JPH11259902A - Device and method for recording optical disk master disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely and ultrahish-densely record a signal on an optical disk master disk. SOLUTION: An objective lens system 80a of this device is provided with a focus servo system 10 adjusting a focus of an objective lens (PFL) 82, a control system 11 controlling the focus servo system 10 and an astigmatic detection system 90 performing the optical axis matching adjustment of the PFL 82 with a solid immersion lens(SIL) 14. The focus servo system 10 is provided with a focus actuator 12 adjusting the focus of the PFL 82, a PFL holder 13 supporting the PFL 82 and an SIL position adjustment part 15 adjusting the position of the SIL 14. The focus actuator 12 moves and controls integrally the PFL 82 and the SIL 14 in the optical axial direction according to an instruction from the control system 11. The SIL position adjustment part 15 adjusts optionally the floating amount of the SIL 14 fixed to a dynamic pressure floating head 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for forming a minute light spot for exposure recording on a resist-coated surface of an optical disc, and more particularly, to an optical disc for performing exposure recording using a lens capable of generating an evanescent wave. Target master exposure equipment.

[0002]

2. Description of the Related Art An optical disk such as a DVD (Digital Video Disk) has a larger recording capacity than a magnetic disk such as a hard disk and is excellent in portability, and is expected to rapidly spread in the future. When manufacturing a read-only optical disk (hereinafter referred to as a commercially available disk), it is common to first manufacture an optical disk master and then manufacture a commercial disk from the master by signal transfer. In the process of manufacturing commercial disks, signal transfer is performed several times,
Deterioration of the recording signal of a commercially available disc is inevitable. For this reason, it is necessary to record a signal on the master optical disc in advance with much higher precision than on a commercially available disc.

[0003] When recording signals on an optical disk master, an optical disk master recording apparatus is used. The optical disk master recording apparatus performs exposure recording by condensing a recording laser beam with an objective lens and exposing the resist while the glass master coated with the resist is rotated. The recording laser beam is a signal that is turned on / off according to a recording signal. By controlling the movement of the objective lens from the inner circumference side to the outer circumference side of the master with high precision, a signal is spirally recorded at a constant pitch on the optical disc.

[0004] Further, in the optical disk master recording apparatus, even if there is a slight undulation (vertical movement) on the optical disk master surface, the object is moved according to the vertical movement of the glass master so that the laser beam always focuses on the recording surface. A focus servo mechanism that causes the lens to perform a tracking operation is provided.

FIG. 5 is a perspective view showing a schematic configuration of a conventional optical disk master recording apparatus. On the anti-vibration table 40, a recording signal light generation system 50, a master disk rotating table system 60, a slider feed system 70, and an objective lens system 80 are provided. The recording signal light generation system 50 includes a laser head 51, an optical power processing system 52 for stabilizing the power of the laser light output from the laser head 51, and a shutter processing system 53 for turning on / off the laser light according to the recording signal. And The optical power processing system 52 has an ultrasonic optical modulation element (AOM) 54, and the shutter processing system 53 has a formatter 55 and an electro-optical element (EOM) 56. The output of the EOM 56 is introduced horizontally into the objective lens system 80 installed on the slider 71 from the slider feed direction.

[0006] The master disk rotating table system 60 has a turntable 62 for chucking the optical disk master 61 and a spindle motor 63 for rotating the turntable 62. The slider feed system 70 has a slider 71 and a feed motor 72, and drives the objective lens system 80 in one horizontal degree of freedom so that a recording signal is recorded on the optical disk master 61 at a fixed track pitch.

The objective lens system 80 includes the recording signal light generation system 5
The recording laser light introduced horizontally from 0 is reflected in the vertical direction by an introduction mirror (not shown), and an objective lens (PFL)
82 focuses on the optical disk master 61. The return light reflected on the optical disk master 61 is guided to the focus position detector 83, and the amount of defocus is detected using astigmatism. Based on this defocus amount, the focus position adjustment unit 81 moves the PFL 82 in the vertical direction (optical axis direction).
The servo control is performed so that the recording laser light is always focused on the master surface even if the spot forming position is moved up and down due to the rotation of the optical disk master 61.

The PFL 82 moves integrally with the slider 71, and the position of the slider 71 is measured by a heterodyne interferometer 73 fixed to the vibration isolator 40. By feeding back the measurement result, the movement of the PFL 82 and the slider 71 is controlled with high precision so that the track advances by one track every time the master 61 makes one rotation.

The conventional optical disc master recording apparatus shown in FIG. 5 cannot perform ultra-high density recording due to the diffraction limit of the PFL 82. That is, in order to perform ultra-high-density recording, it is necessary to improve the distance between adjacent tracks in the radial direction (track pitch) and the amount of information per unit track length (linear recording density). It depends on the minimum pit diameter (determined by the diffraction-limited spot size).

