JP2003036570A - Method for manufacturing recording medium master disk and exposure system for recording medium master disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and so forth for manufacturing a recording medium master disk, which can stably form a pattern having a uniform shape on a photoresist layer using a contrast-enhanced photolithographic method and a super-resolution. SOLUTION: In an exposure step, for a substrate 101 having the photoresist layer 102 and the contrast-enhanced layer 103, the diameter of the light main- spot concentrated on the photoresist layer 102 in at least one direction is equal to or less than the diffraction limit defined on the basis of the wavelength of the light from a light source and the numeric aperture of an objective lens 104, and El/Ep<0.45 is satisfied, where Ep is the integrated exposure amount of the contrast-enhanced layer 103 corresponding to the exposed region of the photoresist layer 102, and El is the integrated exposure amount of the contrast- enhanced layer 103 corresponding to the region of the photoresist layer 102 for which the exposure is not required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a recording medium master disk such as an optical disk and an exposure apparatus for the recording medium master disk, and more particularly to a manufacturing method and an exposure apparatus for a recording medium master disk having a fine uneven pattern. Regarding

[0002]

2. Description of the Related Art Information tracks are provided on an optical disk disk in a spiral or concentric pattern. A guide groove for tracking of the recording / reproducing laser and an uneven pit representing address data are formed in advance along the information track. The formation of such guide groove and pit patterns begins with the production of a master.

To manufacture the master, first, for example, a positive photoresist film is applied on a glass substrate which is a support.
Next, the light beam whose intensity is modulated according to the pattern to be formed is condensed and exposed on the photoresist film by the objective lens of the master exposure device. The exposure forms a latent image of the pattern. By developing the exposed photoresist film, uneven guide grooves and pits are formed in the photoresist film on the surface of the glass substrate. In the negative type photoresist film, the irregularities are reversed.

Next, a conductive film treatment is applied to the surface of the photoresist film. Then, the glass substrate is peeled off to obtain a stamper on which irregularities of a predetermined pattern are transferred. A large number of replica substrates are manufactured by injection molding using the stamper as a mold. Finally, a recording film and a reflective film are formed on the replica substrate, and an optical disc is completed.

As a light source of the master exposure apparatus, a TEM00 mode short wavelength laser (λ = about 400 nm) is usually used. Then, with an objective lens having a numerical aperture NA = about 0.9,
The exposure beam is narrowed down to the diffraction limit, which is the smallest spot diameter that can realize the light from the light source. Such an exposure beam is a Gaussian beam whose intensity distribution is Gaussian.

The intensity distribution of the Gaussian beam has a skirt-spreading shape. Therefore, the cross-sectional shape of the guide groove and the pit obtained by exposing the photoresist film has a shape corresponding to the bottom spread of the intensity distribution of the Gaussian beam. Figure 12
FIG. 3 is a diagram showing a cross-sectional shape of a guide groove and a pit formed by exposing the photoresist layer 11 formed on the glass substrate 10. As can be seen from FIG. 12, the cross-sectional shape is not rectangular, but the wall surface sags corresponding to the skirt spread of the Gaussian beam, and becomes a trapezoid of opening width Wtop> bottom width Wbtm. Therefore, the trapezoidal cross-sectional shape of the guide groove and the pit is directly transferred to the replica substrate with the stamper interposed.

Further, in order to further miniaturize the guide groove and the pit in response to the high density of the optical disc and the like, the opening width Wtop and the bottom width Wbtm of the pit and the guide groove may be reduced. Therefore, it is necessary to reduce the diameter of the exposure beam.
The minimum spot diameter of the Gaussian beam is determined by the diffraction limit. The diffraction limit is the wavelength λ of the light source used for exposure.
And the numerical aperture NA of the objective lens, λ / NA.
In the present master disc exposure apparatus, both the wavelength λ of the light from the light source and the numerical aperture NA of the objective lens have almost reached their limit values. Therefore, when a Gaussian beam is used for exposure, there is a limit to further reducing the spot diameter of the exposure beam. Therefore, in order to make the spot diameter of the exposure beam smaller than the diffraction limit, a method utilizing super-resolution, a contrast-enhanced photolithography method, and a method combining these methods have been proposed.

First, a method of utilizing super-resolution will be described. A typical method for reducing the spot diameter of the exposure beam using super-resolution is, for example, Japanese Patent Laid-Open No. 6-215408.
Japanese Patent Laid-Open Publication No. 10-302300. In JP-A-6-215408, a light-shielding mask including a rectangular area and a circular area is arranged on the light source side of the objective lens. Further, in Japanese Unexamined Patent Publication No. 10-302300, a phase shift mask is installed closer to the light source than the objective lens of the master exposure apparatus. As a result, a main beam having a spot diameter smaller than the diffraction limit can be formed at the focus position of the objective lens.

FIG. 13 is a diagram showing the intensity distribution of the Gaussian beam G condensed to the diffraction limit and the intensity distribution of the exposure beam S when the above-mentioned super-resolution technique is used. The Gaussian beam G has a beam profile with a central intensity Ig and a width Dg. On the other hand, the main beam (0th-order diffracted light) of the super-resolution beam S has a beam profile with a central intensity Im and a width D. The width D of the exposure beam S by super-resolution is
It is smaller than the width Dg of the Gaussian beam G. Therefore, by using the main beam of the super-resolution beam S for exposure, it is possible to form an uneven pattern having a diffraction limit or less.

The super-resolution beam S has a side beam (first-order diffracted light) having a peak intensity Is outside the main beam. The side beams of the diffracted light of the second and higher orders are ignored because their peak intensities gradually decrease. When the peak intensity of the side beam is large, an unnecessary pattern is formed in the photoresist layer. Therefore, the side beam is unnecessary light for exposure. JP-A-10-302
In Japanese Patent Laid-Open No. 300, the pattern is not formed when the peak intensity of the side beam is 5% or less of the peak intensity of the main beam. Then, by using a ring-shaped phase shift mask, it is possible to realize a super-resolution beam that is not affected by such side beams.

Next, the contrast enhanced photolithography method will be described. Representative methods of reducing the spot diameter of the exposure beam using the contrast-enhanced photolithography method are proposed in, for example, Japanese Patent Laid-Open Nos. 6-243512 and 9-245383. The contrast-enhanced photolithography method uses a photobleaching material to reduce the spot diameter of the exposure beam.

The photobleachable material has a low transmittance and is optically opaque in the initial state where the exposure beam is not irradiated. On the other hand, in the state where the exposure beam is irradiated and the exposure amount is increased, a photoreaction occurs, fading proceeds, and the transmittance increases. When a Gaussian beam is made incident on the photobleaching material layer, the central portion where the beam intensity is high is transmitted. On the other hand, the skirt portion where the beam intensity is weak does not transmit. Therefore, the spot diameter of the Gaussian beam after passing through the photobleaching material layer is smaller than the spot diameter before passing through the photobleaching material layer.

