JP2002245655A - Optical device for optical pickup and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device for an optical pickup, which is suitable for high density recording and capable of stably and speedily performing recording, reproducing or erasing operation without needing precise and high dynamic positioning (tracking) between a probe part and a condensing point. SOLUTION: An object lens 3 which condenses collimated light is formed on a substrate 2, and the probe part 6 which generates near-field light (or near- field light and propagating light) is formed at the condensing point (or the vicinity of the condensing point) of the object lens 3. Thus, precise and high dynamic positioning (tracking) between the probe part 6 and the condensing point is not needed and recording, reproducing or erasing operation is stably performed at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical element for an optical pickup suitable for high-density, large-capacity optical recording or magneto-optical recording and a method of manufacturing the same.

[0002]

2. Description of the Related Art A conventional example of this type will be described with reference to several examples.

[PRIOR ART 1] JP-A-2000-21550
There is an example of an optical disk device disclosed in Japanese Patent Laid-Open Publication No. H10-209. In this publication, the optical head has a flying slider that floats on the optical disk, and for example, an AgG
an edge emitting semiconductor laser made of aInP and emitting a laser beam having a wavelength of 630 nm, a collimator lens for shaping the laser beam emitted from the semiconductor laser into a parallel beam, and a fused silica plate for mounting the semiconductor laser on a flying slider , A holder for supporting the semiconductor laser via a piezoelectric element, a polarization beam splitter for separating a parallel beam from the semiconductor laser from the reflected light from the optical disk, and a circular polarization for the parallel beam from the semiconductor laser. A quarter-wave plate for polarizing, a condensing lens and a transparent condensing medium for condensing a parallel beam from the quarter-wave plate, and a beam splitter mounted on a flying slider and reflecting light from the optical disk. And a photodetector input through the interface. Further, the whole is housed in a head case, and the head case is fixed to a tip of a suspension.

A transparent light-collecting medium has, for example, a refractive index n = 1.
Made of heavy flint glass having a height of 1 mm,
It has a length of 2 mm. This transparent condensing medium has an incident surface and a reflecting surface, but the flying slider is formed of a transparent medium having the same refractive index as the transparent condensing medium, and the flying slider surface is configured to correspond to the spot forming surface. The light spot is formed on the spot forming surface of the flying slider. A light shielding film having a pinhole is formed on the spot forming surface of the flying slider.

In the flying slider, a concave portion is formed so as to generate a negative pressure in a portion other than the peripheral portion of the light spot formed on the spot forming surface. The space between the flying slider and the optical disk is kept constant as the flying height by the action of the negative pressure by the recess and the spring force of the suspension. In the proposed example, the flying height is about 0.06 μm.

[Prior Art 2] JP-A-2000-28036
There is an example of a manufacturing method of a microlens disclosed in Japanese Unexamined Patent Publication No. 6 (1994) -67,639. In the gazette proposal example, in order to provide a microlens manufacturing method capable of easily manufacturing a high NA microlens, at least one side, the microlens formed at a position deeper than the substrate surface 1st, 2nd
And a step of bonding the first and second substrates so that the surfaces of the first and second substrates on which the microlenses are formed face each other.

[Prior Art 3] There is an example disclosed in Japanese Patent Application Laid-Open No. 11-45455. In this publication, the objective lens and the solid immersion lens are integrated or bonded together, so that the positional accuracy between the objective lens and the solid immersion lens is easily secured, the spot size is reduced, and For the purpose of realizing recording, reproduction or erasing, collimate coherent light having a predetermined wavelength, focus the collimated light on an optical recording medium as a minute spot, and then focus the collected light. In an optical element for an optical pickup for recording, reproducing, or erasing information on an optical recording medium by using an objective lens for condensing collimated light, the objective lens is formed on a substrate having a thickness equal to the converging length of the objective lens. It is something to do.

[0008]

In the prior art 1, since all the optical systems necessary for recording, reproduction, or erasing are mounted on the slider, the solid state which determines the light spot diameter on the recording medium dominantly is determined. The optical alignment with the immersion mirror can be determined at the time of manufacture, and there is no need to record, reproduce, or erase information on the recording medium while aligning the two. If the slider and the optical system that focuses light on the solid immersion mirror are mechanically separated and installed outside the slider, the focus of the optical system must be aligned with the incident surface of the solid immersion mirror .

Therefore, it is necessary to perform high-precision and high-speed positioning and tracking between the external optical system and the solid immersion mirror. However, it is technically very difficult. In addition, since the solid immersion mirror has an aspherical curved surface and uses glass instead of a resin that can be manufactured by injection molding or the like, it must be subjected to technically difficult aspherical polishing.

In the prior arts 2 and 3, in order to improve this point, the lens is integrally formed with the slider substrate by photolithography and etching, not by polishing, but by a method suitable for batch mass production.

The present invention eliminates the need for precise and advanced dynamic positioning (tracking) between the probe section and the focal point.
An object of the present invention is to provide an optical element for an optical pickup suitable for high-density recording in which reproduction or erasing operation can be performed stably and at high speed, and a method for manufacturing the same.

Further, the present invention provides an optical element for an optical pickup capable of realizing a high light use efficiency of a laser light source to achieve the above object, and a method of manufacturing the same.

Further, the present invention achieves a higher recording density to achieve the above object.

Further, according to the present invention, an optical system can be formed on a slider without using a technically difficult solid immersion mirror, and an excellent feature of low cost and high reliability is achieved. While reducing the size and weight of the equipment,
It is an object of the present invention to provide an optical element for an optical pickup suitable for high-density recording that can achieve high operation speed and high reliability.

[0015]

According to the first aspect of the present invention,
Recording, reproducing or erasing information on the optical recording medium is performed by injecting coherent light having a predetermined wavelength, collimating the light, and condensing the collimated light as a minute spot on the optical recording medium. In the optical element for an optical pickup, an objective lens for condensing the collimated light is formed on a substrate, and near-field light or near-field light and propagating light are collected at or near the converging point of the objective lens. It is characterized in that a probe part which generates is formed.

Accordingly, an objective lens for condensing the collimated light is formed on the substrate, and a probe unit for generating near-field light or near-field light and propagation light at or near the converging point of the objective lens. The need for precise and sophisticated dynamic positioning (tracking) between the probe unit and the focal point is eliminated, and the recording, reproduction, or erasing operation can be performed stably and at high speed.

According to a second aspect of the present invention, in the optical element for an optical pickup according to the first aspect, the probe section comprises:
The film is formed by forming a minute opening in a film that is deposited on the substrate and does not transmit the coherent light.

Therefore, since the probe portion is formed by forming a small opening in the film that is deposited on the substrate and does not transmit coherent light, precise and high-level dynamic alignment between the probe portion and the condensing point is performed. (Tracking) becomes unnecessary, and recording, reproduction, or erasing operation can be performed stably and at high speed.

According to a third aspect of the present invention, in the optical element for an optical pickup according to the first aspect, the probe section comprises:
It is characterized in that the film that is deposited on the substrate and does not transmit the coherent light is formed by a hole penetrating in a tapered shape so that the medium facing surface side becomes a minute opening.

