JP2002245685A - Method of forming fine pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form fine patterns in a method of forming the fine patterns by forming a deteriorated resin layer which has the width smaller than the diameter of a light beam spot and is insoluble in developer on a substrate. SOLUTION: A metallic layer is formed on the surface of the substrate and the resin layer is formed on this metallic film and thereafter the resin layer is condensed and irradiated with a light beam in the prescribed positions from above the resin layer, by which the deteriorated layers insoluble in the developer are formed in the regions of the resin layer heated up to a prescribed temperature or above. The segments of the resin layer exclusive of the deteriorated layers are selectively removed so as to allow the deteriorated layers to remain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a fine pattern, and more particularly to a method for forming a fine pattern required when manufacturing an optical disk master for manufacturing an optical disk or the like for recording information at high density. About.

[0002]

2. Description of the Related Art Today, in order to realize a higher density of an optical disk, a track pitch of a guide groove and a prepit of the optical disk have been reduced. The formation of the guide grooves and prepits is generally performed by a so-called mastering process in which a photoresist applied to a glass substrate is condensed and irradiated with a laser beam, and the photoresist is exposed and developed to produce an optical disc master. Will be here,
Assuming that the wavelength of the laser light is λ and the numerical aperture of the objective lens for condensing the laser light is NA, the light beam spot diameter of the condensed laser light is approximately 0.8λ / NA.

Conventionally, in order to reduce the track pitch of a light beam spot in order to reduce the track pitch of a guide groove or a pre-pit of an optical disk, the wavelength λ of a laser beam is reduced.
Is shortened, and the numerical aperture NA of the objective lens is increased.

Conventionally used positive photoresist 6
A description will be given of laser cutting of the optical disk master to which the coating is applied. FIG. 1 shows a schematic configuration diagram of a conventional laser cutting. In FIG. 1, a laser beam 2 emitted from a laser light source 1 is reflected by mirrors 3-1 and 3-2, and after a light intensity control is performed by an optical modulator 4, a falling mirror 3-
By being reflected by 3 and passing through the objective lens 5, the positive photoresist 6 applied on the glass substrate 7 is focused and irradiated.

[0005] The glass substrate 7 is mounted on a spindle motor 8. The falling mirror 3-3 is synchronized with the rotation of the glass substrate 7 accompanying the rotation of the spindle motor.
The exposure corresponding to the spiral guide groove and the pre-pit is performed on the positive photoresist 6 by moving the and the objective lens 5. After exposure, the positive photoresist 6 is developed to form a positive photoresist pattern corresponding to the spiral guide groove and the pre-pit.

FIG. 2 shows a standardized light intensity distribution with respect to a spot diameter of a light beam converged on a positive photoresist 6 in the related art. This indicates an almost Gaussian light intensity distribution. It has a substantially Gaussian light intensity distribution.

Generally, the light beam spot diameter BS is defined by a range where the light intensity is 1 / e ² of the maximum light intensity. The light beam spot diameter BS is determined by the wavelength λ of the laser light 2 to be used and the numerical aperture NA of the objective lens 5 for condensing the laser light 2, and the light beam spot diameter BS is approximately 0.8 × λ / NA. Can be approximated by For example, as the laser light 2, a laser light having a wavelength of 351 nm from the Kr laser light source 1 is used, and the numerical aperture NA is 0.95.
In the case where the objective lens is used, the light beam spot diameter BS becomes 296 nm.

FIG. 3 shows that a positive photoresist 6 on a glass substrate 7 is irradiated with the light beam 2 having the light beam spot diameter BS.
Shows the state of formation of the latent image 9 when is exposed. As the light beam 2 passes through the positive photoresist 6, the light intensity decreases due to light absorption, and a wide latent image 9 is formed on the positive resist surface, which is narrow on the glass substrate surface.

FIG. 4 shows the state of formation of the latent image 9 when exposing adjacent guide grooves at a track pitch TP substantially equal to the light beam spot diameter BS. For example, the light beam spot diameter BS is 296 nm and the track pitch TP
Is 300 nm. The position of the latent image 9 corresponds to a guide groove.

FIG. 5 shows a state of the latent image 9 formed on the positive photoresist 6 after such spiral guide grooves are continuously formed. FIG. 6 shows the latent image 9 shown in FIG.
2 shows the positive photoresist pattern 10 after the development.

