JP2002092980A - Device for exposing mater disk of optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new device for exposing master disk for obtaining rectangular groove shapes which are different in depth, and a new resist master disk structure to be exposed. SOLUTION: A resist master disk 10 is mounted on a turntable 11 after removing the eccentricity referred to the outer diameter as reference and is adsorbed thereon by an air spindle motor 12. Grooves for detecting the eccentricity on the outer periphery of the resist master disk 10 is detected by a pickup 16 and the eccentricity is calculated as (n) period × set pitch by an eccentricity calculating circuit 22 and is added to a drive controlling circuit 21 as an offset signal to a slider unit 14. The drive controlling circuit 21 performs an exposure drive for a command value from a system controlling unit 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk master exposure apparatus.

[0002]

2. Description of the Related Art A conventional optical disk master exposure apparatus is disclosed in, for example,
As in the eccentricity adjusting device disclosed in Japanese Patent No. 62251, the disk-like object such as an optical disk master is attached to a rotating table that holds and rotates at the time of measurement. 2 arranged to touch
A monitor unit for detecting the amount of movement of the outer periphery of the disk-shaped object during rotation so that the two positioning stoppers and the cylindrical ring of the movement adjusting mechanism that moves in the center line direction of the two positioning stoppers rotate uniformly. In some cases, the eccentricity adjustment is performed by moving the movement adjustment mechanism by monitoring the eccentricity, thereby accurately measuring the preformat signal modulation degree of the master optical disc. Further, as in an eccentricity adjusting device disclosed in Japanese Patent Application Laid-Open No. 5-266581, a rotary table for holding and rotating a disk-shaped object, and two rotary tables fixed to the rotary table and arranged so as to be in contact with the outer periphery of the disk-shaped object A positioning stopper, a movement adjusting mechanism that moves in the direction of the center line of the two positioning stoppers, and a video monitor that monitors an area including an outer peripheral edge of a pattern formed on the disk-shaped object. In some cases, the pattern eccentricity during rotation of a disk-shaped object can be reduced, so that a signal inspection device such as an optical disk master can accurately measure a preformat signal modulation factor and the like. In addition, Japanese Unexamined Patent Publication
As in the eccentricity adjusting device disclosed in Japanese Patent No. 4891, at the time of measurement, a disk-shaped object such as an optical disk master is mounted on a rotating mechanism that rotates while holding the disk-shaped object. A laser beam is radiated onto the pattern, and the first-order diffracted light diffracted by the pattern formed on the disc-shaped object is captured by the optical position sensor unit. An eccentricity correction signal is output, and the position adjustment unit moves the disk-shaped object by the eccentricity correction signal, and adjusts the eccentricity between the rotation center of the rotating mechanism and the pattern center on the disk-shaped object. There is also. Further, as in the centering device for a glass master disclosed in Japanese Patent Application Laid-Open No. 7-240037, each link arm swings around the pivot axis so that each guide piece is moved in the same direction with respect to the rotation center of the turntable. A centering device for a glass master is configured such that the center of the glass master can be brought into contact with the outer periphery of a glass master placed on a turntable by moving the glass master at an equal distance.

[0003] In the prior art as described above, FIG.
As shown in the figure, the ROM area (groove depth λ
/ 4) and the RAM area (groove depth λ / 8) are formed in the same master using a two-layer resist structure in which the amount of exposure light is switched to switch the groove depth. 1A shows a glass master 1, FIG. 1B shows a state where a resist 2 is applied to a recording area, FIG. 1C shows an exposed state, FIG. 1D shows a developed state, and FIG. Indicates a state in which the light amount is switched, (F) indicates a state in which a two-layer resist is formed,
(G) shows a state where an R @ M / RAM area is desired to be formed. Ideally, each of the grooves formed by exposure is preferably rectangular.
In the case of OM and CD & DVD-R / RW, the groove depth is controlled by the thickness of the resist applied on the glass master to form a rectangular groove.