In Japanese Patent Laid-Open No. 9-245383, a contrast enhancing layer made of a photobleaching material is formed on a photoresist layer on a glass substrate. This causes the Gaussian beam to reach the photoresist layer through the contrast enhancing layer. Then, the Gaussian beam has a small beam diameter by passing through the contrast enhancing layer. As a result,
A spot diameter smaller than the diffraction limit can be obtained.

Further, Japanese Laid-Open Patent Publication No. 6-243512 proposes that unnecessary exposure due to side lobes is prevented and exposure is performed only with a main lobe by combining a contrast-enhanced photolithography method and a method by super-resolution. ing. The methods proposed in Japanese Patent Laid-Open Nos. 9-245383 and 6-243512 are formed when the wavelength λ of the light source light is 400 to 450 nm and the NA of the objective lens is about 0.9. It is said that the line width of the pattern can be made smaller than the conventional one.

[0015]

However, when the conventional contrast-enhanced photolithography method and super-resolution are combined to further miniaturize the pattern formed in the photolithography layer, the pattern may be formed depending on the super-resolution condition. There is a problem that the pattern shape formed when the interval is narrowed is disturbed. FIG. 14 is a diagram showing a cross-sectional shape of a pattern such as a guide groove or a pit formed in the photoresist layer when observed with an atomic force microscope (hereinafter abbreviated as “AFM”). As is clear from FIG. 14, the uneven shape of the pattern is non-uniform, and especially the height of the convex portion of the pattern is non-uniform.

The present invention has been made to solve the above problems, and a first object of the present invention is to obtain a uniform shape of a photoresist layer by using a contrast enhanced photolithography method and super resolution. It is an object of the present invention to provide a method of manufacturing a recording medium master disc that can stably form a pattern. A second object of the invention is to provide an exposure apparatus for a master recording medium capable of stably forming a pattern having a uniform shape on a photoresist layer.

[0017]

[Means for Solving the Problems]
In order to achieve the object, a method of manufacturing a recording medium master according to the invention of claim 1 comprises a step of forming a photoresist layer on a substrate, and a contrast formed of a photobleaching material on the photoresist layer. Forming the enhancement layer,
An exposure step of irradiating the photoresist layer with light from a light source collected by an objective lens through the contrast enhancement layer to expose a predetermined region of the photoresist layer, and a step of removing the contrast enhancement layer. A developing step of developing the exposed photoresist layer to form an uneven pattern on the photoresist layer; and transferring the uneven pattern formed on the photoresist layer to a recording medium. A transfer step of producing a master, and in the exposure step, the diameter of the main spot of the light focused on the photoresist in at least one direction is the wavelength of the light from the light source and the numerical aperture of the objective lens. Is less than or equal to the diffraction limit determined based on, and the integrated dew of the contrast enhancing layer corresponding to the exposed region of the photoresist layer. The amount of Ep, when the accumulated exposure amount of the contrast enhancement layer corresponding to the exposure required region of the photoresist layer was respectively El, El / Ep <0.
45 is satisfied.

Here, “below the diffraction limit” means that the diameter of the first dark ring formed around the main spot of the light focused on the photoresist is d, the wavelength of the light is λ, and the objective is Assuming that the numerical aperture of the lens is NA, d <1.
It means a state of satisfying 22 × λ / NA.

According to the first aspect of the present invention, the ratio of the integrated exposure amount for the contrast enhancing layer corresponding to the exposed region of the photoresist layer to the integrated exposure amount for the contrast enhancing layer corresponding to the unexposed region is determined. It is set to 0.45 or less. As a result, it is possible to stably form a concavo-convex pattern below the diffraction limit on the photoresist layer.

According to a second aspect of the present invention, there is provided a method of manufacturing a recording medium master disk, which further comprises forming an intermediate layer between the photoresist layer and the contrast enhancing layer, and collecting the light by the objective lens. The light from the light source,
An exposure step of irradiating the photoresist layer through the contrast enhancing layer and the intermediate layer to expose a predetermined region of the photoresist layer.

According to the invention of claim 2, the provision of the intermediate layer makes it possible to stably form the contrast enhancing layer.

The method of manufacturing a recording medium master according to the invention of claim 3 is characterized in that the intermediate layer has a transmittance of 90% or more with respect to the wavelength of the light from the light source.

According to the invention of claim 3, the conditions for forming the intermediate layer and the contrast enhancing layer are controlled so that the transmittance of the intermediate layer at the exposure wavelength is 90% or more. Therefore, the pattern formation of the photoresist layer can be stabilized.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a recording medium master disc, wherein a light blocking mask for blocking a predetermined area of incident light is arranged in an optical path between the light source and the objective lens, and the light blocking mask is provided. The photoresist layer is exposed by light passing through.

According to the fourth aspect of the invention, the pattern by super-resolution can be easily formed only by adding the light-shielding mask.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a recording medium master disc, wherein the light shielding mask has a plurality of light shielding regions.

According to the fifth aspect of the present invention, the side lobes are dispersed at a plurality of locations by the plurality of light shielding regions. Thereby, the integrated light amount ratio is improved and the pattern interval can be further reduced.

According to a sixth aspect of the present invention, there is provided a recording medium master disc manufacturing method, wherein a phase shift mask for causing a phase shift with respect to incident light is disposed in an optical path between the light source and the objective lens. The photoresist layer is exposed by light passing through the phase shift mask.

According to the invention of claim 6, a pattern by super-resolution can be easily formed only by adding a phase shift mask. Further, the light utilization efficiency is improved as compared with the case where the light shielding mask is used.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a recording medium master disc, wherein the phase shift mask has a plurality of phase shift areas, and adjacent phase shift areas have different phase shift amounts. And

According to the seventh aspect of the present invention, the side lobes are dispersed at a plurality of locations by the plurality of phase shift regions. Thereby, the integrated light amount ratio is improved and the pattern interval can be further reduced.

According to the eighth aspect of the present invention, there is provided a method of manufacturing a recording medium master disc, wherein the difference in the amount of phase shift between the adjacent phase shift areas is an odd multiple of π.

According to the eighth aspect of the present invention, the phase difference between the adjacent phase shift regions is π (radian), that is, 1
/ It is an odd multiple of 2 wavelengths. As a result, the spot diameter can be reduced most efficiently.

According to a ninth aspect of the present invention, there is provided an exposure device for a recording medium master, which comprises an objective lens for condensing light from a light source on a photosensitive substrate having a photoresist layer and at least a contrast enhancing layer in order from the substrate side. A focusing unit for focusing the objective lens on the photosensitive substrate, and an offset amount control unit for setting or canceling a predetermined offset signal for the objective lens based on a focus signal from the focusing unit. An optical path from the light source to the objective lens, a light-shielding mask for blocking a predetermined area of the light entering the objective lens, or a phase shift mask for shifting the phase of the predetermined area of the light entering the objective lens. The position of the mask holder for inserting / removing into / from the mask holder is in a plane perpendicular to the optical axis of the objective lens. And having a mask holder adjustment unit that adjusts the interlinking two directions.