As shown in FIG. 6, the light beam spot diameter B
Since S and the track pitch TP are almost equal, the guide groove 1
It was found that only a small amount of the positive type photoresist pattern 10 remained during 1 and that the pattern did not become a rectangular pattern. In such a state, a slight change in the light beam intensity at the time of cutting or a track pitch change due to an external vibration causes the positive photoresist pattern 1 to change.
It was confirmed that the shape of No. 0 was remarkably changed, and in the worst case, the positive type photoresist pattern 10 was missing and stable tracking became difficult.

In order to avoid such a situation, it is necessary to make the width of the positive photoresist pattern 10 wider. Therefore, an attempt was made to form a wider positive photoresist pattern 10 by weakening the intensity of the laser beam 2 when exposing the positive photoresist 6.

FIG. 7 shows a state of the latent image when the intensity of the laser beam is reduced. As shown in FIG. 7, when the intensity of the laser beam 2 at the time of exposure is reduced, a V-groove latent image 9 corresponding to the light intensity distribution of the light beam spot is formed. In this case, too, a rectangular positive photoresist pattern is formed. Was not formed. Further, in order to obtain a rectangular pattern, the trough pitch TP is larger than the light beam spot diameter BS and needs to be about twice.

As described above, when a positive optical photoresist 6 is applied directly on a glass substrate for manufacturing an optical disk master, the track pitch is reduced while maintaining stable tracking performance. It turned out that realization was difficult.

[0015]

At present, the numerical aperture NA of the objective lens has already been used near the limit, and the wavelength of the laser light also uses the ultraviolet laser light. Therefore, it is difficult to further shorten the wavelength. For example, an objective lens having a numerical aperture NA of 0.95 is used, and a Kr laser having a wavelength of 351 nm is used as a light source. In this case, the light beam spot diameter is about 0.3 μm, and it is impossible to realize a track pitch of 0.3 μm or less.

The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to form a modified resin layer having a narrow width on a substrate surface using an objective lens and a laser beam similar to those of the related art. Accordingly, it is an object to provide a method for forming a fine pattern having a guide groove smaller than the light beam spot diameter.

[0017]

According to the present invention, a metal film is formed on a surface of a substrate, a resin layer is formed on the metal film, and a light beam is collected at a predetermined position from above the resin layer. Forming a deteriorated layer insoluble in a developer in a region of the resin layer heated to a predetermined temperature or higher by irradiating light; selectively removing a portion of the resin layer other than the deteriorated layer; An object of the present invention is to provide a method for forming a fine pattern, wherein a layer is left. Thereby, a fine pattern having pre-pits and guide grooves smaller than the light beam spot diameter can be formed.

[0018]

Here, it is preferable that the altered layer is formed in a region smaller than the spot diameter of the concentratedly irradiated light beam. In particular, the metal film and the resin layer are preferably It is preferable to have an anti-reflection structure for the light beam condensed and irradiated. The substrate having the fine pattern thus formed can be used as an optical disk master or the like.

For the selective removal of the resin layer other than the altered layer, a developer for a positive photoresist, for example, Microposit 351 manufactured by Shipley Co., Ltd. can be used. Here, the portion of the altered layer was irradiated with a light beam, and the temperature was raised to a predetermined temperature. As a result, the positive photoresist was hard baked. On the other hand, it became insoluble.

Further, the metal film in a region where the deteriorated layer is not formed is etched using the deteriorated layer as a mask on the substrate where the deteriorated layer remains, and then the deteriorated layer is selectively removed. Good. The substrate after the metal film has been etched in this manner can also be used as an optical disk master or the like. Here, the etching of the metal film may be performed by dry etching.

Further, after selectively removing the altered layer, the substrate in the region where the metal film is not formed is etched using the remaining metal film as a mask, and then the metal film is selectively removed. Good.

Further, if so-called transfer is performed using an optical disk master having such a fine pattern, a stamper for an optical disk can be manufactured. Further, if the resin injection molding and the formation of the recording layer of the recording medium and the like are performed using the optical disk stamper, an optical disk can be manufactured. As the metal film, Ta, Ni, or the like can be used, but Ti, Co, or the like may also be used. As the substrate, glass, silicon, plastic, or the like can be used. In addition, a positive photoresist can be used for the resin layer.

Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. Note that the present invention is not limited to this. The conventional laser cutting device shown in FIG. 1 is also a laser cutting device used for manufacturing the optical disc master of the present invention. Conventionally, a positive photoresist 6 directly coated on a glass substrate was used. In the present invention, a metal film formed on a glass substrate 7 is used. The present invention is characterized in that an optical disk master having a fine pattern is manufactured by the following method. In the following embodiments, for a fine pattern formed on the substrate surface, a single track is formed by a pair of concave portions and convex portions, and a land recording method or group recording in which information is recorded only in either the concave portions or the convex portions. Target optical disks. In this method, the length obtained by adding the width of the pair of concave portions and convex portions is the track pitch TP.

FIG. 8 is a schematic explanatory view of laser cutting in the method of manufacturing an optical disk master according to the present invention.
As an optical disk master, a metal film 12 (for example, T) is formed on a substrate 7 made of glass (quartz) or silicon or the like.
a), a positive photoresist 13 as a resin layer formed in this order is used.

Here, it is necessary to set the thickness of the positive photoresist 13 so as to exhibit an antireflection effect with respect to the laser beam 2 used for exposure. For example, assuming that the wavelength of the laser beam 2 is λ and the refractive index of the positive photoresist 13 is n, a desirable positive photoresist 1
The film thickness w of No. 3 can be represented by w = (mλ) / (4n). Here, m is an odd number.

As described above, the light beam 2 is absorbed by the metal film 12 and the positive photoresist 13 by forming the positive photoresist 13 formed on the metal film 12 into an antireflection structure. When the light beam is absorbed by the positive photoresist 13, a Gaussian temperature distribution corresponding to the intensity distribution of the light beam 2 is formed on the positive photoresist 13. FIG. 9 shows an example of the temperature distribution with respect to the diameter of the light beam spot irradiated on the positive photoresist.

Here, the positive type photoresist 13 deteriorates with the rise in temperature. For example, in a region where the temperature rises to 150 ° C. or more, a resin layer insoluble in a developing solution is formed.

For example, when the light beam spot diameter BS is 300 nm in the temperature distribution shown in FIG.
The temperature peak of the positive photoresist 13 is 200 ° C., and the width of the region where the temperature has risen to 150 ° C. or more, that is, the width of the altered layer is about 100 nm. Here, 150 ° C
Is a boundary temperature at which the positive type photoresist 13 starts to deteriorate (hereinafter, also referred to as a deterioration temperature).

The portion of the positive photoresist 13 in the region of 150 ° C. or less does not change significantly, and is removed by development in a later step. Here, “deterioration” means that the positive photoresist 13 chemically changes so as to be insoluble even when dipped in the developing solution.

FIG. 8 shows a latent image formation state of the positive photoresist 13 when laser cutting is performed in a state where such a temperature distribution exists. A deteriorated positive-type photoresist layer 14 having a temperature rise of not less than ° C. is formed, and a developable latent image 9 is formed in a peripheral area thereof. Here, the width of the positive photoresist deteriorated layer 14 is equal to the light beam spot diameter B.
It is smaller than S. The formation of the altered layer 14 having such a small width was confirmed by observing the developed pattern with an electron microscope.

Here, as can be seen from FIG. 2, even outside the range of the light beam spot diameter BS, the laser beam 2 of a certain intensity is irradiated, and the positive photoresist 1
Light beam 2 of strong intensity capable of raising the temperature of the light beam 3
Is applied, the latent image 9 is formed in a range wider than the light beam spot diameter BS.

FIG. 10 shows a cross-sectional shape when an adjacent track is exposed at a track pitch TP substantially equal to the light beam spot diameter BS. In this case, the deteriorated positive type photoresist layer 14 is formed to be separated in the track direction, and the latent images 9 between adjacent tracks overlap.

FIG. 11 shows a cross-sectional shape after such laser cutting is continuously performed and the spiral laser cutting is performed. In the positive photoresist 13, the altered layer 14 of the positive photoresist and the latent image 9 are alternately arranged. This continuous cutting is performed by gradually moving the rising mirror 3-3 and the objective lens 5 shown in FIG.

FIG. 12 shows a cross-sectional shape after developing the positive photoresist 13 in the state shown in FIG. 11 using a developing solution. Only the positive photoresist 13 in the portion of the latent image 9 is removed, and a guide track 14 composed of the altered layer 14 of the positive photoresist is formed. Here, the portion between the guide tracks 14 is the guide groove 11. Figure 1
The structure shown in FIG. 2 can be used as an optical disk master.

