JP2003045096A - Method of making optical disk substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of making an optical disk substrate which regulates the depth of recessed parts to the prescribed depth even if the recessed parts are deepened by elongation of a resin substrate in making the optical disk substrate. SOLUTION: The method of making the optical disk substrate 1 having rugged parts 3 and 4 by transfer from the stamper to the resin substrate 2, then peeling the resin substrate 2, in which, in peeling the resin substrate 2 from the stamper, the optical disk substrate 1 is irradiated with the wavelength light longer than the depth of recessed parts 3 in a nitrogen atmosphere to make the high polymer of the resin in projecting parts 4 monomolecular when the depth of the recessed parts 3 is increased by elongation of the resin substrate 2 and the volume thereof is shrunk, by which the depth of the recessed parts 3 are regulated to the prescribed depth.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk substrate used for an optical disk such as a CD and a DVD. 2. Description of the Related Art In general, an optical disk capable of storing high-density data for audio and video applications and as a computer memory is formed by forming grooves and pits on the surface of a transparent optical disk substrate, and then forming a recording layer and various protective layers. Are laminated. These grooves and pits are formed by transfer from a stamper using metal or glass. An optical disk substrate is manufactured as follows. After a photoresist pattern is formed on a glass substrate by a photolithography method, etching is performed by an etching method to produce a glass master having irregularities serving as grooves and pits. Next, the photoresist pattern on the glass substrate is removed by etching, and a metal is electroformed on the concave and convex portions by an electroforming method. Then, the metal is peeled off from the glass substrate to produce a stamper. Further, the concave and convex portions formed on the stamper are transferred to a resin substrate and then peeled off to produce an optical disk substrate. [0004] However, when the resin substrate is peeled off from the stamper to produce an optical disk substrate, the resin substrate is stretched and the depth of the concave portion formed in the optical disk substrate is 30 to 40 nm. It can be deep. Therefore, at the time of recording information in the concave portion of the optical disk manufactured using this optical disk substrate or reproducing the information recorded in the concave portion, the laser beam does not sufficiently reach the bottom surface of the concave portion, causing noise. Good C / N could not be obtained. Accordingly, the present invention has been made to solve the above-mentioned problems, and when manufacturing an optical disk substrate, even if the resin substrate extends and the concave portion becomes deep, the depth of the concave portion is reduced. An object of the present invention is to provide a method for manufacturing an optical disk substrate having a predetermined depth. According to the present invention, there is provided a method for manufacturing an optical disk substrate having an uneven portion after transferring from a stamper to a resin substrate, wherein the resin substrate is separated from the stamper. When the depth of the concave portion is increased due to the extension of the resin substrate, the optical disk substrate is irradiated with light having a wavelength longer than the depth of the concave portion in a nitrogen atmosphere, and the polymer of the resin in the convex portion is irradiated. And a method for producing an optical disk substrate, characterized in that the depth of the concave portion is made to be a predetermined depth by reducing the volume of this into a single molecule. A method for manufacturing an optical disk substrate according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view illustrating a method for manufacturing an optical disk substrate according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a relationship between the integrated amount of ultraviolet light and the depth of the concave portion. As shown in FIG. 1, similarly to the conventional example, an optical disc substrate 1 having a rectangular uneven portion 3, 4 transferred from a stamper (not shown) to a polycarbonate resin substrate 2 is formed.
Is prepared. At this time, the pitch of the uneven portions 3 and 4 is 900
nm, the width of the concave portion 3 is 450 nm, and the depth of the concave portion 3 is a depth described later. Next, the optical disk substrate 1 is irradiated with ultraviolet light having a wavelength longer than the depth of the concave portion 3 from the side of the concave and convex portions 3 and 4 in a nitrogen atmosphere to monomolecularize the polymer of the resin in the convex portion 4. By contracting