According to the ninth aspect of the present invention, a predetermined offset voltage can be set or released with respect to the focus error signal of the objective lens. Therefore, the focus position of the exposure beam can be controlled. This exposes a glass substrate having a photoresist layer and a contrast enhancing layer,
Exposure to a glass substrate having only a photoresist layer can be selectively used. Further, a light-shielding mask or a phase shift mask for super-resolution can be freely inserted into and removed from the optical path and positioned as necessary. This makes it possible to selectively use super-resolution exposure and Gaussian beam exposure. As a result, by combining the proper use of the glass substrate and the proper use of the exposure method, it is possible to easily form a pattern corresponding to a high density optical disc and an ordinary optical disc such as a CD or a DVD. Therefore, the single exposure apparatus can be used very efficiently.

An exposure apparatus for a recording medium master according to a tenth aspect of the present invention is characterized by further comprising a spot image observation section for observing the spot image condensed by the objective lens.

According to the tenth aspect of the present invention, it is possible to easily observe the super-resolution spot image condensed by the objective lens. Thereby, the positioning of the light-shielding mask or the phase shift mask for super-resolution can be performed with high accuracy and efficiency.

An exposure apparatus for a recording medium master according to the invention of claim 11 is characterized in that the spot image observation section has at least a focusing section for the spot image.

According to the eleventh aspect of the invention, the spot image can be focused by moving the spot image observing portion itself. As a result, the objective lens of the exposure apparatus is not driven, so that no load is applied to the actuator.

According to the twelfth aspect of the present invention, in the exposure apparatus for the recording medium master, the spot image observation section has at least a beam diameter measurement section for measuring the beam diameter of the spot image.

According to the twelfth aspect of the invention, the beam diameter of the spot image can be measured. As a result, the positioning of the light shielding mask and the phase shift mask can be performed with high accuracy and efficiency.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a method for manufacturing a recording medium master and an exposure apparatus for a recording medium master according to the present invention will be described in detail below with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a diagram showing steps of a method of manufacturing a recording medium master according to the first embodiment. Hereinafter, each step will be described.

(Photoresist Layer Forming Step) FIG. 1A
On the surface-treated glass substrate 101, as shown in
A photoresist layer 102 having photosensitivity to an exposure beam having a wavelength λ is formed. The glass substrate 101 is subjected to a cleaning treatment and a surface treatment for improving the adhesiveness of the photoresist layer 102. Photoresist layer 102
Is applied on the glass substrate 101 by spin coating or the like. After application, heat treatment, drying treatment, cooling treatment, or the like is performed as necessary. In addition, the photoresist layer 102
Becomes alkali-soluble after the exposure step described later.

The film thickness of the photoresist layer 102 is formed to the same extent as the depth of the groove formed on the stamper surface. Although this film thickness varies depending on the conditions, it is about 150 to 300 nm. This step will be specifically described. The disk-shaped polished glass substrate 101 is surface-treated for about 3 minutes by an optical ozone ashing device called UV / O ₃ . The optical ozone ashing treatment is intended to remove organic substances on the surface of the glass substrate 101 and to form an oxide film on the surface. Thereby, the wettability (hydrophilicity) of the water-soluble resin to the glass substrate 101 can be improved and the film thickness of the water-soluble resin can be made uniform. Further, the water-soluble resin and the glass substrate 10
The adhesiveness with 1 can be strengthened.

Further, as long as it is a treatment capable of improving the wettability with water, a method other than the optical ozone ashing treatment can be substituted. For example, the surface may be washed with a solvent such as isopropyl alcohol to remove organic substances, and then the glass surface may be replaced with hydrophilicity by sufficiently washing with pure water. Considering the excellent removability of organic substances and the fact that the glass substrate is dry and does not need to be dried, the optical ozone ashing treatment is most desirable.

Next, hexamethyldisilazane (hereinafter referred to as "HMDS") is spin-coated on the glass substrate 101. Then, in an oven at a temperature of 130 ℃ 30
Heat for 1 minute to dry completely. The HMDS treatment is performed to make the surface of the glass substrate 101 hydrophobic. By the HMDS treatment, the photoresist layer 102 can be uniformly applied to the surface of the glass substrate 101, the adhesion between the glass substrate 101 and the photoresist layer 102 can be increased, and the peeling of the photoresist layer 102 during development can be prevented. Produce the effect of.

Then, the glass substrate 10 coated with HMDS
A photoresist is applied onto 1 by a spin coater. After that, heat treatment is performed in an oven at a temperature of 80 ° C. for 30 minutes. As the photoresist material, a positive photoresist manufactured by Tokyo Ohka is used. The film thickness of the photoresist layer 102 is about 600Å.

(Contrast Enhancement Layer Forming Step) After forming the photoresist layer 102, as shown in FIG. 1B, a contrast enhancement layer 103 made of a photobleaching material is formed on the surface of the photoresist layer. The application of the contrast enhancing layer 103 is performed by the spin coating method similarly to the photoresist layer 102. It is desirable that the solvent in which the photobleaching material is dispersed does not dissolve the photoresist layer and that the contrast enhancing layer 103 can be easily removed before the developing process. For this reason, it is preferable to disperse the photobleachable material in a water-soluble resin solvent and apply it.

This step will be specifically described. A solution in which a spiropyran-based photobleaching material is dispersed in a water-soluble resin is applied onto a glass substrate 101 having a photoresist layer 102 formed thereon by a spin coater. Then, in the oven 80
Heat treatment is performed at a temperature of -100 ° C for 30 minutes. As the water-soluble resin material, TPF manufactured by Tokyo Ohka (trade name: polyvinyl alcohol as a main component) is used. The thickness of the contrast enhancing layer 103 is adjusted to about 1000Å. In addition,
As the water-soluble resin material, methyl cellulose or polyvinyl pyrrodrine may be used instead of polyvinyl alcohol.

(Exposure Step) After the contrast enhancing layer 103 is formed, the photoresist layer 102 is exposed as shown in FIG. For exposure, wavelength λ = 40
An exposure apparatus for a recording medium master disk is used which includes a laser light source that supplies light of about 0 nm. Note that in FIG. 1C, for convenience of description, the configuration of the exposure apparatus main body is omitted, and only the objective lens 104 is shown.

