JP2002083449A - Method for processing optical master disk, method for manufacturing optical master disk, optical master disk, method for manufacturing optical disk substrate, optical disk substrate, and equipment for processing optical master disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for processing an optical master disk by which a groove, a pre pit group on a groove track, and a pre pit group on a land track can be processed by a laser beam in high quality and in a balanced manner. SOLUTION: A light deflector is mounted on the optical path of a laser optical system by which the pre pit group is processed, and is adjusted so that a laser beam for processing the pre pit group is made incident on almost the center between the groove track and the land track. Laser beams are deflected at the same quantity of deflection and in the opposite direction by the light deflector, and then both the pre pit groups are processed. The difference of the diffraction efficiency due to the difference in the deflection direction is corrected by independent control of laser power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for processing an optical disk master. In particular, the present invention relates to a method for processing an optical disk master, a processing apparatus enabling the manufacturing method of the present invention, an optical disk master manufactured by the method, and an optical disk substrate formed from the master.

[0002]

2. Description of the Related Art As a recording system for increasing the recording density of an optical disk, a land and groove system has been proposed. This recording method records information on both a spiral or concentric groove track formed along a groove and a spiral or concentric land track formed along a land adjacent to the groove. It is.
Then, a group of prepits for storing preformat information such as address information and a synchronization pattern for controlling the rotation of the disk is formed in each header portion of the groove and the land. In order to make the signal levels of the groove track and the land track equal, the groove width of the groove is almost equal to the width of the land adjacent to the groove. On the other hand, the pre-pit group is formed with a width smaller than the groove width of the groove.

In order to process such a physical format, a laser beam for processing a groove, a laser beam for processing a group of prepits on the same spiral or on the same circumference as a groove track, and a laser beam on a same spiral or as a land track. It is known that a photosensitive material on a glass master is exposed by using a total of three laser beams for processing prepit groups on the same circumference.

[0004]

However, according to the prior art, there is a problem that the optical system of the mastering device becomes huge and complicated. Further, it becomes difficult to prevent interference of the laser beam. Further, since the laser beams for processing the prepit groups on the groove track and the prepit groups on the land track are different from each other, the quality tends to be different. Further, if the quality of the pre-pit group is to be adjusted, it becomes difficult to optimize the groove quality.

On the other hand, it is conceivable to process grooves and prepit groups with one laser using an optical deflector. However, since the groove and the prepit group need to be formed in different widths, it is difficult to optimize their quality. In addition, while the deflection amount of the laser beam when processing the prepit group on the groove track is almost 0 as in the case of the laser beam when processing the groove, the laser beam when processing the prepit group on the land track is used. The deflection amount of the beam substantially corresponds to the track pitch. Due to the difference in the diffraction efficiency of the deflector due to this deflection and the occurrence of optical aberration, there arises a problem that the balance between the prepit characteristics of the two becomes poor.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to perform prepit group processing on an optical disk master having the above-mentioned physical format with one laser beam. Further, it is possible to perform laser processing on the prepit groups on the groove track and the land track with high quality and good balance. Also, groove processing is performed with another laser beam. Thereby, laser beam formation suitable for each characteristic can be performed.

Further, according to the present invention, in a mastering apparatus, an optical deflector is mounted on an optical path of a laser optical system for processing a group of prepits. The incident position when the laser beam is not deflected is set to a position that differs from the incident position of the groove processing laser beam in the radial direction (radial direction) by approximately half the track pitch. That is, the adjustment is performed so that the laser beam for processing the prepit group falls almost at the center of the groove track and the land track.

Further, the laser beam for processing the pre-pit group is made to have substantially the same deflection amount by the optical deflector at the time of processing on the groove track side and at the time of processing on the land track side.
Further, a subtle difference in diffraction efficiency due to a difference in deflection direction is corrected and optimized by independent control of laser power. Also,
Processing is performed by controlling the optimum laser power in accordance with the length of each pit on the groove track and the land track.

