JP2001023252A - Optical master disk base material, manufacture of optical master disk and optical picking up device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a master disk and to accurately control an operating distance by providing a conductive film over a whole region to be exposed, which is transparent which respect to light having a wavelength equal to the wavelength which an exposing luminous flux has. SOLUTION: The device for manufacturing a master disk has an optical means consisting of a condenser lens 2 which converges a laser beam L projected from a light source to irradiate a layer 101 of a photosensitive resist applied on an optical master disk base material 51 attached to a disk rotary driving device of the device for manufacturing a master disk and a solid immersion lens(SIL) 3 which is an objective lens interposed between the optical master disk base material 51 and the condenser lens 2. A conductive film 102 formed on the side of the optical master disk base material 51 does not generate reflected light even when a laser beam is focused on the photosensitive resist layer 101 and brings recorded data capacity of higher density comparing with the case using an optical master disk forming a conductive film having metal reflection.

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 material that becomes an optical disk master by exposure, a method for manufacturing an optical disk master, and an optical pickup device for recording and reproducing information using an optical recording medium. The present invention relates to an apparatus which enables high-density recording by increasing the numerical aperture of an objective lens.

[0002]

2. Description of the Related Art In recent years, with the development of technology for digitally recording video data of moving images and still images, large-capacity data has been handled, and floppy disks and the like which have been generally used conventionally have been used. Optical recording media such as magneto-optical disks and phase-change optical disks using optical recording with a higher recording density are becoming widespread in place of the magnetic disks described above.

In the optical recording technique, a laser beam is condensed and radiated to a position where data is reproduced on an optical recording medium using an optical pickup device, and the data is read by monitoring the reflected light. . Therefore, the density of the data recorded on the optical recording medium depends on the spot size of the focused laser light. That is, the smaller the spot size of the laser beam, the higher the data density can be.

[0004] The spot size of the focused laser light is
Since it has a characteristic that is proportional to the wavelength (λ) of the laser beam and inversely proportional to the numerical aperture (NA) of the objective lens, in order to increase the recording density of the optical recording medium, Two improvements, that is, shorter wavelength and higher NA, are continuously performed.

Here, the numerical aperture (NA) of the lens is obtained by using the incident angle (θ) of the light to be condensed and the refractive index (n) of the medium on which the light is condensed. Is described. Therefore, when a focusing optical path is provided in air having a refractive index of 1, the numerical aperture is 1
It is virtually impossible to go beyond.

Therefore, as a method of further increasing the numerical aperture, the thickness of the air layer between the lens medium and the optical recording medium is reduced as much as possible, so that there is no air layer optically, that is, the optical contact state. Thus, there is an attempt to realize a numerical aperture exceeding one. Such attempts are, for example, "Terr
is et al., Appl. Phys. Lett. 65 (4), p388-p390, 25 July, 1
994 "or" Terris et al., Appl.Phys. Lett, 68.
(2), p141-p143, 8 January, 1996 '' etc., and using a substantially hemispherical solid immersion lens as an objective lens, with the flat portion of the objective lens facing the surface of the optical recording medium. And in optical contact. The laser light that is incident from the spherical portion of the substantially hemispherical objective lens and collected near the plane portion is:
The light reaches the surface of the optical recording medium without being reflected by the flat surface, and is irradiated onto the optical recording medium. At this time, the numerical aperture of the laser light can be set to a value exceeding 1.

[0007]

However, in order to set the numerical aperture to a value exceeding 1 as described above, the facing surface of the objective lens facing the optical recording medium is optically opposed to the optical recording medium. Must be kept in contact with
The state of optical contact is a state in which the air layer between the opposing surface of the objective lens and the optical recording medium is within 100 nm at the maximum, preferably about 50 nm.

Therefore, in the optical pickup device, unless the thickness of the air layer between the opposing surface of the objective lens and the optical recording medium is controlled to be sufficiently thin as described above, the optical recording medium cannot be used. The decrease in the intensity of the laser light applied to the signal recording surface causes deterioration in the accuracy of the recording signal and the quality of the reproduction signal.

Here, a conductive portion made of a conductive material such as aluminum is provided on a surface of the objective lens facing the optical recording medium, and the conductive portion is provided between the conductive portion and the conductive film of the optical recording medium. It is conceivable to detect the capacitance and detect the distance between the objective lens and the optical recording medium based on the detected capacitance.

