JP3483539B2 - Stamper, mold system, recording medium substrate, stamper manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stamper for forming a recording medium substrate, a mold system, a method for manufacturing the stamper, and the like.

[0002]

2. Description of the Related Art Conventionally, as an optical information medium for recording various information for audio, video, computer, etc.,
CD (compact disc), MD (mini disc),
There are DVD (Digital Versatile Disc) etc.,
It is necessary to further improve the recording density of these optical information media in response to the increase in the amount of information in the future.

In order to improve the recording density of an optical disk or the like, it is necessary to reduce the focused spot diameter of the laser light used, and for that purpose, the wavelength of the laser light is shortened and the NA of the objective lens in the laser optical system is increased. (Numerical aperture) is required.

The laser light as described above is focused on the information recording surface through the light transmitting layer covering the information recording surface.
As described above, when the wavelength is shortened and the NA is increased, the problem of optical aberration becomes remarkable. Therefore, in order to suppress the optical aberration, the light transmission layer should be as thin as possible.

For a CD or MD, the wavelength of the laser light used is 780 nm, the NA is 0.45, the thickness of the light transmission layer is 1.2 mm, and it is used for a DVD that records information at a higher density than a CD. Laser light wavelength is 650n
m, NA is 0.6, and the thickness of the light transmission layer is 0.6 mm. Within this range, a substrate formed of a transparent material by injection molding can usually be used as the light transmitting layer.

In order to further increase the recording density in the future, when the wavelength of the laser light is further shortened and the NA is further increased, the light transmission layer which is the substrate must be further thinned. However, it has become technically extremely difficult to manufacture a substrate thinner and more accurately than ever by the conventional injection molding method (including injection compression). That is, in the optical disc having the conventional structure using the substrate as the light transmission layer, the method of improving the recording density by shortening the wavelength of the laser light and increasing the NA has almost reached the limit in terms of manufacturing technology.

On the other hand, for example, Japanese Patent Laid-Open No. 10-289
As disclosed in Japanese Patent Publication No. 489, a protective plate that does not need to transmit light is used as a substrate to form a thick film by injection molding, and a recording film / reproducing reflective film is formed on the information recording surface of the substrate, and then a protective film is formed thereon. There is an optical disc having a structure in which a thin light transmitting layer is formed in a laminated manner. With this configuration, the light transmission layer can be formed thin and the entire strength can be secured on the substrate side, so that the wavelength of the laser light can be shortened and the NA can be increased.
It will be possible to flexibly respond to changes.

As a method of forming the light transmitting layer, a method of applying an ultraviolet curable resin liquid on the substrate by a spin coating method and then curing it, or a transparent sheet formed separately is used.
There is a method in which an ultraviolet curable resin or an adhesive material is used as an adhesive to adhere to a substrate for integration. However, the method of adhering the transparent sheet to the substrate has a problem that the manufacturing cost becomes high because the optical characteristics and thickness accuracy of the light transmitting layer are required to be strict. On the other hand, the spin coat method is relatively easy to satisfy the required characteristics, and specific spin coat methods are disclosed in, for example, JP-A-10-289489, JP-A-11-73691, and JP-A-11-203724. A method of forming a light transmitting layer by the method is disclosed.

[0009]

As described above, although the optical disc having the structure in which the protective plate side is used as the substrate can improve the recording density, it has the following problems in terms of manufacturing technology. .

(1) Problem of Substrate Shrinkage Error When a substrate is manufactured by injection molding, the vicinity of the outer periphery of the substrate may become thicker than the center side due to the difference in cooling rate during molding. That is, as shown in FIG. 10, a rise portion 2 called a ski jump may be formed on the outer periphery of the resin substrate 1 formed by injection molding, and if it is left as it is, the incidence and reflection angles of the laser beam may deteriorate, or There is a possibility that the laser optical system such as the objective lens may collide with the raised portion 2. Therefore, as disclosed in, for example, Japanese Patent Laid-Open No. 5-200791, the raised portion 2 has to be removed by a post-treatment, which increases the manufacturing cost.

(2) Substrate Burr Problem FIG. 11 shows a mold system 100 for manufacturing a substrate of this type. The mold system 100 includes a ring-shaped mold 102 that forms an outer peripheral surface of the substrate 1, and a flat mold 104 that is arranged so as to face the ring-shaped mold 102 so as to sandwich the ring-shaped mold 102 and form front and back surfaces of the substrate 1. 106 and at least one of the flat molds 104 and 106 (both here)
And a stamper 108 installed in the. When only one stamper 108 (for example, the flat mold 104) is installed, the other flat mold 106 and the ring-shaped mold 10 are installed.
It is also possible to integrate the two.