The minimum pit diameter R is expressed by the following equation (1) from the diffraction limit due to the Airy diameter. R = k · λ / NA (1) where k is a coefficient depending on a resist material and a process,
λ is the recording laser wavelength, and NA is the PFL 82 numerical aperture.

At present, an optical disk master recording apparatus for high-density recording uses an Xr ion laser (wavelength λ = 351n) in the ultraviolet region.
m) and a PFL 82 having a high aperture (NA = 0.9) is generally used, but the aperture of the PFL 82 cannot be increased to 1 or more.
The recording laser light is also limited by the material limitation of the usable resist and the material limitation of the optical system such as PFL 82 due to the transmittance.
It is difficult to significantly reduce the wavelength. Therefore, at present, research is being conducted to reduce k in equation (1) by devising a resist and an etching process. However, even if the process is devised, the pit width that can be formed is limited to about 0.15 μm.

In view of the above, it has been generally considered that in order to increase the capacity of an optical disk, it is necessary to develop a master recording device for an electron beam or X-ray instead of ultraviolet light.

However, in recent years, researches on information recording utilizing a new minute spot forming technique called near-field recording have been attracting attention. For example, an example applied to information recording on a magneto-optical disk (MO drive) is known. Proposed.

In the near-field recording, information is recorded by using an evanescent wave, which has been studied for improving the resolution of a microscope. More specifically, an imaginary attenuated wave called an evanescent wave is generated using a micro-aperture probe or solid immersion lens (SIL), and propagated as a real wave to the recording medium before the wave is attenuated. is there.

FIG. 6 is a diagram for explaining the principle of near-field recording using SIL. Prefocus lens (PF
L: objective lens) perpendicularly incident on the PFL 91
Is guided to a hemispherical lens 92 having a high refractive index called a SIL (Solid Immersion Lens). The wavelength of the laser light entering the SIL 92 is 1 / n (n is the refractive index of the laser light)
Therefore, the diffraction limit of the laser light in the SIL 92 becomes 1 / n of the original value. That is, this is apparently the same as increasing the numerical aperture NA of the PFL 91 by n times.

As a result, the light spot size formed on the bottom surface of the SIL 92 is considerably smaller than the light spot size at the focal position of the PFL 91. However, the signal recording surface 93
Is not at the bottom of the SIL 92 but at a point that separates air from the bottom of the SIL 92. Therefore, even if the numerical aperture NA is increased inside the SIL 92, the beam diameter increases again when the laser beam passes through the SIL 92 and enters the air.

However, the situation is different when the bottom surface of the SIL 92 and the optical disk recording surface 93 are close to each other. SI
Light incident at the total reflection angle on the bottom surface of the L 92 leaks out from the bottom surface of the SIL 92 as an evanescent wave, and when there is a photo conductor near the bottom surface of the SIL 92, propagation to the photo conductor occurs due to photon tunnel effect. Because. Moreover, the evanescent wave propagates through the tunnel effect of photons,
The effect of the air layer can be almost ignored, and the signal can be recorded with the spot size formed on the bottom surface of the SIL 92.

However, the amplitude of the evanescent wave exponentially attenuates according to the distance from the bottom surface of the SIL 92,
If the distance from the bottom surface of L 92 is large, it will not contribute to signal recording. Therefore, the bottom surface of SIL 92 and signal recording surface 93 need to be close to one half or less of the wavelength of laser light. In addition, since the positional relationship between the SIL 92 and the PFL 91 affects the spot size and the spot position, the distance between the two lenses must always be kept constant.

As described above, when recording information on an optical disc,
The technology using SIL 92 has already been studied in MO drives and the like. In addition, as an applied research of MO drive, SI
A unit configured integrally with L 92 and PFL 91 is attached to a dynamic pressure floating head used in a hard disk or the like,
There is also proposed a technique for maintaining a constant proximity gap between a unit and an optical disk by utilizing dynamic pressure levitation caused by rotation of the optical disk.

[0020]

When information is recorded on an optical disk master using SIL 92, the same recording laser light as that used in the prior art can be used, so that an electron beam or an X-ray beam is used as the recording laser light. It can be inferred that a master recording apparatus capable of performing ultra-high-density recording can be relatively easily developed with little change of the apparatus, but there are actually various problems, and practical application is not easy.

The first problem is the wavelength of the recording laser light. As described above, the master optical disc requires much higher precision than the commercial disc, and the spot size of the recording signal also needs to be smaller than the spot size of the commercial disc. Like the current master recording device,
When using an ultraviolet laser as the recording laser light,
As the optical lens, it is necessary to use a lens with high precision and high aperture which has almost no aberration for ultraviolet rays, and the PFL 91 becomes heavy.

That is, like the MO drive, the PFL 91
And SIL 92 are integrated, and these are passively levitated by a flying head similar to a hard disk. If the rotation speed of the optical disk master is slow and the PFL 91 is heavy, sufficient proximity gap accuracy is guaranteed. Floating head design becomes difficult. Further, if the recording laser beam is set to have a short wavelength, the transmittance is reduced, so that the SIL 92 is likely to be deteriorated by heat at the bottom surface, and the SIL 92 needs to be replaced periodically. Therefore, PFL 91 and SIL 92
It is difficult to make a single unit.

