JPS5821337B2 - Production method of information recording medium master disc - Google Patents

Description

Detailed Description of the Invention For example, as one of the recording media for recording and reproducing necessary information signals having a wide frequency band such as television video signals, it is possible to record information signals at a high recording density. A disc-shaped information recording medium (information recording disc) is sometimes used, and the information recording disc used for recording and reproducing the above-mentioned necessary information signals can be either a non-grooved type or a grooved type. Each thing with one thing is known.

When reproducing the information signal recorded on the grooved information recording disk, the groove can be used as a guide groove and the reproducing operation can be performed while tracing the guide needle in the groove. Because it has the advantage of not requiring a servo system such as a tracking servo system with a complicated configuration, it is often adopted in various information recording and reproducing systems.

By the way, information recording medium master discs used as master discs for obtaining grooved information recording discs have conventionally been manufactured by applying, for example, the following manufacturing methods.

In other words, one of the conventional manufacturing methods for information recording medium masters is to mechanically cut spiral guide grooves using a cutter □ needle on the above-mentioned surface of a disk-shaped base whose surface has been finished smoothly. Then, a thin film of a beam-sensitive material sensitive to light and/or electron beams is deposited on the surface thereof, and in the grooves in the thin film of beam-sensitive material,
An information signal is recorded by a light beam or an electron beam (hereinafter simply referred to as a beam) whose intensity is modulated according to the information signal to be recorded, and then a development process is performed to form the grooves in the thin film of the beam-sensitive material. This method obtains an information recording medium master disk on which a concavo-convex recording corresponding to the information signal is formed. Another conventional method is to obtain a thin film of a beam-sensitive material on the surface of a disk-shaped substrate with a flat surface. A signal is formed on the thin film of the beam sensitive material in which a corresponding signal on the guide groove to be provided in the thin film of the beam sensitive material and an information signal to be recorded in the guide groove are superimposed. By applying a beam whose intensity has been modulated according to the signal, and then performing development processing,
There is a method of obtaining an information recording medium master disc in which the thin film of the beam-sensitive material described above is provided with guide grooves having concavities and convexities corresponding to the information signals to be recorded. Since mechanical cutting means are used to create grooves on the substrate, it is necessary to cut the grooves while the disk-shaped substrate is rotating at a low speed, so the efficiency of groove cutting is low. , a special machine for cutting grooves is required for cutting grooves, and the cutter needle used for cutting grooves has short lifespan. There are problems such as the groove shape changing due to surface runout of the shaped substrate, making the pitch of the grooves non-uniform, and causing unstable reproduction. Although it has the advantage of being able to efficiently produce the master recording medium, the finished product is not as good as it should be.

Both the guide groove and the unevenness corresponding to the information signal to be recorded in the guide groove are unstable, which causes unstable reproduction.

The present invention provides a method for producing an information recording master without the drawbacks of the conventional method described above, and the details thereof will be specifically explained below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional side view of a portion of a disc-shaped substrate A used as a material for an information recording medium master.

As the disk-shaped substrate A, for example, a glass plate is used.

FIG. 2 shows that on the surface of the disk-shaped substrate A shown in the first diagram,
0.6μm due to so-called positive beam sensitive material
It is a longitudinal sectional side view of a part of the device in which a lid is formed to cover the thin film B with a thickness of about 1.0 μm.

As the above-described positive beam-sensitive material, AZ-4350 resist manufactured by Shipley, Inc. in the United States may be used. In contrast, baking is performed in an atmosphere at a temperature of 75° C. for about 1 hour.

Next, as shown in the second diagram, a thin film B of the beam sensitive material is formed on the surface of the disk-shaped substrate A, and the spot diameter is set to about 1 μm to 5 μm with respect to the thin film B of the beam sensitive material. A beam controlled to focus at a predetermined pitch of about 2
Scan in a spiral shape of μm to 6 μm.

The spiral scanning by the beam described above is performed by the relative movement of the disc-shaped base and the beam. For example, a disc-shaped base that moves in a fixed direction while rotating and the disc-shaped base In combination with a fixed beam configured to always irradiate one specific location 1 within the range of movement of the disc-shaped base, for example, a disc-shaped base configured to perform only rotational movement at a fixed location;
In combination with the beam configured to irradiate the disc-shaped substrate while moving in the radial direction of the disc-shaped substrate,
Alternatively, it can be easily carried out by other known appropriate means.

As described above, with respect to the thin film B made of the sensitive material, the part corresponding to the spiral scanning part with a predetermined pitch is the disk-shaped substrate A.
When the development process is performed until the surface of is exposed, spiral groove-shaped removed portions 1, 1, . . . with a predetermined cross-sectional shape are formed in the thin film B.