In this case, if a conductive material such as aluminum is disposed in a portion which becomes an optical path of the laser light, the laser light is blocked, and therefore, the conductive material which corresponds to a central portion which becomes an optical path of the laser light is used. Must be removed by a technique such as so-called patterning. Such a removal operation is complicated, and is not suitable, for example, when a large number of objective lenses must be processed at once, such as mass production.

Further, since the conductive material forming the conductive portion has a thickness, it is necessary to bring the objective lens close to the optical recording medium even in a portion which does not form an optical path, such as the peripheral side of the objective lens. And it is difficult to reduce the thickness of the air layer to 100 nm or 50 nm or less. That is, when the surface facing the recording medium is relatively large, such as a head slider in a so-called hard disk, the thickness of the electrode material is set to a thickness which cannot be ignored for the thickness of the air layer of 100 nm or less or about 50 nm. It will be.

Further, it is conceivable that only the portion of the opposing surface of the objective lens which becomes the optical path of the laser beam is a protruding portion protruding toward the optical recording medium, and a conductive portion is formed around the protruding portion. In this case, the thickness of the air layer at the portion corresponding to the optical path of the laser beam can be reduced while ensuring a sufficient space for forming the conductive portion. However, in this case, the thickness of the air layer detected via the capacitance is the thickness around the protrusion. Therefore, when the height of the protrusion has an error, the control of the thickness of the air layer that is actually effective in a portion corresponding to the optical path of the laser beam has an error.

[0013] In addition, by using the above-described optical pickup device to expose a master optical disc material having a photosensitive resist layer to produce a master disc, a master disc on which information signals are recorded at a high density can be obtained. (Mastering master) can be manufactured. However, in the optical pickup device using the solid immersion lens as described above, if the optical disc master material has a reflective surface, a condition that a minute light spot cannot be obtained due to interference by reflected light on the reflective surface. Therefore, it has been impossible to form a layer of a metal material that becomes a reflection surface on the optical disc master material. Therefore, it is not possible to use means for detecting the operating distance between the objective lens and the optical disk master material by the capacitance therebetween, and to accurately determine the operating distance between the objective lens and the optical disk master material. It is difficult to control.

Therefore, the present invention provides an optical pickup device using a solid immersion lens as an objective lens so that the manufacturing distance can be easily controlled and the operating distance between the objective lens and the optical recording medium can be accurately controlled. What you want to do.

The present invention also relates to an optical disk master material capable of performing exposure using an optical pickup device using a solid immersion lens as an objective lens, and an optical disk master performing exposure using such an optical pickup device. It is intended to provide a manufacturing method.

[0016]

In order to solve the above-mentioned problems, an optical disk master material according to the present invention comprises an optical recording medium having a base and a photosensitive resist layer formed on the base. An optical disc master material, which becomes an optical disc master by being exposed and developed using a pickup device, is provided with a conductive film that is transparent to light having a wavelength of a light beam to be exposed over the entire surface to be exposed. It is characterized by having.

Further, the method of manufacturing an optical disk master according to the present invention is a method for manufacturing an optical disk master material which is configured as an optical recording medium to be an optical disk master by performing exposure and development processing. Using a transparent conductive film provided over the entire surface of the region where the exposure is performed, the capacitance between the conductive portion of the optical means of the optical pickup device and the conductive film of the optical disk master material is measured. By detecting the operating distance of the optical means, the optical disk master material is exposed through the optical means to manufacture an optical disk master while controlling the operating distance to be constant. .

The optical pickup device according to the present invention includes an optical unit configured to include a solid immersion lens and for converging and irradiating a light beam emitted from a light source onto an optical recording medium, and an optical recording medium of the solid immersion lens. A conductive portion provided on the opposing surface, capacitance detection means for detecting each capacitance between the conductive portion and the conductive film of the optical recording medium, and the capacitance detection Operating distance detecting means for detecting an operating distance between the surface of the optical means closest to the optical recording medium and the surface of the optical recording medium based on the detection result by the means. In this optical pickup device, the conductive portion provided on the opposing surface of the solid immersion lens is formed of a material transparent to light having a wavelength of a light beam.

In the optical disk master material, the optical disk master manufacturing method, and the optical pickup device according to the present invention, a material transparent to the wavelength of a light beam used for recording / reproduction or exposure is used as a conductive material. The operating distance between these optical means and the optical recording medium can be determined and controlled from the capacitance between the optical recording medium and the optical recording medium.

In the above-described optical pickup device,
Since there is no need to remove the conductive material on the optical path of the light beam used for recording / reproduction and exposure, manufacturing is simplified, and the accuracy of detecting the operating distance between the optical means and the optical recording medium is improved. Can be done.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an optical disc master material, a method of manufacturing an optical disc master, and an optical pickup device according to the present invention.

