JPH10143927A - Master disk exposing device for optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an optical recording medium with less pitch unevenness in recording information, with high recording density and a high transfer rate capable of narrowing an interval between pitches. SOLUTION: In a master disk exposing device 1 for the optical recording medium, a beam position detecting means 10 detecting positions of exposing laser beams La and Lb and a beam position correcting means 20 setting the positions of the exposing laser beams La, Lb. Thus, the positional deviation of the exposing laser beams are corrected, and the interval between beams is head constant when plural exposing laser beams are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master disc exposure apparatus for an optical recording medium.

[0002]

2. Description of the Related Art Conventional optical recording media such as a compact disk (CD) and a laser disk (LD) for recording various kinds of information for audio and video use.
Fine irregularities such as phase pits and pre-grooves for recording data information and tracking servo signals are formed on the information recording layer.

The production of the optical recording medium having the fine irregularities is performed by injection molding or photopolymerization, a so-called 2P method. In the injection molding or the 2P method, a stamper having fine irregularities for transferring and forming fine irregularities to be finally formed is used. In manufacturing the stamper, first, a master is manufactured. This master is coated with photoresist on a substrate that constitutes it, for example, a polished smooth glass plate,
This is subjected to pattern exposure to form fine irregularities, and the surface thereof is subjected to, for example, Ag plating. The master thus prepared is subjected to metal plating, and a stamper is formed by repeating this process.

As schematically shown in FIG. 6, a master exposure apparatus 70 for performing pattern exposure on a photoresist at the time of manufacturing the master includes an exposure laser beam generation source 50 for generating an exposure laser beam L, an exposure pattern For example, a modulator 51 that modulates according to recording information, and an exposure laser beam L that is intensity-modulated thereby, for example,
Is focused through an objective lens 52 onto a surface of a photoresist 54 on a substrate 53 for producing a master.

In a conventional general optical recording medium, a track pitch is in a range of 1.4 to 1.7 μm, and a tolerance thereof is allowed in a relatively wide range of about ± 0.1 μm.

In the conventional master exposure apparatus 70 for producing such an optical recording medium, the displacement of the exposure laser beam L is caused by the fluctuation of air with respect to the recording optical system of the master exposure apparatus 70, laser cooling water, table,
Although caused by the influence of vibration caused by slide feed, cooling fan, etc., the recording density format of a conventional optical recording medium such as a CD did not cause much problem due to the large tolerance of pitch unevenness.

However, in recent years, the recording density of optical recording media has been increasing, and optical recording media having a two-layer structure, for example, DV
When the recording density of a D (Digital Video Disk) or the like is increased to about four times that of a conventional CD, the track pitch of the fine unevenness forming the information recording layer is 0.7 to 0. Severe demands are made to be about 8 μm and the tolerance is ± 0.03 μm, which is 1/3 or less of the conventional one, and in this case, displacement of the exposure laser beam becomes a serious problem.

The scanning of the photoresist laser beam L on the photoresist surface in the preparation of the master is performed, for example, by rotating the substrate 53 and moving the laser beam in the radial direction of the substrate 53 so that the exposure laser beam L is scanned on the photoresist 54 surface. In this case, scanning is performed in a spiral manner. In this case, the rotation speed of the substrate 53 is increased in order to increase the transfer rate of exposure, that is, information recording.

However, as described above, as the rotational speed of the substrate 53 is increased, vibration is more likely to occur, and the above-described displacement of the exposure laser beam L is more likely to occur, particularly as described above. Therefore, it becomes more difficult to cope with a decrease in tolerance of pitch unevenness accompanying an increase in recording density.

As a method of increasing the transfer rate without increasing the rotation speed of the substrate 53, a method of simultaneously scanning a plurality of, for example, two exposure laser beams in parallel on a photoresist surface on the substrate by using a double spiral is described. A method for performing exposure is known.

These two exposure laser beams, for example, perform exposure for forming tracking grooves or fine irregularities for address signals on the one hand, and record data information on lands, for example, on the other hand. Exposure is performed according to the format.

However, in either case,
The positions of a plurality of, for example, two exposure laser beams, need to be accurately set, and in the above-described high-density recording, the accuracy needs to be further improved.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to accurately set the position of an exposure laser beam in a master exposure apparatus used for manufacturing the master described above.

Another object of the present invention is to make it possible to accurately set the mutual positions of a plurality of exposure laser beams in a similar master exposure apparatus.

[0015]

According to the present invention, there is provided an apparatus for exposing a master for an optical recording medium, comprising: an exposure laser beam generating source for generating an exposure laser beam for exposing a photoresist surface coated on a substrate forming the master; Position detecting means for detecting the position of the exposure laser beam on the photoresist surface, and position correcting means for changing and controlling the position of the exposure laser beam on the photoresist based on a detection signal detected by the position detecting means. To correct the displacement of the exposure laser beam.

