JPS60182031A - Information recording mother disk and its production - Google Patents

Abstract

PURPOSE:To satisfy simultaneously the electrical conductivity and surface smoothness required in an electroforming stage by constituting a titled disk of the 1st metallic layer formed on a polished glass disk and the 2nd metallic layer formed thereon and using the 1st metal which is not dissolved by an etching liquid dissolving the 2nd metal. CONSTITUTION:A motor disk has no peripheral build-up at all as the 2nd metallic layer is removed to the shape of pits or concentrical spiral grooves by etching. Said disk is produced by a method of forming the 1st metallic layer 2 consisting of the 1st metal and having a uniform thickness and smooth surface on polished glass and forming the 2nd metallic layer 3 consisting of the 2nd metal and having a uniform thickness on the layer 2. A photoresist layer 4 is uniformly formed on the layer 3 and laser light is irradiated on the layer 4 into a desired pattern to sensitize said layer. The uncured photoresist is removed. The 2nd metallic layer in the part where the photoresist is removed is etched by using an etching liquid which dissolves the 2nd metal but does not dissolve the 1st metal and thereafter the cured photoresist is removed, by which the mother disk is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing an information recording master which is a master of an information record disk from which recorded information is optically read out (prior art); an information record from which recorded information is optically read out; Discs include video discs, digital audio discs, write-once document file discs, image file discs, etc. These discs convert signals into minute irregularities.
A type of recording medium that uses the interference effect caused by the difference in the path of laser light; a tracking groove is provided for scanning by laser light, and holes are formed in the recording medium in the form of a thin film along the tracking groove. Is there a type that inputs or reads information by opening the hole, changing the reflectance, or reversing the perpendicular magnetization direction? Or is there a type of signal bit and tracking groove type? It is necessary to form a spiral or continuous spiral or concentric circle on the base disk to be used even if the stamper is used for plastic injection molding. The 9 copolymerizable monomers can be transferred to the grooves of the stamper and the Plasti-Nox substrate by being placed in the mold of a compression molding machine or compression molding machine, or by a method called the so-called 2P method. Methods such as photopolymerizing with ``-'' to create a plastic film with grooves transferred thereon have been used.

The usual method for manufacturing a stamper is to transfer grooves formed on a master by one-step or three-step electroforming as described below.

When making a master disc, a positive resist is applied to a predetermined thickness on a polished glass disc, the resist film is exposed to a focused laser beam, and the exposed areas are dissolved and removed to create grooves. The most common method is to form grooves, and intermittent grooves depending on signals can be easily obtained by modulating laser light.

Since the master disc obtained by this method has no conductivity, it cannot be electroformed as it is, and methods such as vapor deposition, sputtering, ion plating, electroless plating, etc., of a conductive metal film on the resist film are used. It is necessary to form it by After electroforming, these conductive films become a surface layer with grooves transferred to them, so if this is used as a molding stamper as it is, it must have sufficient mechanical properties such as surface hardness and corrosion resistance. It is necessary to give. However, metals such as silver, which have excellent conductivity and can form a smooth and homogeneous 11-layer film, do not have sufficient hardness or corrosion resistance.
The electroformed product obtained by electroforming from the master disk cannot be used as a stamper as it is, so a mother disk with the grooves reversed is made from the father disk by electroforming, and then a stamper is made by transferring from the mother disk. We have no choice but to take the three-step electric υj method. In this way, the method using a glass master disk requires the addition of a process for imparting conductivity, and the defects in the final disc increase as the process increases, which is not preferable. Since the master disc made of a resist film on glass is also a dielectric material, it is easily charged with surface electricity during the process, and the seat valve is attracted to form defects, causing disc errors and hits. Thus, since the resist master disk on the glass is a dielectric material, it has defects such as conductivity (additional steps for adding q) and defects and cavities caused by static electricity adsorption of the seat valve.

