JPS61202353A - Production of information carrier disk - Google Patents

Abstract

PURPOSE:To form signal pits or guide grooves having less variance in depth within disks and between the disks by using only the glass and other inorg. materials by selecting a specific nitride and carbide as a dielectric material. CONSTITUTION:The dielectric film selected from the group consisting of germanium nitride, titanium nitride, boron nitride, chromium nitride, zirconium nitride, cobalt nitride, phosphorus nitride, silicon carbide, tungsten carbide, titanium carbide, chromium carbide, molybdenum carbide and zirconium carbide is formed on a glass substrate to the thickness corresponding to the depth of the desired signal pits or guide grooves by a vacuum thin film forming technique. A resist pattern having the pattern of the desired signal pits or guide grooves is then formed thereon and the dielectric film exposed through the resist pattern is removed by etching and thereafter the resist pattern is removed.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention relates to a carrier for an optical disc, a video disc, a digital audio disc, a magneto-optical disc, etc., which is attracting attention as a high-density information recording medium, or in some cases, as a carrier itself. The present invention relates to a method for manufacturing the information carrier disc used.

(Background of the Invention) With the development of the information society, the demand for high-density, randomly accessible information recording media is increasing.

Therefore, video discs, digital audio discs, optical discs, etc. have already been put into practical use.

Among these, those that are only for playback and use an optical playback method have "indentations" or "islands" called signal pits formed in a concentric or spiral shape on a carrier disk that has a flat surface. Information is recorded based on the presence or absence of focus or bit length. One pit has minute dimensions, for example, 0.5 microns in width x 0.9 to 3 microns in length x 0.1 microns in depth or height, and the track spacing is also as small as 1.6 microns, for example. be.

In addition, rewritable magneto-optical disks have grooves (including protrusions) called "guide grooves" on the surface for tracking.
A magnetic material such as TbFe, GdTbFe, G
It is a thin layer of amorphous perpendicularly magnetized films such as dTbFeCo, and the guide groove has a width of, for example, 0.7 microns.
The depth or height is 700 mm, and the spacing is 2.5 microns.

Both signal bits and guide grooves are minute and require strict precision (on the order of submicrons), especially in terms of depth or height.

Conventionally, such a carrier disk in which a signal focus or guide groove is formed is produced by using an inverted mold, and
Injection molding, press molding, using molding resins such as MMA and PC
Another method for mass production is to use a mold with an inverted mold, apply a radiation-curable resin lacquer on it, and then cure it by irradiating it with radiation such as ultraviolet rays, electron beams, gamma rays, etc. , A method of making a thin resin film with signal bits or guide grooves formed thereon and pasting it onto metal Ad, plastic, glass, or other substrates (for example, see Japanese Patent Application Laid-open No. 58-108042 and No. 58-159202), ■Glass. A photoresist is applied onto a substrate, a predetermined pattern is projected, exposed, and developed to form a resist pattern (this exposes a predetermined area of the substrate), and then plasma etching is performed to corrode the glass substrate. , if a predetermined guide groove is obtained and fC is obtained, the remaining resist pattern can be dissolved and removed (see Figure 7 and Lecture N12a-A-4 at the 1985 Spring Applied Physics Conference), etc., in an industrial or laboratory manner. has been manufactured in

However, in methods (1) and (2), since the part constituting the bit or guide groove is made of organic resin, it has a high water absorption rate, a low heat distortion temperature, is easily damaged, deforms when peeled from the mold, and has poor shape transferability. It has disadvantages such as poor performance,
The durability and reliability of the resulting disc is poor. On the other hand, method (■) uses glass, so it has drawbacks such as organic resin.
(2) Since there is no suitable etching gas for plasma etching, the resist pattern is also corroded considerably. (c) The etching speed varies depending on the location on the substrate, so the depth of the grooves will vary within the disk. (2) The reproducibility of etching is poor, so the depth of the grooves will vary. (e) Plasma etching equipment is mechanically difficult to scale up, so there are variations between disks.
It has drawbacks such as a limited number of sheets that can be processed, and is not suitable for mass production.

(Objective of the Invention) The object of the present invention is to create a signal with little variation in depth or height) within a disk and between disks by using only glass or other inorganic materials without using organic resins with poor durability and reliability. The object of the present invention is to produce an information carrier disk in which pits or guide grooves are formed.

(Summary of the invention) The present invention provides the following steps: First step: germanium nitride (GeN), titanium nitride,
A dielectric film selected from the group consisting of boron nitride, chromium nitride, zirconium nitride, cobalt nitride, phosphorus nitride, silicon carbide (SiC), tungsten carbide, titanium carbide, chromium carbide, molybdenum carbide, and zirconium carbide is coated with a desired signal. 2nd step: Forming a desired signal bit or guide groove pattern (or its inverted pattern) on a glass substrate by vacuum thin film forming technology to a thickness corresponding to the depth or height of the bit or guide groove. ), a step of removing the dielectric film exposed from the resist pattern in the third step by etching, and a step of removing the resist pattern in the fourth step. Provided is a method for manufacturing an information carrier disk in which signal pits or guide grooves are formed.