The second problem is the positional relationship between the PFL 91, the SIL 92 and the master optical disc 93. PFL 91 and SIL
If 92 is not in the ideal positional relationship, the spot size of the recording signal will increase due to the influence of aberration. In addition, SIL 9
Fluctuation in the gap between the optical disk 2 and the optical disk master 93 tends to cause a change in the intensity of the exposure light, causing variations in the signal width and signal length, making it impossible to achieve the strict accuracy required for master disk recording. For this reason, it is necessary to maintain the PFL 91 and the SIL 92 in an ideal positional relationship, and to always keep the gap between the SIL 92 and the master optical disc 93 constant. In particular, the latter gap management is important.

The third problem is how to deal with different types of master optical discs. This is also a matter of the specification of the master recording device, but the corresponding optical disk is not limited to one type.
For example, just as the DVD standard has a plurality of formats, the future high-density optical disk standard also needs to be able to record information on a plurality of types of optical disks. That is, since the recording speed and the thickness of the master differ depending on the type of the optical disc, the wavelength of the recording laser beam is switched according to the recording speed, or the PFL 91 or SIL 9 is changed according to the thickness of the master.
The positional relationship between the two must be changed.

Further, even if the thickness and recording speed of the master are constant, the optical disc master is polished and reused, so that the thickness varies among the optical disc masters. Therefore, it is difficult to passively manage the flying height of the head using a dynamic pressure floating head similar to a hard disk.
If the speed changes, the buoyancy decreases, and if the master thickness changes, the applied pressure changes. As a result, the flying height changes.

There are many other problems, and the near-field recording technology using the SIL 92 cannot be applied to an optical disk master recording device by analogy with a conventional master recording device and an SIL application example in an MO drive. Ingenuity is required.

The present invention has been made in view of the above points, and has as its object to provide an optical disk master recording apparatus and an optical disk master recording method capable of recording signals on an optical disk master with ultra-high density and high accuracy. Is to provide.

[0028]

According to a first aspect of the present invention, there is provided an optical disk master on which a resist is applied while rotating the optical disk master on which the resist has been applied. In an optical disc master recording apparatus for performing exposure recording by irradiating a laser beam according to a signal, a prefocus lens for condensing the laser beam, and a laser beam condensed by the prefocus lens, a predetermined reference surface A lens capable of generating an evanescent wave to be further condensed, and a resist coating surface of the optical disk master and the evanescent wave so that exposure and recording can be performed with a beam spot diameter substantially the same as the beam spot diameter on the reference surface. Gap adjusting means for adjusting the distance to a lens that can be generated, and the laser light passing through the prefocus lens is Focus adjustment control means for adjusting the focus of the prefocus lens so as to form an image on a quasi-plane, and optical axis adjustment adjustment means for adjusting the optical axis of the prefocus lens and a lens capable of generating the evanescent wave Wherein the reference plane is a bottom surface of the lens that can generate the evanescent wave, and the gap adjusting unit is a distance that does not attenuate the evanescent wave leaking from the bottom surface of the lens that can generate the evanescent wave. Then, the position of the lens capable of generating the evanescent wave is controlled so that the resist-coated surface of the optical disk master is arranged in the optical disk master.

As shown in FIG. 1, for example, the prefocus lens and a lens capable of generating an evanescent wave can be integrally moved in the optical axis direction of the laser beam by the focus adjustment control means.

Further, for example, as shown in FIG. 4, the prefocus lens can be moved in the optical axis direction of the laser beam by the focus adjustment control means without moving the lens capable of generating the evanescent wave.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical disk master recording apparatus to which the present invention is applied will be specifically described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an objective lens system 80a in the first embodiment of the optical disk master recording apparatus. The configuration other than the objective lens system 80a is almost the same as that of the conventional optical disk master recording apparatus shown in FIG. Before describing the configuration of the objective lens system 80a of FIG.
The schematic configuration of the optical disk master recording apparatus of the present embodiment will be described based on FIG.

The optical disk master recording apparatus according to the present embodiment comprises:
A recording signal light generation system 50, a master disc rotating table system 60,
It has a slider feed system 70 and an objective lens system 80a. The recording laser light output from the recording signal light generation system 50 is horizontally introduced into the objective lens system 80a disposed on the slider 71 from the slider feed direction. This recording laser light is parallel light.

The slider 71 moves in the horizontal direction integrally with the objective lens system 80a, and
The position coordinates of 1 are measured by the heterodyne laser interferometer 73. On the basis of the measurement result by the laser interferometer 73, the feed motor 72 is controlled by a slider 71 so as to follow a position profile preset by a control computer (not shown).
Is performed. The position profile is managed in synchronization with the spindle motor 63 of the master rotating table system 60 and the formatter 55 of the recording signal light generation system 50, and more specifically, the recording linear velocity and linear velocity of the recording signal. Density is controlled.