In the exposure process, first, the objective lens 1 is attached to the glass substrate 101 placed on a rotary table (not shown).
The focus position of 04 (NA = about 0.9) is adjusted. The glass substrate 101 coated with the photoresist layer 102 is rotated by the rotating table. Then, while moving the objective lens 104 in the radial direction of the glass substrate 101, the laser light 105 is applied to the photoresist layer 102 through the contrast enhancing layer 103. In the contrast enhancing layer 103, a photoreaction occurs in a region of the irradiated region 106 where the integrated exposure amount is a predetermined value or more. Then, the region where the photoreaction has occurred discolors and the light is transmitted. As a result, a latent image having a concavo-convex pattern can be formed on a spiral or concentric information track with respect to the photoresist layer 102. Here, when laser light is continuously emitted, a continuous guide groove for tracking is formed. Further, when the laser beam is irradiated intermittently as necessary, information pits such as addresses are formed.

The spot diameter of the laser beam 105 focused on the photoresist layer 102 by the objective lens 104 is
It is made smaller than the diffraction limit by using a light-shielding mask or a phase shift mask described later.

Further, the integrated exposure amount of the contrast enhancing layer 103 corresponding to the exposed region of the photoresist layer 102 is Ep, and the integrated exposure amount of the contrast enhancing layer 103 corresponding to the unexposed region of the photoresist layer is El. Then, exposure is performed so as to satisfy the condition of El / Ep <0.45. This condition will be described in detail later.

This step will be specifically described. For exposure, a master exposure apparatus with a light source wavelength λ = 413 nm and an objective lens NA = 0.9 is used. C with constant linear velocity (about 7 m / s)
The guide groove is exposed by the LV method. In this case, the diffraction-limited spot diameter of the Gaussian beam is about 0.40 μ at 1 / e ² intensity.
m. In this embodiment, ZnS / SiO _{2 is formed on} BK7 glass having a thickness of 0.6 mm on the light source side of the objective lens 104.
A phase shift mask formed by sputtering a film (refractive index 2.26) is arranged. FIG. 7A is a diagram showing the configuration of the phase shift mask. A circular region having a diameter D = 1.05 mm is a phase shift region that gives a phase shift δ1. Objective lens 1
The ratio of 04 to the pupil diameter φ is 0.3. ZnS / S
The thickness of the iO ₂ film is 169 nm. As a result, the phase difference from the portion where the phase shift amount is zero is π radian, that is, 1
/ 2 wavelengths.

Other thin film materials such as SiO, SiO ₂ and S
You may form iN etc. so that the following formula may be satisfy | filled. (Refractive index of film-1) × film thickness = 1/2 wavelength (phase difference π) or an odd multiple thereof Further, instead of forming a thin film, the glass itself may be etched into a circle. The thin film pattern can be easily manufactured by photoetching. Therefore, using the photo-etching method, the phase shift mask can be manufactured more easily than the glass-etching method.

(Contrast enhancing layer removing step) After the exposure step, as shown in FIG.
The contrast enhancement layer 103 on 2 is removed. When the solvent used when the photobleaching material forming the contrast enhancing layer 103 is applied is a water-soluble resin, the contrast enhancing layer 103 can be easily removed with water. This step will be specifically described. In this embodiment, the contrast enhancing layer 103 made of a water-soluble resin is washed and removed with pure water.

(Developing Step) After removing the contrast enhancing layer 103, a developing process is performed as shown in FIG. The photoresist layer 102 in the area 107 where the latent image is formed by exposure is removed by an alkaline developer. Then, rinse with pure water and dry. After the development process,
Concavo-convex patterns 108a and 108b of pits or guide grooves are formed on the photoresist layer 102. This step will be specifically described. The glass substrate 101 from which the contrast enhancing layer 103 has been removed is developed with an alkaline developer for 90 seconds. After that, it is rinsed with pure water and shaken off at high speed to dry.

(Metal coating process, electroforming process, peeling process, etc.) After development, as shown in FIG. 1 (f), a metal coating 109 of nickel or the like is sputtered on the surface of the glass substrate 101 having an uneven pattern. Form. After the metal coating treatment, as shown in FIG. 1 (g), the coated glass substrate 10 is provided.
By electroforming No. 1, electroforming 110 is laminated. And
As shown in FIG. 1H, an electroformed glass substrate 101
The electroformed 110 laminated is peeled off. The back surface (the surface on which the concavo-convex pattern is not formed) of the electroformed 110 is polished, and the lower layer water-soluble resin remaining on the surface is washed and dried.
Finally, the inner and outer diameters are processed into desired dimensions to complete an optical disc master (a stamper for mass production of substrates by molding).

This step will be specifically described. In the metal coating treatment step, a nickel film (film thickness 500 to 1000Å) is formed on the lower surface by sputtering. A nickel film is used as an electrode during electroforming. In the electroforming process, the plate thickness is about 300 μm
Until nickel is deposited by electroforming. In the peeling step, the nickel plate is peeled from the glass substrate 101.
After peeling, the lower layer (water-soluble resin) remaining on the surface is washed and removed with pure water and dried. Here, when the residual deposits cannot be sufficiently removed, it is desirable to use warm water by utilizing the characteristic that the dissolution rate of the water-soluble resin is increased.

(Intermediate layer forming step and its removing step) FIG.
In the above step shown in FIG. 3, in order to simplify the coating and peeling of the contrast enhancing layer 103, the photobleaching material is mixed with the water-soluble resin and applied. However, not limited to this, the photobleaching material may be dissolved in an organic solvent. In terms of manufacturability, availability, and solubility in a solvent, the case where the photobleachable material is dissolved in an organic solvent is slightly more advantageous than the case where it is mixed with a water-soluble resin. The manufacturing process of the recording medium master disk when the photobleachable material is dissolved in an organic solvent will be described with reference to FIG.

In the step shown in FIG. 2, an intermediate layer 111 is formed between the contrast enhancing layer 103 made of a photobleaching material dissolved in an organic solvent and the photoresist layer 102 to prevent the layers from being mixed. (FIG. 2B) and the intermediate layer 1
The process is different from the process shown in FIG. 1 in that a process for removing 11 (FIG. 2 (f)) is added. Since the other steps are the same as those described with reference to FIG. 1, the description of the overlapping steps will be omitted.

As shown in FIG. 2B, the intermediate layer 111 is formed on the photoresist layer 102. Middle layer 11
1 is formed by spin-coating a water-soluble resin such as polyvinyl alcohol or by sputtering a dielectric film such as In ₂ O ₃ . Further, as shown in FIG. 2F, the intermediate layer 111 is removed with pure water when the intermediate layer 111 is a water-soluble resin, or with acid or the like when the intermediate layer 111 is a dielectric film. Further, as described later, it is desirable that the transmittance of the intermediate layer 111 at the exposure wavelength is 90% or more. Thereby, the shape of the concavo-convex pattern formed on the photoresist layer 102 can be stabilized.

