JPH0811225A - Stamper for optical information recording medium - Google Patents

Abstract

PURPOSE:To solve a problem of defective transfer of a patterned part or a warp of a board by cooling an edge part of a sheet under a state in contact with a stamper without the edge of the sheet being twisted, by making the outside of an effective sphere of the stamper thin. CONSTITUTION:Outside spheres 4 of an effective part of a stamper 1 are provided on both sides of the effective part 3 of the stamper 1 and the outside region 4 is provided so that they come into contact with a thick neck part. The whole width of the stamper to be obtained by adding the widths of the effective part 3 of the stamper and the outside region 4 together is either identical with the width of the molded sheet or set up wider than the width of the molded sheet. As for a method to provide a thin sphere, either a method grinding only the fixed outside sphere of the stamper 1 or a method to obtain the stamper by transferring from a mother mask by swelling a position of the fixed outside sphere of a mother mask beforehand are recommendable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stamper for manufacturing a substrate for an information recording medium for optically recording / reproducing information.

[0002]

2. Description of the Related Art An optical recording medium substrate for optically recording / reproducing information is provided with a concave and convex guide groove for tracking and a fine preformat pattern such as address information pits. Conventionally, an injection molding method and a compression molding method are known as methods for forming a substrate having these preformat patterns.
In these molding methods, the productivity is poor because it is processed in a single-wafer process. In addition, thin and low birefringence substrates with a thickness of 0.4 mm or less, such as optical card substrates, can be manufactured in large quantities at high speed. Is very difficult.

A roller grooving method by continuous extrusion molding is known as a method for molding a substrate having a low birefringence and having a preformat pattern at a high speed and in a large amount. This is a thermoplastic resin that is heated and melted by an extruder and extruded from a T-die, passed between a mirror roll and a stamper roll, made into a sheet, and at the same time, the pre-formatted concavo-convex pattern is transferred to the resin surface, and then an optical disk or optical card. ,
It is a method of continuously molding a substrate for an optical information recording medium such as an optical tape.

Specifically, as shown in FIG. 4, as a roller grooving method, an uneven shape such as a guide groove or a preformat pattern is transferred to a molding resin by a three-roll method.
A schematic view of a manufacturing apparatus for molding a substrate for an optical recording medium, 13 is an extruder, 14 is a T die, 16 is a first roll for molding, 17 is a second roll (stamper roll), and 18 is a second roll. 3 rolls, 15 is a heat-melted resin sheet, and 19 is a molded sheet on which a preformat pattern is transferred and cured.

The resin 15 in a molten state extruded in a sheet form from the T die 14 of the extruder 13 is introduced between a first roll 16 and a stamper roll (second roll) 17, where the rolls 16 and 17 are used. While being pressed, the shape of the stamper 1 attached to the outer peripheral surface of the stamper roll 17 is transferred. Resin sheet 19 after transfer
After being passed between the third roll 18 and the stamper roll 17, it is taken up by a take-up machine.

As a method for manufacturing the roll-shaped stamper roll, there is known a method for producing a roll-shaped stamper by subjecting a roller to contact exposure using a paper-shaped glass mask and directly engraving. JP-A-2
-110841).

However, in the method for manufacturing a roll-shaped stamper roll by directly stamping as described above,
The stamper roll of the book is usually formed with a plurality of preformat patterns of the information recording medium (spiral including tracking grooves, information pits, concentric circles or stripe patterns). If a defect occurs on the pattern, the stamper roll itself must be replaced.

In order to solve such a problem, for example, as described in Japanese Patent Application Laid-Open No. 2-132661,
There is a method in which a flexible sheet-shaped stamper is produced and is fixed to the peripheral surface of the roll with an adhesive or mechanical means to form a stamper roll.

As described above, according to the method of separately producing a sheet-shaped stamper and fixing the sheet-shaped stamper on the roll surface, when a defect occurs on the preformat pattern, the sheet-shaped stamper can be simply replaced. This stamper roll can be repaired, so this is better in practice.