An optical pickup device according to the present invention is an optical pickup device for writing and reading information signals to and from an optical recording medium, and for exposing an optical disk master material formed as an optical recording medium to produce an optical disk master. is there. As shown in FIG. 1, the optical pickup device includes an optical disk master material 51 mounted on a disk rotation drive of a disk master manufacturing apparatus.
Lens 2 that converges a laser beam L emitted from a light source (not shown) to be irradiated on the photosensitive resist layer 101 applied on the substrate, and is interposed between the optical disc master material 51 and the condenser lens 2 An optical unit including a solid immersion lens (SIL) 3 serving as an objective lens is provided. Condensing lens 2 and solid immersion lens 3
Are integrally held by a lens holder 4 serving as a holding member. The lens holder 4 is moved by an electromagnetic actuator 5. The electromagnetic actuator 5 has a focus actuator 5a for moving the lens holder 4 in the optical axis direction of the laser light.

Since the condenser lens 2 and the solid immersion lens 3 are integrally held by one lens holder 4, when the lens holder 4 is moved in the optical axis direction by the focus actuator 5a, the distance between each other is increased. Is moved while maintaining the constant.

The solid immersion lens 3 has a shape obtained by cutting a part of a spherical lens by a plane, and is generally called “SUPER SPHERE SIL” or “H”.
YPER SPHERE SIL ". The solid immersion lens 3 has a spherical portion facing the condenser lens 2 and a flat portion opposite to the spherical portion,
That is, it is held by the lens holder 4 with the facing surface facing the optical disk master material 51.

The solid immersion lens 3 is designed to converge the laser beam L without aberration (satisfies the condition of stigmatic focusing), and as shown in FIG. Where r is the refractive index and n is the refractive index, the thickness t of the solid immersion lens 3 in the optical axis direction of the laser light L is determined as in the following equation.

T = r · (1 + 1 / n) In this embodiment, the converging lens 2 has a numerical aperture of 0.4
5, and a solid immersion lens 3 made of a medium having a refractive index of 1.83 is used. The numerical aperture (NA _eff ) of the entire optical means is represented by the following equation, where the numerical aperture of the condenser lens 2 is NA _obj .

NA _eff = n ² · NA _obj Therefore, the numerical aperture (NA _eff ) of this optical means is
1.5.

As shown in FIG. 2, the bottom surface of the solid immersion lens 3 has a diameter (D) of 1.5 mm, a projection 3a is formed at the center, and a periphery of the projection 3a. 3b is a plane. The projection 3a has a diameter (φ) of about 40 μm and a height of 2 μm.

In the peripheral portion 3b, a film 6 serving as a conductive portion made of a conductive material is formed thinner than the height of the protrusion 3a. This film 6 is transparent to light having the wavelength of the laser beam, and may be formed only on the peripheral portion 3b avoiding the protrusion 3a, or may be provided over the protrusion 3a. Good. The material forming the film 6 includes tin oxide.

Further, a conductive film 102 made of a material having transparency and conductivity to laser light is formed below the photosensitive resist layer 101 on the optical disk master material 51. As a material forming the conductive film 102, there is tin oxide or the like. The conductive film 102 is formed to a uniform thickness by, for example, an evaporation method. By providing the conductive film 102, a capacitance is formed between the film 6 of the solid immersion lens 3 and the conductive film 102 of the optical disk master material 51.

The capacitance value C is defined as S, the area of the film 6 facing the optical disk master material 51, and h as the distance (air gap) between the film 6 and the conductive film 102 of the optical disk master material 51. Then, it is obtained by the following equation.

C = ε ₀ · ε _r · S / h where ε ₀ is the vacuum dielectric constant (8.854 × 1
0 ⁻¹² F / m) and ε _r are relative dielectric constants (almost 1 in air). As described above, since the diameter D of the facing surface of the solid immersion lens 3 is 1.5 mm,
It is about 1.766 × 10 ⁻⁶ (m ² ). Also, the distance h
(Air gap) has a minimum value of 2 μm when the protrusion 3a contacts the optical disk master material 51, that is, when the operating distance is 0 nm, and the operating distance is 50 nm, 10 nm.
When it becomes 0 nm and 200 nm, respectively, 2.05 μm
m, 2.10 μm, and 2.20 μm.

Therefore, the operating distance is 0 nm, 50 n
The capacitance values C at m, 100 nm, and 200 nm are 7.82 pF, 7.63 pF, and 7.4, respectively.
5 pF and 7.11 pF.