In the manufacturing process of the recording medium master disk described above, if the pattern interval to be formed is made small, the pattern shape of the photoresist layer, especially the pattern height is not uniform depending on the super-resolution condition as shown in FIG. May be. When the pattern interval is reduced to about the exposure beam diameter, the tails of the intensity distribution of the exposure beam overlap between adjacent patterns. Then, the overlap of the skirts of the intensity distribution is accumulated, so that the contrast enhancement layer 103 corresponding to the pattern convex portion 108a of the photoresist layer 102 of FIG. 1E after development is a region where the photoresist layer 102 is not exposed. A decrease in transmittance occurs also in the area. As a result, the exposure beam reaches a region of the photoresist layer 102 that does not need to be exposed. In this way, the pattern shape after development becomes non-uniform.

FIG. 3 shows the case of exposure with a Gaussian beam.
The cumulative exposure amount due to the overlap of the bottoms of the exposure beams is set to the track pitch TP = 0.33 μm, 0.40 μm, 0.74 μ
It is a figure shown about three kinds of pattern intervals of m. Figure 3
The horizontal axis indicates the pattern position, and the vertical axis indicates the exposure amount (unit is arbitrary). As is clear from FIG. 3, as the track pitch decreases, the overlap of the skirts of the adjacent exposure beams increases. Also, when super-resolution is used to obtain a beam diameter below the diffraction limit, side lobes cannot be essentially removed. Therefore, this overlapping phenomenon is likely to be remarkable.

When the guide groove is formed, it is perpendicular to the information track, that is, the recording medium (optical disk).
An overlapping phenomenon occurs only in the radial direction of the master. Furthermore, when the information pits are formed, an overlapping phenomenon may occur not only in the radial direction of the recording medium master but also in the direction along the information tracks. However, in general, the track pitch interval is smaller than the information pit interval and the track pitch interval. From this, whether the pattern is a guide groove or a pit, this overlapping phenomenon becomes noticeable in the radial direction. Therefore, when the track pitch is reduced, the overlapping phenomenon becomes more noticeable.

In this embodiment, the photoresist layer 102 is used.
Ep is the cumulative exposure amount of the contrast enhancing layer 103 corresponding to the exposure region of E, and E is the cumulative exposure amount of the contrast enhancing layer 103 corresponding to the non-exposure region of the photoresist layer 102.
When it is respectively set to l, the conditional expression El / Ep (hereinafter “K”)
Exposure) to satisfy <0.45. As a result, it is possible to form a uniform pattern on the photoresist layer 102.

Next, the conditional expression K <0.45 will be described. FIG. 4 is a diagram showing the relationship between the track pitch TP and the parameter K in exposure using a contrast enhancement layer with a Gaussian beam. In FIG. 4, “Gaus
"s" is exposure with a Gaussian beam, and "phase ring zone 0.3-
“0.45” is the relationship in the exposure when the phase shift mask shown in FIG. 7B is used, and “phase circle 0.3” is the relationship in the exposure when the phase shift mask shown in FIG. 7A is used. . The phase shift mask will be described later. Then, the parameter K is changed, and the cross-sectional shape of the pattern formed on the photoresist layer 102 is observed and evaluated by the AFM. As a result, it was found that the shape of the pattern formed on the photoresist layer 102 was uniform up to the track pitch TP = 0.35 μm and there was no problem. 4 to T
P = 0.35 μm corresponds to K = 0.45. As a result, if K <0.45, a uniform pattern can be formed on the photoresist layer 102. The parameter K
Does not depend on the shape of the exposure beam. Therefore, this conditional expression is effective even when super-resolution is used.

Further, in the present embodiment, the spot diameter of the focused exposure beam is narrowed down to the diffraction limit or less by super-resolution. Super-resolution is performed by blocking a part of the light incident on the objective lens or by causing a phase shift. The shape and arrangement of the light shielding area or the phase shift area,
By appropriately setting the size or the amount of phase shift, the spot diameter of the exposure beam focused by the objective lens can be made smaller than the usual diffraction limit spot diameter.

FIGS. 5A to 5D are views showing the structure of the light shielding mask SM. In the super-resolution using the light-shielding mask, for example, the rectangular light-shielding region S1 shown in FIG.
Light-shielding mask SM having a circular light-shielding region S2 shown in (b)
To use. The light-shielding mask SM is arranged so that the centers of the light-shielding regions S1 and S2 are aligned with the optical axis of the objective lens 104.
It is arranged closer to the light source than 04.

Further, as shown in FIG. 5C, a light-shielding mask SM having a plurality of rectangular light-shielding regions S3 provided in stripes, or FIG.
A circular light-shielding region and a plurality of ring-shaped light-shielding regions S shown in (d)
A light-shielding mask SM provided with 4 may be used. Also in the case of these masks, the centers of the light shielding regions S3 and S4 and the objective lens 104
It is arranged on the light source side of the objective lens 104 so as to coincide with the optical axis of. Thereby, the intensity itself can be dispersed by generating the side beams at a plurality of locations.

FIGS. 6A to 6D are diagrams showing the structure of the phase shift mask PM. The phase shift mask is composed of a phase object that causes a phase shift in a part of the light incident on the objective lens. FIG. 6A is a diagram showing a configuration of a phase shift mask PM having a rectangular region P1 that causes a phase shift δ1 and an outer peripheral region P2 that causes a phase shift δ2.

FIG. 6B shows a circular area P3 which causes a phase shift δ1 and an outer peripheral area P4 which causes a phase shift δ2.
It is a figure which shows the structure of the phase shift mask PM which has and. FIG. 6C shows a rectangular region P that causes a phase shift δ1.
5 is a diagram showing a configuration of a phase shift mask PM including a rectangular region P6 that causes a phase shift δ3 and an outer peripheral region P7 that causes a phase shift δ2. FIG. FIG. 6D shows a phase shift mask PM having a circular region P8 that causes a phase shift δ1, an annular region P9 that causes a phase shift δ3, and outer peripheral regions P10 and P11 that cause phase shifts δ2 and δ4. It is a figure which shows the structure of.

The phase shift mask PM having such a configuration is arranged closer to the light source than the objective lens 104 so that the center of the phase shift region coincides with the optical axis of the objective lens 104. Thereby, the intensity itself can be dispersed by generating the side beams at a plurality of locations. Further, it is desirable that the amount of phase shift between the phase shift regions (for example, | δ1-δ2 |) be an odd multiple of π. As a result, the effect of reducing the spot diameter of the exposure beam can be maximized.

Thus, comparing with the Gaussian beam,
In super-resolution, the diameter of the main beam can be reduced. However, the intensity of the main beam in super-resolution decreases. Comparing a light-shielding mask that gives the same beam diameter with a phase shift mask, the phase shift mask has a higher main beam intensity. Therefore, when the light amount of the light source is small, it is desirable to perform super-resolution using the phase shift mask because the light amount can be effectively used.