A transfer surface 108A is prepared on the stamper 108, and minute irregularities corresponding to information signals and grooves are formed on the transfer surface 108A. When the cavity in the mold system 100 is filled with resin, the stamper 1
It is possible to obtain the substrate 1 on which the fine unevenness is transferred by the transfer surface 108A of 08. The area to which the minute irregularities are transferred becomes the information recording area.

However, as shown in an enlarged view in FIG. 12A, there is a high possibility that resin will leak between the ring-shaped mold 108 and the stamper, and burrs B are formed on the peripheral edge of the substrate 1. There was a problem that When the substrate 1 is taken out from the mold system 100, the burr B is bent in the direction perpendicular to the plane as shown in FIG. 12B and protrudes from the information recording area (substrate surface) or is dropped to form the information recording area. To adhere to. If a light-transmitting layer or the like is formed by spin coating in this state, the burr B forms a pool of the coating liquid and cannot form a uniform film, or the coating becomes defective. Therefore, the burr B is cut off in advance. Or, there was a problem that it had to be removed. This problem is the same in the conventional optical recording medium in which the substrate is used as the light transmitting layer.

(3) Problem of mold deterioration As already shown in FIG. 12, in order to reduce the occurrence of the burr B, the stamper 108 and the ring-shaped mold 102 are strongly pressed to form a gap. It is necessary to prevent it. However, in doing so, the edge 110A of the inner peripheral wall 110 of the ring-shaped mold 102 is damaged, and the ring-shaped mold 10 is damaged.
There was a problem that 2 had to be replaced frequently. Further, the expansion and contraction of the stamper due to the heat of the molten resin is hindered, which makes it difficult to perform good molding.

(4) Problem of Non-uniform Thickness of Light-Transmissive Layer In the spin coating method, the substrate is rotated by a spindle while the coating liquid is made to flow down on the surface so that the coating liquid spreads uniformly as the substrate rotates. It is a thing. In this case, the thickness of the coating liquid can be adjusted by controlling the number of rotations of the spindle, the coating time, and the viscosity of the coating liquid, but unevenness of the coating liquid inevitably occurs in the outer peripheral portion of the substrate, and swelling occurs. There was a problem that it was easy. This state is shown below.

For example, in the substrate 1 shown in FIG. 13, a signal recording area 4 is provided on the inner circumference side of a region (blank area 3) of the outermost circumference of the surface (upper surface), and the blank area 3 and the signal recording area are provided. The surface (upper surface) of the region 4 is covered with the light transmission layer 5. As a result of applying and curing the resin by the spin coating method to form the light transmitting layer 5, a raised portion 5A is formed from the outermost peripheral portion of the signal recording area 4 to the blank area 3. In particular, as an application example of the spin coating method, when the light transmission layer 5 (for example, 100 μm) that falls into a relatively thick category is formed, the thickness T and the width W of the raised portion 5A become extremely large and overlap with the signal recording area 4. However, there is a problem that the area in which information can be recorded is reduced.

Further, since there is a high possibility that the laser optical system will collide with the raised portion 5A, as disclosed in, for example, Japanese Patent Laid-Open Nos. 11-86355 and 11-86356. It was necessary to remove the rising portion 5A by post-treatment, which led to an increase in manufacturing cost.

Further, in the above-mentioned Japanese Patent Laid-Open No. 11-86356, as shown in FIGS. 14 (A) and 14 (B), light transmission is performed by using a substrate 1 having an outer diameter slightly larger than that in the case of FIG. A method of removing the entire outer peripheral portion including the raised portion 5A by cutting or the like after applying the layer 5 is disclosed.

However, in this method, if the processing accuracy when removing the outer circumference of the substrate is poor, the concentricity of the outer diameter (side surface of the outer peripheral portion) with respect to the inner diameter of the substrate decreases, so that the disk drive is mounted and rotated. However, there is a problem in that the dynamic imbalance becomes large during recording, causing a problem in recording / playback. Further, there is a problem that the yield of the material is poor because the peripheral portion is removed.

The present invention has been made in view of the above problems of the prior art, and reduces the manufacturing cost of the recording medium substrate and further suppresses the expansion of the non-uniform outer peripheral portion of the substrate or the light transmitting layer. With the goal.

[0021]

Means for Solving the Problems As a result of diligent study by the present inventor on the structures of stampers and dies, the shapes of substrates, etc., it was found that the above-mentioned objects can be achieved by the following inventions.