When the film 6 is formed on the projection 3a, it is possible to obtain the capacitance corresponding to the operating distance without being affected by the height error of the projection 3a from the peripheral portion 3b. Can be.

The film 6 of the solid immersion lens 3 is
As shown in FIG. 1, it is joined to the lens holder 4 by solder 7. The lens holder 4 is made of a conductive material, for example, aluminum. Thereby, a voltage signal indicating the capacitance value C can be extracted through the lens holder 4.

In the disk rotation driving device of the disk master manufacturing apparatus, as shown in FIG. 3, the optical disk master material 51 is rotationally driven by the spindle motor 11 in a CLV (constant peripheral speed recording) system. Feeding in the tracking direction, that is, relative movement of the optical spot position and the optical disk master material 51 in the radial direction of the optical disk master material 51 is performed by moving the optical pickup device or the spindle motor 11 by the precision moving stage. .

In the disc master manufacturing apparatus, the optical disc master material 51 is irradiated with a laser beam having a wavelength of 413 nm, which is a wavelength at which the photosensitive resist layer 101 is sensitive, by the optical pickup device. The resist layer 101 is exposed, and an information signal is recorded. The photosensitive resist layer 101 thus exposed is subjected to a development process,
Fix the recorded information signal. Photosensitive resist layer 1
The optical disk master material that has been subjected to the development process 01 becomes an optical disk master and is used for manufacturing an optical disk.

Since the conductive film 102 formed on the optical disk master material 51 side is made of a material having transparency to light having a wavelength of 413 nm, laser light having a wavelength of 413 nm is focused on the photosensitive resist layer 101. In this case, unnecessary reflected light is not generated. Therefore, when using this optical disc master material, it is possible to form a light spot according to the optical performance, as compared to when using an optical disc master material in which a conductive film having metal reflection is formed. As a result, the data capacity recorded on the master optical disc can be increased.

As shown in FIG. 3, the optical pickup device has a capacitance detecting means for detecting the capacitance between the solid immersion lens and the material of the master optical disc, based on the detected capacitance. A control circuit serving as an operating distance detecting means for detecting an operating distance between the solid immersion lens and the optical disk master material, and an operating distance control means for controlling the operating distance to a constant distance based on the detection result by the operating distance detecting means It has.

In this control circuit, a voltage signal indicating the capacitance value C taken out of the lens holder of the optical pickup device is supplied to a voltage controlled oscillator (VCO) 13. The voltage-controlled oscillator 13 includes an oscillation circuit that generates a signal in which at least one of the frequency and the phase changes according to the capacitance between the conductive film of the solid immersion lens and the conductive film of the optical disk master material. It is. The voltage controlled oscillator 13 is composed of an LC oscillator. Based on a capacitance value C indicated by the voltage signal and a constant inductance L inside the voltage controlled oscillator 13, a signal having an oscillation frequency f represented by the following equation is obtained. Is output.

F = 1 / 2π√ (LC) Here, as an example, it is assumed that the inductance L inside the voltage controlled oscillator 13 is 100 μH. Therefore, when the operating distance is 0 nm, 50 nm, 100 nm, and 200 nm, the capacitance value C is 7.82 pF,
Since they are 7.63 pF, 7.45 pF, and 7.11 pF, the oscillation frequencies f are 5.69 MHz and 5.
76 MHz, 5.83 MHz, 5.97 MHz.

The output signal of the voltage controlled oscillator 13 has a reference frequency of 5.76 MHz output from the reference voltage controlled oscillator (VCXO) 14, that is, an operating distance of 50 nm.
Is supplied to a frequency-phase comparator (phase-locked loop: PLL) 15 together with a signal having a frequency equal to the oscillation frequency f of the voltage-controlled oscillator 13 at the time. The reference voltage control oscillator 14 is a reference signal oscillation circuit that generates a reference signal. The frequency phase comparator 15 is a comparison circuit that compares the signal output from the voltage controlled oscillator 13 with a reference signal and generates an operating distance detection signal according to the operating distance between the solid immersion lens and the optical disk master material. .

The frequency / phase comparator 15 compares the frequency and phase of the output signal of the voltage controlled oscillator 13 with the frequency and phase of the output signal of the reference voltage controlled oscillator 14, and outputs a signal corresponding to an error between the two. Is output. The output signal from the frequency-phase comparator 15 is phase-compensated by a phase compensation circuit 16 and amplified by an amplifier 17 and then supplied as a control signal for controlling an operating distance to a focus actuator among electromagnetic actuators of an optical pickup device. You.