The depth of the recess 3 is controlled to a predetermined depth. The reason why ultraviolet light having a wavelength longer than the depth of the concave portion 3 is used is that the ultraviolet light does not reach the bottom surface of the concave portion 3 and the polymer of the resin does not become a single molecule. Here, the initial depth of the concave portion 3 transferred from the stamper is set to 150 nm and 180 nm.
Using a laser beam with a wavelength of 254 nm longer than the depth of
The integrated light amount was changed in the range of 0 to 10000 mJ / cm ² , and the depth of the concave portion 3 was measured using an atomic force microscope. The result is shown in FIG. In FIG. 2, ● indicates that the initial depth of the concave portion 3 transferred from the stamper is 180 nm, and Δ indicates that the initial depth of the concave portion 3 transferred from the stamper is 150 nm.
The case of nm is shown. As shown in FIG. 2, when the initial depth of the concave portion 3 transferred from the stamper is 150 nm and 180 nm, the depth of the concave portion 3 changes in the range of 0 to 5000 mJ / cm ² , 5000 to 10000 J / cm ²
In the range, the depth of the concave portion 3 does not change. This means
This can be explained as follows. The integrated amount of ultraviolet light is 0 to 50
This is because, in the range of 00 mJ / cm ² , the polymer of the resin in the convex portion 4 becomes a single molecule, and this volume is reduced, so that the depth of the concave portion 3 changes. Further, when the integrated light amount is in the range of 5000 mJ / cm ^{2 to} 10000 mJ / cm ² , since the polymer of the resin in the convex portion 4 does not become a single molecule, the depth of the concave portion 3 does not change and remains constant. It is. That is, the initial concave portion 3 transferred from the stamper
Is 150 nm, the integrated amount of ultraviolet light is 0
By changing the depth in the range of up to 5000 mJ / cm ² , the depth of the concave portion 3 can be changed in the range of 110 to 150 nm. Similarly, when the initial depth of the concave portion 3 transferred from the stamper is 180 nm, the depth of the concave portion 3 is changed in the range of 140 to 180 nm when the integrated amount of ultraviolet light is in the range of 0 to 5000 mJ / cm ² . be able to. In other words, the depth of the recess 3 can be controlled in the range of 0 to 40 nm by changing the integrated amount of ultraviolet light in the range of 0 to 5000 mJ / cm ² . When manufacturing the optical disk substrate 1 by peeling the resin substrate 2 from a stamper (not shown), even when the resin substrate 2 is elongated and the depth of the concave portion 3 formed on the optical disk substrate 1 is increased, the depth of the concave portion 3 is increased. Irradiating the optical disc substrate 1 with ultraviolet light having a longer wavelength than that, the resin polymer in the convex portion 4 is made into a single molecule, and the volume is shrunk, so that the concave portion 3 is formed in a predetermined shape. Can be to depth. As a result, the laser beam during recording and reproduction is
The optical disk manufactured using the optical disk substrate 1 on which the concave and convex portions 3 and 4 having a predetermined depth are formed can perform recording and reproduction with a good C / N. it can. According to the method of manufacturing an optical disk substrate of the present invention, when the depth of the concave portion is increased due to the extension of the resin substrate, light having a wavelength longer than the depth of the concave portion is irradiated in a nitrogen atmosphere. Since irradiation is performed on the optical disk substrate in the inside, the polymer of the resin in the convex portion is made into a single molecule, and this volume is reduced, whereby the depth of the concave portion can be made a predetermined depth. As a result, an optical disk manufactured using this optical disk substrate can perform recording and reproduction with a good C / N.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a method for manufacturing an optical disk substrate according to an embodiment of the present invention. FIG. 2 is a diagram showing a relationship between an integrated amount of ultraviolet light and a depth of a concave portion. [Description of Signs] 1 ... optical disk substrate, 2 ... resin substrate, 3 ... concave portion, 4 ... convex portion

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Satoshi Yamashita             3-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa             Local Victor Company of Japan F term (reference) 5D121 AA02 DD06 GG02

Claims (1)

Claims: 1. A method for manufacturing an optical disk substrate having an uneven portion after transferring from a stamper to a resin substrate, wherein the resin substrate extends when the resin substrate is separated from the stamper. Thereby, when the depth of the concave portion is increased, the optical disc substrate is irradiated with light having a wavelength longer than the depth of the concave portion in a nitrogen atmosphere to monomolecularize the resin polymer in the convex portion. A method of manufacturing an optical disk substrate, wherein the depth of the concave portion is set to a predetermined depth by reducing this volume.