JPH0664757B2 - Base for information storage medium and base manufacturing method - Google Patents

Description

The present invention relates to a base of an information storage medium such as a CD (compact disc) and a VD (video disc), and a base manufacturing method.

[Conventional technology]

For optical disc memory, optical technology using a semiconductor laser as a light source has been established for read-only CDs and VDs, and is currently on the market. In addition, DRAW (Direct Read After Write) type optical disk memory that can record and reproduce desired information is used for filing system of images, documents, etc. Has already reached the market. Furthermore, the development of so-called eraseable optical discs having an erasing function is currently in rapid progress.

By the way, an optical disk (information storage medium) that makes use of the high-density recording property, which is the greatest feature, is formed by forming an information medium film on a transparent substrate having a guide groove (groove) for guiding an optical head. In consideration of mass productivity and low cost, the base that has been put into practical use at present is
Acrylic resin (MMA), Polycarbonate resin (PC)
Etc., a transparent organic resin substrate is used.

However, the acrylic resin has a problem of deformation due to hygroscopic swelling due to its high hygroscopicity. On the other hand, the polycarbonate resin has a small hygroscopic swelling, but has a large optical anisotropy and a birefringence due to internal strain during molding. There is a problem that becomes large. Moreover, since both are organic resins, there is a problem that they are basically vulnerable to heat.

In particular, in an eraseable optical disc that utilizes the magneto-optical effect as a recording medium film, the output signal S / N during reproduction is smaller than that of a normal DRAW type disc because the force-rotation angle or Faraday rotation angle is minute. The problem of the organic resin-based substrate is remarkable.

The above problems are basically solved by using a glass substrate as the base of the optical disc.
Spiral guide groove with a pitch of 1.6 μm
The technology for directly forming the has not yet been developed. In addition, a method of coating a photoresist on a glass substrate and laser cutting one by one can be considered, but it takes about 3 hours to cut one sheet, which is completely unsuitable for mass production.

Therefore, in recent years, a plasma etching method for a glass substrate using a photoresist as a mask has been proposed.

In this method, first, a photoresist is evenly coated on a glass substrate, and then UV exposure corresponding to the shape of the guide groove is performed, and this is developed to form a photo resist on a portion of the glass substrate surface corresponding to the guide groove. The photoresist is selectively patterned so that there is no resist. Then, this glass substrate is exposed to the plasma of CHF ₃ gas to dry-etch only the portion of the glass substrate where the photoresist does not exist, and then the photoresist is peeled off, thus forming the optical disk substrate. is there.

[Problems to be solved by the invention]

According to this method, compared with the method of cutting the guide groove shape on the glass substrate one by one with a laser beam, the time required for forming the guide groove is short and there is an advantage that a large amount of processing can be performed at one time. On the other hand, the etching rate of the surface of the glass substrate with CHF ₃ gas is 20Å / mi.
There is still a problem in mass production due to the fact that it is as slow as n and exhaust treatment of HF radicals generated in the plasma of CHF ₃ .

The present invention has been made based on the above circumstances, and an object thereof is to maintain the advantages of a glass substrate,
An object is to provide a base for an information storage medium and a base manufacturing method which are excellent in mass productivity and can be manufactured safely.

[Means for solving problems]

In order to solve the above problems, the present invention is characterized in that a transparent amorphous member containing Si atoms is provided on a glass substrate, and a guide groove for guiding an optical head is formed on the amorphous member by etching. To do.

Further, in the method of manufacturing a substrate for an information storage medium in which a guide groove for guiding the optical head is provided, in the step of laminating an amorphous member on which a transparent amorphous member containing Si atoms is provided on a glass substrate, and the step of laminating the amorphous member. And a guide groove forming step of forming the guide groove in the amorphous member by selectively etching the provided amorphous member.

[Action]

The guide groove is formed by etching not on the glass substrate but on the amorphous member provided on the glass substrate.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a base of an optical disk. In FIG. 1, reference numeral 1 is a disk-shaped glass substrate, and a transparent amorphous member 2 containing Si atoms is provided on the glass substrate 1. That is, this amorphous member 2 is made of any material such as hydrogenated amorphous silicon nitride film, hydrogenated amorphous silicon carbide film or hydrogenated amorphous silicon oxide film, or contains Si atoms and H atoms, and contains N, C. ,
It is made of a material containing two or more atoms among O atoms, and is uniformly provided on the glass substrate 1.

In addition, a guide groove 3 for guiding an optical head (not shown) is formed in the amamorphous member 2 in a spiral shape, for example.

Next, a method of manufacturing a substrate having such a structure will be described.

First, as shown in FIG. 2 (a), a transparent hydrogenated amorphous silicon carbide film (a-SiC; H film), an amorphous silicon nitride film (a-SiN; H film), amorphous silicon nitride film (a-S
An amorphous member 2 composed of either iO; H film) is formed to a thickness of about 700Å to 5000Å.

Then, as shown in FIG. 2B, the liquid of the negative photoresist 4 is uniformly coated on the amorphous member 2 by a spinner.

Then, as shown in FIG. 2 (c), the mask 5 patterned into a desired guide groove 3 with Cr or the like is exposed to ultraviolet light, and then, as shown in FIG. 2 (d), a negative film is formed. The photoresist 4 in the portions not exposed by the mold developing solution (not shown) is selectively removed.