The operating distance is adjusted to 50 nm by the focus actuator moving the lens holder in the optical axis direction according to the control signal. At this time, the distance between the condenser lens 2 and the optical disk master material 51 is also adjusted to be constant, and the focus servo is realized.

By the operation of the focus servo, an adjustment is made so that the focus position of the laser beam constantly follows the photosensitive resist layer 101 formed on the surface side of the rotating optical disk master material 51.

As described above, in this optical pickup device, by providing the solid immersion lens, the numerical aperture of the optical means is set to about 1.5, and the control for setting the operating distance to 50 nm is performed by controlling the optical means and the optical disk. This is performed with high accuracy based on the capacitance between the master material.

Further, in this optical pickup device, the focus servo is realized by one focus actuator, and the actuator for moving the holder holding the solid immersion lens as the focus actuator and the actuator for moving the holder holding the condenser lens as the focus actuator The configuration is simplified as compared with the configuration using the two actuators.

In this optical pickup device, as shown in FIG. 3, a focus servo is realized by one system of signal processing from the voltage controlled oscillator 13 to the amplifier 17 operating based on the detected capacitance. Therefore, as signal processing for the focus servo, for example, compared with the case where signal processing such as matrix processing of an output signal of a photodetector that has received laser light reflected by the optical disk master material is performed, the focus servo Signal processing is simplified.

In the present invention, as shown in FIG. 2, a film 6 made of a conductive material is formed on the opposite surface of the solid immersion lens 3, and the film 6 is formed under the photosensitive resist layer 101 of the optical disk master material 51. By forming the conductive film 102 having transparency, the capacitance between the solid immersion lens 3 and the optical disk master material 51 is formed. As compared to the case where the capacitance is formed, the capacitance value C is increased due to the decrease in the distance between the electrodes, and the generation of the focus servo control signal based on the capacitance is high. Can be done with precision.

Further, since the conductive film 102 formed on the optical disk master material 51 is formed of a material having transparency with respect to the wavelength of the laser beam, the conductive film 102 is formed in the vicinity of the conductive film 102, For example, even when laser light is condensed on the photosensitive resist layer 101 formed on the conductive film 102, the optical system is compared with a case where a conductive film made of metal is formed. It is possible to form a light spot of a very small size according to the performance of the device.

In the above embodiment, the conductive portion made of a conductive material having transparency is formed on both the optical disk master material and the solid immersion lens. However, when the optical disc master material according to the present invention is used, the solid immersion lens does not necessarily need to have a conductive portion made of a conductive material having transparency. That is, in this case, the solid immersion lens may have a conductive portion made of an opaque conductive material formed avoiding the optical path portion. In addition, when the optical pickup device according to the present invention is used, a conductive portion made of a conductive material having transparency does not necessarily need to be formed in the optical disc master material. That is, in this case, a conductive film made of an opaque conductive material may be formed on the optical disk master material.

Also, in the above-described embodiment, a case has been described where an optical disk master material is used as an optical recording medium to manufacture an optical disk master. However, the optical pickup device according to the present invention uses a phase-change optical disk as an optical recording medium. It can also be used when recording and reproducing information signals using a magnetic disk or a magneto-optical disk.

In the optical pickup device according to the present invention, as shown in FIG. 4, the optical means including the condenser lens 2 and the solid immersion lens 3 is connected to the slider 204.
It is good also as holding and comprising. In the following description, a case will be described in which a phase change optical disk 52 is used as an optical recording medium to record and reproduce information signals.

As shown in FIG. 4, this optical pickup device has a condenser lens 2 for converging a laser beam L emitted from a light source, and a solid immersion lens interposed between the condenser lens 2 and the optical disk 52. (SIL) 3
And an optical unit for condensing the laser light L on the optical disk 52 mounted on a disk rotation driving device (not shown). The condenser lens 2 and the solid immersion lens 3 are mounted on a slider 204. When the optical disk 52 is rotated, the slider 204 forms an air lubricating layer between itself and the optical disk 52 at a speed relative to the optical disk 52 and floats above the optical disk 52. The condenser lens 2 and the solid immersion lens 3 are integrally held by one slider 204, and the distance between them is kept constant even if the slider 204 moves.

