JPH04170732A - Device and method for manufacturing information recording medium - Google Patents

Abstract

PURPOSE:To control a film thickness with good accuracy by a method wherein an optical detection device which measures a change in a reflection factor is installed on the film-formation side of a transparent substrate and a filter used to shut off light at a short wavelength is installed in its light path. CONSTITUTION:A dielectric layer having a prescribed refractive index is formed on a disk substrate 4 composed of a resin material. A change in the quantity of reflected light from the film face of the substrate 4 is detected by using an optical detection device 13; a film-formation operation is stopped when the quantity of light has reached a prescribed value. When a filter 14 used to shut off a wavelength which is shorter than the wavelength of incident light is installed on the front end of the device 13, it is possible to prevent a noise generated when light at the discharge operation of a target 8 enters the device 13.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for manufacturing an information recording medium on which information can be recorded, reproduced, and erased with high density and large capacity using a laser beam or the like.

Conventional technology Conventionally, a recording thin film layer is formed on one side of a disc-shaped disk substrate, and a laser beam is irradiated from the disk substrate side to form minute holes in the recording thin film layer or change the reflectance. Write-once disks that perform recording and playback by forming pits have been put into practical use.

Furthermore, erasing disks that allow repeated recording and erasing by reversibly changing the reflectance of the recording thin film layer are being put into practical use. This erasing disk is made by heating the recording thin film layer to above its melting point with a laser beam, then cooling it quickly or gradually.
Since erasing is performed and the temperature is high for a short time in a minute area of around 1 μm, it is common to provide a dielectric layer such as SiO2 as a protective layer on both sides of the recording thin film layer.

Furthermore, there is also a so-called three-layer structure in which a reflective layer is provided on the dielectric layer above the recording thin film layer to improve recording sensitivity by reflecting the laser light that has passed through the recording thin film layer. Vapor deposition and sputtering are commonly used to form these recording thin film layers, dielectric layers, and reflective layers, and sputtering is often used as a high-quality film formation method with few defects.

Conventionally, the methods for controlling the thickness of thin films in these film deposition methods have generally been to control the film thickness using a film thickness monitor using a crystal oscillator, or to control the film thickness as the thin film is being formed. Optical control methods are used that take advantage of the fact that the reflectance changes over time.

A conventional method for controlling film thickness optically is shown in FIG.

Fig. 3 is a schematic diagram showing a method of optically controlling the film thickness when forming a thin film by sputtering, in which 1 is a vacuum vessel, 2 is a gas inlet to the vacuum vessel 1, and 3 is a vacuum The exhaust port 4 from the container 1 is a disk substrate made of a disk-shaped transparent substrate, and is attached to a substrate holder 6, and is configured to rotate as shown by an arrow 6. 7 is a high frequency electrode on which a target 8 is placed. 9 is a shutter provided between the disk substrate 4 and the target 8; 10 is an adhesion prevention plate for preventing the sputtered film from getting around to the back surface of the disk substrate 4; 1;
Reference numeral 1 denotes an optical detection device mounted on an anti-adhesion plate 1o, and the anti-adhesion plate 10 is fixed to the vacuum container 1 by a Nuvasa 12. For film formation, after the vacuum chamber 1 is evacuated, an inert gas such as Ar is introduced into the vacuum chamber 1 through the gas inlet 2, and a high frequency voltage is applied to the high frequency electrode 7 to cause electric discharge, which causes the target to be evacuated. 8 is applied to form a thin film on the disk substrate 4. The method for controlling the film thickness is to detect the amount of reflected light from the film-forming surface of the disk substrate 4. For example, if a dielectric material with a refractive index of 2.0 is formed, as shown in FIG. The film thickness is controlled by utilizing the fact that the amount of reflected light changes.

Problems to be Solved by the Invention However, to control the film thickness using an optical detection device, a constant amount of incident light is irradiated onto the film forming surface and the amount of reflected light is detected by the optical detection device. There is a problem in that noise enters the optical detection device and degrades the accuracy of the optical detection device.

Means for Solving the Problems In order to solve the above problems, the present invention provides an optical detection device that irradiates incident light from the film-forming side and detects optical changes in the reflected light from the film-forming side. An optical filter is provided in the reflected light path for blocking at least wavelengths on the shorter wavelength side than the wavelength of the incident light.

Effect: With the above structure, the method and apparatus for manufacturing an information recording medium of the present invention can prevent noise caused by light from discharging a target in the visible light region entering the optical detection device, and can improve film thickness control accuracy. It is meant to be.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a diagram showing a configuration using a detection device for detecting optical changes according to the present invention. The entire sputtering apparatus is the same as that described in the conventional example shown in FIG. 3, and is designated by the same reference numerals. In FIG. 1, reference numeral 13 denotes an optical detection device according to the present invention, which is equipped with an optical filter 14 at its tip that blocks wavelengths at least shorter than the wavelength of the incident light. is fixed.