These drawbacks can be solved by using a smooth metal disk and forming grooves thereon by direct mechanical cutting or by etching after forming a pattern with resist. It is well known that a dielectric material, ie, a resist film, on a grounded metal is less likely to be charged than a resist film on a dielectric material, such as a glass. Since the metal master disk is of course conductive, there is no need to perform conductive treatment when making a replica by electroforming, and one-step electroforming is sufficient to reversely transfer the grooves of the master disk. This metal master disc is damaged by one electroforming process, whereas the resist master disc is damaged by one electroforming process.
It can be reused and electroformed up to several times. Therefore, when using a master disk with a resist on glass, the relative gap is shortened, the chance of seat valve adsorption is reduced, and the generation of defects that cause disk noise can be reduced. For a master disc using a metal disc, see, for example, Japanese Patent Laid-Open No. 169234/1983.

However, there are problems that need to be solved in order to take advantage of these advantages of metal master discs. In other words, it is first necessary to obtain a smooth, scratch-free metal master, but it is difficult to polish metal to a certain level of precision, and for purposes such as reflectors, diamond ultra-precision grinding is used to produce oxygen-free copper, Either it is usually done to cut out a smooth surface from aluminum, or it is required to cut a groove with a depth of less than 100OX, with a surface roughness of the order of R111ax = 200-300X. It is clear that this is not sufficient for optical disc masters.

In addition, during the etching process to form grooves, corrosion progresses along the grain boundaries of the metal and the metal dissolves, so the bottom surface of the etched grooves inevitably has a rough surface. The molded article obtained from such a stamper is transferred so roughly that light is scattered and the noise level relative to the signal read by the laser increases.

Another well-known method is to irradiate a metal thin film with a laser beam without using a photoresist and selectively evaporate the metal thin film to create a master disc. The periphery of the image is raised and the shape of the focus becomes poor. In order to improve this drawback, a method has been proposed that combines a first metal layer that forms a focal point by irradiation with a laser beam and a second metal layer that is etched using the first metal layer as a mask. JP-A No. 54-134604), even with this method, it is not possible to satisfy both the problems in the electroforming process, that is, both electrical conductivity and surface smoothness.

(Objective of the Invention) Therefore, the first object of the present invention is to provide an information recording master disk that simultaneously satisfies both the electrical conductivity and surface smoothness required in the electroforming process.

A second object of the present invention is to provide a method for manufacturing the above-mentioned information recording master disc.

(Structure of the Invention) An information recording master disc according to the present invention includes a polished glass disc, a first metal layer formed on the polished glass disc and having a uniform thickness and a smooth surface. a second metal layer formed on one metal layer and discontinuous in the circumferential direction and/or radial direction; the first metal is etched by dissolving the second metal; It is characterized by being a metal that cannot be dissolved in some liquids.

In the information recording master according to the present invention, the second metal layer is removed by etching into a focus shape, a concentric circle, or a spiral tfl'j shape, so these shapes are extremely uniform and different from the conventional one. There are no surrounding areas. Furthermore, the first metal layer provides complete electrical conductivity and extremely high surface smoothness to the bottom surface of the bit or τ14.

1] 2. The combination of the first and second metals is such that the first metal is the second metal.
Any known combination can be used as long as it is not dissolved by the etching solution that dissolves the metal. For example, in the case of an acidic etching solution, a combination of ``-- the first metal is nickel and the second metal is copper; the first metal is nickel;
In the case of an alkaline esotynda liquid, the first metal may be zinc, tin, antimony, berylam, etc., and the second metal may be aluminum, chromium, etc.

The information recording master disc of the present invention is made by Prafuchi Tsukudi.

It is clear that the present invention can be used not only as a master disk for electroforming of a stamper used for forming fabrics, but also as a recording disk from which information can be extracted from the master disk itself using a reproducing device.

The method for manufacturing an information recording master disc according to the present invention is to prepare a first metal having a uniform thickness and a smooth surface on a polished glass.
A second metal layer made of a second metal and having a uniform thickness is formed on the first metal layer. A photoresist layer is uniformly formed on the second metal layer. The resist layer is exposed to laser light in a desired pattern to remove the uncured photoresist, and then the photoresist is removed using an etching solution that dissolves the second metal but does not dissolve the first metal. the second metal layer in the exposed areas and then removing the hardened photoresist.