According to the present invention, the position of the exposure laser beam can be set accurately. Also, the present invention
In a similar master exposure apparatus, the mutual positions of a plurality of exposure laser beams can be accurately set. As a result, the interval between the pitches of the recording information can be reduced, a high recording density can be achieved, and a master disc exposure apparatus for an optical recording medium having a high transfer rate can be realized.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described. In the following, a description will be given of a case where the present invention is applied to pattern exposure of a photoresist of a glass master disk manufactured by transferring a stamper used by an injection molding method or a 2P method when manufacturing a disk-shaped, so-called disk-shaped optical disk. However, the master disc exposure apparatus in the present invention is not limited to such a shape, and various optical recording media having fine irregularities in the information recording layer, such as a magneto-optical disc, a phase-change disc, and other card-like and sheet-like shapes. The method can be applied when exposing a master used in the production of a substrate.

An embodiment of the present invention will be described. FIG. 1 shows a schematic view of a master exposure apparatus 1 according to the present invention. In the master exposure apparatus of the present invention, an exposure laser beam generation source 35 that emits an exposure laser beam that exposes a photoresist 101 surface coated on a glass substrate 100, for example, forming a master disk; Beam position detecting means 10 for detecting the position of an exposure laser beam
And the detection signal detected by the beam position detecting means 10, the photoresist 10 of the exposure laser beam is used.
A beam position correcting means 20 for changing and controlling the position on one surface is provided.

In this example, the exposure laser beam generating source 35 includes, for example, one laser 30 for generating an exposure laser beam, a half mirror 31a, and a mirror 31.
b, the exposure laser beam from the laser 30 is partially reflected and separated by the half mirror 31a, and the remaining exposure laser beam is reflected by the mirror 31b to obtain two exposure laser beams La and Lb. This is the case.

These exposure laser beams La and Lb
Are focused on the photoresist surface 101 on the glass substrate 100 through, for example, the light modulators 60a and 60b, the polarization beam splitters 33a and 33b, the stop lens 40, the mirror 32, and the objective lens 41, respectively. Exposure is performed.

At this time, the polarization beam splitter 33a
By selecting the mutual inclination of the apertures 33b and 33b, by changing the angle of incidence on the aperture lens 40, the mutual spots on the photoresist 101 are maintained at a required interval.

On the other hand, each of the exposure laser beams La and L
The return light of b is the polarization beam splitters 33a and 33
3b, and is sent to the beam position detecting means 10, whereby each exposure laser beam La
And Lb on the surface of the photoresist 101 are detected.

As the beam position detecting means 10, for example, a position sensor or a CCD (charge coupled device) camera is used. That is, for example, FIG.
As shown by a curve 61 in A, the return positions of the exposure laser beams La and Lb are detected, for example, as light intensity distributions on a CCD camera, that is, as beam spots Spa and Spb shown in FIG. . That is, the positions of the exposure laser beams La and Lb on the photoresist 101 are detected.

This position is detected by the beam position detecting means 10.
Thus, a voltage change of the voltage value is detected, a peak-to-peak distance of the voltage value is measured, and a signal deviating from a predetermined value is extracted as an error signal.

For example, 50 μm is generated by the vibration of the exposure apparatus.
When there is an angular displacement of rad, the exposure laser beam L on the surface of the photoresist 101 on the substrate 100
The displacement of the spots a and Lb is
Is 100 mm and the magnification of the objective lens 41 is 100 times, (50 μ × 100 mm) / 100 =
It becomes 0.05 μm. At this time, the exposure laser beam L passing through the polarization beam splitters 33a and 33b
Assuming that the optical path lengths of a and Lb are 1 m, for example, the displacement on the beam position detecting means 10 is 50 μm. This can be sufficiently detected by a CCD camera or a position sensor.

When a CCD camera is used as the beam position detecting means 10, the voltage values of the upper and lower scanning lines of the scanning lines running at the center of the exposure laser beams La and Lb on the sensor of the CCD camera are peak-held. By monitoring the difference, the mutual positions of the exposure laser beams La and Lb can be detected.

When a position sensor is used as the beam position detecting means 10, the error signal of the sensor is set to be zero with respect to the initial set values of the positions of the exposure laser beams La and Lb. Then, the beam position is corrected by the beam position correcting means 20, and feedback is performed so that the output voltage becomes zero.

That is, when an error is detected by the beam position detecting means 10 as described above, the interval between the exposure laser beams La and Lb is set in advance according to the error as shown in FIG. The beam position is fed back to the beam position correcting means 20, where the correction is applied. Thus, the exposure laser beams La and L
The traveling direction and angle of b are set, and the positions of the exposure laser beams La and Lb are controlled.

The beam position correcting means 20 includes, for example,
As shown in FIGS. 2 and 3, the prism 20a and the reflection mirror 20d are used to change the direction of the optical path axis of one of the exposure laser beams, or as shown in FIG. 4, an acousto-optic device (AOD ( Acousto-Optic Deflecte
r)) 20c, and similarly, for example, it can be configured to change and control the direction of one optical path axis of the exposure laser beam.

