JP2001338444A - Method for manufacturing original disk, stamper and information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an original disk in which a deeply recessed part and a shallowly recessed part are formed and the bottom faces of both parts are made flat. SOLUTION: A lower layer 21 is formed on a glass disk 1 as the first photoresist layer by application, subjected to exposure 31 and hardened by heating. An upper layer 22 is formed on the layer 21 as the second photoresist layer by application and subjected to exposure 32, which is then developed and hardened by heating to obtain the objective original disk where the deeply recessed part 41 is formed in the exposed regions 31, 32-superposed section and the shallowly recessed part 42 is formed in the exposed region 32 of the upper layer 22. The bottom faces of both parts 41, 42 can be made flat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a master and a stamper for molding an information recording medium made of a synthetic resin such as an optical disk or a magneto-optical disk, and a method of manufacturing a resin information recording medium using the stamper. Method and.

[0002]

2. Description of the Related Art Optical disks can be broadly classified into read-only and recordable media. Recordable media further
Media can be classified into write-once media and write-once media. At present, CDs and DVDs, which are widely used, also have read-only and recordable media. As a read-only CD, CDDA, CD-ROM, CD-ROMX which are so-called CD families are used.
A, CDV, CD-I, CD-MIDI and the like. CD-R (C), which is a recordable medium of the CD system and has rapidly spread in recent years as an external storage memory for personal computers
D-Recordable is a write-once medium, and CD-RW (CD-rewritable) is 1
It is a medium that can be rewritten about 000 times. DV
In D, DVD-ROM is a read-only medium,
DVD-R has been commercialized as a write-once medium, and DVD-RW and DVD-RAM have been commercialized as rewritable media.

[0003] In order to manufacture this disk, a master on which concave and convex pit rows and grooves are formed is manufactured, and a stamper is manufactured from the master. Then, from this stamper, a substrate made of a light-transmitting polycarbonate or the like to which irregularities have been transferred usually by injection molding is manufactured, and a layer corresponding to various disks is formed on the surface on which the pits and grooves are formed. For example, in the case of a CD-ROM disk, a reflective layer made of a metal film such as a noble metal or an Al alloy is formed on a substrate by a method such as sputtering, and a protective layer made of a photocurable resin is further formed thereon.

[0004] Also, CD-RW discs and DVD-RW
In a disk, a first protective layer (dielectric layer) / recording layer / second protective layer (dielectric layer) / reflective layer is generally formed on a substrate in this order by a sputtering method or the like, and a photo-curing type is further formed thereon. A protective layer made of a resin is formed and bonded to another substrate as needed.

FIG. 3 is a schematic explanatory view showing a conventional method of manufacturing a master and a stamper.

After a primer is applied to the surface of the glass disk 1 whose surface has been polished, a positive type photoresist is applied to form a photoresist layer 2 (). The photoresist layer 2 is laser-exposed according to an arrangement pattern of concave portions such as pits or grooves (). Reference numeral 4 indicates a portion irradiated with the laser 3.

Next, development is performed with an alkaline developer (). The laser-exposed portion 4 is solubilized in a developing solution, etched by the developing solution, and
Is formed. Next, the photoresist layer 2 is cured by a heat curing treatment (baking) to form a master 6 ().

The master 6 is sputtered with Ni (nickel) (symbol 7 denotes a sputtered layer) to make the surface conductive (), and then Ni plating (for example, electrolytic plating)
Then, for example, a plating layer 8 having a thickness of about 300 μm is formed (). Next, the sputtering layer 7 and the plating layer 8 and the master 6
And a stamper 9 is obtained by punching into a predetermined size. The master 6 after separation is sent to a reuse process.

Although not shown, the stamper 9 is set in a mold for injection molding, and polycarbonate or the like is injected to mold a substrate for an information recording medium (disk).

In recent years, it has been studied to form both a relatively shallow concave portion and a relatively deep concave portion on one substrate.

FIG. 4 is a plan view showing an example of such an information recording medium, and FIG. 5 is a perspective view in which the cross section of the surface portion is significantly enlarged.

