JPH11120629A - Production of optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an optical disk having good characteristics without deformation with high productivity by forming a thin film by sputtering on a thin plastic substrate for an optical disk, and immediately after that, by blowing the film surface with a cooling gas. SOLUTION: A dye layer is formed, for example, by spin coating on the recording side of a thin substrate such as a polycarbonate having about 0.6 mm thickness. Then a reflection film of >=40 nm film thickness is formed by sputtering. Since the substrate is thin and the one surface of the substrate is exposed to radiation heat from a sputtering target or to plasma heat for sputtering discharge, the substrate can not endure the heat. It is found by detecting the substrate with several reflection type optical sensors, that the substrate produces warpage with several or more degrees just after films are formed. To stabilize the substrate, a nozzle is disposed near the substrate on the film forming side to blow a cooling gas from which dust is removed. The gas temp. is preferably 15 to 30 deg.C and the blowing rate is preferably 10 to 30 m/sec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk, and more particularly, to a digital video disk (DV).
D) and the like.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a compact disc (CD) and a write-once compact disc (CD-R), a metal reflective film such as aluminum alloy, silver or gold is sputtered on one side of a substrate having a thickness of about 1.2 mm. After forming by a method, a protective coating agent made of an ultraviolet curable resin is generally applied thereon by a spin coating method and cured by irradiation with ultraviolet light.

[0003]

SUMMARY OF THE INVENTION However, DVD
Has a structure in which thin substrates are bonded together, and has a thickness of approximately 0.6 m before the step of bonding the substrates.
It is necessary to handle substrates as thin as m, and it is very difficult to work while suppressing warpage from the molding process to immediately before bonding.

[0004] It is extremely difficult to correct the warpage of a substrate immediately after molding by forming a reflective film or a protective coating process using an ultraviolet curable resin. In addition, since the substrate is thin, the substrate may be further thermally deformed by heating during sputtering or heating in an ultraviolet irradiation step. In other words, in the sputtering film forming process of the reflective film, the radiant heat from the sputtering target and the so-called plasma heat of the sputter discharge itself are applied to one side of the substrate on which the film is formed. Is easily measured for warpage of several degrees or more.

[0005] Further, even in the curing step of an ultraviolet curable resin by irradiation of ultraviolet light, the temperature of the substrate rises due to the radiant heat from the ultraviolet ray generating lamp or the absorption of ultraviolet rays on one side of the substrate, that is, the surface on which the protective coating is applied. A large warpage similar to the sputtering process is observed on the substrate immediately after the process. It is not easy to transport a warped substrate.

[0006] Usually, the disk is conveyed by a method such as rotation of a table or a walking beam, and proceeds to the next step.
At this time, the method of detecting the substrate at each transport stage is generally performed using an optical sensor. However, if the substrate is warped excessively, the amount of reflected light returning to the light receiving unit is insufficient, and a detection error is detected. May occur.

That is, in order to detect a substrate provided with a reflective film with light, transmitted light is usually used because the amount of transmitted light is small when the film thickness is large and there is a risk of detection error. If the warpage is large, the reflected light travels to a position deviating from the light receiving unit, so that the amount of light becomes insufficient and a detection error occurs. In addition, a reversible phenomenon is observed in which the substrate warped due to the applied heat returns to its original shape at the same time as the temperature decreases, but if any physical force is applied during transport, it will not return to its original shape, and it will A phenomenon may occur.

That is, when a substrate is transported, a force due to physical movement such as pushing up or rotating a non-film-forming region in the inner or outer periphery is generally applied to the substrate.
In the case of a 0.6 mm thick thin substrate for VD, the warpage caused by heat is returning to its original state, and when the above-mentioned force is applied, the warpage is caused by a new strain. It may be deformed without returning to.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the present invention has succeeded in stably preventing the deformation of the substrate immediately after sputtering, in which the deformation of the substrate is large, thereby stably achieving an optical system. It has been found that a medium for recording information can be manufactured, and the present invention has been completed. The gist of the present invention resides in a method for manufacturing an optical information recording medium, characterized in that when forming a thin film by sputtering a thin plastic substrate for an optical disk, after forming the thin film by sputtering, a cooling gas is blown to the film surface side. .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a thermoplastic resin having excellent transparency, such as polycarbonate, polymethyl methacrylate, and amorphous polyolefin, is used as a plastic substrate. Particularly, polycarbonate is preferable.

The thickness of the substrate is 0.5 mm or more and 0.7
The target is a thin substrate of about mm or less. DVD-Re
The substrate usually used in cordable (DVD-R) is 0.58 mm or more and less than 0.63 mm, and the shape of the substrate is a circle having a center hole, but the diameter of the center hole is usually 15 mm or more and less than 15.2 mm. Is done. The substrate has a diameter of 119.7 mm or more and 120.3 mm or less.

In the case of a DVD-R, a dye layer is formed on the recording surface of the substrate by, for example, a spin coating method.
As the dye in this case, a dye that decomposes by absorbing light having a wavelength of 630 to 660 nm is preferably used. For example, a dye such as a cyanine-based, phthalocyanine-based, or azo-based dye is used. Examples of the type of the reflective film formed by sputtering include gold, silver, aluminum, and alloys containing these as main components.