Therefore, the probe portion is formed by a hole which is formed on the substrate and does not transmit coherent light through a tapered shape so that the medium facing surface side becomes a minute opening. Precise and advanced dynamic alignment (tracking) of the light and the focal point is not required,
Reproduction or erasing operation can be performed stably and at high speed.

According to a fourth aspect of the present invention, in the optical element for an optical pickup according to the first aspect, the probe section comprises:
It is characterized in that the coherent light is formed as a tapered projection whose material facing side is made thinner by transmitting the material.

Therefore, since the probe section is formed as a tapered protrusion whose medium facing side is narrowed by a material that transmits coherent light, precise and advanced dynamic positioning (tracking) between the probe section and the condensing point is performed. ) Becomes unnecessary, and the recording, reproducing or erasing operation can be performed stably and at high speed.

According to a fifth aspect of the present invention, in the optical element for an optical pickup according to the first aspect, the probe section comprises:
It is characterized in that the medium facing side is formed as a tapered projection made thinner from the same material as the substrate.

Therefore, since the probe portion is formed as a tapered protrusion having the medium facing side made thinner from the same material as the substrate, precise and sophisticated dynamic positioning (tracking) between the probe portion and the light condensing point is unnecessary. Thus, the recording, reproducing, or erasing operation can be performed stably and at high speed.

According to a sixth aspect of the present invention, in the optical element for an optical pickup according to the first aspect, the probe section comprises:
It is characterized in that it is formed as a tapered projection in which the medium facing side is made thinner by a material having a higher refractive index than the substrate material.

Therefore, since the probe section is formed as a tapered protrusion whose medium facing side becomes thinner with a material having a higher refractive index than the substrate material, the probe section and the focusing point can be precisely and highly dynamically positioned. Matching (tracking)
Becomes unnecessary, and the recording, reproducing or erasing operation can be performed stably and at high speed.

According to a seventh aspect of the present invention, coherent light having a predetermined wavelength is incident, and this light is collimated.
An optical pickup optical element for recording, reproducing or erasing information on the optical recording medium by condensing the collimated light as a minute spot on the optical recording medium; Forming, on a substrate, a second objective lens coaxial with the optical axis of the first objective lens and further condensing the light condensed by the first objective lens; A probe section for generating near-field light or near-field light and propagation light is formed at or near the focal point of the objective lens.

Therefore, it is possible to improve the light use efficiency of the light source while realizing the objects of the first to sixth aspects of the present invention.

According to an eighth aspect of the present invention, in the optical element for an optical pickup according to the seventh aspect, the probe portion is
The film is formed by forming a minute opening in a film that is deposited on the second objective lens and does not transmit the coherent light.

Therefore, the light use efficiency of the light source can be improved.

According to a ninth aspect of the present invention, in the optical element for an optical pickup according to the seventh aspect, the probe section comprises:
The film deposited on the second objective lens and not transmitting the coherent light is formed by a tapered hole penetrating the medium facing surface so as to form a minute opening.

Therefore, the light use efficiency of the light source can be improved.

According to a tenth aspect of the present invention, in the optical element for an optical pickup according to the seventh aspect, the probe portion has a tapered shape in which a medium facing side is made thin by a material that transmits the coherent light. Characterized by being formed on an objective lens.

Therefore, the light use efficiency of the light source can be improved.

According to an eleventh aspect of the present invention, in the optical element for an optical pickup according to the seventh aspect, the probe portion has a tapered shape in which the medium facing side is made thinner by the same material as the second objective lens. 2 is formed on the objective lens.

Therefore, the light use efficiency of the light source can be improved.

According to a twelfth aspect of the present invention, in the optical element for an optical pickup according to the seventh aspect, the probe portion is made thinner on the medium facing side by a material having a higher refractive index than the material of the second objective lens. It is characterized in that it is formed on the second objective lens as a tapered projection.

Therefore, the light use efficiency of the light source can be improved.

The invention of claim 13 is the third or ninth invention.
The optical element for an optical pickup according to the item, characterized in that the minute opening at the tip of the hole penetrated in a tapered shape has an elongated shape.

Therefore, in realizing the invention of claim 3 or 9, since the minute opening at the tip of the hole has an elongated shape,
Even higher recording density can be realized.

According to the fourteenth aspect of the present invention,
13. The optical element for an optical pickup according to 6, 10, 11 or 12, wherein the apex portion of the tapered projection has an elongated shape.

Accordingly, in realizing the invention described in claims 4, 5, 6, 10, 11 and 12, since the apex of the tapered projection is elongated, higher recording density can be realized.

According to a fifteenth aspect of the present invention, in the optical element for an optical pickup according to any one of the first to fourteenth aspects, an optical system for recording, reproducing, or erasing information on the optical recording medium is provided together with the objective lens. Another constituent optical component is mounted on the substrate.

Accordingly, an optical system can be formed on the slider without using a technically difficult solid immersion mirror as in the prior art 1, thereby achieving low cost and high reliability. While achieving excellent features,
It is possible to provide an optical element for an optical pickup suitable for high-density recording capable of realizing miniaturization and weight reduction of an apparatus, high operation speed, and high reliability.

According to a sixteenth aspect of the present invention, in the optical recording method, coherent light having a predetermined wavelength is incident, the light is collimated, and the collimated light is condensed on an optical recording medium as a minute spot. A method for manufacturing an optical element for an optical pickup for recording, reproducing, or erasing information on a medium by using a semiconductor manufacturing process, wherein the first element for condensing the collimated light is provided. Forming an objective lens on the substrate, forming a concave surface on the side opposite to the first objective lens formed on the substrate, and having a higher refractive index than the substrate with respect to the concave surface A second objective lens is formed by depositing a material and further condensing the light collected by the first objective lens at a position coaxial with the optical axis of the first objective lens. And processing the material having a higher refractive index than the substrate deposited on the concave surface to produce near-field light or near-field light and propagation light on the second objective lens. And forming a mold probe portion.

Therefore, a manufacturing method suitable for the optical element for an optical pickup as described above can be provided.

[0047]

Embodiments of the present invention will be described.

[First Embodiment] A first embodiment of the present invention will be described with reference to FIGS. FIG.
FIG. 1 is a vertical sectional side view showing a configuration of an optical element 1 for an optical pickup according to the present embodiment. This optical pickup optical element 1
For example, an objective lens 3 having a microlens structure for converging collimated light is formed integrally on a transparent substrate 2 made of glass, quartz, or the like. Also, the substrate 2
The thickness at the portion of the objective lens 3 is set to a thickness at which the objective lens 3 collects light.

In the optical element 1 for an optical pickup configured as described above, the collimated light from the optical system 4 becomes light converged by the objective lens 3 and is collected on the bottom surface of the substrate 2. Further, in the present embodiment, the solid immersion lens is not provided, but since the smallest spot is formed in the substrate 2, the wavelength of light in the substrate 2 is
Is multiplied by the reciprocal of the refractive index. Assuming that the refractive index of the lens is n, the spot size W 'is represented by the following equation (1): W'∝λ / nsin θ' (1)

The focal point of the objective lens 3 is located on the approximate surface of the substrate 2, and a light-shielding film (a film that does not transmit coherent light) 5 located on this surface has a small opening 6. The diameter of the minute aperture 6 (not necessarily a circle) is made smaller than the spot size at the converging point. In particular, if the diameter is smaller than the so-called diffraction limit, the significance of the present embodiment is increased.

