresist master 110 are the same. By irradiating the laser beam 101 to the virtual area S ′ of the photosensitive material layer 110 b, the same pit P k is formed in the virtual recording cell, and at the same recording level, Since data can be recorded, different operations can be performed on the same optical recording medium 1 with extremely simple operations. In cutlet coating machine 1 0 0 linear velocity V, it is possible to record the data of 3 bits.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say, there is. For example, in the above embodiment, a description has been given of a case where 3-bit data is recorded in each virtual recording cell S of the optical recording medium 1. The present invention is not limited to the case where 3-bit data is recorded in the cell S, but is widely applied to the case where 2-bit or more data is recorded in each virtual recording cell S of the optical recording medium 1. Can be.

Further, in the above embodiment, the case where 3-bit data is recorded on the CD-ROM type optical recording medium 1 has been described. However, the present invention relates to the CD-ROM type optical recording medium 1. However, the present invention is not limited to the case where 3-bit data is recorded, but can be widely applied to the case where 2-bit or more data is recorded on an optical recording medium including at least a ROM area. it can.

Further, in the embodiment shown in FIGS. 11 and 12, a pit Pk of the same size is formed in the virtual recording cell S of the optical recording medium 1 to record data of the same level. In this case, regardless of the linear velocity V of the cutting machine 100, the photo resist master 110 is adjusted so that the exposure power w of the laser beam 101 and the pulse width of the exposure power are constant. The power of the laser beam 101 for exposing the photosensitive material layer 110b is set, but a pit Pk of the same size is formed in the virtual recording cell s of the optical recording medium 1. When recording data of the same level, the photosensitive material layer 110 of the photo resist master 110 is so adjusted that the exposure power of the laser beam 101 and the pulse width of the exposure power P are constant. Set the power of the laser beam 101 to expose b It is not always necessary.

Further, in the above embodiment, when the laser beam 101 reaches the starting point of the virtual area S ′ of the photosensitive material layer 110 b corresponding to the starting point of the virtual recording cell S of the optical recording medium 1, Although the power of the laser beam 101 is raised from the base power to the exposure power P, the timing for raising the power of the laser beam 101 from the base power P to the exposure power must be determined arbitrarily. Can be. Further, in the embodiment shown in FIGS. 1 to 11, when recording 3-bit data in each virtual recording cell S of the optical recording medium 1, the maximum light allocated to the virtual recording cell S Set the reflectance Ra and the maximum relative light reflectance RRa, the minimum light reflectance Rh, and the minimum relative light reflectance RRh, and set the maximum light reflectance Ra and the minimum light reflectance Rh or the maximum relative light. The difference between the reflectance RR a and the minimum relative light reflectance RR h is roughly divided into seven equal parts, and six different types of light reflectances R b, R c, R d, R e, R i, and R g are obtained. Although it is determined, it is not always necessary to set the maximum light reflectance Ra assigned to the virtual recording cell S, the maximum relative light reflectance RRa, the minimum light reflectance Rh, and the minimum relative light reflectance RRh. Not required and assigned to virtual recording cell S Maximum light reflectance Ra and maximum relative light reflectance RRa or virtual recording The minimum light reflectance R h and the minimum relative light reflectance RR h to be assigned to the virtual recording cell S are assigned to the maximum light reflectance Ra and the maximum relative light reflectance RR a to be assigned to the virtual recording cell S or to the virtual recording cell S. Based on the minimum light reflectivity R h and the minimum relative light reflectivity RR h, different sizes of pits are formed and reflected from the virtual recording cell S where data of different recording levels are recorded. When reproducing the data by detecting the emitted laser beam, assign a different light reflectivity or relative light reflectivity by light reflectivity difference or relative light reflectivity difference that can recognize the difference in data recording level. You can also

In the above embodiment, the optically transparent substrate 11 is manufactured by the injection molding method using the optical recording medium master 205, but the optical recording medium master 205 is used. Therefore, it is not always necessary to manufacture the light-transmitting substrate 11 by an injection molding method. The light-transmitting substrate 11 is formed by using a light-curing method ( 2P method).

ADVANTAGE OF THE INVENTION According to this invention, ^2N types of different pits are allocated to the virtual recording cell of the optical recording medium, and the optical reflectance of the virtual recording cell can be changed in ^2N steps. It becomes possible to provide a method for manufacturing a master. Further, according to the present invention, there is provided a method for manufacturing an optical recording medium in which 2 ^N kinds of different-sized pits are assigned to virtual recording cells and the light reflectance of the virtual recording cells is changed in ^2N steps. Can be provided.

Claims

Claims. An optical recording medium for producing an optical recording medium in which 2 ^N types of pits are formed in a plurality of virtually set virtual recording cells and data of 2 bits or more are recorded. A method for manufacturing a master, comprising: irradiating a laser beam to expose a photoresist master to form a pattern on the photoresist master; and Transferring and producing an optical recording medium master, and irradiating the photoresist master according to the maximum light reflectance and the Z or the minimum light reflectance assigned to the virtual recording cell of the optical recording medium. A method for manufacturing an optical recording medium master, comprising setting an exposure power of the laser beam. The exposure power of the laser beam applied to the photoresist master is set to a higher level as the maximum reflectance assigned to the virtual recording cell of the optical recording medium is higher. Item 13. The method for producing a master for an optical recording medium according to Item 1. The exposure power of the laser beam irradiating the photoresist master is set to a lower level as the minimum reflectance assigned to the virtual recording cell of the optical recording medium is lower. 2. The method for producing an optical recording medium master according to item 1. The higher the maximum relative reflectivity assigned to the virtual recording cell of the optical recording medium, the higher the exposure power of the laser beam applied to the photoresist master, and the higher the relative light reflectivity RRaH. 3. The production of an optical recording medium master according to claim 2, wherein the minimum relative light reflectance RRhH is set so as to satisfy 100—RRaH and RRliH. Method.

