JPH0758563B2 - Information storage original plate and disk manufacturing method using the same - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information storage original plate (stamper) used for a magnetic disk, an optical disk, a magneto-optical disk capable of high density storage, and a method for manufacturing the information storage disk. .

2. Description of the Related Art Optical disks and magnetic disks are one of the important points to ensure the reliability of data for long-term storage, and the stability and reliability of the board for high-speed writing and reading. It is necessary to use a substrate that does not deform, and it is desirable to use a glass substrate or an aluminum (Al) substrate. For example, when glass is used for the substrate, it has been customary to provide guide grooves by the photopolymer method. (For example, Kanamaru Hitoshi optical video disk system, Journal of the Television Society, Vol. 32, No. 1, 1978.
15P a year, these optical disc original plates (stampers) are nickel original plates (stampers), and it is generally impossible to transfer the guide groove to a highly heat-resistant substance such as glass or Al. It was In addition, recently, a method has been developed in which an uneven guide groove is directly provided on a glass substrate by a reactive ion etching method which is a further improved method. (For example, Kenji Ohta et al., Vacuum, 28 (2), 77 (1985)) A process of forming a guide groove on a typical glass substrate is shown below. After cleaning the glass disk, apply a positive resist with a spin coater to a thickness of 200-300 nm, pre-bak it, focus the argon laser light, and rotate the disk at a constant speed while rotating the laser light. A spiral guide groove having a groove width of about 0.8 μm and a pitch of 1.6 μm is recorded by moving the plate in the radial direction of the plate. Next, this guide groove is developed, and then, using the remaining resist as a mask, reactive ion etching is performed in CHF ₃ gas. After etching the glass to a depth of about 70 nm, the unnecessary resist is ashed with oxygen gas and removed to form a guide groove in the optical disk glass substrate. This is the original plate (stamper)
It is said that productivity is extremely poor because it is a method that does not use. In addition, since a substrate for a magnetic disk generally does not have a guide groove unlike an optical disk, it has a high track density like an optical disk.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the conventional photopolymer method, an optical disk can be manufactured with a certain degree of productivity, but since the original plate (stamper) for the optical disk is made of nickel, the optical disk made of resin is manufactured by the photopolymer method or the injection method. However, there is a drawback that it is not possible to add a guide groove to glass or Al. In addition, the method of directly forming uneven guide grooves on the glass substrate by the reactive ion etching method is expensive because the resist is applied to each glass substrate and the guide groove pattern on the resist is developed and the reactive ion etching step is performed. It has a drawback that it involves complicated steps and has extremely poor productivity and the quality of the guide groove is not good.

The present invention has been made to overcome such drawbacks, and an information storage original plate having extremely excellent heat resistance and low reactivity with glass and Al, and an extremely low number of steps and a high number of steps using the original plate. An object of the present invention is to provide a method for producing a guide groove of a high quality optical disk and a substrate for a magnetic disk.

Means for Solving the Problems In order to solve the above problems, the present invention provides iridium (Ir)
A guide groove is formed on the cemented carbide or cermet coated with an alloy film by the photolithography method and the ECR ion etching method, and this is used as a stamper for an optical disk or a magnetic disk, and then a pair of stampers provided with these guide grooves. Inside, scissor glass or Al,
The guide groove of the optical disk or the magnetic disk substrate is formed by pressure molding while heating.

Action The present invention is a method of forming a guide groove by hot press forming a glass material or Al with a master plate (a stamper) having a pair of guide groove patterns as if press forming a record disk. At the same time, the pattern of the guide groove can be formed with high accuracy while reducing the number. In this way, the guide groove can be formed on glass or Al with high accuracy because of the high heat resistance of the iridium alloy layer on the surface of the original plate (stamper), the inertness that does not react with glass and Al at high temperatures, and the ECR ( Electron cyclotron resonance) This is due to the very accurate workability of the original plate by the ion etching method.

Example Hereinafter, a configuration and a manufacturing method of an information storage original plate and an optical disk manufacturing method using the original plate of one example of the present invention will be described with reference to the drawings.

Example 1 Hereinafter, an example of the present invention will be described with reference to FIG. First
As shown in Fig. (A), first, a cemented carbide base material containing WC with a diameter of 90 mm and a thickness of 5 mm as the main component is mirror-polished to finish its surface roughness to RMS = 8-10Å. As shown in b), an iridium alloy film was formed by sputtering to a thickness of 3 μm.