In such a configuration, the near-field light 7 localized in a region from the surface of the light shielding film 5 to a distance substantially equal to the diameter of the aperture may exist. Since the region where the near-field light 7 exists is almost the same as the minute aperture 6, if the diameter of the minute opening 6 is set to be equal to or less than the diffraction limit, high-density optical recording exceeding this can be performed.

As described above, in the prior art, when the recording medium is moved relative to the slider, double tracking is required. In this regard, in the present embodiment, since the collimated parallel light is incident on the objective lens 3 integrated with the substrate 2 functioning as a slider, the accuracy of the alignment between the collimated light and the objective lens 3 is high. , Directly,
It may be much lower than irradiating the micro aperture 6 with condensed light from the external optical system 4. For example, as shown in FIG. 2, even if the small aperture 6 and the external optical system 4 are displaced, light can be focused on the small aperture 6 without any problem. Since the relative positions of the objective lens 3 and the minute aperture 6 are already integrated by the substrate 2, there is almost no displacement.

Then, the substrate 2 on which the objective lens 3 and the minute aperture 6 are formed is used as an optical element 1 for an optical pickup for recording, reproducing or erasing an optical recording medium.
At this time, the optical element is provided with an actuator, a light source, and a light receiving unit which are not shown but operate on a target pit.

The lower part in FIG. 1 is patterned (chamfered) so that the optical element 1 for optical pickup itself can float at a desired floating amount. However, the lower part is controlled so that the floating amount can be controlled using an actuator. You may comprise. Further, the optical pickup optical element 1 may be maintained at a distance from the recording surface by a method other than floating.

FIG. 3 is a process chart sequentially showing the steps of manufacturing the optical element 1 for an optical pickup according to the present embodiment. The objective lens 3 is formed on one side of the substrate material as described above in the following procedure.

(A) First, a photosensitive material (resist) 8 is applied on the glass substrate 2. The thickness of the resist 8 to be applied is determined by the height of the objective lens 3 formed on the substrate 2 and the ratio (selectivity ratio) of the etching rate of the substrate material to be etched using a photosensitive material as the resist 8 and the etching rate of the resist 8. ). For example, when both etching rates are equal (selectivity 1), the thickness of the resist 8 is made equal to the height of the objective lens 3 to be formed. Also,
If the etching rate of the material of the substrate 2 is twice as large as the etching rate of the resist 8 (selectivity 2), the resist 8
May be の of the height of the objective lens 3.

As a photosensitive material to be applied on the substrate 2, a photoresist or a photosensitive dry film used in ordinary semiconductor manufacturing is used. Specifically, OF
PR-800 (positive resist), OMR-85 (negative resist), or the like may be used. The shape of the photomask used in the step of transferring the shape to the resist 8 (photolithography step) changes depending on the selection of the positive type or the negative type, but the basic manufacturing procedure does not change. In this embodiment, a case where a positive resist is used will be described.

(B) Next, light is irradiated through a mask (photomask) in which a pattern equivalent to the diameter of the objective lens is formed on the resist 8 formed on the substrate 2 to expose the photosensitive material. Thus, when development is performed after light irradiation, the substrate 2
The pattern resin 9 equivalent to the diameter of the objective lens remains on the top.

(C) Subsequently, the remaining pattern resin 9
To the resist surface by applying heat and / or pressure to the surface of the resist 10 by the effect of gravity and surface tension.
To form The temperature and pressure to be applied vary depending on the resist shape.
The pressure may be selected in the range of 1 to 10 atm.

(D) (e) Further, the glass substrate 2 is subjected to etching (anisotropic etching) in a direction perpendicular to the substrate by using the resin 10 having a convex lens shape formed as described above as a mask. As a means for this etching, dry etching usually used in a semiconductor manufacturing process can be used. Specifically, reactive ion etching (RIE)
And electron cyclotron resonance etching (ECR). The gas used for dry etching is selected according to the substrate material.

For example, when the substrate material is glass, CF
₄ , CHF ₃ or the like is used. In order to adjust the etching rate and the selectivity, N ₂ , O
₂ , a gas such as Ar may be mixed. That is, the objective lens 3 is formed on the substrate 2 by the above steps.

(F) A light shielding film 5 is deposited on the surface opposite to the surface on which the objective lens 3 is formed.

(G) A small opening 6 having a diameter smaller than the diffraction limit is formed in the light shielding film 5.

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIGS. The same parts as those described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted (the same applies to the following embodiments).

FIG. 4 is a vertical sectional side view showing the structure of the optical element 11 for an optical pickup according to the present embodiment. In FIG. 4, under the same conditions as those described with reference to FIG.
Is formed in a convex shape with respect to a position below the surface of the substrate 2. In order to produce this shape, a photomask 12 having a pattern as shown in FIG. 5 (in the drawing, it is a mere hole shape, but it is given a gradation so that the exposure amount becomes smaller toward the center). Alternatively, a method of manufacturing by reflowing the resist as in the case of FIG. 3 can be adopted.

[Third Embodiment] A third embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a vertical sectional side view showing the configuration of the optical element 13 for an optical pickup of the present embodiment. In contrast to the above-mentioned objective lens 3 having a convex shape with respect to the base 2 surface, in the optical element 13 for an optical pickup, the objective lens 14 is formed with a concave shape with respect to the substrate 2 surface. At this time, the refractive index of the objective lens 14 is set to be higher than the refractive index of the substrate 2. The thickness of the substrate 2 is set to a length at which the minimum spot size can be obtained on the bottom surface of the substrate 2 in this optical system.

FIG. 7 is a process chart showing the steps of manufacturing the optical element 13 for an optical pickup according to the present embodiment in the order of steps.

Here, an objective lens 14 having a concave lens shape having a higher refractive index than the substrate 2 is formed. The formation of the concave lens is performed basically in the same manner as the formation of the above-mentioned convex lens. In this embodiment, a case where a negative resist is used will be described as an example.

(A) A negative resist 15 is applied to the surface of the substrate on which a solid immersion lens is to be formed. (B) The resin is left around the substrate 2 except for the portion 16 where the objective lens 14 is formed by using the photolithography process described above. (C) Next, a resist 17 is applied to the entire surface including the portion where the objective lens 14 is formed. This is an application for promoting thermal deformation of the resin, and the application thickness may be small. Specifically, the thickness may be 5 μm or less as required. (D) Subsequently, heat and / or
The resin is deformed by the action of pressure to form a concave lens shape 18. (E) (f) Further, using the same etching method,
A concave lens shape portion 19 is formed on the substrate 2. (G) Next, a material 20 having a higher refractive index than the substrate 2 is formed on the concave lens shape portion 19. In the present embodiment, a target having a desired refractive index is used as a target, and a sputtered film is formed on the surface of the substrate 2 including the concave lens-shaped portion 19 by using a sputtering method. (H) Further, the objective lens 14 is formed by selectively leaving the sputtered film 20 on the concave lens shape portion 19 by etching back and flattening the surface of the substrate 2. (I) A small opening 6 having a diameter equal to or less than the diffraction limit is formed in the light shielding film 5.