Figures 3a and 3b show that spiral groove-shaped removed portions 1, 1, . In the one shown in FIG. 3a, the spiral groove-shaped removed portion 1.1... has a U-shaped cross-sectional shape, and in the one shown in FIG. In the illustrated example, the spiral groove-shaped removed portions 1, 1, . . . have a trapezoidal cross-sectional shape.

The cross-sectional shape of the spiral groove-shaped removal parts 1, 1... is, for example,
Taking as an example the case where spiral scanning is performed using a light beam, as the exposure amount increases, the disk-shaped substrate 2
Due to reflection from the surface, the shape changes from semicircular to U-shaped to trapezoidal.

In addition, if the disc-shaped substrate A is made of a transparent glass plate, by irradiating bias light from the back side thereof, the cross-sectional shape can be obtained by irradiating it with bias light, which is the same as in the case of scanning with a light beam with an increased exposure amount. A spiral groove-shaped removed portion 1.1... is formed.

As described above, the spiral groove-shaped removed portions 1, 1, . A thin film C of a suitable metal, oxide, or insulator is deposited on the upper surface side (the side on which the thin film B of the sensitive material is deposited) as shown in FIG.

The above-mentioned thin film C of an appropriate metal, oxide, or insulator has a thickness of, for example, about 0.6 μrrr-1 μm, and it has a spiral groove shape in the upper surface portion of the thin film B of the sensitive material and in the thin film B of the sensitive material. It is desirable that the surface portion of the disc-shaped substrate A exposed at the bottom of the removed portions 1, 1... be completely separated into two parts and attached to each part. Then, the cross-sectional shape of the spiral groove-shaped removed portions 1, 1... to be formed on the thin film B of the sensitive material is
If the trapezoidal shape is used as shown in FIG. 3, the separation state of the thin film C attached to the two parts will be better when a suitable substance is deposited as the thin film C by vapor deposition or other means. Thin film B of sensitive material because it is likely to be good.
The spiral groove-shaped removed portions 1, 1... are formed in the following manner.
It is preferable that the cross-sectional shape is trapezoidal as shown in FIG. 3 rather than U-shaped as shown in FIG. 3a.

In FIGS. 4a and 4b, the thin film C is shown as being completely separated into two parts.
In reality, a thin film B of sensitive material remained on the surface of the disc-shaped substrate A.
There is also an extremely thin film on the side of the film with a thickness of about 1/100 to 1/10 of the thickness of thin film C! It is impossible to avoid being attached.

However, the mechanical strength of the extremely thin film portion described above is extremely weak, and therefore, when the beam-sensitive material thin film B is dissolved and removed in the next step, it is automatically cut and removed, so that the thin film C is essentially Alternatively, it may be treated as being completely separated into two parts as shown in FIGS. 45a and 45b.

As shown in FIGS. 4a and 4b, a thin film C of a suitable material is exposed on the upper surface of the sensitive material thin film B and the bottom of the spiral groove-shaped removed portions 1, 1, etc. in the sensitive material thin film B. .

Next, the thin film B of the beam-sensitive material is applied to the thin film B of the beam-sensitive material using a solvent capable of dissolving only the beam-sensitive material. After being dissolved and removed, as shown in Figure 5 a and b,
Only the thin film C of the appropriate material adhered to the surface portion of the disk-shaped substrate remains, and the spiral protrusion C1 of the above-mentioned thin film of the appropriate material is adhered to and formed on the disk-shaped substrate A. You can get something.

Needless to say, the spiral protrusions ℃1 shown in FIGS. 5a and 5b are similar to the spiral grooves in the thin film B of the sensitive material shown in FIGS. Removal section 1, 1...
This is the thin film C of a suitable material that was attached to the surface of the disk-shaped substrate A exposed at the bottom of the substrate.

Next, a thin film of a beam-sensitive material having a fluidity of a predetermined viscosity, for example, a viscosity of about 5 CP, is coated on the upper surface side of the object in the state shown in FIGS. 5a and 5b. Spiral grooves E exhibiting a smooth surface condition on the top surface of the thin film
That is, a guide groove E is formed.

This state is shown in FIGS. 6a and 6b.

An example of a specific means for forming a spiral guide groove E on the surface of a thin film of the beam-sensitive material described above will be explained as follows.