In this embodiment, as shown in FIG.
The phase shift mask PM having the configuration shown in is used. When the circular phase shift mask is used, the calculated spot diameter of the main beam is 0.36 μm, and the main beam peak intensity is 0.65 times that of the Gaussian beam. Further, the peak intensity ratio of the main beam and the side beam is 0.11. Further, the track pitch where the parameter K = 0.45 is 0.32 μm (curve of “phase circle 0.3” in FIG. 4). The intensity profile of the exposure beam is shown in FIG.

Further, according to the present manufacturing method using the above-mentioned conditions, the track pitch of the photoresist layer 102 is 0.
A 32 μm uniform pattern can be stably formed. FIG. 9 illustrates the photoresist layer 102 according to the present embodiment.
It is a figure which shows the result of having observed the shape of the pattern formed in AFM with AFM. As is clear from FIG. 9, it can be seen that a uniform pattern is formed.

(Second Embodiment) In the method of manufacturing a recording medium master according to the second embodiment, in the exposure step, the guide groove is exposed by using a ring-shaped phase shift mask PM. Different from the form. Other steps are the same as above
Since it is the same as the embodiment, the duplicated description will be omitted. As shown in FIG. 7B, the phase shift area of the phase shift mask PM has an inner diameter D1 = 1.05 mm and an outer diameter D2 = 1.5.
It has an annular shape of 8 mm. The phase shift region gives a phase shift δ1. The ratio of the objective lens to the pupil diameter φ is 0.
It is 3 to 0.45. The film thickness, phase difference and other conditions are the same as those in the first embodiment.

In the present embodiment, the calculated spot diameter of the main beam is 0.36 μm, and the peak intensity of the main beam is 0.55 times the peak intensity of the Gaussian beam. The peak intensity ratio between the main beam and the primary side beam is 0.06, and the peak intensity ratio between the main beam and the secondary side beam is 0.04. Further, the track pitch at which K = 0.45 is 0.31 μm (curve of “phase ring zone 0.3-0.45” in FIG. 4). The intensity profile of the exposure beam is shown in FIG. Through the same process as in the first embodiment, a uniform pattern can be stably formed on the photoresist layer 102 with a track pitch of 0.31 μm. In this embodiment, the track pitch can be made slightly smaller than that of the circular phase shift mask having the same beam spot diameter.

(Third Embodiment) The third embodiment is different from the first embodiment in that the solvent of the photobleaching material constituting the contrast enhancing layer 103 is an organic solvent instead of the water-soluble resin. The other steps are the same as those in the first embodiment described above, and thus duplicated description will be omitted. Photoresist layer 1
After forming 02, a water-soluble resin of polyvinyl alcohol is spin-coated on the upper layer of the photoresist layer 102 to form a film. Next, after applying the water-soluble resin,
Bake at ~ 100 ° C to evaporate the solvent. The polyvinyl alcohol film thickness of the intermediate layer 111 is 400Å.
The transmittance of the intermediate layer 111 is about 95%.

The material of the intermediate layer 111 may be a water-soluble resin such as polyvinylpyrrolidone or methylcellulose. Further, as the intermediate layer 111, a dielectric film may be formed by a stapper or vapor deposition instead of the water-soluble resin.
As the dielectric film, In ₂ O ₃ , Al ₂ O ₃ , SiO ₂ , MgF are used.
Materials such as ₂ , ZnS, CeF ₃ , ZrO ₂ , TiO ₂ and CeO ₂ are desirable. In any case, the refractive index and the film thickness of the intermediate layer 111 and the contrast enhancing layer 103 are controlled,
It is desirable to maintain the transmittance of the intermediate layer 111 with respect to the exposure wavelength at 90% or more. As a result, the exposure amount reaching the photoresist layer can be secured, so that the photoresist layer 1
It is possible to stably form a uniform-shaped pattern in No. 02.

When the contrast enhancing layer of the photobleaching material is formed on the intermediate layer 111, a solution of the photobleaching material in an organic solvent containing a binder component and the photobleaching material is applied by spin coating. . As the binder component, for example, polyethylene glycol, vinyl acetate resin or the like is used. A spiropyran-based material is used as the photobleaching material. After applying a binder component and a photobleaching material dissolved in this organic solvent to the intermediate layer 111, 8
Bake at 0-100 ° C to evaporate the solvent. As a result, a contrast enhancing layer having a film thickness of about 1000Å is formed.

The various conditions of the master exposure including the super resolution are the same as those in the first embodiment. In the present embodiment, 0.14 μm below the contrast enhancing layer 103 (glass substrate 1
The offset voltage is applied to the focus error signal so that the (01 side) becomes the zero point of the focus error signal. This makes it possible to eliminate the sagging of the pattern. The offset of the focus error signal will be described in detail in the fourth embodiment below.

After exposure, the contrast enhancing layer 103 is removed with an organic solvent, and then the intermediate layer 111 is removed.
When the intermediate layer 111 is a water-soluble resin, it is removed with pure water. When the intermediate layer 111 is a dielectric film, it is removed with an acid such as nitric acid. The steps subsequent to the development are the same as those in the first embodiment, and thus the duplicate description will be omitted. As a result, a uniform pattern can be formed on the photoresist layer 102.

(Fourth Embodiment) FIG. 10 is a view showing the schematic arrangement of an exposure apparatus for a recording medium master according to the fourth embodiment. The light from the Kr laser 200, which is the light source, has its optical path bent by the bending mirrors M1 and M2, and enters the EO modulator / deflector 201. EO modulator / deflector 201
Emits light from the light source 200 after being modulated according to an input signal. Further, the light source light may be modulated by the AO modulator 202 using the bending mirror M3.

The light emitted from the EO modulator / deflector 201 is
It is incident on the phase shift mask PM. Phase shift mask P
As described in each of the above-described embodiments, M causes a phase shift in a partial region of the incident light and emits the light. The phase shift mask PM is held by the mask holder 203. The mask holder 203 can be moved and adjusted by a micrometer (mask holder adjusting unit) in two directions (XY directions) orthogonal to each other in a plane perpendicular to the optical axis of the objective lens. Further, the mask holder 203 and the phase shift mask PM may be provided in the optical path after the AO modulator 202 is emitted, if necessary. Further, the mask holder 203 and the phase shift mask PM can be provided both in the optical path after the EO modulator / deflector 201 is emitted and in the optical path after the AO modulator 202 is emitted. The light emitted from the phase shift mask PM has its optical path bent 90 degrees by the bending mirrors M4 and M5, and enters the objective lens 204.