In FIG. 1, reference numeral 11 denotes a driver for driving and controlling the above-mentioned beam position correcting means 20. The driver 11 receives a signal from an error detecting circuit 12 which obtains an error signal from the above-mentioned detection signal from the beam position detecting means 10. Is supplied, and the beam position correcting means 20 changes the optical path of each of the exposure laser beams La and Lb or one of them, whereby the respective exposure laser beams La and L on the surface of the photoresist 101 are changed. The mutual positions of b are set to a predetermined positional relationship such that the error signal becomes zero.

In this manner, with the mutual positional relationship between the two exposure laser beams La and Lb on the surface of the photoresist 101 set, for example, the substrate 100 is
The position of the exposure spot of the exposure laser beams La and Lb is rotated in the direction along the radial direction, for example, of the substrate 100 by being rotated about the central axis and moving the master exposure apparatus with respect to the substrate 100, for example. By moving the exposure laser beams La and Lb relatively, the scanning trajectory of the exposure laser beams La and Lb on the surface of the photoresist 101 on the substrate becomes a double spiral trajectory. And for L b
When the light modulators 60a and 60b perform intensity modulation in accordance with a recording signal or the like, required pattern exposure is performed, for example, data information for forming a tracking groove and an address pit formed on an optical disk to be finally obtained. Can be performed.

Then, by developing the photoresist 101 which has been subjected to the pattern exposure in this manner, desired fine irregularities for transfer are formed. Therefore, a master is produced by applying, for example, metal plating on this.

As described above, according to the master exposure apparatus of the present invention, the positions of the exposure laser beams La and Lb can be set accurately. In the master exposure apparatus of the present invention described above, the exposure is performed using two exposure laser beams. However, the master exposure apparatus can use three or more exposure laser beams or one exposure laser beam. Thus, in the master exposure apparatus of the present invention,
Since the position of the exposure laser beam can be set accurately, it is possible to narrow the interval between pattern exposure pitches of the master disk, which ultimately becomes recording information, and achieve high recording density and high transfer with good characteristics. It is possible to realize a master disc exposure apparatus for an optical recording medium having a high rate.

[0034]

According to the optical recording medium master exposure apparatus of the present invention, the position of the exposure laser beam can be accurately set. Further, the mutual positions of the plurality of exposure laser beams could be set accurately. This makes it possible to narrow the interval between pattern exposure pitches of the master which ultimately becomes recording information, thereby realizing a master exposure apparatus for an optical recording medium having a high recording density and excellent characteristics and a high transfer rate. Was completed.

[Brief description of the drawings]

FIG. 1 shows a schematic view of a master disc exposure apparatus for an optical recording medium according to the present invention.

FIG. 2 is a schematic diagram of a beam position correcting unit using a prism.

FIG. 3 is a schematic diagram of a beam position correcting unit when a reflection mirror is used.

FIG. 4 is a schematic diagram of a beam position correcting unit when an acousto-optic device (AOD) is used.

FIG. 5A shows the intensity distribution of the exposure laser beam. B
3 shows a spot of an exposure laser beam.

FIG. 6 is a schematic view of a conventional optical recording medium master exposure apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Master exposure apparatus, 10 Beam position detection means, 11
Driver, 12 error detection circuit, 20 beam position correcting means, 20a prism, 20c acousto-optic element (AOD (Acousto-Optic Deflecter)), 20d reflection mirror, 30 laser, 35 exposure laser beam source, 31a half mirror, 31b, 32 mirrors,
33a, 33b polarizing beam splitter, 40 aperture lens, 41 objective lens, 50 exposure laser beam source, 51 modulator, 52 objective lens, 53 substrate, 54, 101 photoresist, 60a, 60b
Light modulator, 61 Beam intensity distribution curve, 70 Master exposure apparatus, 100 Glass substrate, L, La, Lb exposure laser beam, Spa, Spb beam spot

Claims (4)

[Claims] An exposure laser beam source for generating an exposure laser beam for exposing a photoresist surface applied on a substrate forming a master; and detecting a position of the exposure laser beam on the photoresist surface. Position detecting means, and a detection signal detected by the position detecting means,
A position correcting means for changing and controlling the position of the exposure laser beam on the photoresist; and correcting the positional deviation of the exposure laser beam, wherein the apparatus is a master disc exposure apparatus for an optical recording medium. 2. The exposure laser beam generation source is an exposure laser beam generation source that generates a plurality of exposure laser beams, and the position detection unit is a position detection unit that detects positions of the plurality of exposure laser beams. The position correction means of the exposure laser beam is a position correction means for changing and controlling the position of at least one exposure laser beam according to a detection signal detected by the position detection means. 2. A master disc exposure apparatus for an optical recording medium according to claim 1. 3. An apparatus according to claim 1, wherein said exposure laser beam position correcting means changes an angle of the exposure laser beam. 4. The apparatus according to claim 2, wherein said exposure laser beam position correcting means changes an angle of at least one exposure laser beam.