In the method for processing an optical disk master according to the present invention, a groove constituting a groove track, a group of prepits on the same spiral or on the same circumference as the groove track, and a land track adjacent to the groove track on the same spiral. Or a pre-pit group on the same circumference and a method for processing an optical disc master for forming a pre-pit group on the same spiral or on the same circumference as the groove track. Irradiating the laser beam onto the master, and irradiating the laser beam onto the master to form a pre-pit group on the same spiral or the same circumference as the land track, comprising: Each irradiation step is performed in accordance with a change in the circumferential relative position between the prepit group processing laser beam and the master. It is performed alternately by sequentially switching the radial irradiation position over arm, a method of processing a master optical disk.

In the above-mentioned method for processing an optical disc master,
In order to form the groove in parallel with each of the irradiation steps, it is preferable to irradiate the pre-pit group processing laser beam and another groove processing laser beam onto the master.

In the above method for processing an optical disc master,
In each of the irradiation steps, the switching of the radial irradiation position of the pre-pit group processing laser beam is performed by optical deflection, and the irradiation position when the pre-pit group processing laser beam is not subjected to the optical deflection is defined by the groove. It is preferable that the deflection is set at substantially the center between the track and the land track adjacent thereto, and the deflection toward the groove track and the deflection toward the land track are in the opposite directions and substantially the same amount of deflection.

In the above method for processing an optical disk master,
In each of the irradiation steps, it is preferable that the laser powers before the deflection are different from each other based on the magnitude of the diffraction efficiency in the deflection toward the groove track and the deflection toward the land track.

According to the method of manufacturing an optical disk master of the present invention, a step of irradiating a laser beam onto the master using the above-described method of processing an optical disk master, and a step of developing the master to form the groove and the prepit group And.

The method of manufacturing an optical disk substrate according to the present invention comprises the steps of manufacturing an optical disk master using the above-described method of manufacturing an optical disk master, electroforming the optical disk master, manufacturing a stamper, and using the stamper. Injection molding.

An optical disk master according to the present invention is characterized by being manufactured by using the above-described method for manufacturing an optical disk master.

An optical disk substrate according to the present invention is manufactured by using the above-described method for manufacturing an optical disk substrate.

According to the apparatus for processing an optical disk master of the present invention, a groove constituting a groove track, a group of prepits on the same spiral or on the same circumference as the groove track, and a land track adjacent to the groove track on the same spiral. Or an apparatus for processing an optical disc master for forming a group of prepits on the same circumference, a means for generating a laser beam for processing a group of prepits, a master coated with a photosensitive material, and Means for moving a circumferential relative position with respect to a laser beam; and forming the latent image of the prepit group on the groove track and the land track, respectively. Means for sequentially switching the radial irradiation position of the application laser beam.

In the above-mentioned optical disk master processing apparatus,
Control means for controlling the laser power of the pre-pit group processing laser beam is further provided, and means for switching a radial irradiation position of the pre-pit group processing laser beam is provided on a path of the pre-pit group processing laser beam. It is preferable that an optical deflector is provided, and the control means controls the laser power based on the magnitude of the diffraction efficiency of the optical deflector before and after switching of the radial irradiation position of the pre-pit group processing laser beam.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus and a method for processing an optical disc master according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic structural view of an exposure apparatus used in a method for processing an optical disk master according to an embodiment of the present invention, and particularly shows an optical path of a laser beam. The exposure apparatus includes a laser device 101 that generates a laser beam,
Optical modulator 10 for controlling laser power according to control signal
7 and 108, an optical deflector 111 for switching the irradiation position of the prepit group processing laser beam, and a turntable 118 for rotating the glass substrate.

A laser beam 102 emitted from a laser device 101 is divided by a beam splitter 103 into a laser beam 105 for groove processing and a laser beam 106 for prepit group processing. These laser beams are
Optical modulation is performed in the optical modulators 107 and 108 according to the control signal output from the signal generator 119. The laser beam 106 for processing the prepit group is optically modulated by the optical modulator 108, and thereafter, is demultiplexed by the optical deflector 111.
The light is deflected according to the signal output from 19.