The wavelength of the incident light of this optical detection device 13 is 830 nm. The signal detected by the optical detection device 13 is taken out to the outside of the vacuum container 1 through a lead wire and an introduction terminal (both not shown).

A method for detecting the amount of reflected light during film formation in the configuration shown in FIG. 1 will be explained. For example, when a dielectric layer with a refractive index of 2.0 is formed on a disk substrate 4 made entirely of resin, the amount of light reflected from the film surface of the disk substrate 4 changes as shown in FIG. 4 due to light interference. show. This figure shows the relationship between the amount of light reflected from the substrate and the film formation time.
The amount of reflected light increases and changes to show a peak at a film thickness of λ/(4·n) (λ: wavelength of light incident on the optical detection device, n: refractive index of the dielectric layer). If such a change in the amount of reflected light is detected by the optical detection device 13 and, for example, the film formation is stopped at the peak of the amount of reflected light, then under the conditions that the refractive index of the dielectric layer is 2.0 and the wavelength of the incident light is 830 nm, the above calculation Approximately 1104n from the formula
It is possible to obtain a film thickness of . At this time, the optical detection device 1
By providing an optical filter 14 at the tip of 3 that blocks wavelengths shorter than the wavelength of the incident light, it is possible to prevent noise caused by light from entering the optical detection device 13 when the target 8 is discharged. , it is possible to control the film thickness with high precision. Furthermore, since the optical change in reflected light is detected from the film forming side, even when a multilayer thin film is formed, the amount of reflected light from each layer can be accurately detected without attenuation. In addition, in the present embodiment, the optical filter 14 is
Although a filter that blocks wavelengths shorter than the wavelength of the incident light on the optical detection device 13 is used, a similar effect can be obtained by using a filter that only transmits light near the wavelength of the incident light.

Another embodiment of the invention is shown in FIG. Fig. 2 shows an example in which an optical detection device is used for simultaneous film formation of a large number of disk substrates, and 13 is an optical detection device according to the present invention, and the tip thereof has a wavelength on the shorter wavelength side than several lengths of the incident light. An optical filter 14 is provided to block the air, and is fixed to a vacuum container 17 with a fixture 16. A disk substrate 18 is mounted on a pallet 20 that revolves around a rotating shaft 19. 21 is a target for nupatta.

In the configuration shown in FIG. 2, the method for controlling the film thickness using the optical detection device 13 is the same as that described in the embodiment shown in FIG. This can prevent noise caused by light entering the optical detection device. Particularly when forming films on a large number of substrates at the same time as shown in FIG. ) is very effective in controlling the film thickness with high precision. Although this embodiment has been explained using an example of a phase-change type original disk, it can be applied to many methods of forming thin films such as magneto-optical disks in which recording and erasure are performed using the heat and magnetic field of laser light. .

Effects of the Invention In forming a multilayer film on a disc-shaped transparent substrate, the present invention provides an optical detection device for measuring changes in optical reflectance on the film forming side, and at least detects incident light in the reflected light path of the optical detection device. By providing an optical filter that blocks wavelengths shorter than the wavelength of the target, it is possible to prevent the light generated during the target discharge from entering the optical detection device and becoming noise, making it possible to control the film thickness with high precision. be.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a method for manufacturing an information recording medium in one embodiment of the present invention, and FIG. 2 is a schematic diagram showing a method and apparatus for manufacturing an information recording medium in another embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a conventional method of manufacturing an information recording medium;
FIG. 4 is a diagram showing changes in reflectance when the film thickness is optically controlled. 1... Vacuum container, 4... Disc substrate, 8... Target, 11.13...
Optical detection device, 14... optical filter. Name of agent: Patent attorney Akira Okaji and 2 others = Sec.
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Claims (3)

[Claims] (1) A method of forming a thin film on a substrate for an information recording medium using a detection device that irradiates incident light from the film formation side during thin film formation and detects an optical change in the reflected light, the method comprising: A method of manufacturing an information recording medium, wherein an optical filter is provided in a reflected light path to block at least wavelengths on the shorter wavelength side than the wavelength of the incident light. (2) The method for manufacturing an information recording medium according to claim 1, wherein a plurality of information recording medium substrates are placed on four pallets, and the thin film is formed while rotating the pallets. (3) A plurality of information recording medium substrates are placed on four pallets, and when forming a thin film, incident light is irradiated from the film forming side, and the reflected light path has a wavelength at least on the shorter wavelength side than the wavelength of the incident light. 1. A manufacturing apparatus for an information recording medium, comprising an optical detection device having an optical filter that blocks light.