The thickness of the reflection film is preferably 40 nm or more. Since the substrate is thin, the substrate is deformed by heating during sputtering. In other words, in the sputtering film forming process of the reflective film, the radiant heat from the sputtering target and the so-called plasma heat of the sputter discharge itself are applied to one side of the substrate on which the film is formed. Is easily observed warpage of several degrees or more.

Therefore, it is necessary to stabilize the substrate,
In the present invention, a cooling gas is blown to the substrate for this stabilization. An inert gas such as nitrogen or argon or air is preferable as a type of gas blown to the substrate film forming surface side, but it is important that dust is not included. For this purpose, a gas (clean gas) passed through a filter for removing dust having a size of a few microns is preferably used.

When dust adheres to the film formation surface, a recording signal in an area where dust normally adheres causes an error at the time of signal reproduction. Therefore, it is necessary to manufacture dust in a sufficiently small state.
Here, as the gas spraying method, it is preferable that the distance between the nozzle and the substrate is as small as possible because the cooling effect is high. The temperature of the gas is usually 15 ° C to 30 ° C.

The gas is preferably cooled below room temperature by using a cooler. However, if the temperature is too low, the substrate shrinks rapidly, which may cause irreversible deformation. If the temperature of the gas is too high, the cooling capacity is insufficient, and the gas moves to the next station without returning to its original state, which is not preferable. As the gas blowing speed,
50 m / sec is a normal range.

Preferably, the speed is 10 to 30 m / sec. If the wind speed is lower than the above range, the cooling capacity is too small, and the effect of returning the warp is not so much exhibited. Conversely, even if the blowing speed is increased beyond the above range, the effect does not change much.

[0018] Rather, dust in the manufacturing apparatus may be rolled up and contaminate the substrate, which is not preferable. It is preferable to provide a plurality of reflective optical sensors for detecting a substrate on a transfer stage for transferring a substrate heated by sputtering. In order to detect a substrate with a reflective film with light, when the transmitted light is too thick, the amount of transmitted light is small and there is a risk of detection error. Since the warp is large, the reflected light proceeds to a position deviated from the light receiving unit, and thus the amount of light is insufficient, and a detection error occurs. Therefore, it is preferable to provide a plurality of reflective optical sensors for detecting a substrate on the transfer stage.

An optical sensor for detecting a substrate has, for example, a component configuration for emitting and receiving red light, and includes an integrated portion and a separated portion of an emitting portion and a light receiving portion. This is a method of receiving light reflected on an object.
On the other hand, for the latter, for example, for detection of a transparent substrate, the light-emitting portion and the light-receiving portion are usually arranged to face each other with the substrate interposed therebetween.

In the curing process of the ultraviolet curable resin by the irradiation of ultraviolet rays, the temperature of the substrate rises due to the radiation heat from the ultraviolet ray generating lamp or the absorption of the ultraviolet rays on one surface of the substrate, that is, the surface on which the protective coating is applied. A large warpage similar to the sputtering process is observed for the substrate. Therefore, it is preferable to provide a plurality of reflection-type optical sensors for detecting a substrate on the transfer stage immediately after the curing step.

[0021]

EXAMPLES Examples will be shown below, but the present invention is not limited to the following examples without departing from the gist of the invention. Example 1 An air blow nozzle was installed on the unloading side disk transfer stage of a sputtering tank for a reflective layer of an apparatus for manufacturing an optical information recording medium, and air at 25 ° C. and 20 m / sec was applied to the substrate on the transfer stage immediately after sputtering. Was sprayed. In addition, two Keyence disk detection sensors (long-distance limited reflection type PS-49) were also installed.

An approximately 80 nm gold reflection film is formed on the substrate by sputtering, and the nozzle position is adjusted so that the film formation surface of the disk is cooled. Tangen before and after deposition of gold reflective film (before and after sputtering)
The amount of change in the σ value of tialTilt was 0.001 degrees at r = 40 mm, and the cooling effect was recognized.

Here, σ is defined by the following equation. σ = {[{n} X ² − ({X) ² } / {n (n−1)}] n: Number of data X: Data itself There was no detection error in the sensor during transport of 100 sheets. Comparative Example 1 The same test was performed as in Example 1 except that air blowing was not performed, and the change in the σ value of the Tangential Tilt before and after gold deposition was r =
It was 0.007 degrees at 40 mm. There was no detection error during transport of 100 sheets. Comparative Example 2 When one sensor was used in Example 1, an error in which three sheets could not be detected occurred on the transfer stage after sputtering during transfer of 100 sheets, and the line was temporarily stopped.

[0024]

According to the manufacturing method of the present invention, an optical information recording medium having good characteristics without deformation can be manufactured with high productivity.

Claims (2)

[Claims] 1. A method for manufacturing an optical information recording medium, comprising: forming a thin film on a thin plastic substrate for an optical disk by sputtering, followed by blowing a cooling gas on the film surface side after forming the thin film by sputtering. 2. The method for manufacturing an optical information recording medium according to claim 1, wherein a plurality of reflective optical sensors for detecting a substrate are provided on a transfer stage for transferring a substrate heated by sputtering. .