(1) At least an information recording area can be formed on the recording medium substrate by a transfer surface that is placed on at least one of the molds that face each other and can form the recording medium substrate, and that transfers predetermined information. A stamper that is outside the transfer surface for forming the information recording area.
The peripheral side step portion of the annular state is bent is constituted,
The step portion has a projecting side end surface projecting from the transfer surface to the recording medium substrate side, and the projecting side end surface is
A stamper characterized in that the vicinity of the center is recessed on the side opposite to the recording medium substrate .

(2) In the above (1), the projecting side end surface of the step portion is in contact with the end edge of the mold inner peripheral wall forming the outer peripheral surface of the recording medium substrate. A stamper characterized in that the size of the ring is set.

(3) In the above item (2), since the radial ends of the projecting side end face are bent, the radial cross section of the step portion is convex toward the recording medium substrate side. Characteristic stamper.

(4) A ring-shaped mold having an inner peripheral wall forming the outer peripheral surface of the recording medium substrate, a pair of flat molds facing each other to form the front and back surfaces of the recording medium substrate, and the pair of 5. The stamper according to claim 1, 2 or 3, which is installed on at least one of the flat molds and is capable of forming an information recording area on the recording medium substrate by a transfer surface for transferring predetermined information. Mold system characterized by.

(5) In the above (4), the stamper is installed in the flat mold in a state where a predetermined space is formed on the side opposite to the substrate in the step portion. .

(6) A recording medium substrate manufactured by the mold system described in (4) or (5) above.

(7) In the above (6), the stepped portion of the stamper in the die system forms a circumferential recessed portion outside the information recording area on at least one surface of the stamped portion. Radial outer edge
Is lower in the thickness direction than the radially inner end of the recess and
A recording medium substrate , wherein the depth is set higher than the deepest part of the recess .

[0029]

( 8 ) An information recording area can be formed on the recording medium substrate by a transfer surface that is placed on at least one of the molds that face each other and can form the recording medium substrate, and that transfers the predetermined information. A manufacturing method for manufacturing a stamper using a stamper manufacturing plate, wherein the stamper manufacturing plate has a positive pattern area having fine irregularities that substantially match an information pattern formed on the recording medium substrate, By forming a step forming recess in the circumferential direction that is larger in both depth and width than the fine irregularities and using the stamper manufacturing board, the circumferential direction formed in a state where the material is bent by the step forming recess. a stepped portion of the a transfer surface to which a positive pattern region is transferred, forming a stamper having a becomes Nde including said step portion, said transfer surface
It is formed in an annular shape on the outer peripheral side of the
End face projecting from the surface to the opposite side of the step forming recess
And in the vicinity of the center of the protruding end surface,
A stamper manufacturing method characterized in that the stamper is recessed on the side opposite to the recording medium substrate .

( 9 ) An information recording area can be formed on the recording medium substrate by a transfer surface that is placed on at least one of the molds that face each other and can form the recording medium substrate, and that transfers predetermined information. A method of manufacturing a stamper using a master board and a mother board, the method comprising the step of forming a master board having an anti-pattern area opposite to an information pattern formed on the recording medium substrate, and the master board. Using a step of forming a mother board having a positive pattern area to which the anti-pattern area is transferred, on the side of the positive pattern area of the mother board, both the depth and the width of the fine pattern of the positive pattern. In the step of forming a large step forming recess, and by using the mother board, a step formed in a state where the material is bent by the step forming recess, Serial positive pattern region and the transfer surface is transferred, forming a stamper having a free Ndena
The stepped portion is formed in an annular shape on the outer peripheral side of the transfer surface.
Is formed, and the step forming concave portion is formed from the transfer surface.
It has a projecting side end surface projecting to the opposite side, and the projecting side end
The surface is concave near the center to the side opposite to the recording medium substrate.
Stamper manufacturing method characterized by and Nde.

( 10 ) An information recording area can be formed on the recording medium substrate by a transfer surface which is placed on at least one of the molds which are arranged to face each other and can form the recording medium substrate, and which transfers predetermined information. A manufacturing method for manufacturing a stamper using a master board and a mother board, the method comprising the step of forming a master board having a positive pattern area that substantially matches an information pattern formed on the recording medium substrate; A step of forming a first mother board having an anti-pattern area to which the positive pattern area is transferred, and a second positive pattern area to which the anti-pattern area is transferred using the first mother board. A step of forming a second mother board having, and the pattern on the side of the positive pattern area of the master board or the side of the second positive pattern area of the second mother board. By using the step of forming a step-forming recess that is larger in both depth and width than the fine concavo-convex and using the master board or the second mother board, the material is formed in a bent state by the step-forming recess. Forming a stamper having a step portion and a transfer surface on which the positive pattern or the second positive pattern region is transferred,
The result Nde including the step portion, the outer circumferential side than the transfer surface
It is formed in an annular shape and has the step shape from the transfer surface.
Has a projecting side end surface projecting to the opposite side of the application recess, and
The protrusion-side end surface has the recording medium substrate near the center thereof.
A stamper manufacturing method characterized in that it is recessed on the opposite side .