The configuration of the optical disk master recording apparatus described above is the same as the conventional optical disk master recording apparatus.
Next, the objective lens system 80a which is a feature of the present embodiment is described.
Will be described with reference to FIG. Objective lens system 8
0a is a focus servo system 10 for adjusting the focus of the PFL 82 and a control system 1 for controlling the focus servo system 10.
1 and an astigmatism detection diameter 90 for adjusting the optical axis of the PFL 82 and the SIL 14. Focus servo system 10
Is connected to the slider 71 together with the introduction mirror 81. The introduction mirror 81 reflects the recording laser light horizontally introduced from the recording signal light generation system 50 in the vertical direction, and
L 82.

The focus servo system 10 comprises a focus actuator 12 for adjusting the focus of the PFL 82 and a PFL 8
2 has a PFL holder 13 for supporting the SIL 2, and a SIL position adjusting unit 15 for controlling the position of the SIL 14. The focus actuator 12 controls the PFL 8 in response to an instruction from the control system 11.
2 and the SIL 14 are integrally moved and controlled in the optical axis direction. In addition,
Since the numerical aperture NA of the PFL 82 and the SIL 14 needs to be set to 1 or less, the numerical aperture NA of the PFL 82 is
The numerical aperture NA of L82 is set to be smaller (for example, NA = 0.
53).

SIL 14 is a spherical lens with φ = 0.8,
It is adhesively fixed to the dynamic pressure floating head 16. The dynamic pressure floating head 16 is supported by one end of an elastic support member 17 so as to be movable in the vertical direction (optical axis direction), and the other end of the elastic support member 17 is capable of displacing the SIL by about several μm in the optical axis direction. Part 15
It is fixed to.

The SIL position adjuster 15 is provided with the SIL 14 and the PFL 8
The structure is such that an XY fine movement actuator 21, an XY fine movement stage 22, a Z fine movement actuator 23, and a Z fine movement stage 24 are sequentially stacked on the PFL holder 13 so that the positional relationship with the 2 can be finely adjusted. The order of laminating the Z fine movement actuator 23 and the XY fine movement actuator 21 may be reversed.

In the dynamic pressure floating head 16 and the elastic support member 17, the holding end of the elastic support member 17 is at a predetermined height with respect to the master surface, and the master is rotating at a linear velocity of 3 m / s. Sometimes designed to fly about 50nm. Also,
If the height position of the holding end of the elastic support member 17 is within an error of 1 μm, the design is such that the floating error is 5 nm or less.

Next, adjustment of the optical axis alignment between the PFL 82 and the SIL 14 will be described. In the present embodiment, PFL 82 and SI
L14 and SIL 14 are elastic support members 1
7, the alignment of the optical axes of the PFL 82 and the SIL 14 is indispensable. Further, since a short-wavelength laser in the ultraviolet region is used as a recording laser and a medium having a high refractive index is used for the SIL 14, the SIL 14 tends to deteriorate in performance due to heat. It is necessary to replace the entire elastic support member 17. For this reason,
It is desirable to periodically perform the optical axis alignment adjustment processing so that the SIL 14 and the PFL 82 have an almost ideal positional relationship.

The optical axis alignment adjustment is performed in a state where the master 61 is not placed, that is, in a state where evanescent light is not generated and light incident at a total reflection angle is almost completely returned light. The returned light is introduced into the astigmatism detection system 90, and the defocus amount on the bottom surface of the SIL 14 is detected by the four-segment photodetector in the astigmatism detection system 90.

FIG. 2 is a diagram showing the shape of the return light spot detected by the four-segment photodetector. Assuming that the detection values of the respective photodetectors are a, b, c, and d, the focus error (defocus amount) FE is expressed by equation (2). FE = (a + c) − (b + d) (2) When the PFL 82 and the SIL 14 are in an ideal positional relationship, FIG.
If a circular spot is formed at the center of the four-segmented photodetector as shown in (a), the focus error FE in this case becomes zero. On the other hand, when the SIL 14 is farther than the ideal position with respect to the PFL 82 as shown in FIG. 2B, FE> 0, and conversely, as shown in FIG.
If SIL 14 is closer to L82 than the ideal position, FE <0. Therefore, the positional relationship between the SIL 14 and the PFL 82 can be easily and accurately detected based on the value of the focus error FE detected by the four-divided photodetector and the sign.

The optical axis alignment between the PFL 82 and the SIL 14 is adjusted in the following procedure. In the initial state, no buoyancy acts on the dynamic pressure floating head 16 shown in FIG. 1, so that the elastic support member 17 is in an extended state and is out of focus.
In this state, the Z fine movement stage 24 is pulled up by the Z fine movement actuator 23 until FE = 0. Where F
Even if E = 0, if the SIL 14 and the PFL 82 are displaced in the horizontal direction, focusing will not be performed as shown in FIG. However, conversely, if the XY fine movement actuator 21 is driven in a push-pull manner based on a signal from the four-segment photodetector, the optical axes of the SIL 14 and the PFL 82 can be aligned.