The optical element 13 for an optical pickup is manufactured by the steps shown in FIG.

[Fourth Embodiment] A fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is an explanatory diagram illustrating a manufacturing process of the optical element 21 for an optical pickup according to the present embodiment.

In the present embodiment, two objective lenses 14a and 14b shown in the third embodiment are prepared and bonded together. In the bonding method, an adhesive may be used to firmly fix the two substrates 2a and 2b, or electrochemical bonding may be used. As the adhesive, an ultraviolet curable resin having a refractive index substantially equal to that of the substrates 2a and 2b is used. Further, direct bonding at room temperature may be used. Room temperature bonding is performed by so-called RCA cleaning of a mirror-polished silicon wafer, glass substrate, or metal substrate.
^-9 Ar FAB (Fast At) in a Torr vacuum chamber
omic Beam) on each of the two substrates 2a and 2b for 300se.
After irradiating about c times at the same time, pressure bonding is performed at a pressure of 10 MPa. The bonding strength after returning to the atmosphere becomes 12 MPa or more.

[Fifth Embodiment] A fifth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a vertical sectional side view showing the configuration of the optical element 22 for an optical pickup of the present embodiment.

In the present embodiment, two objective lenses 3a and 3b shown in the optical element 11 for an optical pickup of the second embodiment are prepared and bonded together. The bonding method may be the same as in the above-described fourth embodiment.

[Sixth Embodiment] A sixth embodiment of the present invention will be described with reference to FIG. In the present embodiment, for each of the optical elements 1, 11, 13, 21, 21 and 22 for an optical pickup of each of the above-described embodiments, a high refractive index film that has a higher refractive index than the substrate 2 is provided on the bottom surface of the substrate 2. In this case, a rate film 23 is provided.

That is, by providing the high refractive index film 23 at the position of the minimum spot size of the objective lens 3 or 14,
In the high refractive index film 23, the wavelength of light is multiplied by the reciprocal of the refractive index of the substrate 2 to obtain a spot size as represented by the above-described equation (1). As a result, the spot size becomes smaller, so that the near-field light 7 emitted from the minute aperture 6
Light intensity increases. That is, the light use efficiency increases.
According to the process of the above-described embodiment, after the process of manufacturing the objective lens 3 or 14 is performed, a high-refractive-index material is deposited by sputtering or the like to form a high-refractive-index film 23, and then the light-shielding film 5 is formed. It is sufficient to deposit the material and to make the minute opening 6 therethrough.

[Seventh Embodiment] A seventh embodiment of the present invention will be described with reference to FIGS. FIG.
FIG. 2 is a vertical sectional side view showing the configuration of the optical element for an optical pickup 24 of the present embodiment.

In the illustrated example, the structure is substantially the same as that of the optical element 1 for an optical pickup shown in FIG. 1. However, the minute opening 25 of the light shielding film 5 serving as a probe portion is gradually increased toward the recording medium. It is formed in a tapered shape with a reduced size. That is, it is formed as a hole penetrated in a tapered shape.

By doing so, the minute opening 25 can be manufactured more easily than the case shown in FIG. In other words, the aperture size equal to or smaller than the diffraction limit is about 100 nm, which is a very difficult value even with the latest semiconductor processing process. However, this can be realized relatively easily by using the crystal axis anisotropic etching of single crystal silicon described later.

FIG. 12 is a process chart showing the steps of manufacturing the optical element 24 for an optical pickup according to the present embodiment in the order of steps.

(A) Single-crystal Si having a thickness of several hundred μm
A so-called SOI substrate in which a SiO ₂ (silicon oxide) layer 27 of about 1 μm and a single-crystal Si layer 28 of about 5 to 10 μm are laminated on a (silicon) substrate 26 is used. At the top is an SiO ₂ layer 29 with a thickness of several 100 nm.

The SiO ₂ layer 29 where an opening is to be formed
Is removed by photolithography and etching. The size of the portion to be removed is determined so that the size of the opening is several tens nm to several hundreds nm.

(B) The single crystal Si layer 28 is etched by alkali etching. At this time, as an etchant, hydrazine (N ₂ H ₄ .H ₂ O), KOH,
NaOH, CaOH, EDP (Ethylene diamine Pyroc
atechol (water)), TMAH (tetramethyl ammoniumhy)
A crystal axis anisotropic etchant such as droxide or (CH ₃ ) ₄ NOH) is used. The temperature of the etchant is about 50 ° C. to 80 ° C. These etchants are crystal axis anisotropic etchants, thereby forming an inverted pyramid-shaped hole surrounded by the (111) plane. If the tip portion is made to be just the SiO ₂ layer 28, the hole bottom surface will be square or rectangular. This one side is from several tens nm to several tens
The patterning dimension of the first SiO ₂ layer 29 is determined so as to be 0 nm.

(C) The uppermost SiO ₂ layer 29 is removed with hydrofluoric acid or the like.

(D) The glass 30 is placed on the single crystal Si layer 28, and the electrode 31 is placed on the single crystal Si substrate 26 and the glass 30.
a and 31b are pressed against each other. As the glass 30, for example, # 7740 manufactured by Corning Incorporated, USA The thickness is preferably about 0.1 mm to 3 mm. While heating to 350 ° C. in a nitrogen gas or vacuum, a positive voltage Vb of about 300 V is applied to the single crystal Si substrate 26 for about 10 minutes.

According to such a method, the glass 30 is bonded to the single crystal Si layer 28 as shown in FIG. Between the single-crystal Si substrate 26 and the single-crystal Si layer 28 s, there is an SiO ₂ layer 27 as an insulating layer. However, since the temperature is high and the voltage is high, the current penetrates or leaks, and the current necessary for bonding is reduced. Flows. This bonding method is called anodic bonding.

In (f) to (h), the objective lens 3 is manufactured as in the case described with reference to FIG.

(I) The bonded substrate is put again in the alkaline etchant. The single crystal Si substrate 26 is etched by an alkali etchant. For example, KO
H also etches SiO ₂ (the main component of glass) in addition to Si, but the glass 30 is very thick and is not etched at all. Further, since the single-crystal Si layer 28 and the glass 30 are bonded very firmly, there is no possibility that the etchant penetrates between the two, so that the single-crystal Si layer 2
8 is not etched. Therefore, single crystal Si
Only the substrate 26 is etched. The etching speed of the SiO ₂ layer 27 with respect to the alkaline etchant is Si.
Therefore, the etching can be stopped when the single crystal Si substrate 26 is completely etched.

(J) The fine openings 25 are formed by removing the SiO ₂ layer 27 with hydrofluoric acid. After that, it is cut into a desired size with a dicing saw.