One of the features of the present invention is to obtain a metal surface with a smoothness equivalent to that of a polished lath disk, which is achieved by forming the first metal layer on an abrasive lath disk. . Sputtering, vacuum deposition, ion plating, or electroless plating may be used to form this first metal layer. In particular, according to electroless plating, 360mm1
With LFI, it is easy to form a thin metal film on any glass plate with a uniformity within ±10%, and the film thickness depends on the spread angle of the metal source, i.e., target or crucible, such as sputtering, vacuum evaporation, ion plating, etc. It is superior to the way it appears in the distribution. All types of electroless plating include electroless nickel metal plating, electroless copper plating, electroless tin plating, electroless silver plating, and other known electroless plating. The thickness of the plating should be sufficiently thick compared to the depth of the grooves to be carved later, and the thickness can be from 0.5μ to 10μ.

The second feature of the present invention is to obtain pits or grooves that are uniform in depth and have a smooth bottom surface.
A second metal layer of a different kind from this metal is further formed on the smooth first metal layer obtained as described above. The purpose of forming this dissimilar metal double layer is to form a pattern on the second metal layer using a resist, then dissolve only the second metal layer, and
By treating the metal layer with an etching solution that does not dissolve it, a groove with a depth corresponding to the film thickness of the second metal layer is obtained.The bottom of the groove is the surface of the first metal layer, as described above. The second metal layer can be formed by sputtering, vacuum evaporation, ion plating, electroless plating, or electrolytic plating. It is particularly effective to use so-called bright plating, pulse plating, or PR1R1 plating in which a brightening agent is added to obtain smoothness.

Hereinafter, a special embodiment of the present invention will be described with reference to the accompanying drawings. It is clear that the present invention is not limited to this special embodiment.

Example 1 Precisely polished surface roughness within 10X, outer diameter 356m
Electroless plating was applied to a glass disk (soda glass) 1 having a m5 inner diameter of 7.2 mrn% and a thickness of 6 mm according to the following recipe.

First, glass plate 1 was ultrasonically cleaned using surfactant-containing water and pure water. g210 g/IJ, HCz 10
After treating with an activated water solution containing m1/11 at room temperature for 5 minutes, washing with water and continuing with
/l'i After immersing 13ml/l of IIC in the activation treatment solution at room temperature for 5 minutes, it was washed with water and treated in an electroless nickel plating bath with the following composition at 90℃ for 15 minutes to form a smooth and uniform film with a thickness of 2.6μ. A plating layer, that is, a first metal layer 2 was obtained. (
Figure 1) Nickel chloride N1ol, -611,030
g/1 thorium hypophosphite N, ll2PO□-1-]
20 1 (Jjj/IJ citric salt soda Na 2C61
-1507・2l-1z015 jj/ljj soda
N; ] C21-1302' 31 (205 g/l) An electroless steel plating solution having the following composition was applied to the nickel plating layer 2 thus obtained, and the copper plating layer was immersed for 15 seconds at 20'C. 3 to a thickness of 800X.

(Figure 2) Copper sulfate 299/1 Sodium carbonate 259/11 Potassium sodium tartrate 140 j9/11 Sodium hydroxide 40 g/1 37% formaldehyde 150 ml/1 Equimolar a compound of EDTA and triethanolamine 17 g/l A photoresist film 4 (Sibley AZ 1350
J) was applied uniformly to a thickness of 0.1 μm, and after drying, it was prebaked at 90° C. for 30 minutes (Figure 3). This resist-coated glass disk was exposed to 20 rn/cm using an Alcon laser exposure device equipped with a precision drive device and a mechanism that automatically adjusts the focus of the laser beam spot using an IeNe laser.
While rotating the glass plate at a constant circumferential speed of sec, the output is 0.
A laser beam with a wavelength of 12W Te4575X was focused on the disc 2 with a spot of 1μ, and the resist film 4 was exposed in a spiral shape with a pitch of 2.5μ by moving the rotary force disc in a fixed direction. . Approximately 30% in AZ developer at room temperature
The film was developed by immersion for a second, and the portion exposed to laser light was removed (FIG. 4). After post-haking at 120'C for 130 minutes, the glass disk was heated with Cry324 (
19/A XNa,,5O440,5g/1196%1
After being immersed for 30 seconds in an etching solution containing 1-l2S04180/l and a small amount of surfactant, it was thoroughly washed with water (Figure 5). In addition, the registry remover (Sibley 11, 1
The resist was removed in A), washed successively with isopronol and Freon, and dried. The portions of copper 3 not covered by the resist were etched away, exposing the underlying nickel layer 2.