The objective lens 204 focuses the incident light at the focal position f. Further, a spot image observation monitor 206 is provided on the exit side of the objective lens 204. FIG. 10 is a diagram showing a state in which the spot image observation monitor 206 is in an observation position for observing a spot image. The spot image observation monitor 206 also includes a microscope lens L1 and a relay lens L2.
And a monitor camera MN. The microscope lens L1 is
A micrometer and a piezo element (not shown) allow coarse and fine movement in three orthogonal directions (X, Y, Z directions) including the optical axis direction of the objective lens 204. The microscope lens L1 is positioned using this micrometer and the piezo element. The relay lens L2 relays the spot image magnified by the microscope lens L1. Then, the monitor camera MN monitors the relayed image. As a result, the objective lens 2
The spot image of the beam condensed by 04 can be directly observed.

After that, the spot image is observed by the monitor camera MN. A spot diameter measuring device 207 is connected to the spot image observation monitor 206. The spot diameter measuring device 207 is an image processing device capable of converting the exposure beam spot diameter into an actual size. Thereby, the actual size of the spot diameter of the exposure beam can be measured. The operator adjusts the position of the mask holder 203 until the measured value of the spot diameter measuring device 207 reaches a desired value while observing the image on the spot image observation monitor 206. The spot image observation monitor 206 also has a spot image focusing unit 216. Accordingly, the spot image observation monitor 206 itself can be moved to focus on the spot image. Therefore, since the objective lens 204 of the exposure apparatus is not driven, no load is applied to the actuator 205.

Further, instead of the spot image observation monitor 206, a reflection beam image observation monitor 208 for observing the reflection spot image from the glass substrate 213 may be used. The reflected beam image observation monitor 208 can observe the spot image of the exposure beam with the glass substrate 213 set at the exposure position. The reflected beam image observation monitor 208 includes a magnifying lens L3 and a monitor camera MN. further,
A reflected spot diameter measuring device 209 is connected to the reflected beam image observation monitor 208. The reflection spot diameter measuring device 209 can measure the actual size of the spot diameter of the exposure beam, similarly to the spot diameter measuring device 207.

A procedure for adjusting the mask holder 203 by the reflected beam image observation monitor 208 will be described. First, after roughly positioning the phase shift mask PM, the glass substrate 21
3 is placed on the rotary stage 214. Rotating stage 21
4 is rotated by a motor 215. Next, the focus error signal generation circuit 211 generates a focus error signal corresponding to the focus position shift amount of the objective lens 204.

The focus error signal is sent to the focus servo circuit 210. The actuator 205 drives the objective lens 204 according to the focus error signal from the focus servo circuit 210. As a result, automatic focusing is performed. The operator observes the reflection spot image from the glass substrate 213 with the reflection beam image observation monitor 208. Next, a reflection spot diameter measuring device 209
To measure the spot diameter. Then, the position of the mask holder 203 is adjusted until the measured value of the spot diameter reaches a desired value.

Further, instead of the phase shift mask PM,
A light-shielding mask SM as shown in FIGS. 5A to 5D may be used. In this embodiment, by detaching the phase shift mask PM or the light shielding mask SM from the mask holder 203, these masks can be easily inserted into and removed from the optical path. Therefore, if the phase shift mask PM and the like are retracted from the optical path, conventional exposure with a Gaussian beam can be performed. Therefore, since various pattern formations can be supported, the recording medium master disc exposure apparatus can be efficiently used.

Next, a method of focusing the objective lens 204 will be described. When the glass substrate 213 is exposed, as described above, the actuator 205 servo-drives the objective lens 204 based on the focus error signal corresponding to the focus position shift amount of the objective lens 204.
As a result, automatic focusing is performed.

According to this focusing method, FIG.
As shown in (a), when only the photoresist layer 102 is formed on the glass substrate 101, the focus position fd
Is on the photoresist layer 102. Therefore, the spot diameter d1 on the photoresist layer 102 can be minimized. On the other hand, when the contrast enhancing layer 103 is further formed on the photoresist layer 102, the focus position fd is on the contrast enhancing layer 103, as shown in FIG. Therefore, the spot diameter d2 on the photoresist layer 102 becomes large due to defocus. Due to this defocus, the pattern formed on the photoresist layer 102 is sagging.

Therefore, in this embodiment, the offset voltage setting section 212 applies a predetermined offset voltage to the focus error signal generation circuit 211. As a result, 0.1 μm below the contrast enhancing layer 103 (the glass substrate 10
1 side) is the zero point of the focus error signal. As a result, even when the contrast enhancing layer 103 is formed, it is possible to focus on the photoresist layer 102 so that the beam diameter becomes the minimum.

In each of the above embodiments, the photoresist layer 102 is a positive photoresist in which the exposed area is soluble in the developing process. However, the present invention is not limited to this, and the present invention can be applied to a negative photoresist in which the non-exposed portion is developed and soluble, only by reversing the concavo-convex shape of the pattern.

Further, in each of the above-described embodiments, a method for manufacturing a recording medium master disk such as an optical disk and an exposure apparatus for the same are described. However, the present invention is not limited to this, and the present invention can be similarly applied to a similar optical recording medium, for example, a method of manufacturing a master such as an optical card and its exposure apparatus.

[0097]

As described above, according to the first aspect of the present invention, the integrated exposure amount of the contrast enhancing layer corresponding to the exposed portion of the photoresist layer and the contrast enhancing layer corresponding to the unexposed portion of the photoresist enhancing layer. Main beam (including side beam) of exposure beam by super-resolution
Stipulates 0.45 or less. As a result, it is possible to stably form an uneven pattern having a diffraction limit or less on the photoresist layer.

According to the invention of claim 2, an intermediate layer is further provided. Thereby, the contrast enhancing layer can be stably formed.

According to the invention of claim 3, the conditions for forming the intermediate layer and the contrast enhancing layer are controlled so that the transmittance of the intermediate layer at the exposure wavelength is 90% or more. Thereby, the pattern formation of the photoresist layer can be stabilized.

According to the fourth aspect of the present invention, an exposure beam by super-resolution can be easily obtained only by adding a light-shielding mask to the existing master disc exposure apparatus.

According to the fifth aspect of the present invention, the side lobes are dispersed at a plurality of positions by the plurality of light shielding regions, and the integrated light amount ratio is improved. Thereby, the pattern interval can be further reduced.

According to the sixth aspect of the present invention, the super-resolution exposure beam can be easily obtained only by adding a phase shift mask to the existing master disc exposure apparatus. Further, the light utilization rate is improved as compared with the case where the light shielding mask is used.

According to the seventh aspect of the invention, the side lobes are dispersed at a plurality of locations by the plurality of phase shift regions, and the integrated light amount ratio is improved. Thereby, the pattern interval can be further reduced.

According to the eighth aspect of the invention, the difference between the phase shift amounts of the adjacent phase shift regions is π radian (1 /
2 wavelengths). As a result, the diameter of the spot image can be reduced most efficiently.