The laser beam 106 deflected by the optical deflector 111 is reflected by a mirror 112 and then combined with the laser beam 105 by a beam splitter 113. The two combined laser beams 105 and 106 are reflected by the mirror 114. Then, the light is condensed by the objective lens 115 onto the glass master 117 on which the photosensitive material is uniformly applied,
Beam spots 201 and 202 are formed on the surface of the glass master.

A movable optical table 116 on which an optical deflector 111, an objective lens 115, a beam splitter 113, a mirror 112, and a mirror 114 are mounted is arranged in a radial direction of a glass master 117 with respect to a turntable 118 rotating at a constant angular velocity. Move at a constant speed. The rotation and movement are performed by moving the movable optical bench 116 from the inner circumference to the outer circumference by a groove pitch in the radial direction of the glass master 117 while the glass master 117 makes one rotation.

FIG. 2 is a diagram showing a scanning path of a laser beam in the method for manufacturing an optical disk master according to the above embodiment. The grooves 203 are formed at predetermined intervals in a circumferential direction (horizontal direction in the drawing), and thus a groove track is formed. Adjacent to the groove track, the land track is provided with lands 204 also formed in the circumferential direction. The groove track and the land track may be concentric, but here, the groove track and the land track are formed spirally. Thus, groove tracks and land tracks are alternately formed in the radial direction (vertical direction in the figure).

A pre-pit group 206 for recording address information of each sector and the like is formed between each groove on the same spiral as the groove track. Groove 203 of the adjacent groove track on the same spiral as the land track
A pre-pit group 205 for recording address information and the like of each sector of the land track is formed at a position not overlapping with the radial direction. Especially pre-pit group 2 on groove track
06 and the pre-pit group 205 on the land track adjacent thereto are also formed at positions that do not overlap with each other in the radial direction.

Laser beam 1 for processing groove 203
05 falls on the position indicated by the laser beam spot 201. With the rotation of the glass master 117, the groove 2
03 is performed.

The laser beam 106 for processing the prepit groups 205 and 206 falls on the position indicated by the laser beam spot 202 when the optical deflector 111 is in a neutral state, that is, when the light deflection amount is zero. As described above, when the light deflection amount is 0, the laser beam spot 202 is
In the synthesis of No. 6, the laser beam spot 201 is radially different from the laser beam spot 201 by a distance of about half the track pitch, and the incident position in the circumferential direction is the same. The track pitch mentioned here is a pitch between a groove track and a land track.

When the groove 203 is processed by the laser beam 201, the laser beam 202 is turned off by the optical modulator 108. When the groove processing of the sector is completed, the laser beam 202 is then directed to the optical deflector 111 in the opposite direction to the previously processed groove 203 by approximately 1/2 track pitch in accordance with the output signal of the signal generator.
To shift. That is, the laser beam 202 is deflected to the center position of the adjacent land track 204. After the deflection is completed, the laser beam 202 is transmitted to the signal generator 11 by the optical modulator 108 on the optical path according to the address information of the prepit group 205 on the land track.
9 is optically modulated by the signal output from. At this time, the laser power is controlled so as to balance the characteristics of the pre-pit group 206 on the groove track described later.

Next, the light is deflected by the optical deflector 111 in the same direction as the groove 203 that has been processed immediately before, substantially by the track pitch. That is, the adjacent groove track 203
The laser beam 202 is deflected to the center position of. When this is completed, the laser beam 202 is optically modulated by a signal output from the signal generator 119 in accordance with the address information of the pre-pit group 206 on the groove track. At that time, the pre-pit group 2 on the aforementioned land track
As in the case of the processing in step 05, the laser power is controlled so as to obtain appropriate characteristics.

During the processing of the prepit group, the laser beam 201 for groove processing is turned off by the optical modulator 107 on the optical path. After processing the prepit group, the prepit group processing laser beam 202 is turned off.
Then, the next groove is processed by the groove processing laser beam 201. By the end of the groove processing, the optical deflector on the optical path of the laser beam 202 is returned to the neutral state, and the distance between the laser beams 201 and 202 is reset to a half track.

With the above operation, each time a groove is formed for one sector, a pre-pit group for one sector on a groove track and a pre-pit group for one sector on a land track can be formed. By repeating this, every time the glass substrate 117 makes one rotation,
A groove track for one round and a land track for one round adjacent to the groove track can be formed.