In the former case, the shape of the groove in the RAM area is not rectangular but V-shaped due to the intensity distribution of the exposure laser light. In order to keep the groove depth constant, it is necessary to control the fluctuation of the exposure light amount, the fluctuation of the surface of the resist master, and the focus control of the objective lens with high accuracy. Further, since the groove shape is a V-shape, an appropriate margin with the recording film is small, which causes a reduction in the exposure yield.

[0005] In the latter case, it is difficult to select an intermediate layer for separately applying a two-layer resist and to select resists for upper and lower layers.
The photolithography process becomes complicated and defects tend to increase, which also causes a decrease in yield.

Therefore, as shown in FIG. 2, after a resist 2 is applied to the glass master 1 itself in a place to be a ROM area (B in FIG. 2), it is polished to λ / 4.
A method of making each area rectangular by exposing (FIG. C) is under study.

The problem with this method is that if the center of the glass master 1 and the center of the ROM area and the center of rotation of the exposure do not coincide with each other coaxially, the pit depth of the ROM / RAM switching part due to the eccentricity. This means that the groove depth cannot be made uniform.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a novel master exposure apparatus and a novel resist master structure for exposure for obtaining rectangular groove shapes having different depths. .

[0009]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention is provided with a spindle unit fixed on a surface plate and installed in parallel with a center axis of the spindle unit. The resist master is sucked and rotated on the spindle unit by using the slide unit, and the resist light is modulated by an exposure light source installed on the standard and a laser beam modulated by an optical system by the objective lens installed on the slide unit. In an optical disc master exposure apparatus that forms a latent image by condensing on a master, an eccentricity of the resist master that is rotatably attracted is detected, and the slide unit is driven in conjunction with the eccentricity. And

According to a second aspect of the present invention, in order to achieve the above object, in the optical disk master exposure apparatus of the first aspect, the eccentricity detecting means for detecting the eccentricity is provided on the surface plate. It is installed on the central axis of the spindle unit and the slide unit, and uses a pickup or the like used in an optical disk drive or the like as a detection unit, and uses a signal obtained from the pickup as an eccentricity detection signal. I do.

According to a third aspect of the present invention, in order to achieve the above object, in the optical disk master exposure apparatus according to the second aspect, the eccentricity detection signal includes a plurality of pitches formed outside the exposure area of the resist master. A tracking error signal is detected from the concentric fine grooves formed by the above, and the amount of eccentricity of the resist master is calculated as needed from the tracking error signal and added to the slide control unit as an offset signal.

According to a fourth aspect of the present invention, in order to achieve the above object, in the optical disk master exposure apparatus according to the second aspect, the pickup follows a surface deflection of the resist master which is rotationally attracted to the spindle unit. It is a single-axis pickup having only a focus servo control structure for performing the operation.

According to a fifth aspect of the present invention, in order to achieve the above object, in the optical disk master exposing apparatus according to the third aspect, the control unit for the slide unit and the spindle unit uses a synchronization signal from a system control unit. By driving, spiral, concentric driving is enabled,
The offset signal obtained by calculating the eccentric amount is added to the slide control unit, so that the eccentricity of the resist master can be followed.

According to a sixth aspect of the present invention, in order to achieve the above object, in the optical disk master exposure apparatus of the third aspect, a resist master having an eccentricity detection groove outside the exposure area is used. Λ / 4 including resist layer in region
Is formed, and the center of the concentric groove coincides with the center of the eccentricity detection groove.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In the following, portions common to the related art are denoted by the same reference numerals, and redundant description is omitted. FIG. 3 is a conceptual diagram showing an embodiment of an optical disk master exposure apparatus according to the present invention. The apparatus of this embodiment includes an air spindle motor 12 having a turntable 11 for sucking and rotating a resist master 10, and an air slider 14 for moving a recording head 13 located on the turntable 11.
Optical system 15 for recording (details not shown)
A pickup 16 for detecting the center position of the resist master 10 is mounted on the outer periphery of the air spindle motor 12. In the figure, reference numeral 17 denotes an exposure pickup.