According to the ninth aspect of the invention, the focus position of the exposure beam can be controlled by setting or canceling a predetermined offset voltage in the focus error signal of the objective lens. Further, a light-shielding mask or a phase shift mask for super-resolution can be freely inserted and removed and positioned as required. This allows a single exposure device to combine exposure on a glass substrate having a contrast enhancing layer, exposure on a glass substrate with only a photoresist layer, exposure with a super-resolution beam, and exposure with a Gaussian beam. Can be used properly. Therefore, the exposure apparatus can be used very efficiently because it can be applied to high-density optical disks and ordinary optical disks such as CDs and DVDs.

According to the tenth aspect of the present invention, the spot image observing section for observing the spot image focused by the objective lens can observe the actual state of the super-resolution spot image. As a result, it is possible to accurately and efficiently position the light shielding mask and the phase shift mask for super resolution.

According to the eleventh aspect of the invention, the spot image observation section has a focusing section. Therefore, the spot image observation unit itself moves to focus on the spot image. As a result, the objective lens of the exposure apparatus is not driven, so that no load is applied to the actuator.

According to the twelfth aspect of the invention, the beam diameter of the focused spot image can be measured. This allows
Accurate positioning of light-shielding masks and phase shift masks,
And it can be done efficiently.

[Brief description of drawings]

FIG. 1 is a diagram showing each step of a method of manufacturing a recording medium master according to the first embodiment of the present invention.

FIG. 2 is a diagram showing each step of a method of manufacturing a recording medium master disc when an intermediate layer is further provided in the first embodiment.

FIG. 3 is a diagram showing the relationship between the track pitch and the overlap of exposure beams.

FIG. 4 is a diagram showing a relationship between a track pitch and a parameter K.

5A to 5D are diagrams showing a configuration of a light shielding mask.

6A to 6D are diagrams showing a configuration of a phase shift mask.

7A and 7B are diagrams showing the configuration of another phase shift mask.

FIG. 8 is a diagram showing beam profiles of a Gaussian beam and a super-resolution beam.

FIG. 9 is a cross-sectional shape of a pattern obtained according to the first to third embodiments.

FIG. 10 is a diagram showing a schematic configuration of an exposure apparatus for a recording medium master according to a fourth embodiment of the present invention.

11A and 11B are diagrams showing a focused state.

FIG. 12 is a diagram showing a cross-sectional shape of a pattern exposed by a Gaussian beam.

FIG. 13 is a diagram showing the shapes of a Gaussian beam and a super-resolution beam.

FIG. 14 is a diagram showing a cross-sectional shape of a conventional pattern.

[Explanation of symbols]

101 glass substrate 102 photoresist layer 103 Contrast enhancement layer 104 Objective lens 105 exposure beam 106 beam irradiation area 107 latent image 108a pattern protrusion 108b pattern recess 109 metal coating 110 electroforming 111 Middle class SM shading mask PM phase shift mask 200 Kr laser 201 EO Modulator / Deflector 202 AO modulator 203 Mask holder 204 Objective lens 205 actuator 206 Spot image observation monitor 207 Spot diameter measuring device 208 Reflected beam spot image observation monitor 209 Reflection spot diameter measuring device 210 Focus servo circuit 211 Focus error signal generation circuit 212 Offset voltage setting section 213 glass substrate 214 rotary stage 215 motor M1-M6 mirror

Claims (12)

[Claims] 1. A step of forming a photoresist layer on a substrate, a step of forming a contrast enhancing layer made of a photobleaching material on the photoresist layer, and light from a light source condensed by an objective lens. Irradiating the photoresist layer through the contrast enhancing layer, exposing a predetermined area of the photoresist layer, removing the contrast enhancing layer, and exposing the exposed photoresist layer. A developing step of forming a concavo-convex pattern on the photoresist layer by developing, a transfer step of transferring the concavo-convex pattern formed on the photoresist layer to produce a recording medium master, In the exposure step, the diameter of the main spot of the light focused on the photoresist layer in at least one direction is equal to that of the light from the light source. Is less than or equal to the diffraction limit determined based on the wavelength of the objective lens and the numerical aperture of the objective lens, the integrated exposure amount of the contrast enhancing layer corresponding to the exposure region of the photoresist layer is Ep, and the non-exposure region of the photoresist layer is When the integrated exposure amount of the contrast enhancing layer corresponding to is El, respectively, El / Ep <
A method of manufacturing a recording medium master disc, which satisfies 0.45. 2. A step of further forming an intermediate layer between the photoresist layer and the contrast enhancing layer, wherein the light from the light source collected by the objective lens is supplied to the contrast enhancing layer and the intermediate layer. 2. The method of manufacturing a recording medium master according to claim 1, further comprising: an exposure step of irradiating the photoresist layer through the exposure step to expose a predetermined region of the photoresist layer. 3. The method of manufacturing a recording medium master according to claim 2, wherein the intermediate layer has a transmittance of 90% or more with respect to the wavelength of the light from the light source. 4. A light-shielding mask for shielding a predetermined area of incident light is arranged in an optical path between the light source and the objective lens, and the photoresist layer is exposed by light passing through the light-shielding mask. 4. The method for manufacturing a recording medium master according to claim 1, wherein 5. The method of manufacturing a recording medium master according to claim 4, wherein the light-shielding mask has a plurality of light-shielding regions. 6. A phase shift mask that causes a phase shift in a predetermined region of incident light is arranged in an optical path between the light source and the objective lens, and light passing through the phase shift mask causes the photoresist layer to reach the photoresist layer. Exposure is performed.
A method of manufacturing a recording medium master according to any one of 1. 7. The method of manufacturing a recording medium master according to claim 6, wherein the phase shift mask has a plurality of phase shift areas, and adjacent phase shift areas have different phase shift amounts. 8. The method of manufacturing a recording medium master according to claim 7, wherein the difference in the amount of phase shift between the adjacent phase shift areas is an odd multiple of π. 9. An objective lens which focuses light from a light source on a photosensitive substrate having a photoresist layer and at least a contrast enhancing layer in order from the substrate side, and the objective lens is focused on the photosensitive substrate. A focusing unit for controlling the amount of light, an offset amount control unit for setting or canceling a predetermined offset signal with respect to the objective lens based on a focus signal from the focusing unit, and shielding a predetermined region of light incident on the objective lens. A light-shielding mask, or a mask holder for inserting and removing a phase shift mask for shifting the phase of a predetermined region of light incident on the objective lens in the optical path from the light source to the objective lens; A mask holder adjusting section for adjusting the position in two directions orthogonal to each other in a plane perpendicular to the optical axis of the objective lens. An exposure device of the recording medium master, characterized in that. 10. The exposure apparatus for a recording medium master according to claim 9, further comprising a spot image observation unit for observing a spot image condensed by the objective lens. 11. The exposure apparatus for a recording medium master according to claim 10, wherein the spot image observation section has at least a focusing section for the spot image. 12. The exposure apparatus for a recording medium master according to claim 10, wherein the spot image observing section has at least a beam diameter measuring section for measuring a beam diameter of the spot image.