Next, in the state shown in FIG. 12, using the deteriorated positive type photoresist layer 14 as a mask, the portion of the metal film 12 where the deteriorated layer 14 is not formed is etched.
This etching can be performed using wet etching or dry etching.

FIG. 13 shows a sectional state after the metal film 12 is etched. As shown in FIG. 13, a rectangular guide track in which a positive photoresist deteriorated film 14 is laminated on a metal film 12 is formed at a track pitch TP of about 300 nm.

FIG. 14 shows a modified positive photoresist layer 1.
4 shows the structure after removal of No. 4 with a positive photoresist remover or an organic solvent. As a result, a substrate having a structure in which guide tracks made of the metal film 12 are formed on the glass substrate 7 at a track pitch TR interval is formed. The structure shown in FIG. 14 can also be used as an optical disk master.

Next, using the metal film 12 shown in FIG. 14 as a mask, the portion of the glass substrate 7 where the metal film 12 is not formed is etched. FIG. 15 shows a state after the substrate 7 is etched. FIG. 16 shows an example in which the metal film 12 is dissolved by an acid capable of dissolving the metal film 12 (for example, hydrochloric acid, sulfuric acid, and nitric acid).
2 shows the structure after removal of. According to FIG. 16, a structure in which uneven guide tracks are directly formed on the glass substrate 7 is realized. The pitch of the guide track is equal to the track pitch width TP. The structure shown in FIG. 16 can also be used as an optical disk master.

In the optical disk master completed in this way, a convex portion to be a guide track is formed in a rectangular shape, and the pitch thereof is formed with a narrow track pitch TP substantially equal to the light beam spot diameter BS. So
By using this optical disk master, it is possible to manufacture an optical disk suitable for high-density recording and having more stable tracking performance.

Next, a process of manufacturing an optical disk from the optical disk master completed by the above manufacturing process will be described. Here, a process of manufacturing an optical disk using the optical disk master shown in FIG. 14 will be described. 17 is an electrode film forming step, FIG. 18 is a Ni electroforming step, FIG. 19 is a stamper forming step by peeling, FIG. 20 is a resin optical disk substrate forming step, FIG. 21 is an optical disk substrate completing step, and FIG. FIG. 6 is a diagram showing a cross-sectional state of the disk after each of the forming steps is performed.

First, as shown in FIG. 17, an electrode film 15 serving as an electrode for electroforming is formed on the surface of the master optical disc by sputtering or the like. Ni, Ni,
Metals such as Ta and stainless steel are desirable. In order to facilitate the peeling of the stamper from the electrode film 15 in the subsequent stamper peeling step, the surface of the electrode film is oxidized by ashing or the like.

Next, as shown in FIG. 18, using the electrode film 15 as an electrode, Ni electroforming is performed to form a Ni electroformed film 16. Then, as shown in FIG. 19, after peeling off the Ni electroformed film 16 from the electrode film 15, the back surface of the Ni electroformed film 16 (FIG.
7) is polished. This polished Ni electroformed film 16 becomes the stamper 17.

Next, as shown in FIG.
Is mounted on an injection molding machine, and a resin such as polycarbonate is injection-formed to form a resin optical disk substrate 18 as shown in FIG.

Finally, as shown in FIG. 22, the optical disk is completed by forming the recording medium 19 on the guide track forming surface of the optical disk substrate 18 (the uneven surface of the substrate). Here, the recording medium 19 is a constituent layer composed of a plurality of layers for recording data, for example,
A transparent dielectric layer, a recording layer, a transparent dielectric layer, and a reflective layer are laminated in this order.

The optical disk manufactured in this manner has a light beam spot diameter B used for laser cutting.
A track pitch TP (for example, 300 n
m), a rectangular guide track (a convex portion on the disk surface in FIG. 22) is formed. Since a rectangular guide track can be formed, an optical disk having a narrow track pitch suitable for high-density recording and capable of stable tracking can be accurately formed by using an optical disk master manufactured using the manufacturing method of the present invention. be able to. Next, an embodiment of a method for manufacturing an optical disk master and an optical disk master according to the present invention will be described.

Example 1 A metal film 1 was formed on a glass substrate 7.
As Ta, a Ta film having a thickness of 40 nm was formed.
A positive photoresist was formed with a thickness of 50 nm. These films can be formed using a spin coating method.