The resist master 10 is, as shown in FIG.
Groove 1 for forming λ / 4 pit, groove for detecting master eccentricity
8 and 19 are formed. These grooves 18, 19 are
Since the processing is performed by simultaneous processing, the one whose center position matches is used.

A series of drive controls of the optical disk master exposure apparatus shown in FIG. 1 are synchronously sent from the system control unit 20 to the air spindle motor 12 and the air slider 14 constituting the control unit of the optical system via the drive control circuit 21. It has become. These control units perform position control using a reference scale (not shown) in the case of a slider, thereby realizing an accurate exposure pitch. The air spindle motor 12 also performs rotation control by a control signal sent from the system control unit 20. Since all of these control signals are performed synchronously, spiral or concentric drive is possible. On the other hand, since the exposure optical system 15 also receives a control signal from the system control unit 20 and performs desired light modulation, spiral or concentric exposure can be performed.

At the time of exposure, focus control is also performed so that the objective lens for converging laser light to the submicron level on the resist master 10 always keeps within the depth of focus within the surface deflection of the rotating resist master (see FIG. 1). Not shown).

Next, the eccentricity removing operation of this embodiment will be described. The resist master 10 to be exposed is first mounted on a turntable 11 after removing its eccentricity on the basis of the outer diameter,
An air spindle motor 12 is used to adsorb it. At this point, the grooves 18, 1 formed in the resist master 10 are
The eccentricity of No. 9 is about 100 μm.

Next, the eccentricity detecting groove 18 installed on the outer periphery of the resist master 10 that has been sucked is detected by the pickup 16 whose position is fixed. As a detection method, focusing is performed by the pickup 16 and the resist master 10
Is rotated, a Te signal is generated due to optical interference (see FIGS. 5, 6, and 7). Therefore, the eccentricity of the resist master 10 can be represented by n cycles × set pitch by the Te signal and the set pitch. These calculations are performed by the eccentricity calculation circuit 2
2 and is added to the drive control circuit 21 as an offset signal to the slider unit 14. Note that Rp in FIG. 5 is a reading beam spot, and Tp is a track pitch. R in FIGS. 6 and 7 indicates one rotation. 6 shows a Te signal in a state of large eccentricity, and FIG. 7 shows a Te signal in a state of small eccentricity.

The drive control circuit 21 performs exposure drive in response to a command value from the system control unit 20. For the slider unit 14, a groove already formed in the resist master 10 by adding an offset signal. Driven in synchronism with the eccentricity. The reference scale of the slider unit 14 is generally a magnescale or a laser scale, but has a resolution of 1 to 8 nm / pulse and a sufficient resolution for the eccentricity of 100 μm when the master is attracted. General pitch fluctuation ± 0.03μ
Since the resolution is sufficient for m, the eccentricity between the center of the exposure groove and the center of the resist master can be removed.

FIG. 8 shows a case where the air spindle 12 and the slider unit 14 are driven in the CLV (constant linear velocity) mode. According to FIG. 8, the inner periphery is driven earlier and the outer periphery is driven later synchronously from the inner periphery to the outer periphery of the recording area. In this drive control, the feed speed of the slider unit 14 is synchronized with the eccentricity of one rotation of the resist master 1, so that the actually exposed resist master 1 does not have eccentricity with respect to the reference groove. Becomes possible.

Therefore, when the resist film 2 formed on the resist master 1 as shown in FIG.
When exposure is performed using the resist master 1 having a region of (λ / 4) depth and a RAM (λ / 8 to λ / 10) depth, the depth variation due to the eccentricity of the resist master 1 at the region switching portion is reduced. Therefore, rectangular grooves having different depths corresponding to the respective signal characteristics are formed.

[0024]

The optical disk master exposure apparatus according to the first aspect is as described above. Therefore, pitch fluctuation can be reduced by performing exposure in conformity with a resist master having an eccentricity detection reference groove. This has the effect.

Since the optical disk master exposure apparatus according to claims 2 and 3 is as described above, by aligning the eccentricity detection means with the center of the moving axis, the center of the resist master rotating in an elliptical shape can be adjusted. There is an effect that it can be converted into the amount of movement of the slide unit in one direction.