By fixing this sheet-shaped stamper on the roll, a convex step equal to the thickness of the sheet-shaped stamper is formed on the roll.

On the other hand, since the thermoplastic resin extruded from the T-die becomes thicker at both ends of the sheet than at the center of the sheet due to neck-in, when the preformat pattern of the stamper is transferred to the entire area of the sheet, both ends of the sheet are The thick portion of the sheet (hereinafter referred to as the sheet edge) hinders the transfer.

Therefore, by using a sheet-shaped stamper having a width narrower than that of the entire area of the extruded sheet, it is possible to form the sheet without being affected by the ear of the sheet and transfer the pattern. I was doing.

[0013]

However, in the above-mentioned conventional example, even if the thickness unevenness of the sheet due to neck-in is controlled to 100 μm or less, the sheet-shaped stamper mounted on the roll is not enough. 300 to 50 made of paper glass to obtain high strength
Even with a metal stamper such as 0 micron or Ni,
Since the thickness of 200 μm is required, the step between the roll surface of the second roll and the stamper surface becomes much larger than the uneven thickness of the sheet edge.

When extrusion molding is performed under such conditions, as shown in FIG. 5, the thermoplastic resin sheet 15 is pushed by the stamper projecting on the surface of the second roll and the sheet is cooled, but the stamper is cooled. Since the resin in the edge of the sheet that sticks out is molded without touching the roll, it hangs down without being cooled when the second roll goes around, and is gradually cooled after the third roll after being twisted and deformed. Therefore, there is a problem in that the effective portion (stamper portion) stamped accurately is also deformed such as warping.

As a method for solving this problem, Japanese Unexamined Patent Publication No. Hei 6 (1994)
No. -44616, extrusion molding is performed by passing a thermoplastic resin between a stamper roll having a convex portion provided with a stamper on the surface of a cooling roll and a cooling roll provided with a concave portion facing the convex portion of the stamper roll on the roll surface. The method of doing is proposed. However, in this method, since the central concave portion corresponding to the sheet effective portion is formed by cutting, the concave portion must be formed over the entire surface with high accuracy and surface accuracy, and the process is complicated. Furthermore, when the molding conditions and the thickness of the stamper are changed, the value of the step difference of the recess must be corrected, but in this case, the roll must be reprocessed, which is very complicated. Further, as described in the above-mentioned patent publication, air is blown directly onto the resin (edge of the sheet) protruding from above the stamper,
A method has also been proposed in which the edge portion of the sheet is brought into contact with the outside of the stamper of the stamper roll having a convex portion by the stamper. Since air is blown immediately after sandwiching, it complicates the situation and also affects the sandwiching temperature of the resin, causing transfer failure, birefringence, and substrate warpage.

[0016]

A stamper for an optical information recording medium according to the present invention is a stamper for manufacturing a substrate for an optical information recording medium having an uneven preformat pattern on the substrate surface. It is characterized in that the thickness of the region outside the effective portion is thinner than that of the stamper effective portion.

The stamper for an optical information recording medium of the present invention comprises a stamper for producing a substrate for an optical information recording medium having the preformatted pattern, which is wound around a thermoplastic resin extrusion molding roll to form a sheet. At the same time, it is used in an extrusion molding method (roller grooving method) for transferring the preformat pattern on the stamper onto the sheet.

FIG. 1 is a schematic view of a stamper of the present invention, and FIG. 2 is a sectional view when a sheet is molded using the stamper of the present invention and a resin is sandwiched.

In each drawing, 1 is a stamper, 2 is a preformat pattern area, and 3 is a stamper effective area.