In the astigmatism detection system 90 of this embodiment, X
Since the displacements XE and YE in the axial and Y-axis directions are detected as shown in FIGS. 2D and 2E, XE and YE are set to “0” with the displacement amounts XE = bd and YE = ca. The optical axis is adjusted by feedback control so that XY fine movement stage 22 after adjustment
Is fixed to the PFL holder 13 and the Z fine movement stage 24 is returned to the original defocus position. In addition, PFL 82 and
Since the optical axis alignment adjustment with the SIL 14 is not performed so frequently, it is not always necessary to perform the XY fine movement adjustment using the XY fine movement actuator 21 as shown in FIG.

Next, the recording procedure on the optical disk master 61 will be described in detail with reference to the flowchart of FIG. This flowchart shows the processing operation of the control system 11. It is assumed that the optical axis alignment adjustment between the PFL 82 and the SIL 14 has been completed in advance.

First, after the optical disk master 61 coated with the resist is chucked at the center of the turntable 62, the control system 11 performs the same measurement start processing as the conventional one such as slider position calibration processing (step in FIG. 3). S1). Next, the control system 11 performs rough proximity processing of the PFL 82 (FIG. 3).
Step S2). The rough proximity processing performed here is processing that has been performed conventionally, and the thickness of the optical disk master 61 is 100%.
The master 61 and the PFL are adjusted so that the neutral point of the focus actuator 12 is almost at the in-focus position even if it varies about μm.
Adjust the distance between the two.

Although not shown in FIG. 1, in the present embodiment, the spindle motor 63 for rotating the master 61 is provided with a spindle up-and-down mechanism capable of moving up and down with respect to the anti-vibration table 40 with a stroke of 2 mm. 0 of the astigmatism detection system 40
The master 61 along with the spindle motor 63 is gently lifted up to a position (in-focus position) to bring the master 61 and the PFL 82 close to each other. Further, as the PFL 82 descends, buoyancy is gradually generated in the dynamic pressure flying head 16, the elastic support member 17 contracts, and the distance between the PFL 82 and the SIL 14 starts to change.
The buoyancy acting on the dynamic pressure floating head 16 as the master 61 rotates is omitted because it is expressed by a complicated equation, but is generally expressed by a monotonically decreasing function of the gap, and the Z fine movement stage 24 is positioned at a predetermined distance from the master surface. Is reached, the astigmatism detection system 40 determines that focus is achieved.

Next, after locking the spindle up / down mechanism at the in-focus position, the control system 14 starts PFL focus servo (fine focus) by the focus servo system 10 (step S3 in FIG. 3). Since the PFL focus servo has a wide band characteristic, during the PFL focus servo, the SIL 14 keeps a position floating below the optical disk master 61 by 100 nm or less, and both the PFL 82 and the SIL 14 are undulated on the optical disk master surface. Move up and down along.

The vertical movement of the innermost circumference of the optical disk master 61 is small, so that the pressure fluctuation in the elastic support member 17 can be ignored, and the floating gap is constant without locking the focus servo. In the embodiment, in order to ensure the safety, the servo lock is performed when the floating gap becomes constant.

Next, the control system 14 performs a gap adjusting process (step S4 in FIG. 3). In high-density master recording, the control of the amount of recording laser light is strict, and it is necessary to control the amount of light according to the recording speed. However, the gap between the bottom surface of the SIL 14 and the master 61 greatly affects the transmission efficiency.
The gap between the bottom surface of the master and the master 61 must be kept constant even if the recording speed is changed.

As an example of the gap detection, there is a method utilizing the fact that the amount of reflected light changes according to the gap. In this method, the return light intensity of the light incident at the angle of total reflection is SIL 1
This utilizes a characteristic that changes rapidly according to the gap between the master 4 and the master 61. However, in this embodiment, instead of this method, a wavelength that does not react with the resist (640 nm)
A homodyne-type interferometric length measurement method using the above light is used.

In this method, the laser beam having a narrow beam length measured by the PFL 82 so as not to be totally reflected even at the bottom surface of the SIL 14 is used.
The laser beam is introduced into the SIL 14, and the intensity of the return light of the laser beam is measured by a photodetector. The bottom surface of the SIL 14 is provided with a special coating that selectively reflects the length measuring laser light, and the light reflected from the bottom surface of the SIL 14 and the light reflected from the master surface interfere with each other. The manner of interference changes according to the gap, and the intensity of the return light detected by the photodetector also changes.