Next, the wavelength 351 from the Kr laser light source 1 will be described.
The laser beam 2 of nm was focused and irradiated on the surface of the positive photoresist 13 by the objective lens 5 having a numerical aperture NA of 0.95, and laser cutting was performed. Here, the light beam spot diameter BS of the condensed laser light 2 is about 300
nm.

Laser cutting was performed with a laser power of 4 mW with a track pitch TP of 300 nm. Here, the metal film 12 and the positive photoresist 13 have an anti-reflection structure for laser light having a wavelength of 351 nm. Through the above steps, the latent image 9 having the structure as shown in FIG. 11 and the positive type photoresist altered layer 14 were formed.

Here, the latent image 9 and the positive photoresist deteriorated layer 14 have the track pitch T
P (= 300 nm), the width of the latent image 9 in the horizontal direction on the paper surface is about 180 nm, and the width of the positive photoresist altered layer 14 in the horizontal direction is about 120 nm.

Next, when the latent image 9 is developed by using a developing solution, an optical disk master having guide tracks and guide grooves 11 formed by the positive photoresist deteriorated layer 14 is formed as shown in FIG. . Here, when the formed positive photoresist deteriorated layer 14 is observed using an electron microscope, the pattern width is about 120 nm.

Through the above steps, the light beam spot diameter B
An optical disc master having a guide track having substantially the same track pitch TP as S and having a pattern width smaller than the light beam spot diameter BS could be manufactured. In the above-described conventional manufacturing method, in order to obtain a rectangular concavo-convex pattern, the track pitch TP needs to be about twice as large as the beam spot diameter BS. Is substantially equal to the beam spot diameter BS, a rectangular concavo-convex pattern can be formed. Here, Ta was used as the metal film 12, but the metal film 12 and the positive photoresist 1 were used.
3 may have an antireflection structure for laser light used for laser cutting, and the metal film 12 is not limited to Ta.

Next, a Ni electrode film 15 is formed by sputtering on the optical disk master as shown in FIG. 12, and the surface of the Ni electrode film 15 is oxidized by oxygen plasma. A stamper 17 is formed by casting, and a recording medium 19 including a transparent dielectric layer, a recording layer, a transparent dielectric layer, and a reflective layer is sequentially formed on an optical disk substrate 18 formed by injection molding. Was formed. The recording layer is made of a material on which information can be recorded by a laser beam focused and irradiated by an optical pickup of an optical disk drive, and a magneto-optical recording material or a phase change material can be used. Through the above steps, an optical disk as shown in FIG. 22 was manufactured.

(Embodiment 2) Here, Embodiment 1 described above is used.
The optical disc master (FIG. 12) was placed in a dry etching apparatus, and dry etching was performed using CF ₄ gas plasma. That is, the positive photoresist deteriorated layer 1
Using the mask 4 as a mask, the Ta metal film 12 was dry-etched.

Since the anisotropic etching is performed by the dry etching, as shown in FIG. 14, the pattern edge is closer to a steep rectangle as compared with the guide track pattern formed by the positive type photoresist altered layer 14. An optical disc master having the Ta metal film pattern 12 could be formed. Thereafter, if a method similar to that of the first embodiment is used, a stamper and an optical disk substrate are sequentially formed, and FIG.
2 can be manufactured.

Here, Ta is used as the metal film 12, but it is sufficient that dry etching is possible, and other materials such as Ti and Si can be used as a material that can be dry etched by CF ₄ plasma. is there. Also, CC
As the dry etchable material l ₄ plasma,
Materials such as Al and Cr can be used. Also,
It is also possible to perform etching by wet etching using a metal material that can be dissolved in an acid or an alkali as the metal film 12, but in the case of wet etching, side etching occurs and the unevenness is broken from a rectangular shape. It is desirable to form the optical disk master by dry etching.

(Embodiment 3) In this embodiment 3, the metal film 1
Ni is used for 2 and stainless steel is used for the electrode film 15. On a glass substrate 7, Ni is used as a metal film 12.
and a positive photoresist 13
As a result, an S1400 positive photoresist 13 manufactured by Shipley Co., Ltd. was formed with a film thickness of 50 nm.

Next, the wavelength 351 from the Kr laser light source 1 will be described.
The laser beam 2 of nm was focused and irradiated on the surface of the positive photoresist 13 by the objective lens 5 having a numerical aperture NA of 0.95, and laser cutting was performed. Here, the light beam spot diameter BS of the condensed laser light 2 is about 300
nm. Also, the track pitch TP is set to 300 nm.
And laser cutting was performed with a laser power of 4 mW.