A pre-format pattern 2 (spiral, concentric circles or stripe pattern consisting of tracking grooves, information pits, etc.) of a plurality of information recording media is formed on the stamper 1. Various marks such as a cutting mark and a lot number are provided on the outer area of the pre-format pattern 2, and all of them are arranged in the effective area 3 of the stamper. In order to prevent the effective area 3 from being affected by the ear of the sheet, the effective area 3 is set to be narrower than the width of the molded sheet, and is preferably set to be several millimeters to several centimeters narrow although it varies depending on manufacturing conditions and materials used.

The outer region 4 of the stamper effective portion is provided on both sides of the effective portion 3 of the stamper, and is provided so that the outer region 4 contacts the ear portion of the seat, that is, the thick neck-in portion. ing. The width of the entire stamper including the stamper effective portion 3 and the external region 4 needs to be set equal to or larger than the width of the formed sheet.

As a method of providing a thin region, a method of polishing only a predetermined outer region of the stamper or a method of preliminarily raising the position of the predetermined outer region of the mother mask and transferring from the mother mask to obtain the stamper The step can be provided by a conventionally known method such as a method.

As a cross-sectional shape of the outer area, that is, the thin area, a trapezoid is shown as an example in FIG. Can be taken. Further, the dimension (thickness) of the thin region can be appropriately set according to the sheet forming conditions.

[0024]

Example 1 The present invention will be specifically described below.

First, as shown in FIG. 3A, a photoresist layer was formed on a substrate 5 (34 cm long × 30 cm wide) such as soda lime glass. The photoresist 6 was dropped on the substrate 5 and applied with a spinner to a predetermined film thickness. Then 100
Prebaking was performed under the conditions of 20 ° C. and 20 minutes.

Next, as shown in FIG. 3B, a predetermined pattern (striped pattern) on a plurality of information recording media was exposed using a laser exposure device.

Next, when the resist is developed with an LSI developer, the photoresist 7 where the ultraviolet light hits flows away when the positive type resist is used, and the resist 8 which does not hit remains, whereby the tracking groove, A glass master 9 for an optical card having a fine pattern of concavities and convexities such as information pits was obtained (FIG. 3- (c)).

Next, the outside of the effective area of the pattern surface of the glass master 9 was covered with a polyimide tape having a sufficient thickness to form a portion 10 (spacer) corresponding to the thin area outside the stamper of the present invention (FIG. 3). -(D)).

Further, as shown in (e) of the figure, as a pretreatment for forming a metal film by electroforming, a conductive treatment is carried out using a film forming apparatus such as a sputtering apparatus or a vapor deposition apparatus. Here, a conductive film 11 was formed on the glass master 9 by forming a nickel film by a sputtering device.

Next, as shown in FIG. 1F, the conductive film 1
1 is provided on the glass master 9 provided with a metal film 12 by electroforming.
To form.

First, the nickel chip in the electroforming tank was set as the + side electrode, and the glass master 9 provided with the conductive film 11 was set as the-side electrode. At this time, it is preferable to use an outer peripheral electrode plate as the electrode plate in order to obtain a favorable film thickness distribution.

Next, while gently rotating the glass master having a conductive film in an electroforming solution, nickel metal was deposited to form a metal film 12 (FIG. 3- (f)).

[0033] Here, electrostatic used Ieki, for example nickel sulfamate tetrahydrate _{[Ni (NH 2 SO 3)} 2 · 4
H ₂ O] 500g / l, boric acid [H ₃ BO _3] 35~3
It has a composition such as 8 g / l and a pit inhibitor 2.5 ml / l.

Next, after polishing the back surface of the stamper, as shown in FIG.
As shown in (g), the conductive film 11 and the metal film 12 are integrally peeled from the glass master 9 at the same time, cut into a rectangle of a predetermined size, and a linear tracking track for an optical card having a width of 3 μm and a pitch of 12 μm. A flexible stamper 10 having a pattern of The thickness of the stamper was 200 μm at the effective portion and 150 μm at the stepped portions provided at both ends.