More specifically, the intensity of the returning light varies periodically in a sinusoidal manner according to the gap.
In the following cases, the intensity of the return light becomes a simple increasing function,
The gap and the intensity of the return light are uniquely determined. Therefore, if the Z fine movement actuator 23 is adjusted so that a return light intensity corresponding to a gap of about 50 nm is obtained, the gap can be adjusted with high accuracy. That is, SIL
With the vertical position of the bottom of 14 and the PFL 82 constant,
If the vertical position of the Z fine movement stage 24 with respect to the PFL 82 is changed, the pressure applied to the dynamic pressure flying head 16 changes, and the floating amount of the dynamic pressure flying head 16 can be adjusted. The gap measurement value measured by the above method is sent to the control system 11,
The S / N ratio is improved by passing through a low-pass filter.

In this embodiment, since the gap is constantly measured even during the recording of the master disc to control the Z fine motion actuator 23 in the low band, the recording laser beam and the laser beam for interferometric length measurement are simultaneously transmitted by the SIL. Even when the light is introduced into the light source 14, the light is separated using a mirror having wavelength selectivity so that return light from the laser beam for interferometric measurement can be accurately detected. However, the Z fine adjustment in the optical axis direction is sufficient only by the measurement start processing in step S1, and therefore, the Z fine movement actuator 23 may be locked when the measurement start processing in step S1 ends.

When the processing in step S4 in FIG. 3 is completed,
Next, the control system 14 accelerates the slider 71 toward the recording start position so as to have a desired feed speed, similarly to the processing after the conventional focus servo pull-in, and the recording signal generation system 50 and the master disk rotating table system 60. Are operated in synchronization with each other, and exposure recording is performed spirally from the inner peripheral side to the outer peripheral side of the optical disk master 61 (step S5 in FIG. 3).

Here, the processing during exposure recording will be described in detail. The control of the slider feed system 70, the rotation speed of the master disk, and the relationship between the format signal are the same as those in the related art, and a description thereof will be omitted. Hereinafter, control of the PFL 82 during exposure recording will be described.

The recording laser beam is narrowed down by the PFL 82 and introduced into the SIL 14. Based on the return light from the bottom surface of the SIL 14, the astigmatism detection system 40 shifts the focus laser beam from the bottom surface of the SIL 14 (focus error). Is detected. In order to eliminate this focus error, the focus servo system 10
Drives a focus actuator 12 (for example, a voice coil motor). SIL 14 is the dynamic pressure floating head 1
6, the gap between the recording surface and the SIL 14 is always kept constant even if the recording surface moves up and down due to the rotation of the master 61.

The PFL 82 is actively driven by the focus actuator 12. If the vertical movement of the master is within the control band of the focus servo system 10, the PFL 82 and the SI
It operates integrally with L14, and hardly generates aberration.
Of course, when a steep vertical movement occurs in the master 61,
The distance between PFL 82 and SIL 14 will change,
This is not a problem in practical use.

In this embodiment, the focus servo system 10
In addition, the gap control by the Z fine movement actuator 23 described above is performed. By performing the processing in step S4 of FIG. 3, even if the Z fine movement actuator 23 is not controlled,
Although a gap of 50 nm can be obtained, in the case of special recording in which the recording linear density needs to be changed, the flying gap changes and an appropriate exposure power cannot be obtained. Therefore, in the present embodiment, the gap is managed by the Z fine movement actuator 23. However, the gap control has a control system of a band sufficiently lower than the rotation period of the master, and therefore has no meaning unless the change in the recording linear velocity is gentle.

As described above, in the first embodiment, the PFL 82 and the SIL 14 are separately provided, and only the SIL 14 is fixed to the tip of the dynamic pressure floating head 16.
Even if the fluid resistance generated by the rotation of the optical disc master 61 is small, the SIL 14 can be stably levitated,
The gap between the SIL 14 and the recording surface of the master can always be kept constant.

When the PFL 82 and the SIL 14 are formed separately as shown in FIG. 1, the optical axes of the PFL 82 and the SIL 14 may be shifted due to a variation in the mounting position of the SIL 14. For this reason, in the first embodiment, the astigmatism detection system 40 is provided to adjust the optical axis of the PFL 82 and the SIL 14, so that the influence of aberration can be reduced and disturbance of the light spot size can be reduced. No longer affected by Further, since the optical axis alignment adjustment between the PFL 82 and the SIL 14 can be performed in a simple procedure, the accuracy can be maintained constant even when the consumable SIL 14 is replaced.

Since the focus actuator 12 controls the movement of the PFL 82 and the SIL 14 integrally, the PF
The distance between L 82 and SIL 14 can be kept constant, and PFL 82
The same effect can be obtained equivalently to the case where the SIL 14 and the SIL 14 are integrated.

In order to provide the SIL position adjusting unit 15,
While maintaining the distance between the PFL 82 and the SIL 14 constant, the amount of pressurization of the elastic support member 17 can be arbitrarily changed,
As a result, the dynamic pressure floating amount of the SIL 14 can be arbitrarily adjusted. As a result, even when the linear velocity of the master optical disc during signal recording is changed, the flying height can be set arbitrarily. Even when performing signal recording, SIL 14
Can be controlled so that the flying height of the surface becomes constant.