The present inventor has tried to positively control and determine the shape of the substrate by effectively utilizing the stamper, which has conventionally been specialized in forming (transferring) the information recording area on the substrate. . The stepped portion formed on the stamper is different from the smiling unevenness (formed on the "front surface" of the stamper) for the purpose of recording information such as pits and grooves, and for the purpose of determining the shape of the substrate itself. It is formed with the stamper itself bent. The "bent" case is not limited to the case where the flat stamper is positively bent by pressing or the like. For example, when the stamper is formed by electrolytic plating, the stamper may be bent. It also includes the case where the stepped portion is formed from the beginning.

In this way, when forming an arbitrary concave shape on the substrate side, since the concave portion can be integrally formed by the step portion of the stamper, it is possible to positively suppress the occurrence of burrs.

In particular, by forming the step portion in an annular shape, an annular recess can be formed in the outer peripheral edge of the substrate, so that a so-called ski jump is not formed on the substrate itself.

Although it is unavoidable that burrs are generated at the outermost peripheral edge of the substrate, in this case, since the projecting side end surface of the step portion and the inner peripheral wall of the mold are brought into contact with each other, (corresponding to the contact portion ) Burrs are formed on the radially outer end of the recess on the substrate side. Therefore, burrs are formed at a position lower in the thickness direction than the information recording area of the substrate, so that when the reflective layer, the light transmitting layer, etc. are formed on the information recording area by spin coating, the information recording area is affected. The accumulation of the applied coating liquid is suppressed.

Further, the concave portion of the outer peripheral edge of the substrate formed by the step portion absorbs the swelling of the coating liquid in the vicinity of the outermost periphery during the spin coating, so that the surface of the light transmitting layer or the like to be laminated can be made smoother. .

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a mold system 2 according to this embodiment.
Indicates 00. The mold system 200 includes a ring-shaped mold 202, flat molds 204 and 206 arranged to face each other,
A stamper 208 installed on one (204) of the flat molds 204 and 206. Here, the flat mold 206 and the ring-shaped mold 202 are integrally provided. The ring-shaped mold 202 has an inner peripheral wall 210 capable of forming the outer peripheral surface 60 of the substrate 12 for the recording medium, and the front and back surfaces of the substrate 12 have the pair of flat molds 204, 206.
Formed by. The stamper 208 has a transfer surface 212 on which minute irregularities for transferring predetermined information are formed, whereby the information recording surface (area) 14 is formed on the substrate 12.
Is formed. In addition to the case where a signal is substantially continuously recorded from the inner peripheral side, the information recording surface 14 is
It also includes a case where a signal can be recorded from the inner peripheral side (for example, CD-R).

FIG. 2 shows the stamper 208 removed from the mold system 200. In the stamper 208, a step portion 214 protruding from the transfer surface 212 toward the substrate 12 side (at the time of molding) is formed in a state where the material itself is bent. Particularly, in this embodiment, the step portion 214 is formed in an annular shape, and the step portion 214 is formed.
The end surface 216 on the protruding side of the inner peripheral wall 2 of the ring-shaped mold 202.
The size of the ring is set so as to abut against the edge 210A of the ten.

More specifically, the projecting side end surface 216 of the step portion 214 is bent at both radial ends. As a result, the radial cross section of the stepped portion 214 has a convex shape that projects toward the substrate 12 side. The present invention is not limited to the convex shape, and may be a step shape in which only the radially inner end of the protruding side end surface 216 is bent or another shape. The point is that it only needs to project to the substrate 12 side.

Returning to FIG. 1, the end edge 210A of the inner peripheral wall 210 of the ring-shaped mold 202 has a stamper 208.
It has a convex shape that protrudes to the side. The stamper 208 is sucked and held by the negative pressure acting on the suction groove 204A formed in the flat mold 204, and in that state, between the non-substrate side surface 218 of the step portion 214 of the stamper 208 and the flat mold 204. Has a predetermined space 220 formed therein.