The lower the minimum reflectivity assigned to the virtual recording cell of the optical recording medium is, the lower the exposure power of the laser beam applied to the photoresist master is set to a lower level, and the maximum relative light reflectivity RR a 4. The master for an optical recording medium according to claim 3, wherein H and the minimum relative light reflectivity RRhH are set so as to satisfy 100—RRaL> RRhL. Production method. A method of manufacturing an optical recording medium master for producing an optical recording medium in which 2 ^N types of pits are formed in a plurality of virtually set virtual recording cells and data of 2 bits or more are recorded. Irradiating a laser beam, exposing the photoresist master to form a pattern on the photoresist master, and transferring the pattern formed on the photoresist master. Producing a master for an optical recording medium, forming pits of the same size in the virtual recording cells of the optical recording medium, and recording the data at the same recording level. The exposure power and / or the pulse width of the exposure power of the laser beam applied to the photoresist master is set to be substantially the same regardless of the linear velocity of the laser beam applied to the master. Method for producing a master for optical recording medium characterized and. When pits of the same size are formed in the virtual recording cell of the optical recording medium and data of the same recording level is recorded, regardless of the linear velocity of the laser beam applied to the photoresist master, 7. The optical recording medium master according to claim 6, wherein the exposure power and the pulse width of the exposure beam of the laser beam applied to the photo resist master are set to be substantially the same. Production method. The linear velocity V of the laser beam applied to the photoresist master, the length L of the virtual recording cell, and the photoresist master required to substantially saturate the light reflectance of the virtual recording cell are irradiated. Laser beam The exposure power level of the laser beam irradiating the photoresist master, the length L of the virtual recording cell, and the laser irradiating the photoresist master so that the irradiation time T s satisfies T s L / V. 8. The method for producing a master for an optical recording medium according to claim 6, wherein the linear velocity V of the beam is set.

9. A method for manufacturing an optical recording medium in which ^2N types of pits are formed in a plurality of virtual recording cells virtually set on a substrate and data of 2 bits or more are recorded, wherein a laser beam is emitted. Irradiating, exposing the photoresist master to form a pattern on the photoresist master, and transferring the pattern formed on the photoresist master to produce an optical recording medium master. Transferring the pattern transferred to the optical recording medium master to produce the substrate, wherein the maximum light reflectance and the Z or the minimum to be assigned to the virtual recording cell of the optical recording medium. A method of manufacturing an optical recording medium, comprising setting an exposure power of the laser beam to be applied to the photoresist master according to a light reflectance.

10. The exposure power of the laser beam applied to the photo resist master is set to a higher level as the maximum reflectance assigned to the virtual recording cell of the optical recording medium is higher. Item 10. The method for manufacturing an optical recording medium according to Item 9, wherein

11. The exposure power of the laser beam applied to the photoresist master is set to a higher level as the maximum reflectance assigned to the virtual recording cell of the optical recording medium is higher. Item 10. The method for manufacturing an optical recording medium according to Item 9.

12. The higher the maximum relative reflectance assigned to the virtual recording cell of the optical recording medium is, the more the laser beam irradiates the photoresist master. The maximum relative light reflectance RR a H and the minimum relative light reflectance RR h H are set so that the following relationship is satisfied: 100 0— RR a H <RR h H 10. The method for manufacturing an optical recording medium according to claim 10, wherein:

13. The exposure power of the laser beam applied to the photo resist master is set to a lower level as the minimum reflectance assigned to the virtual recording cell of the optical recording medium is lower, and the maximum relative light reflectance RR is set. 12. The method for manufacturing an optical recording medium according to claim 11, wherein aH and a minimum relative light reflectance RRhH are set so as to satisfy 100_RRaL> RRhL.

14. A method of manufacturing an optical recording medium in which 2 ^N types of pits are formed in a plurality of virtual recording cells virtually set on a substrate and data of 2 bits or more are recorded, wherein a laser beam is emitted. Irradiating, exposing the photoresist master to form a pattern on the photoresist master, and transferring the pattern formed on the photoresist master to produce an optical recording medium master. Transferring the pattern transferred to the optical recording medium master to produce the substrate; forming pits of the same size in the virtual recording cells of the optical recording medium; When recording data at the recording level, regardless of the linear velocity of the laser beam applied to the photo resist master, the exposure power of the laser beam applied to the photo resist master and the exposure power A method for manufacturing an optical recording medium, wherein pulse widths of z and z or exposure power are set to be substantially the same.

15. When pits of the same size are formed in the virtual recording cells of the optical recording medium and data of the same recording level is recorded, regardless of the linear velocity of the laser beam applied to the photoresist master. Exposure power and exposure power of the laser beam irradiating the photoresist master 15. The method for manufacturing an optical recording medium according to claim 14, wherein the first pulse width is set to be substantially the same.

16. The photoresist master required to substantially saturate the linear velocity V of the laser beam applied to the photoresist master, the length L of the virtual recording cell, and the light reflectance of the virtual recording cell. irradiation time T s of the laser beam irradiated to the, T _S ≤ L / V I meet urchin, said the Photo Regis level of the laser beam of the exposure power to be irradiated to preparative master, virtual recording cell Le length L and the 16. The method for manufacturing an optical recording medium according to claim 14, wherein a linear velocity V of a laser beam applied to the photoresist master is set.