In the present invention, special nitrides and carbides were selected as dielectric materials because their chemical properties are significantly different from those of the underlying glass substrate, so it is possible to select etching agents with different etching rates (called selectivity). be. Furthermore, the reason why dielectric films are formed using vacuum thin film forming techniques such as vacuum evaporation, ion blating, sputtering, and CVD is that these vacuum thin film forming techniques allow the film thickness to be determined with an accuracy of ±(5 to 10)%. This is because control can be performed without local variations, and as a result, the focus (depth or height of the guide groove) is accurate and does not vary within the disc. Furthermore, since the reproducibility is excellent, there is very little variation between discs.

On the other hand, when a recipe or guide groove is formed by etching on the glass substrate itself using the conventional method, there is a local variation of ±(15 to 20)% or more in terms of depth or height. It is difficult to control the value accurately.

Furthermore, since the reproducibility is poor, there are many discrepancies between discs.

Hereinafter, the present invention will be specifically explained by examples with reference to the drawings, but the present invention is not limited thereto.

(Example 1) First step: On a glass substrate (1) with a diameter of 200 mm and a thickness of 1 to 2 mm, a SiC film is sputtered as a dielectric film (2) so that the optical film thickness is 1040 AJI: (See Figure 1). The variation in film thickness was within ±5.

Second step: As a photoresist, AZ1350 manufactured by Shipley was spin-coated to a thickness of about 1 μm on the dielectric film (2) and baked (see FIG. 2).

Next, the A spot diameter was narrowed to 0.8 μm (on the resist surface).
The resist is exposed by irradiating the r laser beam while moving in a spiral manner, and through development, water washing, and post baking, a spiral resist pattern (3) with a width of 0.8 μm and a pitch of 1.6 μm is formed. (See Figure 3)
.

3rd step: R in a plasma etching apparatus into which a mixed gas of C, 4 and q was introduced up to 13 Pa as an etching agent.
The SiC dielectric film (2) was etched under the condition of F power of 150 W (see FIG. 4).

Under these conditions, the selectivity ratio between SiC and resist is approximately 1:5, which significantly reduces resist corrosion, and the selectivity ratio between SiC and glass substrate is approximately 2 minutes. Although etching has been completed, the glass substrate (
Almost no corrosion was observed in 1), and therefore the variation in depth was almost the same as that of the dielectric film (2) (within 5%).

Fourth step: Following the third step, the resist pattern (3) was removed by plasma etching by switching the etching gas to 02 in the same apparatus (see FIG. 5).

An information carrier disc with guide grooves was thus obtained.

A perpendicular magnetization film (5) for magneto-optical recording, such as GdCo, GdFe, TbFe, Tb, is formed on the grooved surface side of this disk.
A magneto-optical disk can be obtained by forming FeCo or the like by sputtering (see FIG. 6).

(Example 2) In Example 1, an information carrier disk was manufactured in the same process using GeN instead of SiC.

If a perpendicular magnetization film is formed directly on the disk obtained in this example and the protruding portions are used as tracks (recording zones), the durability of the perpendicular magnetization film is improved.

(Example 3) In Example IVc, a grooved information carrier disk was prepared in exactly the same manner as in Example 1, except that a substrate (1) in which a MgF2 film with a thickness of 1000 Å was deposited on a glass substrate was used. was manufactured.

In each of the examples, dry etching was used for etching the dielectric film (2), but waist etching may also be used.

(Effects of the Invention) As described above, according to the present invention, the depth or height of signal pits or guide grooves is extremely uniform within the same disk and between disks, and the information carrier disk is highly reliable and durable. Moreover, if the upper part of the dielectric film (2) is used as a trunk, the perpendicular magnetization film will not be oxidized by the dielectric film (2), so magneto-optical recording with improved layer durability can be achieved. A medium is obtained.

[Brief explanation of the drawing]

1 to 5 are schematic vertical cross-sectional views of semi-finished products or finished products at each step when manufacturing an information carrier disk according to Example 1 of the present invention. FIG. 6 is a schematic longitudinal sectional view of the information carrier disk manufactured in Example 1 with a perpendicular magnetization film provided thereon. FIG. 7 is a schematic longitudinal sectional view of a semi-finished product or a finished product at each step when manufacturing an information disc based on a conventional manufacturing method. [Explanation of symbols of main parts] 1...Glass substrate 2...Dielectric film 3...Photoresist or resist pattern 4...Guide groove 5・・・・・・Perpendicular magnetization film

Claims (1)

[Claims] First step: From germanium nitride, titanium nitride, boron nitride, chromium nitride, zirconium nitride, cobalt nitride, phosphorous nitride, silicon carbide, tungsten carbide, titanium carbide, chromium carbide, molybdenum carbide, and zirconium carbide. a step of forming a dielectric film selected from the group consisting of: on a glass substrate to a thickness corresponding to the depth (or height) of a desired signal pit or guide groove by vacuum thin film forming technology; a second step; : Step of forming a resist pattern having a desired pattern of signal pits or guide grooves (or its inverted pattern); Third step: Step of removing the dielectric film exposed from the resist pattern by etching; Fourth step: 1. A method for manufacturing an information carrier disk on which signal pits or guide grooves are formed, the method comprising the step of removing a resist pattern.