JPS62217443A - Method and device for manufacturing disk blank - Google Patents

Abstract

PURPOSE:To shorten an exposure process by exposing the entire surface of the photoresist surface of a disk blank original plate by moving the partial area of the photoresist surface of the disk blank original plate while projecting and exposing the pattern of a guide groove on the partial area. CONSTITUTION:The disk blank original plate 6 is placed on a mount base 8 with the photoresist-coated surface 6a up and the original plate 8 is elevated to press the reverse surface of plane glass 5; and air is pressed in through an air hole 10 and the original plate 6 is put in the focus depth range of a projection lens 4. Then when partial exposure is performed continuously, the pattern of the guide groove pattern mask 3 is projected and exposed within the sectorial exposure range 14 of the original plate 6 and the mask 3 and original plate 6 are rotated at a constant speed simultaneously to complete the exposure of the surface 6a. Further, the exposure can be carried out by rotating the mask 6 and original plate 6 intermittently. This method shortens the exposure process for guide groove formation.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention relates to a disk-shaped storage medium, such as an optical disk or a magneto-optical disk, which has guide grooves (hereinafter simply referred to as guide grooves) formed by spiral or concentric irregularities on the substrate surface. The present invention relates to a method for forming a disk blank and an apparatus for forming the same.

Note that in the case of an optical disk, a disk blank refers to one in which a guide groove is formed but no signal has been written, that is, the focus has not been formed.In the case of a magneto-optical disk, a disk blank has a guide groove formed therein. refers to a state where the magneto-optical storage layer has not yet been formed.

In any case, it is a disk-shaped storage medium in which a guide groove is formed.

Hereinafter, it will simply be referred to as a disc blank.

There are various materials for this disc blank. For example, magneto-optical discs have a disc-shaped glass substrate with guide grooves provided directly on one side, and optical discs have disc-shaped aluminum or disc-shaped glass substrates with guide grooves on one side. There is one in which a plastic disk with guide grooves cut thereon is bonded to the surface opposite to the surface on which the kite grooves are cut with an adhesive.

(Background of the Invention) In order to increase the recording density of information in the radial direction, a spiral or concentric guide groove is formed on a disk-shaped storage medium, such as an optical disk or a magneto-optical disk, and tracking is performed using the guide groove. . FIG. 2 is a plan view of the disc blank, and FIG. 3 is a partial sectional view of the disc blank, taken along the line A--A in FIG.

In the following description, a disk blank will be described in which a guide groove is directly carved on one surface of a transparent disk-shaped glass.

In FIGS. 2 and 3, 6 is a disk blank made of transparent glass, and G is a guide groove. Conventionally, when manufacturing such a disk blank, in the case of a spiral guide groove, a photoresist 11 is spin-corded on one surface of a disk-shaped glass substrate (original disk blank plate) 60, as shown in FIG. After coating the photoresist 11 using a method such as the above, the photoresist 11 is rotated at a constant speed, and the surface of the photoresist 11 is irradiated with a light beam from a laser light source in the form of a spot, and the spot is exposed while moving at a constant speed in the radial direction. In addition, in the case of concentric guide grooves, a disc blank original plate 60 is used as shown in FIG.
After applying a photoresist 11 on one surface of the photoresist 11 using a spin cord or the like, the photoresist 11 is rotated at a constant speed, and the surface of the photoresist 11 is exposed by irradiating a light beam from a laser light source in a spot shape. After stopping the laser beam irradiation and moving the laser beam irradiation position in the radial direction by one pitch, the same laser beam irradiation is performed again, and this is repeated for the number of trunks to complete the exposure. The exposed material is developed in this way, and an original plate as shown in FIG. 5 is prepared. In FIG. 5, Ila is the photoresist remaining after the development. Thereafter, the removed portion 61 indicated by diagonal lines is removed by a known etching method such as dry etching, and the remaining photoresist lla is removed by a known etching process such as a notching process to form a spiral pattern as shown in FIG. Alternatively, a disk blank 6 having concentric guide grooves G is manufactured.

Conventionally, disk blanks were manufactured as described above, so for example, the width W of the guide groove G was 1 μm and the pitch P was 1 μm.
．． 6 μm, depth H 700, disk diameter 1301
The guide groove formation range is 42 mm, and the disc rotation speed is 1.
At 80 rpm, the exposure time is approximately 15 minutes for spiral guide grooves and approximately 30 minutes for concentric guide grooves.
This required an extremely long time of ~40 minutes.