As a result, as the ring-shaped die 202 and the flat die 204 approach each other, the end edge 210A is changed to the step portion 21.
4 pushes up the protruding side end surface 216 of the stamper 20.
When the material of No. 8 is elastically deformed, the vicinity of the center of the projecting end face 216 is recessed toward the flat mold 204. In this way, the edge 210A and the projecting end surface 216 come into contact with each other with an appropriate pressure. It should be noted that, here, only the case where the space 220 is formed on the non-substrate side surface 218 of the step portion 214 is shown, but by injecting an elastically deformable resin or the like into this space 220,
A desired repulsive force may be generated with respect to the pushing-up force of the edge 210A. Alternatively, a metal member may be inserted into the space 220 to completely prevent the protrusion of the end surface 216 on the protruding side.

Next, referring to FIG. 3, the stamper 108
Method of making a will be described.

Although not shown in the drawing, first, a master board 90 is formed using a glass base material. As is generally known, after applying a resist to a glass substrate, by development, fine irregularities corresponding to the information pattern formed on the substrate 12 are formed, and a metal layer is formed thereon by electroforming. It is manufactured by peeling. Therefore, at least the counter pattern area 90A opposite to the information pattern formed on the substrate 12 is formed on the master board 90 (step 300).

Next, the surface treatment (cleaning /
After the oxidation process) (step 302), the mother board 92 having the positive pattern area 92A to which the anti-pattern area 90A is transferred is formed by electroforming using the master board 90.
Are formed (step 304). Furthermore, this mother board 92
A step forming recess 92B, which is larger in both depth and width than the fine irregularities of the positive pattern region 92A, is formed by cutting on the outer side of the positive pattern region 92A in the radial direction (step 306). Generally, the depth of the fine irregularities is about 20 to 250 (nm), but the depth of the step forming recess 92B is about 20 to 300 (μm).
It is preferably set to a degree. Step forming recess 92B
In addition to cutting, it can be formed by etching, laser processing, electric discharge processing, press processing, or the like.

Next, after the mother board 92 is surface-treated (step 308), the stamper 208 is formed by electroforming using the mother board 92 (step 310).
As a result, the step forming recess 92 formed in the mother board 92 is formed.
By B, the stamper 208 is formed with a stepped portion 214 in a state where the material is bent, and further, a transfer surface 212 which is a pattern opposite to the positive pattern area 92A of the mother board 92 is formed (step 312). After that, the outer circumference and the inner circumference are punched out in a ring shape, polished and washed, and then set in a mold.

According to this manufacturing method, as shown schematically in FIG. 4, from one master board 90 to a plurality of (here, 10) mother boards (M1, M2, ..., M10).
Can be formed, and further, each mother board (M1, M
2, ... M10 from each of a plurality (here, 1
It is possible to form zero stampers (C1, C2, ..., C10). In other words, in this example, it is possible to manufacture about 100 stampers from one master board. Since a large number of substrates can be manufactured by each of these stampers, stable mass production of recording media becomes possible.

Although the case where one kind of mother board 92 is interposed between the master board 90 and the stamper 208 is shown here, the present invention is not limited thereto. For example, unlike the above, a master board on which a “normal” pattern is formed is prepared, a first mother board having an anti-pattern area is formed using this master board, and further, a first mother board is used. A second mother board having two positive pattern areas is formed, and a step forming concave portion, which is larger in both depth and width than the fine irregularities of the second positive pattern, is formed on the side surface of the second positive pattern area of the second mother board. Alternatively, the stamper may be formed by using the second mother board. In this way, it becomes possible to manufacture more stampers from one master board. If the steps are omitted, the stamper may be directly manufactured by forming the step forming recess in the master board. The point is that it is sufficient to form the step forming recesses on the stamper manufacturing board (for example, the master board or mother board) used when finally manufacturing the stamper by electroforming or the like.

Next, the substrate 12 manufactured by the mold system 200 and the optical disk manufactured by using the substrate 12 will be described.

As shown in FIG. 5, the optical disk 10
Is at least the light transmitting layer 16 formed on the substrate 12. When the optical disk 10 is a read-only type, data pits are formed on the information recording surface 14 of the substrate 12, and a reflective film of aluminum, aluminum alloy or the like is formed thereon. When the optical disc 10 is a recordable type, lands or grooves are formed on the information recording surface 14, and a reflection film and a recording film or a dielectric film whose reflectance can be modulated by a recording laser beam are laminated thereon. It
The light transmitting layer 16 is formed by applying an ultraviolet curable resin solution to the information recording surface 14 side surface by a spin coating method and then irradiating it with ultraviolet rays to cure it.

A circumferential recess 50 is formed in the vicinity of the peripheral edge of the substrate 12 on the information recording surface 14 side. The recess 50 is set to be gradually shallower from the deepest portion 50B toward the outer side in the radial direction and is substantially continuous with the peripheral edge portion 52. As a result, the radial cross section of the peripheral edge portion 52 has an acute angle at the tip (peripheral edge) 52A. It has a substantially sawtooth shape.