Nickel is not corroded by this etching solution.

Thus, the rIJo, 6μ, 800X deep groove is spirally formed with a pitch of 25μ from 1.10"" to 290".
A notched master disk was obtained within the area of the door (Figure 6). The master of the mouth is 1. J: Sukunoggu was produced by one-time nickel electroforming as a mold. The obtained stambar has fewer defects in each step than conventional stambars obtained by electroforming from a master disk obtained by applying resist directly to a glass master disk and laser cutting. When a 5 (n w I) eNe laser with a Δ7 diameter was used to scan the stand bar in a spiral manner with a 30 μ pinch, and the scattered light was detected, only two defects larger than 50 μ were observed. .

Example 2 Glass of the same shape as used in Example 1, Example 1 on a disk
The same pretreatment and nickel electroless plating were applied. This nickel coating layer was sputtered with silver under the following conditions to form an 800X silver layer.

A photoresist (N1, R1320, manufactured by Nagase Kasei Co., Ltd.) was applied uniformly to a thickness of 0.1 μm using a spin coater on the glass disk having the nickel and silver layers obtained in this way, and was baked at 90°G for 30 minutes. did. This photoresist-coated glass disk was exposed using the same argon laser exposure apparatus used in Example 1 under the same conditions as in Example 1. N i) J) Development was carried out by immersing it in 809 developer for about 20 seconds at room temperature, and the exposed areas were removed. After post-haking at 130° C. for 30 minutes, it was immersed in an etching solution having the following composition for 15 seconds.

Chromic anhydride 5g Concentrated sulfuric acid 5g Pure water 51 Thereafter, it was thoroughly washed with water, further washed with isopropanol and Freon in sequence, and dried. Fo; L. Luzizto - The unprotected silver was etched away, revealing the nickel underlayer. Nickel is not corroded by this etching liquid. In this way, 2 grooves of 111 μm 11 depth 5oo
It was formed in a spiral shape with a pitch of 5 μn and a volume ranging from 110 mm 1 to 290 v+ml. When a stand bar was obtained using this master as a matrix in the same manner as in Example 1, the number of defects was as small as in Example 1.

[Brief explanation of drawings]

Figures 1 to 6 show various types of information recording master discs according to the present invention (numerals in the figures): 1. Nigarasu disc 2. , :First metal layer 3: m2 Gold m layer 4 near odd resist Patent applicant: Daicel Chemical Industries, Ltd. l; 2nd year q month - JL? Kazuo Wakasugi, Commissioner of the Japan Patent Office, 1. Indication of the case, Patent Application No. 36334 of 1159, 2. Title information recording master of the invention and its manufacturing method, 3. Relationship with the amendment person case. Address of patent applicant. 1 Teppo-cho, Sakai City, Osaka Prefecture Name (290) Daicel Chemical Industries, Ltd. □□ 5゜Amend as noted: (1) Correct “copolymerization” in the third line of page 4 to “1 photopolymerization” do. (2) 1 is configured on page 10, line 20. ”, insert the following sentence: “The above photoresist may be of positive type or negative type.” (3) Change r45751J on page 14, line 15 to “457
9A”.

Claims (1)

[Scope of Claims] 1) A first plate having a uniform thickness and a smooth surface, which is made of a polished glass disk and a first metal formed on the polished glass disk.
It is composed of a metal layer and a second metal layer formed on the first metal layer and discontinuous in the circumferential direction and/or the radial direction, and the first metal is An information recording master disk characterized in that the metal is not dissolved by an etching liquid that dissolves a second metal. 2) The information recording master disc according to claim 1, wherein the first metal is nickel, and the second metal is copper. 3) The information recording master disc according to claim 1, wherein the first metal is nickel, and the second metal is silver. - a first metal layer with a smooth surface is formed, a second metal layer made of a second metal with a uniform thickness is formed on the first metal layer, and a photoresist is formed on the second metal N. A layer is uniformly formed, the photoresist layer is exposed to laser light in a desired pattern, the uncured photoresist is removed, and the second metal is dissolved but the first metal is not dissolved. A method for manufacturing an information recording master disc, comprising etching the second metal layer in the portion where the photoresist has been removed using a liquid, and then removing the hardened photoresist. 5) The method of claim 4, wherein the first metal layer is formed by electroless plating.