Next, as shown in FIG. 1 (c), a negative type resist is applied on the alloy film to a thickness of 2000 to 300 Å, prebaked, and then an argon laser beam is focused to rotate the disc at a constant speed. However, with the method of moving the laser beam in the radial direction of the disk, the width is 0.8 μm and the pitch is 1.6 μm as shown in FIG. 1 (d).
The spiral guide groove is recorded (exposed). Then, this guide groove is developed (in this case, the exposed portion remains because it is a negative type resist), and the remaining resist is used as a mask in an Ar gas for electron cyclotron resonance (EC).
R) Iondium alloy film 700 Å by ion etching method
After etching to the depth of (the negative resist was hardly etched in this case), the unnecessary resist was removed, and an information storage original plate having a spiral guide groove with a width of 0.8 μm, a pitch of 1.6 μm, and a depth of 700 Å Could be manufactured stably. In this example, WC was used as the base material, but Cr ₃ C ₂ or cermet could also stably produce the original plate.

Second Embodiment A second embodiment of the present invention will be described with reference to FIG. An information storage original plate (stamper) prepared in Example (1) and two original plates having no guide groove were prepared. As shown in FIG. 2 (a), the composition was SiO ₂ 73 wt%, Na ₂ O16. .5wt%, Al ₂ O ₃ 1wt
%, CaO5wt%, MgO3.5wt% (disk, diameter
(90 mmφ, thickness 1.2 mm) was sandwiched between stampers, pressurized while heating at 780 ° C (pressure 2 kg / cm ² ) and cooled, and the glass disk was taken out.

After that, the inner diameter hole was processed, and the surface and cross section of the glass disk were evaluated using a scanning electron microscope.As a result, the width was 0.8 μm, the pitch was 1.6 μm, the depth was 700 Å, and the surface roughness was less than 10 Å, exactly like the original plate. It was.

The glass disc was rotated at 900 rpm and the signal quality (CN ratio) of the substrate was measured using the optical head. The result was 10Å
The decrease in the CN ratio when the following glass disk with a mirror surface was not rotated and when the CN ratio in the low frequency range was used as the reference (0 dB) was −1.5.
It was as low as dB.

Even when an Al disc was used instead of the glass disc, similarly good guide grooves could be transferred. However, the temperature and pressure at the time of heating and pressurizing Al were about 500 ° C. and 3 kg / cm ² . The above results are shown in Sample No. 1 in Table 1. Similarly, sample numbers 2 to 7 in Table 1 show the shape of the guide groove and the CN ratio in the low frequency region when the composition of the glass was changed.

EFFECTS OF THE INVENTION As described above, according to the present invention, an extremely reliable and highly accurate original plate for information storage, and an optical disk having a highly accurate guide groove using this original plate, It is possible to manufacture a substrate for a magnetic disk, which is an extremely useful invention in industry.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a process for making an information storage original plate (stamper) according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a stamper and a substrate for making a disc. 11 …… Base material (Cemented Carbide, Cermet), 12 …… Iridium alloy film, 13 …… Negative type resist.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Umeya 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Hideto Inventor, 1006 Kadoma, Kadoma City Osaka Prefecture

Claims (4)

[Claims] 1. A tracking servo method by photolithography on a cemented carbide or cermet containing tungsten carbide (WC) or chromium carbide (Cr ₃ C ₂ ) coated with an iridium (Ir) alloy film. An information storage original plate having a guide groove for use therein. 2. An iridium (Ir) -platinum (Pt) alloy, iridium (Ir) -rhodium (Rh) alloy, iridium (Ir) -osmium (Os) 4. The information storage original plate according to claim 1, wherein the information storage original plate is any one of an alloy and an iridium (Ir) -rhenium (Re) alloy. 3. A pair of information storage original plates composed of cemented carbide or cermet coated with an iridium (Ir) alloy is heated, and glass or aluminum (Al) is sandwiched between the original plates. A method for manufacturing an information storage disk, comprising applying pressure from above and below to the pair of original plates to transfer the guide groove shape of the original plates onto glass or aluminum (Al). 4. A negative type resist is spin-coated on a cemented carbide or cermet coated with an iridium (Ir) alloy, prebaked, a guide groove for tracking servo is exposed by a laser, and then development is performed. After that, the iridium alloy film is etched by ECR ion etching, and then the resist is removed to obtain an information storage original plate, which is a method for manufacturing the information storage original plate.