In the information recording medium 10, a pit area 11 having a width of about 80 μm is set in a portion close to the inner peripheral edge, and the groove area 12, the inner peripheral side and the outer peripheral side of the pit area 11, respectively. 13 is set.

FIG. 5 shows a surface portion near a boundary between the groove area 12 on the inner peripheral side and the pit area 11. 14 indicates a groove, and 15 indicates a pit.

In order to manufacture such an information recording medium having two types (or more) of concave portions, a master having the same plural types of concave portions is required.

As a method of manufacturing such a master, as shown in FIG. 6, a photoresist 2 is applied on a glass disk 1 and then irradiated with a strong laser beam to form a deep exposed portion 4a on the master 1. At the same time, it is conceivable that a shallow exposure portion 4b is formed by irradiating a weak laser beam, and then developed to form a deep recess 5a and a shallow recess 5b.
In this case, the bottom surface of the shallow concave portion 5b that stops in the middle of the photoresist layer 2 becomes a non-flat surface that is curved or bent in an arc shape or a substantially V shape. Such a concave portion having a non-flat bottom has the following disadvantages, for example.

That is, the reproduction noise when a signal is recorded on a groove having a non-flat bottom surface is generally higher than that when a signal is recorded on a groove having a flat bottom surface. In particular, there is a concern that repeated recording durability may be adversely affected. When exposure is performed with a weaker laser beam, the groove shape becomes more sensitive to fluctuations in light quantity, so that the uniformity of the groove shape is significantly deteriorated in a groove having a non-flat bottom.

[0017]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing a master having a flat bottom surface even with such a shallow recess, a method for manufacturing a stamper using the master, and a method using the stamper. An object of the present invention is to provide a method for manufacturing an information recording medium.

[0018]

According to a first aspect of the present invention, there is provided a method of manufacturing a master, wherein a photoresist is applied to a surface of a master body, exposed according to a pattern, and then developed to form a concave portion. In a method for manufacturing a master for manufacturing an information recording medium, wherein a hardened photoresist layer is formed, a deep recess is formed in a hardened photoresist layer in a first region on the master body, A method for manufacturing a master in which a shallow recess reaching halfway in the thickness direction of the photoresist hardened layer is formed in the second region, wherein the first and second regions on the master body are Forming a first photoresist layer by applying a positive photoresist, exposing the entire first region of the first photoresist layer, and rendering the first photoresist layer hardly soluble Process of processing Applying a positive photoresist on the first photoresist layer to form a second photoresist layer, and exposing the second photoresist layer in the first and second regions according to a pattern; Heat curing the second photoresist layer; and curing the first and second photoresist layers.
And developing the photoresist layer in this order.

The treatment for making the first photoresist layer hardly soluble refers to a treatment for curing the first photoresist layer so that the first photoresist layer is not dissolved in the resist solvent when the second photoresist layer is applied.

The first area is an area in which a deep concave portion is to be formed, for example, like the pit area 11 of the information recording medium shown in FIG. , 13 are regions where shallow concave portions are to be formed.

In the present invention (claim 2), after the exposure of the first photoresist layer, the first photoresist layer is developed, and then the insolubilization treatment may be performed.

According to the method of manufacturing the master, since the portion of the first region of the first photoresist layer is solubilized by exposure, it is exposed together with the exposed portion of the second photoresist layer thereon during the development process. Etched. Thereby, a deep recess is formed in the first region. Preferably, the deep recess reaches the master body and its bottom surface is a flat surface along the surface of the master body.

On the other hand, in the second region, since the first photoresist layer has been subjected to the insolubilization treatment, even if the first photoresist layer is also exposed when the second photoresist layer is exposed, the first photoresist layer is exposed. The resist layer does not solubilize. Therefore, by exposing the second photoresist layer with strong light reaching the bottom surface of the second photoresist layer (that is, the top surface of the first photoresist layer), a shallow concave portion having a flat bottom surface is formed. Can be.