The slider 204 is moved by the actuator 205 in the optical axis direction of the laser light. The actuator 205 has an electrostrictive element (PZT) actuator 205a. The function of the actuator 205 is as follows: the presence of an air lubrication layer between the slider 204 and the optical disk 52
4 is to adjust the pressing force applied. That is, the flying height of the slider 204 depends on the optical disk 52 and the slider 2.
It is determined by the balance between the lift generated by the relative speed with the actuator 04 and the pressing force by the actuator 205. As a result, the flying height of the slider 204 floating on the rotating optical disk 52 can be adjusted by the actuator 205.

As shown in FIG. 5, in the solid immersion lens 3, the radius of the surface facing the optical disk 52 is 0.5 mm. Are flush with each other. Also, the bottom surface 2 of the slider 204
04a includes a lift generating unit 2 for mainly generating a lift necessary for floating by the relative speed with respect to the optical disc 52.
04b and a groove 204c are formed.

On the opposite surface of the solid immersion lens 3, a film 206 made of a conductive material having transparency with respect to the wavelength of the laser light L, for example, tin oxide or the like constitutes a conductive portion. The bottom surface 20 of the slider 204
4a.

On the optical disk 52, a metal film formed as a reflection film, for example, an aluminum film, or a phase change material film (GeSbT
e) is formed. As a result, a capacitance is formed between the film 206 made of tin oxide or the like and the conductive material of the optical disk 52. As described above, by detecting the value C of the capacitance, the thickness of the air layer between the opposing surface of the solid immersion lens 3 and the optical disk 52, that is, the air between the slider 204 and the optical disk 52, The thickness (flying height) of the lubricating layer can be determined accurately.

The film 206 of the solid immersion lens 3
Is a bottom surface 204a of the slider 204, as shown in FIG.
Therefore, a voltage signal indicating the capacitance value C can be extracted through the slider 204.

As described above, by adjusting the pressing force applied to the slider 204 by the actuator 205a, the flying height of the slider 204 can be adjusted. Therefore, the thickness of the air lubricating layer between the optical disk 52 and the slider 204 can be adjusted. By detecting the distance between the optical disk 52 and the film 206 of the solid immersion lens 3 and using the control circuit described above with reference to FIG. 3, the flying height of the slider 204, that is, the solid immersion lens 3 and the optical disk It is possible to control the thickness of the air layer between the first and second air gaps 52.

When the optical disk 52 is rotationally driven by the spindle motor 11 in a CAV system in which the number of rotations is constant, the relative speed between the optical disk 52 and the slider 204 varies with the radial position of the slider 204 on the optical disk 52. Will change. In this case, it was difficult to keep the flying height of the slider 204 constant when the pressure applied to the slider 204 was kept constant. However, in the optical pickup device according to the present invention, the flying height of the slider 204 was difficult. The amount is detected and the slider 20
By applying a servo to the pressure applied to 4, the flying height can be easily controlled.

Further, in the optical pickup device according to the present invention, the film 206 made of a transparent material is formed as a conductive portion on the bottom surface 204a of the slider 204 and the surface facing the solid immersion lens 3. In addition, the optical operating distance of the solid immersion lens 3 can be sufficiently reduced. In other words, when the conductive portion is formed of an opaque material, the conductive portion cannot be formed on the portion through which the laser beam passes, that is, on the optical path. Even if the bottom surface of the conductive portion is close to the optical disk, there is a disadvantage that the portion of the optical path is separated by the thickness of the conductive portion, but in the optical pickup device according to the present invention, such a problem exists. There are no major drawbacks.

Therefore, in this optical pickup device, the thickness of the air lubrication layer between the slider 204 and the optical disk 52 can be made thin enough to sufficiently exhibit the characteristics of the slider 204. A light spot corresponding to the optical performance of the solid immersion lens 3 can be formed, and as a result, data can be recorded on the optical disc 52 at high density.

As described above, in this optical pickup device, the use of the solid immersion lens 3 makes it possible to reduce the numerical aperture of the optical means to about 1.5, and to reduce the operating distance of the solid immersion lens 3. Control to 50 nm can be performed with high accuracy based on the capacitance between the conductive part of the optical means and the optical disk.

As shown in FIG. 5, a conductive portion is formed not only on the opposite surface of the solid immersion lens 3 but also on the bottom surface 204a of the slider 204, so that the solid immersion lens 3 and the optical disk 52 can be located between the solid immersion lens 3 and the optical disk 52. Since the capacitance is formed, the distance between the conductive portions is extremely small, and the capacitance value C is increased due to the large area. Therefore, servo control based on this capacitance value is performed. The signal can be generated with high accuracy.

