JPH0656672B2 - Manufacturing method of master plate for optical interference guide groove of optical disk - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a master plate for forming an optical interference type guide groove of an optical disc, and more specifically, an interference obtained by causing light having a high coherence such as a laser beam to interfere with each other. It has a guide groove with excellent accuracy and easy to detect by using stripes,
The present invention relates to a method of manufacturing a master plate for optical disc production, which is easy to randomly access and suitable for mass production.

[Prior Art] Generally, the optical recording system is adopted as an excellent recording system capable of increasing the recording density by one digit or more as compared with the magnetic recording system.

In this optical recording system, in order to record specific information at a predetermined position and to perform detection, a mark indicating the recording position is required. Without this marker, the positional accuracy of the written information is determined by the mechanical positioning accuracy, so recording at any position, reproduction from the recorded position, maintenance of the written information (addition, deletion, modification, etc.) ) Becomes impossible and so-called random access cannot be performed.

Therefore, conventionally, it has been known that a spiral guide track is formed by rotating a disk coated with a photoresist layer and continuously irradiating it with light while moving it in the radial direction to expose it and then developing it. (Japanese Patent Application Laid-Open No. 49-113601).

Such spiral guide tracks are mainly used for record discs (recording plates for music, etc.), etc., but in order to record and reproduce various information using one optical disc, the recording areas are concentric circles. It is easier for the information groups to be distinguished from each other when it is in the shape of a letter. Therefore, conventionally, a photosensitive material having a photoresist or the like formed on the surface thereof is
It has been practiced to form concentric guide tracks by exposing each one of the circles, that is, one circle and then developing.

[Problems to be Solved by the Invention]

However, the spiral guide track has a difficulty in distinguishing the information groups from each other as described above, and in the method of developing after exposing one by one, that is, one by one, using a laser beam, a spiral guide track is used. Although the difficulty of the flat guide track is solved, it is inefficient because the guide tracks are formed one by one, and the interval (pitch) between adjacent circles is determined by the mechanical accuracy, so it is difficult to improve the accuracy. Met.

The present invention is to eliminate the above-mentioned conventional drawbacks, and utilizes a method of manufacturing an original plate capable of producing an optical interference type guide groove with high production efficiency and excellent precision by utilizing the interference of laser light. The purpose is to provide.

[Means for Solving the Problems]

Therefore, in the method of manufacturing the optical interference guide groove forming original plate of the optical disk of the present invention, two beams of laser light, one of which is a parallel light beam and the other of which is a divergent light beam, are applied to the photoresist layer formed on the substrate from the same direction. It is characterized in that it is developed by irradiating and recording circular interference fringes.

[Action]

According to the present invention, a photoresist layer formed on a substrate is irradiated with laser light of two light fluxes of a parallel light flux and a divergent light to record interference fringes, and thereafter, development is performed, so that a concentric guide is formed by one exposure. Tracks can be formed.

〔Example〕

 Embodiments will be described below with reference to the drawings.

The types of optical discs suitable for the present invention include materials, recording and
Regardless of the principle of reproduction, in consideration of mass production, a thermoplastic synthetic resin sheet or plate is used as a substrate, and the optical recording layer is a low melting point metal thin film such as Te, Bi, In, Pb, and a laminated body of the metal thin films. Etc. are preferred.

Next, the optical interference type guide groove provided on the surface of the optical disc for indicating the recording position during optical recording and reproduction will be described. As shown schematically in FIG. 1, the optical disc 2 having a hole in the center thereof will be described. Is provided with a concentric circle on the surface thereof.

FIG. 2 is a cross-sectional view showing the shape of the optical interference type guide groove of the optical disc of FIG.
And the bottom 4 of the recess is flat and their faces are parallel to the base.

In FIG. 2, the width of the convex portion 3 in the horizontal direction in the drawing is 0.5 to 0.2 μm in actual use, and the width of the concave portion is 0.5 to 2 μm.
m is preferable but not limited to this. The length from the bottom of the concave to the top of the convex, that is, the depth of the optical interference type guide groove can be 0.1 to 1.0 μm, but the depth of the optical interference type guide groove is used for recording and reproduction. When the wavelength of the laser light to be emitted is λ, it is desirable that λ / 4, λ / 8, ....