That is, a beam-sensitive material having a fluidity with a viscosity of 5 CJm is placed on the top surface of the object in the state shown in FIGS.
For example, after applying AZ-1350 resist manufactured by Shisoplay*, USA, a disc-shaped substrate A (300 mm, g) is coated with 5
After rotating at 0 rpm for about 1 minute to remove excess beam-sensitive material, the rotation speed was suddenly lowered to 5 to 10 rpm and rotated for 15 to 30 minutes in a suitably airtight container. , so that guide grooves E with a smooth surface are formed on the surface of the thin film of beam-sensitive material, and then 7
The baking process is carried out in an atmosphere at 5° C. for about 1 hour.

In this way, the guide groove E formed in the thin film has a distance between its peaks and valleys of about 0.2 μm to 055 μm,
Further, the distance between the valley portion of the guide groove E and the surface of the disc-shaped substrate A is set to be 0.05 μm or more.

If the information signal is recorded by shining a beam having an appropriate spot diameter whose intensity is modulated by the information signal into the guide groove E of the structure as described above, and then development processing is performed, a spiral-shaped An information recording medium master is obtained in which uneven recording corresponding to the information signal is formed in the guide groove E of the information recording medium.

FIG. 7 is a perspective view of a small portion of an information recording medium master disc in which a concave-convex record corresponding to an information signal is formed in a spiral guide groove E. FIG.

In the method for producing an information recording medium master of the present invention, as described above, a state shown in FIG. 5 is obtained through a plurality of steps,
A thin film of beam-sensitive material was applied to it to form a spiral guide groove E with the required smooth surface condition, for example, as shown in Figures 5a and 5b. , in order to obtain the result in fewer steps than in the case of the method of the present invention described above, for example, a thin film of a suitable metal is adhered to one surface of the disc-shaped substrate A, a photoresist is applied thereon, and the film is swirled with light. It is also conceivable that a spiral protrusion of an appropriate thin film of metal be formed on the disk-shaped substrate A by photo-etching, but if this method is adopted, the so-called side etching effect , the edge of the spiral protrusion formed on the disc-shaped substrate A becomes jagged, especially when the thickness of the metal thin film is 0.6
Formation occurs when the width approaches the width of the portion to be removed by etching, such as 1 μm to 1 μm.

In any case, even if a thin film of beam-sensitive material is deposited on it, the thin film of beam-sensitive material has a guide groove with a smooth surface. This method cannot be used because it cannot be formed.

As is clear from the detailed explanation above, according to the method for manufacturing an information recording medium master of the present invention, spiral guide grooves E with a good shape and a smooth surface condition are formed on the surface thereof. Since a thin film of beam-sensitive material is easily formed, information recording disks made based on this master also have a well-shaped spiral guide groove and a good surface condition. Therefore, the information signal recorded by the unevenness in the guide groove can always be stably reproduced.According to the method of the present invention, all the problems of the conventional method mentioned above can be solved satisfactorily. It is.

[Brief explanation of the drawing]

Figures 1, 2, 3a, b to 6a. FIG. b is a longitudinal sectional side view used to explain each manufacturing process in the method for manufacturing an information recording medium master of the present invention, and FIG. 7 is an enlarged perspective view of a part of the information recording medium master. A... Disc-shaped substrate, B, D... Thin film of beam sensitive material, C... Thin film of appropriate material, E...
...Guide groove, CI...Spiral-shaped protrusion,
1... Spiral groove-shaped removal part.

Claims (1)

[Claims] 1. The thin film of the beam sensitive material on the disk-shaped substrate having the thin film of the beam sensitive material coated on the upper surface is scanned in a spiral shape by the beam and then developed, so that the thin film of the beam sensitive material is coated with the thin film of the beam sensitive material in a predetermined manner. a step of forming a spiral groove-like removed portion with a cross-sectional shape of , a step of depositing a thin film of a suitable metal, oxide, or insulator on the upper surface side of the object obtained through the above steps, and a step of forming a thin film of a suitable metal, oxide, or insulator, and a beam-sensitive material. A step of obtaining a state in which spiral protrusions made of the above-described suitable metal, oxide, or insulating thin film are adhered and formed on the upper surface of the disk-shaped substrate by treatment with a solvent that dissolves only the metal, oxide, or insulator; A thin film of a fluid beam-sensitive material having a predetermined viscosity is coated on the upper surface of the product obtained through the above process, and a spiral groove exhibiting a smooth surface condition is formed on the upper surface of the thin film of the beam-sensitive material. The spiral grooves formed on the upper surface side of the thin film of the beam-sensitive material are scanned by a beam whose intensity is modulated by the information signal to be recorded, and then developed. A method for producing an information recording medium master comprising the step of forming unevenness according to an information signal to be recorded therein.