In this optical pickup device, the film 206 can be easily formed because it is not necessary to remove a portion located on the optical path by performing so-called patterning.

In the above embodiment, the film 206 serving as the conductive portion is formed of the solid immersion lens 3.
Is formed on the outermost surface of the opposing surface. However, this membrane 2
06 need not be formed on the outermost surface of the opposing surface of the solid immersion lens 3, and is formed in a state covered with a protective film resistant to friction and the like, for example, a film made of diamond-like carbon or silicon carbide. Is also good.

Further, in the optical pickup device according to the present invention, as shown in FIG. 6, only the solid immersion lens 3 is mounted on the slider 304, and the condenser lens 2 is mounted on another focus actuator 405. You may comprise. Also in this case, a film 30 made of an electrode material that is transparent to light having a wavelength of the laser light L is provided on the surface facing the solid immersion lens 3.
6 is formed as a conductive portion.

In this case, separate drive control is required for the focus actuator 405 for driving the condenser lens 2 and the actuator 305 for adjusting the thickness of the air layer between the solid immersion lens 3 and the optical disk 52. Become. Here, the focus actuator 4
The drive control of 05 can be performed based on an optical signal, and the configuration of each servo circuit can be made almost independent, so that there is little risk that each servo circuit will adversely affect each other. .

Further, in this case, the slider 3
Since the condenser lens 2 is not mounted on the slider 04, the slider 304 including the solid immersion lens 3 can be reduced in size compared with the configuration in which the condenser lens and the solid immersion lens are mounted on the slider as described above. The weight can be reduced, and the servo characteristics such as the seek speed can be improved.

In the above embodiment, the case where a phase change optical disk is used as the optical disk 52 has been described. However, in the present invention, the optical disk 52 is not limited to the phase change optical disk. For example, the above-described effects can be obtained even with a magneto-optical disk.

Further, in each of the above-described embodiments, tin oxide is exemplified as a transparent conductive material. However, in the present invention, these conductive materials are:
If it has transparency to light of the wavelength of the laser light L,
Without being limited to tin oxide, other materials, such as I
It may be TO or the like. The above-described effect can be obtained even when a read-only (ROM) disk is used as the optical disk 52.

Further, in each of the above-described embodiments, the optical disk master material 51 or the optical disk 52 has a signal recording surface on the front surface side. There is no need to provide a surface, and an optical disk master material or an optical disk having a configuration in which a cover layer exists on the signal recording surface may be used.
When there is a cover layer, a large capacitor capacity can be obtained by forming a conductive film made of a conductive material having transparency on the upper surface of the cover layer,
The effects of the present invention can be exhibited. Also, in the case of an optical disc in which a signal recording layer is formed in a plurality of layers per disc, that is, in the case of a so-called multilayer disc, a conductive film made of a conductive material having transparency is formed on the upper surface of the cover layer. Alternatively, by forming a conductive film made of a conductive material having transparency at a position near the surface side, a large capacitor capacity can be obtained, and the effects of the present invention can be exhibited.

The above-described embodiment is a preferred specific example of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is not limited to the specific description in the above description. The present invention is not limited to these embodiments unless stated to limit the invention.

[0075]

As described above, in the optical disk master material, the optical disk master manufacturing method, and the optical pickup device according to the present invention, a material transparent to a wavelength of a light beam used for recording / reproduction or exposure is used as a conductive material. The distance between the optical means and the optical recording medium can be determined and controlled based on the capacitance between the optical means and the optical recording medium.

In the above optical pickup device,
Since there is no need to remove the conductive material on the optical path of the light beam used for recording / reproduction and exposure, manufacturing is simplified, and the accuracy of detecting the operating distance between the optical means and the optical recording medium is improved. Can be done.

That is, the present invention provides an optical pickup device using a solid immersion lens as an objective lens so that the manufacturing distance can be easily controlled and the operating distance between the objective lens and the optical recording medium can be accurately controlled. What you want to do.

The present invention also relates to an optical disk master material capable of performing exposure using an optical pickup device using a solid immersion lens as an objective lens, and an optical disk master performing exposure using such an optical pickup device. It is intended to provide a manufacturing method.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing a configuration of an optical pickup device according to the present invention.

FIG. 2 is a side view showing a configuration of a solid immersion lens constituting an optical unit of the optical pickup device.

FIG. 3 is a block diagram illustrating a configuration of a control circuit of the optical pickup device.

FIG. 4 is a longitudinal sectional view showing a configuration in which optical means is mounted on a slider in the optical pickup device.