More specifically, when the radius of the outermost peripheral surface of the substrate 12 is d, the position of the radially inner end 50A of the recess 50 is set outside 0.965 × d from the center of the substrate. It is preferably set outside 0.975 × d from the substrate center, and more preferably 0.98 from the substrate center.
It is set outside 3 × d.

The substrate center is at least 2 here.
The positions are obtained by the intersections of virtual lines that represent the substrate diameters at various locations.

The radially outer end 50C of the recess 50 (which coincides with the tip 52A here) is the radially inner end 5 of the recess 50.
It is set lower than 0A in the thickness direction by H1 and higher than the deepest portion 50B of the recess 50 by H2 in the thickness direction. That is, the inner end 50A and the deepest portion 5 in the thickness direction
The outer end 50C is located between 0B. The deepest part 50B is
Here, it is set to be located radially inward of the intermediate position M of the width W of the recess 50. This shape is realized by elastically deforming the step portion 214 of the stamper 208 as described above.

Further, in the present embodiment, the concave portion 5 of the substrate 12
The width W of 0 is set to 1 (mm) or less, specifically about 0.5 (mm). Therefore, the range within 1 (mm) radially inward from the peripheral edge 52A of the substrate 12 is
There is a blank area 20A in which no information is recorded, and the signal recording area 20 is located on the inner peripheral side thereof.

The depth of the recess 50 (the difference in height between the inner end 50A and the deepest portion 50B (= H1 + H2)) is 0.02.
(Mm) <H1 + H2 <0.4 (mm), preferably 0.02 (mm) <H1 + H2 <0.2 (mm), more preferably 0.02 (mm) <H1 + H2 <0.1 (m
m). The height difference H1 between the inner end 50A and the outer end 50C is 0.01 (mm) <H1 <0.4 (m
m), preferably 0.01 (mm) <H1 <0.2 (m
m), more preferably 0.02 (mm) <H1 <0.1
(Mm).

Next, the state of the process of forming the light transmitting layer 16 on the main substrate 12 by spin coating will be described.

As shown in FIG. 6, when the coating liquid (light transmitting layer 16) is flown down while the substrate 12 is rotating,
The raised portion 16A is temporarily formed near the peripheral portion 52. Further, the surface energy of the raised portion 16A causes the coating liquid (light transmitting layer 16) in the recess 50 to be drawn out to the raised portion 16A side, so it is presumed that the coating liquid does not stay so much in the recess 50. . That is, while the substrate 12 is rotating, the light transmission layer 1 at a position corresponding to the recess 50 is formed.
A similar recessed space 16B is formed at 6.

When the rotation of the substrate 12 is stopped in this state,
As shown in FIG. 7, the raised portion 16A flows backward in the radial direction and flows into the recessed space 16B by utilizing the inclination of the bottom surface of the recessed portion 50. As a result, the raised portion 16
The residual A is suppressed, and the surface of the light transmission layer 16 can be made smoother than before. The optical disk 10 shown in FIG. 5 is obtained as described above.

In the present embodiment, the presence of the recess 50 as described above positively prevents the peripheral edge of the light transmitting layer 16 from rising. Moreover, the radial width W of the recess 50 can be set to be relatively narrow (for example, 1 (mm)).
Since the rise can be suppressed within that range, the information recording surface 14 can be expanded as a result. Further, after forming the light transmission layer 16, a cutting process (for cutting the bulge portion) is not required, so that it is possible to suppress an increase in processing cost and prevent the dynamic imbalance of the optical disc 10 from being deteriorated due to a processing error. .

If the recess 50 is formed in the substrate 12,
It is not necessary to form so-called ski jumps on the substrate 12 itself after injection molding.

Further, as shown in FIG. 8, when the mold system 200 is used, the burr B is formed at a position lower than the information recording surface 14 in the thickness direction. This is because the radial outer end 50C of the recess 50 is set lower than the radial inner end 50A by H1 in the thickness direction. By doing so, it is possible to reduce the influence of the burr B on the information recording surface 14, and it becomes unnecessary to positively remove the burr B.

Since the peripheral edge portion 52 of the substrate 12 has a substantially saw-tooth shape (cross section), the liquid running out of the coating liquid during spin coating becomes good, the amount of liquid pool is reduced, and the rise of the peripheral edge is further reduced. It will be possible.