In particular, under any signal recording conditions, if the flying height is constant and the efficiency by the SIL 14 is kept constant, a conventional database is used for light quantity management under each signal recording condition. it can.

By using SIL 14, the PFL
82, the numerical aperture NA can be reduced.
While NA = 0.9, in the present embodiment, the numerical aperture NA
= 0.53 can be used. Further, as a material of SIL 14, LaSF having a refractive index n ₄₁₃ = 1.894 is used.
Numerical aperture NA '= 1 inside the lens, internal wavelength λ' = 18
The minimum pit diameter R 'when the optical disk master is assumed to be sufficiently close to the SIL 14 is expressed by the equation (2). R '= k · λ' / NA '= k · λ / (n 2 · NA) = 0.47R ... (2) Here, R is the minimum pit diameter of a conventional method using the PFL 82 of NA = 0.9.

As shown in the equation (2), according to the present embodiment, less than half of the conventional pits can be formed, and ultrahigh-density recording becomes possible.

In this embodiment, the objective lens system 80a
Except for the configuration described above, the configuration is almost the same as the conventional configuration shown in FIG. 5, so that the configuration change is much smaller than when a master exposure apparatus using electron beams or X-rays is developed, Costs are low.

[Second Embodiment] In the second embodiment, the PF
The movement of the L 82 and the SIL 14 can be controlled independently. FIG. 4 is a diagram showing a schematic configuration of an objective lens system 80b in the second embodiment of the optical disc master recording apparatus. In FIG. 4, the same components as those in FIG. 1 are denoted by the same reference numerals, and the following description will focus on the differences from FIG.

The PFL 82 is supported by the PFL holder 13 and the PF
L 82 and PFL holder 13 are the focus actuator 1
2 controls the movement in the optical axis direction. On the other hand, the SIL position adjuster 15 for controlling the movement of the SIL 14 is different from FIG.
It is directly supported by the slider 71. SIL position adjustment unit 15
The XY fine movement actuator 21 for controlling the movement of the SIL 14 in the horizontal direction (the direction orthogonal to the optical axis), the XY fine movement stage 22 for supporting the XY fine movement actuator 21,
It has a Z fine movement actuator 23 that controls the movement of L 14 in the optical axis direction, and a Z fine movement stage 24 that supports the Z fine movement actuator 23.

On the other hand, the SIL 14 is a spherical lens having a diameter of φ0.8, and is adhered and fixed to one end of the dynamic pressure floating head 16. The dynamic pressure floating head 16 is supported by an elastic support member 17 so as to be movable in the vertical direction (optical axis direction).
Is the Z fine movement stage 2 in the SIL position adjustment unit 15 described above.
4 is connected.

In the second embodiment, unlike FIG. 1, since the Z fine movement stage 24 is not stacked on the PFL 82, the PFL 82 does not move even if the optical disk master 61 moves up and down.
As a result, the applied pressure of the dynamic pressure flying head 16 changes. The dynamic pressure floating head 16 and the elastic support member 17
Even if there is a vertical movement of 1, there should be no problem because the gap fluctuation is designed to be slow. However, since the intensity of the recording laser beam largely depends on the gap fluctuation, the vertical fluctuation of the optical disk master 61 is large. On the outer peripheral side, jitter may be deteriorated.

For this reason, in the second embodiment, the gap between the SIL 14 and the optical disk master 61 is reduced by using an actuator having a relatively high band and good controllability such as a voice coil motor as the Z fine movement actuator 23. Control is performed so as to be constant. The gap measurement is performed in the same manner as in the first embodiment.
Unlike the first embodiment, feedback is performed without passing through a low-frequency low-pass filter, and the Z fine movement actuator 23
Devises phase lead / lag compensation so as not to excite the natural vibration by the elastic support member 17. As a result, the fluctuation of the cap is extremely small over the entire recording surface, and stable signal exposure can be performed.

When the optical disk master 61 is in the shape of a mortar, the DC value of the master height changes between the inner circumference and the outer circumference. Pressure is constantly controlled, and as a result, SIL 1
4 and the optical disk master 61 no longer fluctuate.

In each of the above embodiments, a spherical lens is used as a lens capable of generating an evanescent wave. However, any lens capable of generating an evanescent wave may be used.
The lens shape does not matter. Further, the configuration of the optical disk master recording apparatus is not limited to the configuration shown in FIG.

[0074]

As described in detail above, according to the present invention, control is performed such that laser light passing through the first optical system always forms an image on the reference plane via the second optical system. In addition, since the control is performed so that the optical axes of the first and second optical systems coincide with each other, the beam spot diameter on the resist-coated surface can be made much smaller than before, and the recording density can be greatly improved.
Also, even if the optical disk master moves up and down due to rotation, or if the second optical system is replaced halfway, exposure recording can always be performed with the same accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an objective lens system in a first embodiment of an optical disc master recording apparatus.