The method of manufacturing a master according to the present invention (claim 2)
A method of manufacturing a master for information recording medium manufacturing in which a photoresist is applied to the surface of the master body, exposed according to a pattern, and then developed to form a photoresist hardened layer having concave portions. A method of manufacturing a master in which a deep concave portion and a shallow concave portion reaching halfway in the thickness direction of the photoresist hardened layer are formed in the photoresist hardened layer; Applying a photoresist to form a first photoresist layer, exposing the first photoresist layer according to the pattern of the deep recesses, and insolubilizing the first photoresist layer; Applying a positive photoresist on the first photoresist layer to form a second photoresist layer; Exposing the second photoresist layer, heating and curing the second photoresist layer, and developing the first and second photoresist layers in this order. It is assumed that.

The insolubilization treatment of the first photoresist layer means a treatment for curing the first photoresist layer so that the first photoresist layer does not dissolve in the resist solvent when the second photoresist layer is applied.

The first area is an area in which a deep recess is to be formed, for example, like the pit area 11 of the information recording medium shown in FIG. 4, and the second area is the groove area 12. , 13 are regions where shallow concave portions are to be formed.

In the present invention (claim 2), after the exposure of the first photoresist layer, the first photoresist layer is developed, and then the insolubilization treatment may be performed.

In the method of manufacturing the master, the deep recesses are formed by exposing the same portions of the first and second photoresist layers respectively.
This deep recess preferably reaches the master body, and its bottom surface is flat.

Although the shallow recess is formed by etching only the second photoresist layer, the first photoresist layer is not solubilized as in the method of the first aspect, so that a sufficient light amount can be obtained. To form a flat bottom surface.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view in the thickness direction showing a method of manufacturing a master according to an embodiment of the present invention.

First, a primer is applied to the upper surface of the glass disk 1 as the master body, and then a lower layer (first photoresist layer) 21 is applied (). Next, a predetermined region of this lower layer is exposed. The reference numeral 31 in FIG.
Area). Next, the lower layer 21 is baked to be cured by heating ().

Next, an upper layer (second photoresist layer) 22 is applied on the lower layer 21 (). Next, the upper part of the exposure area (first area) 31 and the second
Exposure is performed in the region of. Reference numeral 32 in FIG.
The second exposure area is shown.

Next, development is performed as shown in FIG. As a result, the exposed region 32 is removed to form a shallow concave portion 42, and in the exposed region 31, the exposed region 3
2 is also removed to form a deep recess 41.

Then, as shown in FIG. 1, the upper layer 22 is baked so as to be hardened, so that a hardened photoresist layer 20 is formed on the glass disk 1, and the hardened photoresist layer 20 has a deep recess 41 and a shallow recess. Then, a master on which the reference numeral 42 is formed is manufactured.

In the master disk obtained by this manufacturing method, the deep concave portion 41 reaches the glass disk 1, its bottom surface is flat, and its cross-sectional shape is substantially rectangular. Also, the bottom surface of the shallow concave portion 42 is along the upper surface of the already cured lower layer 21 and is flat. Therefore, the shallow recess 42 also has a substantially rectangular cross-sectional shape.

In the present invention, the shallow concave portion is used as a groove for recording information, and it is necessary that the bottom surface is flat and the noise is small. The deep concave portion is used as a pit row, and it is not necessary that the bottom surface is flat compared to the groove due to the difference in the reproduction principle. However, the bottom surface is preferably flat at a depth reaching the glass disk.

FIG. 2 is a schematic sectional view in the thickness direction showing an embodiment of the present invention. Also in this embodiment, the lower layer 21 as the first photoresist layer is applied to the upper surface of the glass disk 1 as the master body (), and then the lower layer 21 is exposed (). Reference numeral 50 in FIG. 2 indicates the first exposure area.

Next, as shown in FIG. 2, the lower layer 21 is developed to form a concave portion 51. Next, the lower layer 21 is baked so as to be cured by heating ().

Next, as shown in FIG. 2, an upper layer 22 as a second photoresist layer is applied on the lower layer 21.
Next, as shown in FIG. 2, the upper layer 22 is exposed. In this case, the portion directly above the concave portion 51 and the other region are exposed according to the pattern. Reference numeral 52 indicates this exposure area. Next, the upper layer 22 is developed. As a result, a deep concave portion 61 is formed in the portion of the concave portion 51, and a shallow concave portion 62 is formed in a portion where the exposure 52 has been performed in other regions.