If it is desired to prevent the objective lens 3 from being slightly etched, the objective lens 3 may be shielded with an O-ring or the like so as not to be exposed to an alkali etchant or hydrofluoric acid, or may be protected with an alkali wax or the like.
Should be covered.

Further, a metal film may be deposited on the slope inside the opening 25 in order to make the light shielding more complete.

[Eighth Embodiment] An eighth embodiment of the present invention will be described with reference to FIG. In this embodiment, a configuration example in which each of the optical elements 1, 11, 13, 21, and 22 for the optical pickup of each of the above-described embodiments is configured by a tapered minute opening 25 instead of the minute opening 6 will be described. Things.

[Ninth Embodiment] A ninth embodiment of the present invention will be described with reference to FIG. In the present embodiment, in each of the optical elements 1, 11, 13, 21, and 22 for the optical pickup according to the eighth embodiment described above, the high refractive index material 32 is filled in the tapered minute opening 25. Things.

As a result, the light use efficiency is increased as in the case described with reference to FIG. As a step, after FIG. 12C, a high refractive index material 32 is deposited in the tapered minute opening 25, flattened by etch back and the like, and the silicon surface is exposed. May be performed.

[Tenth Embodiment] A tenth embodiment of the present invention will be described with reference to FIGS. FIG.
FIG. 3 is a vertical sectional side view showing a configuration of an optical element 33 for an optical pickup according to the present embodiment. Here, the structure is substantially the same as that of the optical element for optical pickup 24 shown in FIG. 11, but the shape of the probe portion 34 is a tapered projection structure in which the side facing the recording medium becomes thin.

With such a structure, the light incident on the protrusion taper is repeatedly reflected between the opposed tapered surfaces, and condensed on the protrusion tip. Therefore, the light incident on the bottom surface of the protrusion can be used effectively, and the light use efficiency is high. Near-field light 7 is emitted from the tip.

Here, the optical element 33 for the optical pickup which emits the near-field light 7 has been described. However, by optimizing the shape of the protrusion by the completely same manufacturing method, the near-field light and the propagation light are inter-mode interference. And an optical element for an optical pickup having higher light use efficiency can be realized.

Such an optical element 33 for an optical pickup
Will be described with reference to FIG.

(A) First, the objective lens 3 is manufactured in the same manner as in FIGS. 3 (a) to 3 (e). (B) Thereafter, a pattern resin 35 is formed at the focal position of the objective lens 3 by photolithography. (C) Using this as a mask, a projection 36 is formed on the glass substrate 2 (transfer of a resin pattern) in the same manner as when the objective lens 3 was manufactured. (D) The light-shielding film 5 is deposited on the protrusion 36 side. (E) The light-shielding film 5 at the tip of the protrusion 36 is removed by FIB or chemical mechanical polishing.

Although the present embodiment has been described with respect to the example in which the convex objective lens 3 is formed on the surface of the substrate 2, the objective lens 3 shown in FIGS. 3, 6, 8 and 9 is used. , 1
4 may be applied.

[Eleventh Embodiment] The eleventh embodiment of the present invention will be described with reference to FIGS. FIG. 17 is a vertical sectional side view showing the configuration of the optical element 33 for an optical pickup of the present embodiment. In the present embodiment, FIG.
5, but has a structure in which a high-refractive-index material 37 having a higher refractive index than the substrate 2 is filled in the tapered minute opening 25 of the protruding probe portion 34. ing.

As a result, the wavelength in the probe section 34 is shortened, so that the spot diameter emitted from the tip of the projection can be reduced. Further, since the wavelength is relatively short with respect to the diameter of the minute opening 25, the light use efficiency is also increased.

In the case of the present embodiment, both the near-field light and the propagating light can be generated by inter-mode interference by optimizing the shape of the protrusion by the same manufacturing method. An optical element for an optical pickup can be realized.

FIG. 18 is an explanatory view showing the steps of manufacturing the optical element 33 for an optical pickup of this embodiment in the order of steps.

(A) Single-crystal Si having a thickness of several 100 μm
On a (silicon) substrate 26, a SiO ₂ (silicon oxide) layer 27 of about 1 μm and a single-crystal Si layer 28 of about 5 μm to 10 μm
Are stacked, that is, a so-called SOI substrate is used.

(B) (c) The glass 30 is placed on the single crystal Si layer 28, and the electrodes 31a and 31b are pressed against the single crystal Si substrate 26 and the glass 30. As the glass 30, for example, # 7740 manufactured by Corning Incorporated in the United States is used. The thickness is preferably about 0.1 mm to 3 mm. While heating to 350 ° C. in a nitrogen gas or vacuum, a positive voltage Vb of about 300 V is applied to the single crystal Si substrate 26 for about 10 minutes. By such a method, the glass 30 is bonded to the single crystal Si layer 28 as shown in FIG. Between the single-crystal Si substrate 26 and the single-crystal Si layer 28, an insulating layer of SiO
_{Although the two} layers 27 are provided, the temperature is high and the voltage is high, so that the current penetrates or leaks, and the current required for the junction flows.
This bonding method is called anodic bonding.

(D)-(g) The objective lens 3 is manufactured in the same manner as in FIGS. 3 (a)-(e).

(H) to (i) Single-crystal Si substrate 26 and S
The iO ₂ layer 27 is removed as in the case of FIG.

(J) Thereafter, the pattern resin 35 is placed at or near the focal position of the objective lens 3 by photolithography.
To form

(K) Using this as a mask, a projection shape is formed on the high refractive index material 37 (transfer of the resin pattern) in the same manner as when the objective lens 3 was manufactured. At this time, the high refractive index material 37 is silicon. The refractive index of silicon is n = 3.7 at a wavelength λ = 780 nm.
And very high. In the case of a thickness of about 5 μm, the transmittance is about 40%. Further, a light shielding film 5 is deposited on the protrusion side.

(L) The light shielding film 5 at the tip of the projection is
Alternatively, it is removed by a method such as chemical mechanical polishing.

In this embodiment, an example in which the convex objective lens 3 is formed on the surface of the substrate 2 has been described, but the objective lens 3 shown in FIGS. 3, 6, 8 and 9 is used. , 1
4 may be applied.

[Twelfth Embodiment] A twelfth embodiment of the present invention will be described with reference to FIGS.
This embodiment is applied to a probe proposed by the present applicant as Japanese Patent Application No. 11-157699. In the proposed example, in order to achieve a small spot in a direction parallel to the polarization direction of the incident light, and to realize even higher efficiency, a substrate having light transmittance and a substrate formed on this substrate A projection made of a material having a refractive index higher than that of the substrate, the projection having one or more taper angles on its outer wall, and a vertex of the projection having an elongated shape. , And near-field light or propagating light or both near-field light and propagating light are generated at the tip. Here, in the proposal example, the projection type probe is used. However, in the present embodiment, the projection type probe is formed as a hole-shaped probe portion 41.
Since the medium that causes the inter-mode interference is air (or vacuum), the refractive index is lower than that of the proposed example, and the spot diameter increases accordingly, but the inter-mode interference itself occurs.
Similar effects due to inter-mode interference can be obtained.