FIG. 5 is a longitudinal sectional view showing a configuration of a solid immersion lens in the slider.

FIG. 6 is a longitudinal sectional view showing a configuration in which only a solid immersion lens of the optical means is mounted on a slider in the optical pickup device.

[Explanation of symbols]

2 condenser lens, 3 solid immersion lens, 3
a projection, 3b peripheral part, 4 lens holder, 5 electromagnetic actuator, 5a focus actuator,
6 membrane, 11 spindle motor, 13 voltage controlled oscillator (VCO), 14 reference voltage controlled oscillator (VCX)
O), 15 frequency phase comparator (PLL), 16 phase compensation circuit, 17 amplifier, 51 optical disc master material,
52 Optical Disk

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroji Kuroda 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Kiyoshi Osato 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Kenji Yamamoto 6-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) 5D119 AA22 BA01 BB09 JA44 JB02 MA06 MA15 MA22 5D121 BA05 BB04 BB26 BB38

Claims (12)

[Claims] 1. An optical disc master material which is constituted as an optical recording medium having a base and a photosensitive resist layer formed on the base, and which is exposed and developed using an optical pickup device to become an optical disc master. An optical disc master material comprising: a conductive film that is transparent to light having a wavelength of a light beam to be exposed over the entire surface of an area to be exposed. 2. Exposure and development are performed to expose a conductive film transparent to light having a wavelength of a light beam to be exposed, which is a material of an optical disk master configured as an optical recording medium to be an optical disk master. By using the one provided over the entire surface of the area, the operation of the optical means is detected by detecting the capacitance between the conductive part of the optical means of the optical pickup device and the conductive film of the optical disk master material. A method for manufacturing a master optical disc, comprising: detecting a distance; and controlling the operating distance to a constant value, exposing the master material of the optical disc via the optical means to manufacture a master optical disc. 3. An optical unit comprising a light source, a solid immersion lens, and an optical unit for converging and irradiating a light beam emitted from the light source onto an optical recording medium, and an opposing surface of the solid immersion lens facing the optical recording medium. A conductive portion provided thereon, capacitance detection means for detecting each capacitance between the conductive portion and the conductive film of the optical recording medium, and detection by the capacitance detection means Operating distance detecting means for detecting an operating distance between the surface of the optical means closest to the optical recording medium and the surface of the optical recording medium, based on the result, provided on an opposing surface of the solid immersion lens. The optical pickup device, wherein the conductive portion is formed of a material transparent to light having the wavelength of the light flux. 4. The optical pickup device according to claim 3, wherein the optical means including the solid immersion lens has a numerical aperture exceeding 1. 5. The optical pickup device according to claim 3, further comprising an operation distance control means for controlling the operation distance to a constant distance based on a detection result by the operation distance detection means. 6. The optical pickup device according to claim 5, wherein the numerical aperture of the optical means including the solid immersion lens exceeds 1, and the operating distance control means controls the operating distance within 100 nm. 7. A surface of the solid immersion lens facing the optical recording medium has a projection formed at the center and a flat surface around the projection.
4. The optical pickup device according to claim 3, wherein a conductive portion is formed in the peripheral portion. 8. An opposing surface of the solid immersion lens facing the optical recording medium has a projection formed in a central portion, and a periphery of the projection is a flat surface. The optical pickup device according to claim 3, wherein the optical pickup device is formed over the portion and the peripheral portion. 9. The air-lubricating layer is formed between the surface of the solid immersion lens facing the optical recording medium and the surface of the optical recording medium according to the relative speed of each other. The optical pickup device according to claim 3. 10. The solid immersion lens is held by a holding member, and a surface of the holding member facing the optical recording medium and a surface portion of the optical recording medium are separated from each other in accordance with the relative speed of each other. The optical pickup device according to claim 3, wherein an air lubrication layer is formed between the optical pickup devices. 11. The solid immersion lens is held by a holding member together with a condenser lens for converging a light beam from a light source to the solid immersion lens and entering the solid immersion lens. 2. The method according to claim 1, wherein
0. The optical pickup device according to 0. 12. The operating distance detecting means generates a signal in which at least one of a frequency and a phase changes according to each capacitance between the conductive part of the optical means and the conductive film of the optical recording medium. An oscillation circuit for generating a reference signal, a reference signal oscillation circuit for generating a reference signal, and comparing an output signal of the oscillation circuit with the reference signal to generate an operation distance detection signal corresponding to an operation distance between the optical unit and the optical recording medium. 4. The optical pickup device according to claim 3, further comprising a comparison circuit for generating.