Next, when the latent image 9 is developed by using a developing solution, an optical disk master having guide tracks and guide grooves 11 formed by the positive photoresist deteriorated layer 14 is formed as shown in FIG. Was.

Next, wet etching of the Ni metal film 12 using nitric acid was performed using the deteriorated positive photoresist layer 14 as a mask. After that, when the positive photoresist deteriorated layer 14 is removed by ashing (ashing) using oxygen plasma, the metal film 1 as shown in FIG.
2 could form a guide track.

Next, dry etching of the glass substrate 7 was performed using CF ₄ gas plasma with the metal film 12 as a mask. Thus, a groove having a depth of about 40 nm was formed on the glass substrate 7 as shown in FIG. Finally, the Ni metal film 12 was removed by wet etching using nitric acid. As a result, an optical disc master including the guide tracks having the track pitch TR and the guide grooves 11 was formed on the glass substrate 7 as shown in FIG.

Next, a stainless steel electrode film 15 is formed on the optical disk master as shown in FIG. 16 by sputtering, and the surface of the stainless steel electrode film 15 is oxidized by oxygen plasma. A recording medium 19 comprising a transparent dielectric layer, a recording layer, a transparent dielectric layer, and a reflective layer is sequentially formed on an optical disk substrate 18 produced by injection molding. A protective coat layer was formed. The recording layer is made of a material on which information can be recorded by a laser beam focused and irradiated by an optical pickup of an optical disk drive, and a magneto-optical recording material or a phase change material can be used. Through the above steps, an optical disk as shown in FIG. 22 was manufactured.

Embodiment 4 The optical disk master shown in FIG. 16 manufactured according to the present invention is different from the conventional optical disk master in that the concavo-convex shape is reversed. Therefore, even in the optical disk finally manufactured as shown in FIG. 22, the concave / convex shape is reversed.

Thus, in the fourth embodiment, a description will be given of correcting the reverse of the unevenness. Here, FIG.
The stamper 17 formed after the peeling step shown in FIG. First, the surface of the stamper 17 on which the guide tracks are formed is oxidized by oxygen plasma. Thereafter, an Ni electroformed film 16 'is formed on the guide track forming surface using the stamper 17 as an electrode. This Ni electroformed film 1
The uneven surface 6 ′ is different from the Ni electroformed film formed in FIG.
The irregularities are reversed.

Next, the Ni electroformed film 16 ′ is
Then, if the back surface is polished, a work stamper 17 ′ in which concavities and convexities are reversed with respect to the stamper 17 is formed. If an optical disc substrate is manufactured by injection molding using the work stamper 15 ', the pre-pits and the guide grooves (= 150 nm) having the same concavo-convex structure as the conventional one and smaller than the light beam spot diameter (= about 300 nm). The optical disk substrate having the above can be manufactured.

In the present invention, a land recording method or a group recording method in which information is recorded only in either a concave portion or a convex portion of a fine pattern is described about manufacturing a substrate having a fine pattern smaller than a light beam spot diameter. However, a substrate having a fine pattern with a narrow width can also be manufactured in a land group recording method in which information is recorded in both a concave portion and a convex portion.

[0066]

According to the present invention, the substrate on which the metal film and the resin layer are formed in this order has a width smaller than the light beam spot diameter by condensing and irradiating a light beam to the developing solution. Since the region of the deteriorated resin layer which is insoluble to the resin layer is formed in a part of the resin layer, it is possible to manufacture a substrate having a fine pattern composed of pre-pits and guide grooves smaller than the light beam spot diameter. Further, by using a substrate having such a fine pattern, an optical disk master having a narrow track pitch, an optical disk stamper, and an optical disk can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a laser cutting device used for manufacturing an optical disc master in the present invention.

FIG. 2 is an explanatory diagram of a normalized light intensity distribution with respect to the diameter of a focused light beam spot.

FIG. 3 is a cross-sectional view illustrating a conventional laser cutting exposure process.

FIG. 4 is a cross-sectional view illustrating a conventional laser cutting exposure process.

FIG. 5 is a cross-sectional view illustrating a conventional laser cutting exposure process.

FIG. 6 is a cross-sectional view of a positive photoresist pattern formed by conventional laser cutting.

FIG. 7 is a cross-sectional view illustrating a conventional laser cutting exposure process.