Here, in the probe part 41 of the optical element 40 for an optical pickup according to the present embodiment, as shown in FIG.
For example, it has a so-called elongated shape such as an oval shape or a rectangular shape. FIG. 20 shows a sectional view thereof. In the tapered hole 42 shown in FIGS. 19 and 20, the shape of the opening 42a on the bottom surface is rectangular. As shown in FIG. 21, the substrate 2 on which the objective lens 3 is formed is provided on the light shielding film 5 or the substrate 2 on which the opening 42a is formed. As shown in FIG. 21, the moving direction of the recording medium 46 and the direction of the short side may be the same, or may be reversed, or may be inclined. 48 is a support arm.

An example of the manufacturing method may be the same as the case described above with reference to FIG. However, in FIG.
SiO _{2 is formed} so that the opening 42a on the bottom surface has a rectangular shape.
Is patterned. FIG. 12 shows the objective lens 3.
The shapes and configurations shown in (a) to (e) may be used. Further, the high refractive index material 32 can be filled in the tapered hole 42 as in the case of FIGS. Thereby, the light use efficiency is increased. As a step, after the step shown in FIG.
Is deposited, planarized by etch back or the like, and the silicon surface is exposed. Thereafter, the same steps as those shown in FIG.

The opening 42a at the bottom of the tapered hole 42 will now be described.
The effect obtained by making the shape of a rectangle rectangular will be described. Specifically, as will be described later, by making the shape of the opening 42a on the bottom surface into a so-called elongated shape, a substantially elliptical beam spot generated by inter-mode interference can be moved in the major axis direction.
That is, a small spot can be realized even in a direction parallel to the polarization direction of the incident light.

The material for forming the tapered hole 42 may be single crystal silicon as described above with reference to FIG. 12, or a metal layer (for example, Al, Au) may be formed on the material for forming the tapered hole 42. ) May be formed to a thickness that does not allow light to pass through, for example, by a thin film forming technique such as an evaporation method. This metal film is formed to a thickness of about 100 nm or more when using, for example, an Al material. This metal layer is formed on the tapered surface of the hole. Such a probe unit 41 is provided on the glass substrate 2 on which the objective lens 3 is provided.
When light is incident from the side, the light is scattered at the tapered portion and condensed so as to increase the light intensity at the bottom opening 42a, and near-field light is generated between the bottom opening 42a and the optical recording medium 46. 7 is generated. By forming the metal layer, light other than light generated from the opening 42a on the bottom surface can be blocked, and the S / N of a reproduction signal can be improved.

Further, as described above, in such a probe section 41, by using the inter-mode interference effect, it is possible to simultaneously achieve a small spot and high efficiency. However, as described above, the opening 4 in the bottom surface of the tapered hole 42
When the shape of 2b is a square shape, a circular shape or a similar shape, the beam spot shape generated by the inter-mode interference proposed by the present applicant becomes an elliptical shape. That is, as shown in FIG. 22, the beam spot diameter becomes smaller in the direction perpendicular to the polarization direction of the incident light, and high resolution beyond the diffraction limit can be achieved.
In the direction parallel to the polarization direction of the incident light, it is difficult to increase the resolution by reducing the beam spot diameter to only about half a wavelength.

Therefore, in this embodiment, as shown in FIG. 23, the shape of the opening 42a on the bottom surface of the tapered hole 42 is
The rectangular shape is such that a direction parallel to the polarization direction of the incident light indicated by an arrow in the drawing is a short side b, and a direction perpendicular to the polarization direction of the incident light is a long side a. By making the shape of the opening 42a on the bottom surface of the tapered hole 42 into a rectangular shape, FIG.
As shown in FIG. 2, in the direction parallel to the polarization direction of the incident light for which it was difficult to reduce the spot, that is, in the short side direction of the bottom surface shape of the tapered hole 42, the bottom surface shape of the tapered hole 42 Light will be confined. Further, there is no cutoff for light incident parallel to the short side of the bottom surface shape of the tapered hole 42. This makes it possible to reduce the size of the beam spot even in a direction parallel to the polarization direction of the incident light, thereby achieving higher resolution and higher efficiency.

As the bottom shape of the tapered hole 42, specifically, the length a of the long side is in the range of a ≧ λ / 2n, that is, the length a of the long side is the lowest order mode. It is necessary that the diameter be equal to or larger than the cutoff diameter (λ / 2n). However,
Here, n is the refractive index of the medium in the opening 42a. Also,
The length b of the short side needs to satisfy a> b. Specifically, when the wavelength λ is 830 nm in the tapered hole 42 in which the medium in the opening 42 a is air or vacuum (refractive index n = 1), a> 415 nm.
If the length a of the long side is set to be equal to or larger than the cutoff diameter (λ / 2n) of the lowest mode, b may be reduced as much as possible.

Although the present embodiment has been described with respect to the example in which the convex objective lens 3 is formed on the surface of the substrate 2, the objective lens 3 shown in FIGS. 3, 6, 8 and 9 is used. , 1
4 may be applied.

[Thirteenth Embodiment] A thirteenth embodiment of the present invention will be described with reference to FIGS.
This embodiment is also applied to a probe proposed by the present applicant as Japanese Patent Application No. 11-157699.

In the probe (optical element for optical pickup) 51 of the present embodiment, as shown in FIG.
Has a so-called elongated shape such as an elliptical shape or a rectangular shape. FIG. 25 shows a sectional view thereof. 24 and 25, the apex portion has a rectangular shape. Such a protrusion 5
As shown in FIG. 26, the substrate 2 on which the objective lens 3 is formed is provided on the light shielding film 5 or the substrate 2 on which the substrate 2 is formed. FIG.
As shown in FIG. 6, the moving direction of the recording medium 46 and the direction of the short side may be the same, or vice versa.
Alternatively, it may be inclined.

As an example of the manufacturing method, the same step as that shown in FIG. 16 may be used. However, FIG.
In (b), the pattern resin 35 is patterned so that the apex 52a of the projection 52 has a rectangular shape. As the objective lens 3, examples shown in FIGS. 13A to 13E can be used.

The effect obtained by making the shape of the apex portion 52a of the projection 52 rectangular is the same as that of the above-described embodiment.

The metal layer forming the light shielding film 5 is, for example, A
It is made of a light-shielding material such as 1 or Au, and is formed to a thickness that does not transmit light by a thin film forming technique such as an evaporation method. This metal film, for example, when using an Al material,
It is formed with a thickness of about 100 nm or more. This metal layer
It is formed on the side surface of the glass substrate 2 and the protrusion 52.

When light enters from the glass substrate 2 side on which the objective lens 3 is provided, the probe portion 51 scatters the light with the light shielding film 5 made of a metal layer, and the projection portion 52
Are focused so that the light intensity at the apex of the
The near-field light 7 is generated between the recording medium 2 and the recording medium 46. By forming the light shielding film 5, light other than the light generated from the tip of the projection 52 can be blocked, and the S / N of the reproduction signal can be reduced.
Can be improved.