FIG. 3 is a time chart of a control signal output from the signal generator 119 to realize the laser scanning shown in FIG.

The signal 301 is a signal for modulating the laser beam 201 (105) in order to process the groove 203. A rectangular signal is applied to form the groove in accordance with the processing timing of the groove 203 appearing at the left and right ends of FIG. A group of pre-pits 205 appearing in the center of FIG. 2,
At the time of processing 206, no signal is applied, so that no groove is formed.

The signal 302 includes pre-pit groups 205 and 2
The signal is a signal for modulating the laser beam 202 (106) for processing No. 06. Here, the pulse width is controlled according to each pit length. In addition, analog modulation is performed so as to correct a difference in diffraction efficiency due to a difference in deflection direction in light deflection. The laser power is controlled by these controls. In processing the groove, no signal is applied.

The signal 303 comprises pre-pit groups 205 and 2
A signal for controlling the optical deflection of the laser beam 106 to settle the radial position of the laser beam 106. Pre-pit group 2
At the time of processing of 05 and the processing of the pre-pit group 206, light deflection is performed in opposite directions by applying rectangular signals of opposite positive and negative potentials. At the time of processing the groove, no signal is applied.

FIG. 4 shows the modulation signal level (relative value) for controlling the laser power of the prepit group processing laser beam output from the optical modulator 108, and the measurement of asymmetry when the prepit group is processed by the laser beam. It is a graph which shows the relationship with a result. According to this graph,
For example, when the asymmetry is 0.1, the signal level is about 0.8 when processing the pre-pit group on the groove track, and the signal level is about 0.8 when processing the pre-pit group on the land track. Must be 94.
By independently controlling the signal level when processing the pre-pit groups on the groove track and when processing the pre-pit groups on the land track, asymmetry can be made uniform.

FIG. 5 shows a comparison of the asymmetry of the pre-pit group when the laser power is not independently controlled and when the laser power is independently controlled. When independent control was not performed, that is, when the same level of modulation signal was applied when processing the prepit group on the groove track and when processing the prepit group on the land track, the The asymmetry averaged 0.06, and the asymmetry of the pre-pit group on the land track averaged 0.12. On the other hand, when lasers having different powers are made incident on the deflector by the independent control, the asymmetry of the prepit groups on the groove track and the land track is 0.11 on average, and the quality of the prepit groups can be made uniform. It has become possible.

As described above, by exposing the glass master 117 coated with the photosensitive material, latent images of the groove 203 and the prepit groups 205 and 206 are formed. Thereafter, by developing the glass master 117, an optical disk master having a concave portion forming a groove and a group of pre-pits is formed on the glass master.

Next, in order to form a stamper based on this, a Ni film serving as a conductive film is formed on the optical disk master by sputtering or the like. Then, this optical disc master is Ni electroformed, and Ni is laminated to form a Ni plate. Then, the Ni plate is peeled from the master optical disk, the photoresist layer is removed, and the back surface of the Ni plate is polished, so that a stamper having a pattern with the concavities and convexities reverse to those of the master optical disk can be manufactured.

Using this stamper as a mold, optical disk substrates are mass-produced by injection molding.

The contents described above relate to the embodiment of the present invention and do not mean that the present invention is limited to this.

[0042]

As described above, according to the present invention, the above physical format can be easily formed by two laser beams by deflecting the laser beam by the optical deflector. As a result, a high-quality master optical disc can be manufactured. Furthermore, by systematizing the method of the present invention and mounting it on a mastering device, it is possible to provide a mastering device that is highly efficient and excellent in mass productivity without complicating or enlarging the optical system.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an exposure apparatus used in a method for processing an optical disc master according to an embodiment of the present invention.

FIG. 2 is a diagram showing a scanning path of a laser beam in the method for processing an optical disc master according to the embodiment.

FIG. 3 is a time chart of a control signal output from a signal generator to realize the laser scanning shown in FIG. 2;

FIG. 4 is a graph showing a relationship between a modulation signal level for controlling a laser power of a pre-pit processing laser beam output from an optical modulator and an asymmetry measurement result when a pre-pit group is processed by the laser beam. .