(Objective of the Invention) An object of the present invention is to solve the above-mentioned drawbacks and to provide a method and apparatus for manufacturing a disc blank, which makes it possible to shorten the exposure process for forming guide grooves in the disc blank manufacturing process.

(Summary of the Invention) The present invention projects and exposes a pattern of a guide groove pattern mask, in which a guide groove pattern is formed by a transparent part and a non-transparent part, onto a partial area of a disc blank original plate coated with photoresist in advance. The technical point is to carry out the exposure process for forming the guide grooves by moving the area continuously or discontinuously and making one rotation.

(Example) FIG. 1 shows an example of the disk blank manufacturing apparatus of the present invention.

In FIG. 1, reference numeral 1 denotes an exposure light source, such as a mercury lamp. Reference numeral 2 denotes an exposure optical system, which is provided to obtain an exposure light beam having a uniform light intensity distribution. 3 is a guide groove pattern mask in which a guide groove pattern is formed in a transparent part and a non-transparent part. The formed one is used. Here, if the groove width W and the pitch P are W=1 μm and P=1.6 μm as described above, it is necessary to use the projection lens 4 with N larger than λ/NA2. In this case, the depth of focus is very short, about 1 μm, and the surface precision of the disc blank original plate is required to be extremely high. As such a projection lens, for example, a projection lens used in a projection exposure apparatus of a semiconductor manufacturing apparatus can be used. A parallel plane glass 5 is fixed so that its lower surface coincides with the focal plane of the projection lens 4. The flatness is within the depth of focus of the projection lens 4, that is, both the upper and lower surfaces are polished to about 0.1 μm, and the glass is thick and has good parallelism.

6 is 5iOzF on a transparent glass disk or opaque aluminum disk! This is a disk blank original plate on which a film has been deposited, and the surface to be exposed (the top surface in FIG. 1) is coated with photoresist to a uniform thickness (for example, 1.2 μm thick) using a method such as a spin cord. The photoresist is coated on the photoresist coating surface 6a. Normally, the disc blank original plate has a warp of about 2 minutes and a flatness of 20 to 30 μm.
The parallelism is about 10 μm. Therefore, if a projection lens used in a projection exposure apparatus of a semiconductor manufacturing device is used as the projection lens 4, the flatness will be low (,
This means that the depth of focus of the projection lens 4 deviates from 1 μm. 8
can be controlled to move up and down on the mounting table of the disc blank manufacturing device with guide grooves, and its upper surface is uneven, and has a ring-shaped projection (ring-shaped mounting part) 8a and a circular projection (circular mounting part). ) 8b is provided, and the ring-shaped mounting portion 8
The part sandwiched between a and the circular mounting part 8b is a ring-shaped recess 8.
Make C. O-rings 7a and 7b are provided on the upper surfaces of the mounting portions 8a and 8b, respectively. 9 is the annular concave portion 8C.
The central part of the circular mounting portion 8b is communicated with an air hole 10 provided vertically through a communication hole opened to the center of the circular mounting portion 8b. Reference numeral 12 denotes a machined hole, which is provided for drilling the communication hole 9, and after drilling the communication hole 9, a screw 13 is screwed together for airtightness.

Here, the batch exposure method has a problem in that the resolution in the peripheral area decreases due to the performance limit of the projection lens, and the edges of the guide grooves in the peripheral area cannot be formed sharply. Therefore, in the present invention, the disk blank original plate is partially subjected to equal-magnification or reduction projection exposure, and the position of the projection exposed portion on the disk blank original plate is relatively moved to expose the entire surface of the disk blank original plate 6.

At this time, the relative movement may be continuous or discontinuous.

Here, the relative movement between the projection exposure unit and the disc blank original plate can be achieved by rotating the disc blank original plate.

In that case, the shape of the partial projection exposure is preferably a fan-shaped partial projection exposure shape 14 as shown in FIG.

In order to expose the entire surface of the disc blank original plate 6 by continuously moving the partial exposure, the guide groove pattern mask 3 and the disc blank original plate 6 are configured to rotate continuously while keeping their positional relationship fixed. . This method is hereinafter referred to as continuous rotation exposure method.