The flexible stamper was wound around the surface of the roller and fixed by screwing to obtain a roll stamper. As shown in FIG. 4, the roll-shaped stamper was used as a second roll, and an extruder (3
The sheet was extruded by a 00 mm width T die) to form a substrate. At this time, the temperature inside the extruder is 270.
The temperature of the T-die was 300 ° C.

The first to third roll temperatures were set to 130 ° C., the molten polycarbonate resin (Teijin Kasei) was extruded, and molding was carried out at a take-up speed of 4.0 m / min.

Under the above molding conditions, a polycarbonate resin substrate (thickness 0.4 mm) having a preformat pattern for an optical card was obtained. During molding, the edges of the sheet are also cooled while being in contact with the stamper, so that the edges of the sheet do not twist and the problems of defective transfer of the pattern portion and warpage of the substrate are solved.

Further, in this example, the stamper is thinned by 50 microns in the portion corresponding to the ear of the sheet,
As seen in conventional roll stampers without steps,
It was also possible to prevent the transfer failure from appearing in the center of the sheet by hitting the ears first with the roll surface.

Further, since it is not necessary to blow air, which has been conventionally used to press the ears of the sheet against the roll stamper, the sheet can be cooled uniformly.

[0040]

As described above, by thinning the outside of the effective area of the stamper, the edge portion of the sheet is also cooled while being in contact with the stamper during molding, so that the edge portion of the sheet is twisted. Therefore, there is an effect that problems such as defective transfer of the pattern portion and warp of the substrate are solved, and transferability of the central effective portion is improved.

[Brief description of drawings]

FIG. 1A is a schematic view of a stamper according to the present invention. (B) It is a schematic diagram of the stamper which concerns on this invention.

FIG. 2 is a cross-sectional view when a sheet is formed using a stamper according to the present invention and a resin is sandwiched.

FIG. 3 is a process drawing showing the method of manufacturing a stamper according to the present invention.

FIG. 4 is a schematic view of a roller grooving molding method.

FIG. 5 is a schematic diagram showing conventional problems of the roller grooving method.

FIG. 6 is a schematic diagram showing conventional problems of the roller grooving method.

[Explanation of symbols]

1 Stamper 2 Preformat Pattern Area 3 Stamper Effective Area 4 External Area of Stamper Effective Area 5 Glass Substrate 6 Photoresist Layer 7 Exposed Area 8 Unexposed Area 9 Master 10 Spacer for External Area Formation 11 Conductive Film 12 Electroformed Film 13 Extruder 14 T Die 15 Resin Sheet in Heat Melt State 16 First Roll 17 Second Roll (Stamper Roll) 18 Third Roll 19 Formed Sheet with Preformatted Pattern Transfer 20 Roll Stamper Non-Contact Area

Claims (3)

[Claims] 1. A stamper for manufacturing a substrate for an optical information recording medium having an uneven preformat pattern on the surface of the substrate, wherein an outer region of the stamper effective portion is formed thinner than the stamper effective portion. A stamper for an optical information recording medium, characterized in that 2. When a thermoplastic resin is extruded using a stamper roll equipped with a stamper to extrude a substrate for an optical information recording medium, the thickness of an outer region of the stamper roll in the roll end direction is reduced,
A method for extrusion-molding a substrate for an optical information recording medium, characterized in that a sheet edge portion is also brought into contact with a cooling roll to be cooled during extrusion molding. 3. A stamper roll for producing a substrate for an optical information recording medium is wound around an extrusion roll, and a thermoplastic resin is melt-extruded to extrude the substrate for an optical information recording medium. In doing so, the outer peripheral end portion which is thicker than the central portion of the sheet due to the neck-in of the melt-extruded sheet is pressed against the thinned portion of the outer region in the roll end direction of the effective region provided on the stamper roll. As a result, the effective area on the stamper roll is molded, and at the same time, the area outside the effective area where the thickness of the sheet is thick is adjusted so as to come into contact with the cooling roll and be cooled. Extruder for media substrate.