Since the optical disk master exposure apparatus according to claim 4 is as described above, the pickup is not driven in the eccentric direction by using the uniaxial PU.
There is an effect that the eccentric amount of the resist master can be accurately detected without being affected by the eccentric direction due to disturbance or the like.

Since the optical disk master exposure apparatus according to the fifth aspect is as described above, by driving the spindle unit and the slide unit synchronously, CLV and CAV having a high roundness following the eccentricity of the resist master are realized.
There is an effect that driving becomes possible.

Since the optical disk master exposure apparatus according to claim 6 is as described above, by providing concentric steps on the resist master, it is possible to form rectangular grooves having different depths. Since the exposure is performed by removing the eccentricity of the resist master, there is an effect that a variation in the depth of the exposure groove of the step change portion formed in the resist master can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a conventional master exposure process.

FIG. 2 is a cross-sectional view showing another conventional master exposure process.

FIG. 3 is a conceptual diagram showing an embodiment of an optical disk master exposure apparatus according to the present invention.

FIG. 4 is a plan view (A) and a cross-sectional view (B) of a glass master used in an embodiment of an optical disk master exposure apparatus according to the present invention.
It is.

FIG. 5 is a diagram showing eccentricity detection in an optical disk master exposure apparatus according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating a Te signal when the eccentricity is large.

FIG. 7 is a diagram showing a Te signal when the eccentricity is small.

FIGS. 8A and 8B are a diagram illustrating a lateral feed speed and a diagram illustrating a rotation speed of an example in which an air spindle and a slider unit are driven in a constant linear velocity mode.

[Explanation of symbols]

 Reference Signs List 10 resist master 11 turntable 12 air spindle motor 13 recording head 14 air slider 15 exposure optical system 16 pickup 17 exposure pickup 18, 19 groove 20 system control unit 21 drive control circuit 22 eccentricity calculation circuit

Claims (6)

[Claims] 1. A resist master is sucked and rotated on the spindle unit by using a spindle unit fixed on a surface plate and a slide unit installed in parallel with a center axis of the spindle unit. An exposure light source and a laser beam modulated by an optical system are condensed on the resist master by an objective lens installed on the slide unit to form a latent image in the optical disc master exposure apparatus. An optical disc master disc exposure apparatus, wherein the eccentricity is detected and the slide unit is driven in association with the eccentricity. 2. The optical disk master exposure apparatus according to claim 1, wherein the eccentricity detecting means for detecting the eccentricity is installed on a center axis of the spindle unit and the slide unit installed on the surface plate. Yes, using a pickup or the like used for an optical disk drive or the like as a detecting means,
An optical disk master exposure apparatus, wherein a signal obtained from the pickup is used as an eccentricity detection signal. 3. The optical disk master exposure apparatus according to claim 2, wherein the eccentricity detection signal detects a tracking error signal from concentric fine grooves formed at a plurality of pitches formed outside an exposure area of the resist master. An optical disc master exposure apparatus, wherein the eccentricity of the resist master is calculated as needed from the tracking error signal and added to the slide control unit as an offset signal. 4. The optical disk master exposure apparatus according to claim 2, wherein the pickup is a single-axis pickup having only a focus servo control structure for following a surface deflection of the resist master which is rotationally attracted to the spindle unit. An optical disc master exposure apparatus characterized by the following: 5. The optical disk master exposure apparatus according to claim 3, wherein the control unit for the slide unit and the spindle unit is driven by a synchronization signal from a system control unit, thereby enabling spiral and concentric drive, and the eccentricity. An optical disc master exposure apparatus, characterized in that an offset signal whose amount has been calculated is added to the slide control unit so as to follow the eccentricity of the resist master. 6. The optical disk master exposure apparatus according to claim 3, wherein a resist master having an eccentricity detection groove outside the exposure area is used, and a resist layer is included in the exposure area.
An optical disk master exposure apparatus, wherein a concentric groove machined at a depth of 4 is formed, and the center of the concentric groove coincides with the center of the eccentricity detection groove.