On the other hand, in order to expose the entire surface of the disc blank original plate 6 by moving the partial exposure discontinuously, it is necessary to intermittently rotate both the guide groove pattern mask 3 and the disc blank original plate 6 while keeping their positional relationship fixed. Configure. This method is hereinafter referred to as an intermittent rotational exposure method.

The continuous rotation exposure method and the intermittent rotation exposure method will be explained in detail below.

[Continuous rotation exposure method]

(2) Place the disc blank original plate 6 on the mounting table 8 with the photoresist coated surface 6a facing upward.

(2) Raise the mounting table and press it with a constant pressure against the lower surface of the parallel plane glass 5, which has been positioned in advance, so that the lower surface coincides with the focal plane of the projection lens 4.

(2) Air is then forced in through the air hole 10 at a constant pressure.

At this time, the photoresist coated surface 6a, which is the upper surface of the disk blank original plate 6, follows the lower surface of the parallel plane glass 5 and has a flatness comparable to that of the lower surface.

As a result, the upper surface of the disc blank original plate 6 is within the depth of focus of the projection lens, and a sharp projected image can be obtained.

■ While projecting the pattern of the guide groove pattern mask 3 onto the fan-shaped exposure range 14 as shown in FIG. rotates (synchronous rotation)
One rotation completes the uniform exposure of the entire photoresist coated surface 6a of the disc blank original plate 6.

(2) The exposed disc blank original plate 6 is then subjected to a known etching process to form guide grooves and complete the disc blank.

According to the above method, it is possible to expose either a spiral guide groove pattern or a concentric guide groove pattern.

[Intermittent rotational exposure method]

(1) to (2) are exactly the same as (1) to (4) in the continuous rotation exposure method described above.

(2) Projecting and exposing the pattern of the guide groove pattern mask 3 onto a fan-shaped exposure range 14 as shown in FIG.

■When the exposure is completed, keep the positional relationship between the guide groove pattern mask 3 and the disc blank original plate 6 fixed, rotate them both by a predetermined angle and stop, and continue to cover the fan-shaped exposure area of the exposed area with the guide groove pattern mask. Projection exposure is performed on pattern 3.

For example, if the angle of the fan-shaped exposure range 14 is set to 7 to 8 degrees, the exposure of the entire photoresist-coated surface 6a of the disc blank original plate 6 is completed by repeating the above exposure and movement steps about 50 times. - times of exposure and movement time 0.
If it takes about 2 seconds, one rotation takes about 10 seconds.

(2) The exposed disc blank original plate 6 is then subjected to a known etching process to form guide grooves and complete the disc blank.

According to the above method, it is possible to expose either a spiral guide groove pattern or a concentric guide groove pattern.

Particularly in the case of a concentric guide groove pattern, the pattern mask 3 may not be the entire disc blank, but only a partial one, that is, a minimum pattern mask sufficient to cover the fan-shaped exposure range 14.

In this case, the pattern mask is moved relative to the disc blank original plate 6 while its positional relationship with the exposure light beam is fixed, and by repeating the exposure and movement described above, the pattern mask is applied to the entire surface of the photoresist coated surface 6a of the disc blank original plate 6. exposure is completed.

According to the intermittent rotational exposure method, the boundary between each exposure range is double exposed, which results in overexposure of the area, and the shape of the formed guide groove is distorted. However, if this part is used by formatting the track by dividing it into sectors, there will be no problem if it is made to correspond to the gaps.

This will be explained in more detail below.

FIG. 6 shows a disk blank manufactured by the intermittent rotational exposure method, and 14a is the overlapping area of each exposure, and the guide groove shape is distorted in this double exposure area.

In the optical disc currently in use, one revolution is divided into about 50 sectors, and each sector is divided as shown in FIG.

In FIG. 7, 20 is a sector synchronization signal recording area;
12 is a data recording area, 13 is a gear area, 21.2
3 is a synchronization signal recording area, and 22 is an address recording area.

The gap 13 is provided to avoid duplicate recording of data due to rotation error of the optical disk driver, and there is no problem even if the guide groove shape is distorted in the gap region 13.

Therefore, if the format is set so that the circumferential length of the exposed overlapping portion 14a is within the circumferential length of the gap region 13, there will be no trouble due to overlapping exposure.

FIG. 8 is a diagram showing the main parts of another embodiment of the disk blank manufacturing method and apparatus. In FIG. 8, a case will be explained in which the disc blank original plate 6 is made of a transparent material.

In FIG. 8, the same symbols as in FIG. 1 represent members with the same effect.