Further, according to the mold system 200 of this embodiment, the recess 50 can be formed extremely easily by utilizing the elastic deformation of the step portion 214 of the stamper 208. As described above, since the position of the burr B is also formed on the peripheral portion 52, the manufacturing cost can be reduced by the amount that the burr B need not be cut off.

Further, the elastic deformation of the stepped portion 214 effectively works when the air in the cavity is discharged. In particular,
The pressure of the internal air increases when the mold system 200 is filled with the resin, but the elastic deformation of the step portion 214 causes the air to be smoothly discharged, and thereafter, the resin is applied with a predetermined pressure. Can be effectively prevented from leaking. In addition to these effects, it is possible to prevent excessive stress from acting on the end edge 210A of the ring-shaped mold 202 due to the elastic deformation of the step portion 214, and thus the ring-shaped mold 2 can be prevented.
The life of 02 can be extended.

The stamper 208 of the present embodiment is shown only when the stepped portion 214 has a convex cross-section in the radial direction, but the present invention is not limited thereto. For example, as in the stamper 208 shown in FIG. 9, only the radially inner side of the projecting side end surface 216 may be bent and the projecting side end surface 216 may be expanded radially outward. In this case, the support member 204B that projects toward the stamper 208 may be provided on the flat mold 204 side so that the projecting end surface 216 and the edge 210A are brought into contact with each other with an appropriate force.

[0068]

Since the present invention is configured as described above, it is possible to suppress unevenness in the shape of the outer region including the raised portion of the light transmitting layer on the outer periphery while reducing the manufacturing cost. Has excellent effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a mold system according to an example of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a step portion of a stamper in the mold system.

FIG. 3 is a flowchart showing a manufacturing process of the stamper.

FIG. 4 is a system diagram showing a relationship between a master board, a mother board, and a stamper used in the manufacturing process.

FIG. 5 is an enlarged cross-sectional view showing a main part of an optical disc using a substrate manufactured by the mold system.

FIG. 6 is an enlarged cross-sectional view showing an essential part of a state where a light transmission layer is formed on the same substrate by spin coating.

FIG. 7 is an enlarged cross-sectional view showing a main part of the optical disc in a state where a light transmission layer is cured.

FIG. 8 is a cross-sectional view showing the state of burrs on the periphery of the substrate.

FIG. 9 is a sectional view showing a case where the stamper in the mold system has another shape.

FIG. 10 is an enlarged cross-sectional view showing a main portion of a conventional substrate having a raised portion on the outer periphery.

FIG. 11 is a sectional view showing a conventional mold system.

FIG. 12 is a cross-sectional view showing a state where a substrate is injection-molded by the mold system.

FIG. 13 is an enlarged cross-sectional view showing a raised portion of a light transmission layer on a substrate.

FIG. 14 is an enlarged cross-sectional view showing a bulge portion of a light transmission layer on a substrate having a large outer diameter in advance and a state in which the substrate itself is removed including the bulge portion.

[Explanation of symbols]

10 ... Optical disc 12 ... Substrate 14 ... Information recording surface 16 ... Light transmitting layer 16A ... Heating section 16B ... recessed space 20 ... Signal recording area 20A ... blank area 50 ... Recess 50A ... Inner edge 50B ... deepest part 50C ... Outer end 52 ... Peripheral part 52A ... tip 200 ... Mold system 202 ... Ring mold 204, 206 ... Flat mold 208 ... Stamper 210 ... Inner surface 210A ... Edge 214 ... Step 216 ... protruding end face

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kuji Koyaku 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDC Inc. (72) Inventor Yumi Sakai 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDC Inside the corporation (56) Reference JP 2001-47471 (JP, A) JP 5-28533 (JP, A) JP 2-285535 (JP, A) JP 5-325254 (JP, A) ) JP-A-62-222449 (JP, A) JP-A-2002-100074 (JP, A) JP-A-9-282712 (JP, A) JP-A-2-42660 (JP, A) JP-A-9-48048 (JP, A) Actual Kaihei 2-335333 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 7/26 G11B 7/24

Claims (10)