Thereafter, as shown in FIG. 2, the upper layer 22 is baked so as to be cured by heating, and the photoresist cured layer 2 is baked.
Set to 0. As a result, a master including the deep concave portion 61 and the shallow concave portion 62 is manufactured.

Even in this master, the deep concave portion 61 reaches the glass disk 1, and its bottom surface is flat, and a cross-sectional shape substantially rectangular is obtained. The bottom surface of the shallow concave portion 62 is along the upper surface of the heat-cured lower layer 21 and is also flat, and the shallow concave portion 62 also has a substantially rectangular cross-sectional shape.

The master obtained as shown in FIG. 1 and FIG.
Thereafter, as shown in FIG. 3 described above, a conductive treatment is performed, and then plating is performed. A stamper can be obtained by separating the sputtered layer and the plated layer and then punching out the predetermined size.

By setting the stamper in a mold of an injection molding apparatus and performing injection molding, a substrate for an information recording medium (disk) made of synthetic resin is obtained.

[0045]

EXAMPLE 1 (Method of Claim 1) As shown in FIG. 1, after a primer treatment is performed on a glass disk 1 having a diameter of 200 mm and a thickness of 6 mm, the lower layer is made of a novolak resin-based positive photoresist ( It was formed with a film thickness of 580 ° using Mitsubishi Chemical Corporation, MCPR2000H).

Next, as shown in FIG. 1, the region 31 was exposed. The exposure wavelength is 413 mm and the beam diameter is 0.6 μm. The beam was exposed over a width of 80 μm by shifting the beam radially at a 0.5 μm pitch.

This exposure area extends in the circumferential direction of the disk, and the radial width of the disk is 8 as described above.
0 μm.

Next, the photoresist was heated to 160 ° C. for 10 minutes using a hot plate, and the photoresist was cured by heating.

Next, as shown in FIG. 1, an upper layer 22 was applied to a thickness of 700 ° using the same photoresist as described above.
In this case, no primer treatment was performed. Next, as shown in FIG. 1, after exposing the upper layer 22, the development of FIG. 1 was performed.

The light source and intensity of this exposure are the same as those of the lower layer, and the beam diameter is 0.6 μm.

This developer is an alkaline developer (Chipley Microposit Developer, Shipley).
It was supplied from directly above the exposed portion of the master rotated at 00 rpm. The supply amount is 0.52 L / min and the development time is 26
Seconds.

Thereafter, heat curing (post-baking) shown in FIG. 1 was performed. The processing status at this time is that after preheating at 80 ° C. for 2 minutes, the temperature is further maintained at this temperature for 10 minutes.

As a result, the deep recess 41 has a depth of 90
A groove of 0 ° is formed, and a depth of 700
溝 grooves were formed. Each groove width was 0.4 μm.

Example 2 (Method of Claim 2) A lower layer 21 was applied on the same glass disk as in Example 1 using the same photoresist. This coating thickness is 400 °. Next, as shown in FIG. 2, the lower layer 21 was exposed. The exposure area 50 extends in the circumferential direction of the glass disk 1. The light source and intensity of the exposure are the same as described above, and the beam diameter is 0.6 μm.

Next, as shown in FIG. 2, the lower layer 21 was developed.

This developing solution was the same as the above-mentioned developing solution, and was uniformly applied on the lower layer by a spin method and developed for about 30 seconds.

Next, as shown in FIG. 2, the lower layer was baked so as to be cured by heating. Baking conditions are 160 ° C. for about 20 minutes. A hot plate was used for heating.

Next, as shown in FIG. 2, an upper layer 22 was applied to a thickness of 400 ° using the same photoresist as above.
For this coating, a spin coating method was employed. No primer was applied over the lower layer.

Next, as shown in FIG. 2, the upper layer was exposed. At this time, as shown in the figure, exposure was performed with exactly the same width immediately above the concave portion generated by the first development, and further exposure was performed on other regions. Exposure conditions are the same as above.