This embodiment differs from the embodiment shown in FIG. 1 in the stand on which the disc blank original plate is placed, and the rest of the structure is the same.

In this embodiment, reference numeral 17 is a mounting table made of an opaque material such as metal and having a flat upper surface, and a groove 16 is provided in the flat upper surface. The groove 16 communicates with the air hole 10.

Next, the steps according to this example will be explained in detail.

(2) Place the disc blank original plate 6 on the mounting table 17 with the photoresist coated surface 6a facing down.

■Pull air from air hole 10 with a vacuum pump. At this time, the lower surface of the disk blank original plate 6, that is, the photoresist coated surface 6
a is sucked by the groove 16 of the mounting table 17 and
It follows the upper surface and has a flatness comparable to that of the upper surface of the mounting table 17.

As a result, the upper surface of the disc blank original plate 6 is within the depth of focus of the projection lens, and a sharp projected image can be obtained.

(2) The following steps may be applied either by the steps following (2) in the description of the steps using the continuous rotational exposure method, or by the steps after (2) in the description of the steps using the intermittent rotational exposure method.

In this embodiment, it has been explained that it can be applied to the case where the disc blank original plate 6 is transparent, but when the parallelism of the upper and lower surfaces of the disc blank original plate 6 is ensured (for example, 1
(accuracy of less than μm) is the photoresist coated surface 6a.
It is also possible to expose the photoresist coated surface 6a by placing the photoresist on the mounting table 17 so that the photoresist is on the top surface.

(Effects of the Invention) As described above, according to the method and apparatus of the present invention, the disc blank original plate is pressed or suctioned against a flat surface serving as a reference by static pressure, and the photoresist coated surface of the disc blank original plate follows the flat surface. In addition, a mask pattern is exposed on a partial area of the photoresist-coated surface of the disc blank original plate, and the partially exposed area on the disc blank original plate is relatively moved. As a result, the entire surface of the disc blank is exposed to light, so that the exposure process for forming guide grooves in the disc blank manufacturing process can be dramatically shortened.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a disk blank manufacturing apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of the disk blank, FIG. 3 is a partial sectional view of the disk blank, and FIG.
5 is a partial sectional view showing the disc blank manufacturing process, FIG. 6 is a plan view of the disc blank manufactured by the intermittent exposure method, and FIG. 7 is a diagram showing the state of division within one sector. FIG. 2 is a cross-sectional view showing the main parts of the configuration of the disk blank manufacturing apparatus according to the embodiment. (Explanation of symbols of main parts) 1--------- 1. Exposure light source 2. 1. Illumination optical system 3.
--- Guide groove pattern mask 4 --- One projection lens 5 --- One parallel plane glass 6 - --- Disc blank original plate 6 a ---
---Photoresist coated surfaces 7a, 7b -------
---O-ring 8a-----One-ring zone-shaped placement part 8b-----Circular placement part 8 c-----One ring zone-shaped recess Applicant: Nippon Kogaku Kogyo Co., Ltd. Agent Patent attorney Watari Takashi BebeFigure 2Figure 8Figure 4Figure 5Figure 6

Claims (6)

[Claims] (1) The pattern of the guide groove pattern mask, in which the guide groove pattern is formed by a transparent part and a non-transparent part, is projected onto a part of the photosensitive agent-coated surface of a disc blank original plate that has been coated with a photosensitive agent in advance. . A method for manufacturing a disk blank, comprising projecting the guide groove pattern on the entire surface of the disk by projecting exposure and relative movement of the disk, and then photo-etching. (2) A projection optical system that projects and exposes a pattern of a guide groove pattern mask in which a guide groove pattern is formed by a transparent part and a non-transparent part onto a part of the disc blank original plate, and a projection surface provided by the projection optical system. a disc blank original plate holding member including a pneumatic means for causing the disc blank original plate to conform to the reference plane member using air pressure; 1. A disk blank manufacturing apparatus comprising: a moving means that allows relative movement on a disk blank original plate held by a disk blank original plate. (3) The disk blank manufacturing method according to claim 1, wherein the movement is continuous movement. (4) The disk blank manufacturing method according to claim 1, wherein the movement is an intermittent movement. (5) The disk blank manufacturing apparatus according to claim 2, wherein the movement is continuous movement. (6) The disk blank manufacturing apparatus according to claim 2, wherein the movement is an intermittent movement.