FIG. 5 is a comparison of asymmetry of a prepit group when laser power is not independently controlled and when laser power is independently controlled.

[Explanation of symbols]

 Reference Signs List 101 laser device 102 laser beam 103, 104 beam splitter 105, 106 laser beam 107, 108 optical modulator 109, 110 beam splitter 111 optical deflector 112 mirror 113 beam splitter 114 mirror 115 objective lens 116 movable optical table 117 glass master 118 turn Table 119 Signal generator 201, 202 Laser beam spot 203 Groove 204 Land 205, 206 Prepit group 301 Groove modulation signal 302 Prepit group modulation signal 303 Laser beam deflection signal

Claims (10)

[Claims] 1. A groove forming a groove track, a group of prepits on the same spiral or on the same circumference as the groove track, and a group of prepits on the same spiral or on the same circumference as a land track adjacent to the groove track. And a method of processing an optical disc master for forming a laser beam on a master coated with a photosensitive material, in order to form a group of prepits on the same spiral or on the same circumference as the groove track. Irradiating, and irradiating the master disk with a laser beam to form a pre-pit group on the same spiral or on the same circumference as the land track. The radial irradiation position of the pre-pit group processing laser beam is sequentially switched in accordance with the change in the circumferential relative position between the laser beam for master and the master. It is performed alternately by Rukoto processing method of the optical disc master. 2. The method for processing a master optical disc according to claim 1, wherein the laser beam for processing a pre-pit group and another laser beam for processing a groove are formed to form the groove in parallel with each of the irradiation steps. A method for processing an optical disc master, which is applied to the master. 3. The method for processing an optical disc master according to claim 1, wherein in each of the irradiation steps, the switching of a radial irradiation position of the prepit group processing laser beam is performed by optical deflection. The irradiation position when the optical deflection is not applied to the group processing laser beam is set to approximately the center of the groove track and the land track adjacent thereto, and the deflection to the groove track side and the irradiation to the land track side are performed. A method for processing a master optical disc, wherein the deflection and the deflection are made in opposite directions and substantially the same amount of deflection. 4. The method of processing an optical disc master according to claim 3, wherein each of the irradiating steps is performed based on a magnitude of a diffraction efficiency in the deflection toward the groove track side and the deflection toward the land track side. A method of processing an optical disc master having different laser powers. 5. A step of irradiating a laser beam onto the master using the optical disk master processing method according to claim 1, and developing the master to develop the groove and the pre-pit group. Forming an optical disk master. 6. A step of manufacturing an optical disk master by using the method of manufacturing an optical disk master according to claim 5, a step of electroforming the optical disk master and manufacturing a stamper, and injection molding using the stamper. A method for manufacturing an optical disk substrate, comprising: 7. An optical disk master manufactured using the method for manufacturing an optical disk master according to claim 5. 8. An optical disk substrate manufactured by using the optical disk substrate manufacturing method according to claim 6. 9. A groove forming a groove track, a group of prepits on the same spiral or on the same circumference as the groove track, and a group of prepits on the same spiral or on the same circumference as the land track adjacent to the groove track. And a means for generating a pre-pit group processing laser beam, and a circumferential relative position between the master coated with a photosensitive material and the pre-pit group processing laser beam. Means for moving a laser beam for processing the pre-pit group in the radial direction with the movement of the relative position in the circumferential direction in order to form the latent images of the pre-pit group on the groove track and the land track, respectively. Means for successively switching between: and an apparatus for processing a master optical disc. 10. The apparatus for processing an optical disk master according to claim 9, further comprising control means for controlling a laser power of the pre-pit group processing laser beam, wherein a radial irradiation position of the pre-pit group processing laser beam is determined. The switching means includes an optical deflector provided on a path of the pre-pit group processing laser beam, and the control means includes a diffractor of the optical deflector before and after switching of a radial irradiation position of the pre-pit group processing laser beam. An optical disk master processing device that controls laser power based on the level of efficiency.