Next, development was performed under the same developing conditions as the lower layer.

As a result, a master having a groove as the deep concave portion 61 having a depth of 630 ° and a groove as the shallow concave portion 62 having a depth of 380 ° was obtained. Groove width is 0.4 μm
It is.

[0062]

As described above, according to the present invention, when manufacturing masters having different depths, the bottom surfaces of these concave portions can be made flat, and the cross-sectional shape of the concave portions is made substantially rectangular. be able to.

According to the present invention, a stamper can be manufactured by using the master, and an information recording medium can be efficiently manufactured by using the stamper.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view in a thickness direction showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view similar to FIG. 1, showing another embodiment.

FIG. 3 is a cross-sectional view illustrating a method according to a conventional example.

FIG. 4 is a plan view showing an example of an information recording medium.

5 is a cross-sectional perspective view showing a part of the surface of FIG. 4 in a greatly enlarged manner.

FIG. 6 is a cross-sectional view illustrating a conventional example of a method for manufacturing a master.

[Explanation of symbols]

 Reference Signs List 1 glass disc 21 lower layer (first photoresist layer) 22 upper layer (second photoresist layer) 31, 32 exposure area 41 deep depression 42 shallow depression 50, 52 exposure area 51 depression 61 deep depression 62 shallow depression

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Chuichi Nagai 1000 Kamoshitacho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsubishi Chemical Research Institute Yokohama Research Laboratory (72) Inventor Joji Kondo 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Mitsubishi Chemical Corporation Yokohama Research Laboratory F-term (reference) 5D121 AA09 BB23 BB31 CB06 CB07 GG01 GG07

Claims (8)

[Claims] 1. A master for manufacturing an information recording medium, wherein a photoresist is applied to the surface of a master body, exposed according to a pattern, and then developed to form a hardened photoresist layer having concave portions. In the method of manufacturing, a deep concave portion is formed in the photoresist cured layer in the first region on the master body, and the second region on the master is formed in the middle of the photoresist cured layer in the thickness direction. Forming a first photoresist layer by applying a positive photoresist to the first and second regions on the master body; and forming a first photoresist layer on the master body. Exposing the entire first region of the first photoresist layer; insolubilizing the first photoresist layer; and forming a positive photoresist on the first photoresist layer. Applying a second photoresist layer to form a second photoresist layer, exposing the second photoresist layer in the first and second regions according to a pattern, and heating and curing the second photoresist layer; And a step of developing the first and second photoresist layers in this order. 2. A master for manufacturing an information recording medium in which a photoresist is applied to the surface of a master body, exposed according to a pattern, and then developed to form a photoresist hardened layer having concave portions. A method of manufacturing a master in which a deep recess and a shallow recess reaching halfway in the thickness direction of the photoresist hardened layer are formed in the photoresist hardened layer. Applying a positive photoresist on the body to form a first photoresist layer; exposing the first photoresist layer in accordance with the pattern of the deep recesses; Forming a second photoresist layer by applying a positive photoresist on the first photoresist layer; and forming the second photoresist layer on the first photoresist layer. Exposing the second photoresist layer according to the pattern of the concave portion; heating and curing the second photoresist layer; and developing at least the second photoresist layer;
Are performed in this order. 3. The method of manufacturing a master according to claim 1, wherein the master body is made of glass. 4. The method for producing a master according to claim 1, wherein the hard-solubilizing treatment is a baking treatment. 5. The method of manufacturing a master according to claim 1, wherein the surface of the hardened photoresist layer is converted into a conductor thereafter. 6. The method of manufacturing a master according to claim 5, wherein the conductive layer is formed by forming a conductive layer by sputtering a conductive material. 7. A stamper characterized by plating a master disc manufactured by the method according to claim 5 or 6 with a metal, and then separating the conductive layer and the master disc to obtain a stamper composed of a plating layer and a conductive layer. Manufacturing method. 8. A method for manufacturing an information recording medium, comprising forming an information recording medium substrate made of a synthetic resin using the stamper manufactured by the method according to claim 7.