Further, as described above, in such a probe unit 51, by utilizing the inter-mode interference effect,
Small spot and high efficiency are achieved at the same time. However, as described above, when the shape of the apex portion 52a of the protrusion 52 is a square shape, a circular shape, or a similar shape, the shape of the beam spot generated due to the inter-mode interference is elliptical. . That is, as in the case shown in FIG. 22, the beam spot diameter becomes smaller in the direction perpendicular to the polarization direction of the incident light, and high resolution can be achieved beyond the diffraction limit. In the direction parallel to the polarization direction of the light, it is difficult to increase the resolution by reducing the beam spot diameter to only about half a wavelength.

In this respect, in the present embodiment, as in the case shown in FIG. 23, the shape of the vertex 52a is changed such that the direction parallel to the polarization direction of the incident light indicated by the arrow in the drawing becomes the short side b, By making the rectangular shape such that the direction perpendicular to the polarization direction of the light is the long side a, as shown in FIG. 22, the direction parallel to the polarization direction of the incident light, for which it was difficult to reduce the spot, that is, Light is confined in the short side direction of the shape of the vertex 52a by the shape of the vertex 52a.
Also, there is no cutoff for light incident parallel to the short side of the shape of the vertex 52a. This allows
The beam spot can be made smaller even in the direction parallel to the polarization direction of the incident light, and higher resolution and higher efficiency can be realized.

As the shape of the apex portion 52a, specifically, the length a of the long side is in the range of a ≧ λ / 2n, that is, the length a of the long side is the cutoff of the lowest mode. Diameter (λ
/ 2n) or more. Here, n is the refractive index of the projection material. Also, the length b of the short side is
It is necessary to satisfy a> b. Specifically, when the projection material is SiO ₂ (including glass) (refractive index n = about 1.5), when the wavelength λ is 830 nm, a> 277
nm. Note that the cutoff diameter of the lowest order mode (λ /
2n) If the length a of the long side is set to be equal to or greater than
You can make it as small as you like.

[Fourteenth Embodiment] A fourteenth embodiment of the present invention will be described with reference to FIGS.
This embodiment is also applied to a probe proposed by the present applicant as Japanese Patent Application No. 11-157699.

The probe section 56 of the present embodiment has basically the same structure as the probe section 51 shown in FIG. 24 and the like, and has a higher refractive index than the substrate 2 in the projection 52. Is filled with a high refractive index material 57 having Thereby, the wavelength in the probe section 56 is shortened, so that the spot diameter emitted from the tip of the projection section 52 can be reduced. Further, since the wavelength is relatively shorter than the aperture diameter, the light use efficiency is also increased.

However, in the present embodiment, as shown in FIG. 27, the shape of the apex 52a of the projection 52 is a so-called elongated shape such as an ellipse or a rectangle. FIG. 28 shows a cross-sectional view thereof. 27 and 28, the apex 52a has a rectangular shape. As shown in FIG. 29, the substrate 2 on which the objective lens 3 is formed is provided on the light-shielding film 5 or the substrate 2 on which the projections 52 are formed. As shown in FIG. 29, the moving direction of the recording medium 46 and the direction of the short side may be made to match,
In addition, the reverse may be possible, or it may be oblique.

As an example of the manufacturing method, the aforementioned FIG.
The process in the case of (1) may be used. However, FIG.
In the step (3), the pattern resin 35 is patterned so that the apex 52a of the projection 52 has a rectangular shape. As the objective lens 3, examples shown in FIGS. 13A to 13E can be used.

The effect obtained by making the shape of the apex 52a of the projection 52 rectangular is the same as that of the above-described embodiment.

The metal layer forming the light shielding film 5 is, for example, A
It is made of a light-shielding material such as 1 or Au, and is formed to a thickness that does not transmit light by a thin film forming technique such as an evaporation method. This metal layer, for example, when using an Al material,
It is formed with a thickness of about 100 nm or more. This metal layer
It is formed on the side surface of the glass substrate 2 and the protrusion 52.

When light enters from the glass substrate 2 side on which the objective lens 3 is provided, the probe portion 56 scatters the light with the light shielding film 5 made of a metal layer, and
Are focused so that the light intensity at the apex of the
The near-field light 7 is generated between the recording medium 2 and the recording medium 46. By forming the light shielding film 5, light other than the light generated from the tip of the projection 52 can be blocked, and the S / N of the reproduction signal can be reduced.
Can be improved.

Further, as described above, in such a probe section 56, by utilizing the inter-mode interference effect,
Small spot and high efficiency are achieved at the same time. However, as described above, when the shape of the apex portion 52a of the protrusion 52 is a square shape, a circular shape, or a similar shape, the shape of the beam spot generated by the inter-mode interference becomes elliptical. . That is, FIG.
As shown in Fig. 2, the beam spot diameter becomes smaller in the direction perpendicular to the polarization direction of the incident light, and high resolution can be achieved beyond the diffraction limit. In the parallel direction, it is difficult to increase the resolution by reducing the beam spot diameter to only about half a wavelength.

In this regard, in the present embodiment, as shown in FIG. 23, the shape of the vertex 52a is such that the direction parallel to the polarization direction of the incident light indicated by the arrow in the drawing is the short side b, and It has a rectangular shape such that the direction perpendicular to the polarization direction is the long side a. By making the shape of the apex 52a rectangular, as shown in FIG. 22, the direction parallel to the polarization direction of the incident light, for which it was difficult to reduce the spot, that is, the apex 52a
The light is confined in the short side direction of the shape by the shape of the vertex 52a. The vertex 52
There is no cutoff for light incident parallel to the short side of shape a. This makes it possible to reduce the size of the beam spot even in a direction parallel to the polarization direction of the incident light, thereby achieving higher resolution and higher efficiency.

As the shape of the apex 52a, specifically, the length a of the long side is in the range of a ≧ λ / 2n, that is, the length a of the long side is the cutoff of the lowest mode. Diameter (λ
/ 2n) or more. Here, n is the refractive index of the projection material. Also, the length b of the short side is
It is necessary to satisfy a> b. Specifically, when the projection material is silicon (refractive index n = about 3.6), when the wavelength λ is 830 nm, a> 115 nm. In addition,
If the length a of the long side is set so as to be equal to or larger than the cut-off diameter (λ / 2n) of the lowest mode, b may be reduced as much as possible.

[Fifteenth Embodiment] The fifteenth embodiment of the present invention will be described with reference to FIGS. FIG. 30 shows an optical element 61 for an optical pickup according to the present embodiment.
It is a longitudinal side view which shows a structure. The optical element 61 for an optical pickup of the present embodiment includes a first objective lens 3 having a function of condensing light collimated by the optical system 4.
And a second objective lens 62 having a refractive index higher than that of the substrate 2 at a position close to an optical recording medium (not shown), having the same optical axis as the first objective lens 3, and one substrate. It is configured to be formed on the substrate 2. That is, the second objective lens 62 is added to the configuration of the optical element 1 for an optical pickup shown in FIG.
Is added.

The shape of the first objective lens 3 may be spherical or aspherical in consideration of aberration. Further, the shape of the second objective lens 62 may be a hemisphere or a super-hemisphere as long as a refraction action can be obtained. However, the second objective lens 6
2 differs from the substrate 2 only in the refractive index. Further, the thickness of the substrate 2 is set so that the minimum spot size can be obtained on the bottom surface of the substrate 2 with the optical system 4.