FIG. 2 is a diagram showing a shape of a return light spot detected by a four-segment photodetector.

FIG. 3 is a flowchart showing a recording procedure on a master optical disc.

FIG. 4 is a diagram showing a schematic configuration of an objective lens system in a second embodiment of the optical disc master recording apparatus.

FIG. 5 is a perspective view showing a schematic configuration of a conventional optical disk master recording apparatus.

FIG. 6 is a view for explaining the principle of near-field recording using SIL.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Focus servo system 11 Control system 12 Focus actuator 13 PFL holder 14 SIL 15 SIL Position adjustment part 16 Dynamic pressure floating head 17 Elastic support member 21 XY fine movement actuator 22 XY fine movement stage 23 Z fine movement actuator 24 Z fine movement stage 80, 80a, 80b Objective lens system 81 Introducing mirror 82 PFL 90 Astigmatism detection system

Claims (7)

[Claims] An optical disc master recording apparatus for performing exposure recording by irradiating a laser beam corresponding to a recording signal to a resist applied surface of the optical disc master while rotating the optical disc master coated with a resist, A prefocus lens for condensing the laser light; a lens capable of generating an evanescent wave for further condensing the laser light condensed by the prefocus lens on a predetermined reference surface; and a beam on the reference surface. Gap adjusting means for adjusting the distance between the resist-coated surface of the optical disc master and a lens capable of generating the evanescent wave, so that exposure recording can be performed with a beam spot diameter substantially the same as the spot diameter; The focus of the pre-focus lens is adjusted so that the laser light that has passed through forms an image on the reference plane. Focusing adjustment control means, and optical axis alignment adjustment means for adjusting the optical axis of the prefocus lens and the lens capable of generating the evanescent wave, wherein the reference plane is capable of generating the evanescent wave A bottom surface of the lens, wherein the gap adjusting means is configured to set the evanescent wave such that the resist coating surface of the optical disc master is disposed at a distance such that evanescent waves leaking from the bottom surface of the lens capable of generating the evanescent waves are not attenuated. An optical disk master recording apparatus, wherein a lens capable of generating a wave can be positioned. 2. The method according to claim 1, wherein the evanescent wave is generated such that a lens capable of generating the evanescent wave passively floats to a height of 100 nm or less from a resist coating surface of the optical disk master due to fluid resistance generated by rotation of the optical disk master. A dynamic pressure levitation mechanism that supports a lens capable of generating the following. The dynamic pressure levitation mechanism is provided separately from a support of the prefocus lens, and the gap adjustment unit is provided at one end of the dynamic pressure levitation mechanism. 2. The optical disk master recording apparatus according to claim 1, wherein the dynamic pressure levitation mechanism and the lens capable of generating the evanescent wave are integrally moved and controlled. 3. The dynamic pressure levitation mechanism includes a dynamic pressure levitation head and an elastic support member, and a lens capable of generating the evanescent wave is fixed to one end of the dynamic pressure levitation head. The optical disk master recording apparatus according to claim 2, wherein one end of the elastic support member is connected to the other end of the head, and the gap adjusting means is connected to the other end of the elastic support member. 4. A slider for controlling movement of the prefocus lens and the lens capable of generating the evanescent wave in a direction substantially parallel to a resist coating surface of the optical disk master, wherein the focus adjustment control means includes: 4. The optical disk master recording apparatus according to claim 2, wherein a lens and a lens capable of generating the evanescent wave are integrally moved in an optical axis direction of the laser beam. 5. A slider for controlling movement of the prefocus lens and the lens capable of generating the evanescent wave in a direction substantially parallel to a resist coating surface of the optical disk master, wherein the focus adjustment control means includes: The optical disk master recording apparatus according to claim 2 or 3, wherein the prefocus lens is moved in the optical axis direction of the laser light without moving a lens capable of generating the optical disc. 6. The apparatus according to claim 2, wherein said gap adjusting means moves a lens capable of generating said evanescent wave in an optical axis direction of said laser beam without moving said prefocus lens. An optical disc master recording apparatus according to any one of the above. 7. An optical disk master recording method for performing exposure recording by irradiating a laser beam corresponding to a recording signal to a resist-coated surface of the optical disk master while rotating the optical disk master coated with the resist. After focusing the laser beam according to the pre-focus lens, the lens that can generate the evanescent wave is further focused, and the evanescent wave leaking from the bottom of the lens that can generate the evanescent wave is not attenuated. Positioning the lens capable of generating the evanescent wave so that the resist-coated surface of the optical disk master is disposed at a distance, and the laser beam is generated by the evanescent wave regardless of a position change of the lens capable of generating the evanescent wave. In order to focus on the bottom surface of the lens that can generate waves, Performs positioning of the lens, the master optical disc recording method characterized by performing exposure recording after the optical axis alignment adjustment between pre-focus lens enables generating the evanescent wave lens.