Then, as shown in FIG.
After the amorphous member 2 is plasma-etched in a mixed gas of CF ₄ gas and O ₂ gas using the mask as a mask, the photoresist 4 is stripped using a stripping solution as shown in FIG. 2 (f). .

According to the above configuration, the hydrogenated amorphous silicon carbide film (a-SiC; H film), the amorphous silicon nitride film (a-SiN; H film), or the amorphous silicon nitride film (a-SiO) forming the amorphous member 2 is formed. (H film) can easily change the optical bandgap by changing the amount of N, C, O with respect to Si.
It becomes transparent as the atomic percentage of N, C, and O increases, so that the optical band gap and transparency can be easily adjusted.

In addition, hydrogenated amorphous silicon carbide film (a-SiC; H film), amorphous silicon nitride film (a-S
iN; H film), amorphous silicon nitride film (a-SiO; H)
Since the film) is non-hygroscopic and has a small birefringence like glass, it can be handled in exactly the same way as the glass substrate 1.

In addition, hydrogenated amorphous silicon carbide film (a-SiC; H film), amorphous silicon nitride film (a-S
iN; H film), amorphous silicon nitride film (a-SiO; H)
The film was formed by plasma etching in a mixed gas of CF ₄ gas and O ₂ gas at an extremely fast rate (5000Å / mi).
Since it can be etched in n), it has excellent mass productivity.

Furthermore, since the radicals of CF ₄ gas and O ₂ gas are basically harmless, there is no problem even if exhaust is performed in a normal duct, and therefore, it can be safely manufactured.

Next, examples will be described.

First, the Corning tempered glass substrate 1 is set in a capacitively coupled glow discharge CVD apparatus (not shown), and the substrate temperature is set to 230.
A-SiN; H film (amorphous member 2) under the conditions of ℃, SiH ₄ gas flow rate 50SCCM, N ₂ gas flow rate 500SCCM, RF power applied to the counter electrode 300W, film formation time about 2 minutes (film thickness 1000Å) Was deposited. The optical bandgap of this a-SiN; H film is 3.5 eV and is almost transparent.

Then, the steps of coating, exposing, and developing the photoresist 4 shown in FIGS. 2B to 2D are performed to obtain a width of 0.9 μm.
The photoresist 4 was left on the portion except the shape of the guide groove 3 having a pitch of 1.6 μm.

Then, the glass substrate 1 was set in the same glow discharge CVD apparatus again, the substrate temperature was room temperature, and the CF ₄ gas flow rate was 100 SCC.
Plasma etching was performed under the conditions of M and C ₂ gas flow rates of 70 SCCM, RF power of 300 W, etching time of about 10 seconds, and groove depth of 750 Å.

Then, the photoresist 4 on this sample was stripped using a stripping solution.

When the noise level was measured between the substrate according to the present invention manufactured by the above steps and the conventional substrate obtained by applying a photoresist on a glass substrate and performing laser cutting, there was a significant difference between the two. Therefore, it was confirmed that it could be practically used as a base for a magneto-optical disk.

〔The invention's effect〕

As described above, according to the present invention, Si is formed on the glass substrate.
Since a transparent amorphous member containing atoms is provided and a guide groove for guiding the optical head is formed in this amamorphous member, it is possible to mass-produce and safely manufacture without impairing the advantages of the glass substrate. Exerts the excellent effect of.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a sectional view and FIG. 2 is an explanatory view showing a manufacturing process. 1 ... glass substrate, 2 ... amorphous member, 3 ... guide groove, 4 ... photoresist.

Claims (5)

[Claims] 1. A substrate for an information storage medium, characterized in that a transparent amorphous member containing Si atoms is provided on a glass substrate, and a guide groove for guiding an optical head is formed in the amorphous member by etching. 2. The amorphous member contains any material of hydrogenated amorphous silicon nitride film, hydrogenated amorphous silicon oxide film, hydrogenated amorphous silicon oxide film, or Si atom and H atom, and N, C, O
The base for an information storage medium according to claim 1, characterized in that it is composed of an amorphous material containing two or more atoms among the atoms. 3. A method of manufacturing a substrate for an information storage medium, wherein a guide groove for guiding an optical head is provided, and a step of laminating an amorphous member on which a transparent amorphous member containing Si atoms is provided on a glass substrate, and the amorphous member laminating. A step of forming a guide groove in the amorphous member by selectively etching the amorphous member provided in the step of forming a guide groove for an information storage medium. Method. 4. The step of forming the guide groove includes a first step of forming a photoresist on the amorphous member, and a mask in which the shape of the guide groove is patterned on the photoresist formed by the first step. And a third step of irradiating ultraviolet rays from the mask placed by the second step, and a step of irradiating the mask with ultraviolet rays by the third step. A fourth step of removing, and a portion of the photoresist after the mask is removed by the fourth step, which is not exposed to ultraviolet rays, is selectively removed by using a developing solution to form the photoresist. A fifth step of forming the shape of the guide groove, and a photoresist in which the shape of the guide groove is formed by the fifth step are masked. The amorphous member is etched, the sixth step and the foundation manufacturing method for patent information storage medium range third claim of claim, characterized by comprising comprises a forming the guide groove as. 5. The amorphous member contains any material of hydrogenated amorphous silicon nitride film, hydrogenated amorphous silicon carbide film and hydrogenated amorphous silicon oxide film, or contains Si atoms and H atoms and N, C, O
The substrate manufacturing method for an information storage medium according to claim 3, wherein the substrate is made of an amorphous material containing two or more atoms.