(57) [Claims] 1. A transfer surface, which is placed on at least one of the molds facing each other and capable of forming a recording medium substrate, and has a transfer surface for transferring predetermined information, enables at least an information recording area to be formed on the recording medium substrate. The stamper, which is on the outer peripheral side of the transfer surface for forming the information recording area
To, the configuration step portion of the annular state is bent, the stepped portion has a projecting end surface protruding in the recording medium substrate side from the transfer surface, and, the projecting end face, That
A stamper characterized in that the vicinity of the center is recessed on the side opposite to the recording medium substrate . 2. The size of the annular ring according to claim 1, wherein the protruding side end surface of the stepped portion abuts an end edge of a mold inner peripheral wall forming an outer peripheral surface of the recording medium substrate. A stamper characterized by being set. 3. The diametrical cross section of the stepped portion is convex toward the recording medium substrate side, since both ends of the protruding side end surface in the radial direction are bent. Stamper to do. 4. A ring-shaped mold having an inner peripheral wall forming an outer peripheral surface of a recording medium substrate, a pair of flat molds facing each other to form front and back surfaces of the recording medium substrate, and the pair of flat molds. The stamper according to claim 1, 2 or 3, which is installed on at least one of the flat molds and is capable of forming an information recording area on the recording medium substrate by a transfer surface for transferring predetermined information. Characteristic mold system. 5. The mold system according to claim 4, wherein the stamper is installed on the flat mold in a state where a predetermined space is formed on the side surface of the step opposite to the substrate. 6. A substrate for a recording medium manufactured by the mold system according to claim 4. 7. The recess according to claim 6, wherein the step portion of the stamper in the mold system forms a circumferential concave portion outside the information recording area on at least one surface , and the diameter of the concave portion is larger than that of the information recording area.
The outer end in the direction of the thickness in the thickness direction than the inner end of the recess in the radial direction.
It is set low and higher in the thickness direction than the deepest part of the recess.
A substrate for a recording medium, characterized in that 8. A stamper which is provided on at least one of dies capable of forming a recording medium substrate so as to face each other and has an information recording area formed on the recording medium substrate by a transfer surface for transferring predetermined information. In a manufacturing method using a stamper manufacturing board, which is substantially the same as the information pattern formed on the recording medium substrate.
Using the stamper manufacturing board, a step forming recess in the circumferential direction that is larger in both depth and width than the fine unevenness is formed on the stamper manufacturing board having a positive pattern area that becomes fine unevenness. in the circumferential direction of the step portion formed in a state of bent material by said stage forming recess, wherein the transfer surface positive pattern region has been transferred, and forming a stamper having, containing Nde a result, The step
Is formed in an annular shape on the outer peripheral side of the transfer surface.
In principle, it projects from the transfer surface to the opposite side of the step forming recess.
Has a projecting side end surface, and the projecting side end surface is
A stamper manufacturing method, characterized in that the vicinity of the center is recessed on the side opposite to the recording medium substrate . 9. A stamper capable of forming an information recording area on the recording medium substrate by means of a transfer surface, which is placed on at least one of the molds which are arranged opposite to each other and can form the recording medium substrate, and which transfers predetermined information. Is a manufacturing method of manufacturing using a master board and a mother board, the step of forming a master board having an anti-pattern area opposite to the information pattern formed on the recording medium substrate, and the master board Using a step of forming a mother board having a positive pattern area to which the anti-pattern area is transferred, on the side of the positive pattern area of the mother board, in both depth and width than the fine irregularities of the positive pattern. A step of forming a large step forming recess, and a step part formed by bending the material by the step forming recess by using the mother board; A step of pattern regions form a stamper having a transfer surface that has been transferred, the result Nde including said step portion, said transfer surface
It is formed in an annular shape on the outer peripheral side of the
End face projecting from the surface to the opposite side of the step forming recess
And in the vicinity of the center of the protruding end surface,
A stamper manufacturing method characterized in that the stamper is recessed on the side opposite to the recording medium substrate . 10. A stamper capable of forming an information recording area on the recording medium substrate by means of a transfer surface, which is installed on at least one of the molds facing each other and capable of forming the recording medium substrate, and transfers transfer of predetermined information. Is a manufacturing method of manufacturing using a master board and a mother board, the step of forming a master board having a positive pattern area that substantially matches the information pattern formed on the recording medium substrate, and the master board A step of forming a first mother board having an anti-pattern area to which the positive pattern area is transferred using, and a second positive pattern area having the anti-pattern area transferred to using the first mother board. Forming a second mother board, the side of the positive pattern area of the master board or the second board
A step of forming a step-forming recess on the side surface of the second positive pattern region of the mother board that is larger in both depth and width than the fine irregularities of the pattern; and by using the master board or the second mother board ,
Becomes a stepped portion formed in a state of bent material by said stage forming recess, the positive pattern or transfer surface on which the second positive pattern region is transferred, forming a stamper having, including Nde the , The step is more than the transfer surface.
It is formed in an annular shape on the outer peripheral side, and from the transfer surface
It has a projecting side end surface projecting to the opposite side of the step forming recess.
In addition, in the vicinity of the center of the protruding end surface, the recording medium is
A stamper manufacturing method, characterized in that the stamper is recessed on the side opposite to the body substrate .