When laser light is applied to the optical disc having the above-mentioned optical interference type guide groove in the form of a spot having a required size, the light reflected at the top of the convex portion of the guide groove and the light reflected at the bottom of the concave portion are As a result, an optical path difference corresponding to λ / 4, λ / 8, ... Is produced, light interference occurs, and the recording position can be easily detected.

Next, an example of a method of manufacturing an optical disc having the above-described optical interference type guide groove will be described.

3 and 4 are views showing an embodiment of the present invention.

First, a photoresist solution is applied to an appropriate flat substrate 10a such as glass by spinner coating or the like to form a photoresist 10b to form a photoresist original plate 10. The photoresist 10b may be a positive type or a negative type. Next, as shown in FIG. 3, the laser light emitted from the laser light source 5 is reflected by the half mirror 6 to 2
Lens systems 8a and 8b, which are divided into light beams, which are reflected by mirrors 7a and 7b, and two convex lenses as one set are exemplified.
After the two light fluxes are made divergent by using, the two light fluxes are applied to the photoresist at an intersection angle of the angle θ. On this occasion,
The photoresist base plate 10 is fixed to the rotary base 11 by a vacuum chuck or the like, and the mask 12 having slit-shaped windows is fixed in close proximity to the photoresist base plate along the radial direction of the base plate. Rotate 11. Thus, when irradiation is performed while rotating the turntable, interference fringes of concentric light having a pitch of d determined by the relational expression d = λ / Sinθ are recorded in the photoresist layer, and predetermined development is performed. Irregularities are formed according to the intensity of light in the interference fringes.

In the above manufacturing method, the depth of the optical interference type guide groove is determined by the thickness of the resist layer, but it is also possible to further reduce the depth by controlling the development. Further, it is preferable that the mask has a narrow slit width, and if it is wide, the accuracy of the interference fringes recorded on the photoresist will be impaired. Therefore, it is preferably about 0.1 mm to 10 mm.

In the above embodiments, the photoresist original plate is rotated, but an efficient guide track can be produced by the following method of fixing the photoresist original plate and recording.

FIG. 5 is a diagram showing another embodiment of the present invention.

In this embodiment, the laser light emitted from the laser light source 5 is split into two light fluxes by the half mirror 6, one light flux is collimated by the lens system 8 through the mirrors 7a and 7b, and then the photoresist layer 10b and the photoresist layer 10b. The light beam is guided to the photoresist original plate 10 made of the substrate 10a, the other light flux is diverged by the convex mirror 9, and then is guided to the photoresist original plate 10, and the interference fringes of both are generated concentrically. By exposing and developing in this way, concentric guide tracks can be formed by one exposure. However, in this embodiment, since the crossing angle θ is the crossing angle of two light fluxes at an arbitrary point on the photoresist original plate, θ becomes smaller toward the center of the photoresist original plate. It tends to increase toward the center of the original plate.

〔The invention's effect〕

As described above, according to the present invention, one by one as in the conventional case,
That is, the efficiency is higher than the method of exposing the circles one by one, and the accuracy of the concentric circles is determined by d = λ / Sinθ as described above. If the laser light source for exposure is kept constant, then λ is constant. Does not vary as long as the exposure device is fixed, so exposure can be performed accurately without being affected by mechanical precision, and therefore a master plate for producing an optical interference type guide groove can be obtained quickly and accurately. is there.

[Brief description of drawings]

1 and 2 are schematic views and partial cross-sectional views of an optical disc having an optical interference type guide groove, and FIGS. 3 to 5 are views showing an embodiment of the present invention. 1 ... Optical interference type guide groove, 2 ... Optical disk, 3 ... Top of convex portion, 4 ... Top of concave portion, 5 ... Laser light source, 6 ...
Half mirror, 7, 7a, 7b ... Mirror, 8a, 8b
...... Lens system, 9 ... Convex mirror, 10 ... Photoresist original plate, 10a ... Substrate, 10b ... Photoresist, 1
1 ... Turntable, 12 ... Mask.

Claims (1)

[Claims] 1. A photoresist layer formed on a substrate is irradiated with laser light of two light fluxes, one of which is a parallel light flux and the other of which is a divergent light, from the same direction to record concentric interference fringes.
A method for producing an original plate for producing an optical interference type guide groove of an optical disk, which is characterized by developing.