FIG. 8 is a cross-sectional view illustrating an exposure process according to an embodiment of the method of manufacturing an optical disc master according to the present invention.

FIG. 9 is an explanatory diagram of an interface temperature distribution with respect to a light beam spot diameter in the present invention.

FIG. 10 is a cross-sectional view illustrating an exposure process according to an embodiment of the method of manufacturing an optical disc master of the present invention.

FIG. 11 is a cross-sectional view illustrating an exposure process according to an embodiment of the method of manufacturing an optical disc master of the present invention.

FIG. 12 is a cross-sectional view illustrating a state after a latent image is removed in the present invention.

FIG. 13 is a cross-sectional view illustrating a state where a metal film in a region where a deteriorated photoresist layer is not formed is etched in the present invention.

FIG. 14 is a cross-sectional view illustrating a state after removing a deteriorated photoresist layer in the present invention.

FIG. 15 is a cross-sectional view illustrating a state where a substrate surface in a region where a metal film is not formed is etched in the present invention.

FIG. 16 is a completed view of an optical disc master completed by the manufacturing process of the present invention.

FIG. 17 is a cross-sectional view illustrating a state where an electrode film is formed on the master optical disc of the present invention.

FIG. 18 is a cross-sectional view illustrating a state in which a Ni electroformed film is formed on the optical disk master of the present invention.

FIG. 19 is a cross-sectional view illustrating a state in which a Ni electroformed film is peeled off from the optical disc master according to the present invention.

FIG. 20 is a cross-sectional view illustrating a state in which a resin optical disc substrate is molded from a stamper in the present invention.

FIG. 21 is a completed view of a molded optical disk substrate in the present invention.

FIG. 22 is a cross-sectional view illustrating a state where a recording medium is formed on an optical disk substrate in the present invention.

[Explanation of symbols]

 Reference Signs List 1 laser light source 2 laser beam (light beam) 3-1 mirror 3-2 mirror 3-3 falling mirror 4 optical modulator 5 objective lens 6 positive photoresist 7 glass substrate 8 spindle motor 9 latent image 10 positive photoresist Pattern 11 Guide groove 12 Metal film 13 Positive photoresist (resin layer) 14 Positive photoresist deteriorated layer 15 Electrode film 16 Ni electroformed film 17 Stamper 18 Resin optical disk substrate 19 Recording medium

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Rishin Nobue 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (in reference) 4K057 DA11 DB03 DB08 DB15 DB17 DC10 DD03 DD08 DE08 DN03 WA11 WB03 WB15 WB17 WC10 WE02 WN04 5D121 AA02 BA01 BA05 BB05 BB08 BB33 BB34 GG04

Claims (11)

[Claims] 1. A method of forming a metal film on a surface of a substrate, forming a resin layer on the metal film, and condensing and irradiating a light beam to a predetermined position from above the resin layer to obtain a predetermined temperature. A deteriorated layer insoluble in a developer is formed in the region of the resin layer raised above, and a portion of the resin layer other than the deteriorated layer is selectively removed so that the deteriorated layer remains. A method for forming a fine pattern, characterized in that: 2. The method for forming a fine pattern according to claim 1, wherein said altered layer is formed in a region smaller than the spot diameter of the light beam intensively irradiated. 3. The method for forming a fine pattern according to claim 1, wherein the metal film and the resin layer have an anti-reflection structure for a light beam condensed and irradiated. 4. The method according to claim 1, wherein the resin layer is made of a positive photoresist. 5. The method for forming a fine pattern according to claim 4, wherein the portion of the resin layer other than the altered layer is selectively removed using a developer of a positive photoresist. 6. The method according to claim 1, wherein the metal layer in a region where the altered layer is not formed is etched using the altered layer as a mask on the substrate where the altered layer remains, and then the altered layer is selectively removed. The method for forming a fine pattern according to claim 1. 7. The method according to claim 6, wherein the etching of the metal film is dry etching. 8. The method according to claim 1, further comprising: after selectively removing the altered layer, etching the substrate in a region where the metal film is not formed using the remaining metal film as a mask, and then selectively removing the metal film. The method for forming a fine pattern according to claim 6 or 7, wherein: 9. An optical disk master manufactured by using the method for forming a fine pattern according to claim 1. 10. An optical disk stamper manufactured by using the optical disk master according to claim 9. 11. An optical disk manufactured by using the optical disk stamper according to claim 10.