The condensing point of the second objective lens 62 is located on the approximate surface of the objective lens 62, and a minute opening 6 is opened in the light shielding film 5 there. The diameter of the minute aperture 6 (not necessarily a circle) is made smaller than the spot size at the converging point. In particular, if the diameter is smaller than the so-called diffraction limit, the significance of the present embodiment is increased.

In such a configuration, the near-field light 7 localized in a region from the surface of the light-shielding film 5 to almost the same distance as the diameter of the minute opening 6 may exist. Since the region where the near-field light 7 exists is almost the same as the minute aperture 6, if this diameter is set to be equal to or less than the diffraction limit, high-density optical recording exceeding this can be performed.

Here, the effect of using the second objective lens 62 will be described. By using two of the first and second objective lenses 3 and 62 as the objective lens, the aperture ratio (NA) of the two optical systems as a whole can be reduced when only the first objective lens 3 is used (FIG. 1). Reference). Thereby, the spot diameter on the minute aperture surface (that is, the surface of the second objective lens 62) becomes smaller. When the aperture diameter of the minute aperture 6 is the same, as the spot diameter is smaller, the ratio of the energy that becomes the near-field light 7 out of the light energy within the spot diameter increases. That is, the light use efficiency is increased, and stronger near-field light 7 can be obtained. Thereby, recording on the recording medium becomes faster. Alternatively, less light source laser power is required. Also, when reproducing, the signal S /
Since N is improved, errors in reproduction can be reduced, and reproduction can be performed at high speed.

As already described in the first and second embodiments, double high-precision tracking control between the optical recording medium and the slider (substrate 2) and between the slider and the optical system 4 becomes unnecessary. The same applies to the present embodiment.

In the present embodiment, when it is desired to reduce the spot size, the larger the refractive index of the second objective lens 62, the smaller the spot size. What is necessary is just to select a material having a refractive index larger than the refractive index. For example, as a material of the substrate 2, BK7 (wavelength 768.2 nm
Is selected, and LaF ₂ (refractive index at a wavelength of 768.2 nm: 1.7335) or SFS1 (wavelength: 768.2) is used as a material of the second objective lens 62.
The refractive index in nm is 1.8927) or silicon (wavelength 7
The refractive index at 80 nm is selected to be about 3.6).

FIG. 31 is a process chart showing the steps of manufacturing the optical element 61 for an optical pickup of the present embodiment in the order of steps.
Objective lenses 3 and 62 are formed on one side of the material of the substrate 2 by the following procedure.

(A) First, a photosensitive material (resist) 8 is applied on the glass substrate 2. The thickness of the photosensitive material to be applied depends on the height of the objective lens 3 formed on the substrate 2 and the ratio (selectivity ratio) of the etching rate of the substrate material and the etching rate of the resist, on which the photosensitive material is to be etched afterwards. ). For example, when both etching rates are equal (selectivity 1), the height of the resist 8 is made equal to the height of the objective lens 3 to be formed. When the etching rate of the substrate material is twice as large as the etching rate of the resist (selectivity 2), the height of the resist 8 may be １ ／ of the height of the objective lens 3.

Further, as a photosensitive material applied on the substrate 2, a photoresist or a photosensitive dry film used in usual semiconductor manufacturing is used. Specifically, OF
PR-800 (positive resist), OMR-85 (negative resist), or the like may be used. Step of transferring shape to resist by selecting positive type or negative type (photolithography step)
Although the shape of the photographic mask used for the above changes, the basic forming procedure does not change. In this embodiment, a case where a positive resist is used will be described.

(B) Next, light is irradiated onto a resist 8 formed on the substrate 2 through a mask (photomask) in which a pattern equivalent to the diameter of the objective lens 3 is formed to expose the photosensitive material. . As a result, when developed after light irradiation, a pattern resin 9 equivalent to the objective lens diameter remains on the substrate 2.

(C) Subsequently, the remaining pattern resin 9
Then, heat and / or pressure is applied, and the surface of the resist 8 is formed into a convex lens shape by the effects of gravity and surface tension. The temperature and pressure to be applied vary depending on the resist shape, but the temperature may be selected from 200 ° C. to 400 ° C. and the pressure may be selected from 1 to 10 atm.

(D) (e) Further, the glass substrate 2 is etched (anisotropic etching) in a direction perpendicular to the substrate, using the resin 10 having the convex lens shape formed as described above as a mask. As a means for this etching, dry etching usually used in a semiconductor manufacturing process can be used. Specifically, reactive ion etching (RIE)
And electron cyclotron resonance etching (ECR). The gas used for dry etching is selected according to the substrate material.

For example, when the substrate material is glass, CF
₄ , CHF ₃ or the like is used. In order to adjust the etching rate and selectivity, N ₂ , O
₂ , a gas such as Ar may be mixed. Through such steps, the first objective lens 3 is formed on the substrate 2.

Next, the procedure moves to the step of manufacturing the second objective lens 62. Here, a concave lens having a higher refractive index than the substrate 2 is formed. The formation of the concave lens is performed basically in the same manner as the formation of the above-mentioned convex lens. In this embodiment, a case where a negative resist is used will be described as an example.

(F) A negative resist 63 is applied on the surface of the substrate 2 on which the solid immersion lens is to be formed.

(G) The resin is left around the substrate 2 except for the portion 64 where the objective lens 62 is formed by using the photolithography process described above.

(H) Next, a resist 65 is applied to the entire surface including the portion 64 where the objective lens 62 is formed. This is an application for promoting thermal deformation of the resin, and the application thickness may be small. Specifically, the thickness may be 5 μm or less, and may be as thick as necessary.

(I) Subsequently, similarly to the above, the resin is deformed by the action of heat and / or pressure, and the concave lens shape 66 is formed.
To form

(J) (k) Further, a concave lens-shaped portion 67 is formed on the substrate 2 by using the same etching method.

(K) A material 68 having a higher refractive index than the substrate 2 is formed on the concave lens-shaped portion 67. In this embodiment mode, a target having a desired refractive index is used as a target, and a sputtered film is formed on the surface of the substrate 2 including the concave lens shape by using a sputtering method.

(L) Further, a sputtered film is selectively left on the concave lens-shaped portion 67 by etching back and flattening the surface of the substrate 2.

(M) A minute opening 6 having a diameter smaller than the diffraction limit is formed in the light shielding film 5.

Thus, the optical element 61 for an optical pickup is manufactured by the steps shown in FIGS.

[Sixteenth Embodiment] A sixteenth embodiment of the present invention will be described with reference to FIG. FIG. 32 is a vertical sectional side view showing the configuration of the optical element 69 for an optical pickup of the present embodiment.

In the present embodiment, the first objective lens 3 is formed to have a convex shape with respect to a position below the surface of the substrate 2 under the same conditions as in the fourteenth embodiment. In comparison with the optical element 11 for an optical pickup shown in FIG.
The objective lens 62 of FIG. In order to produce this shape, a method of using a photomask 12 having a pattern as shown in FIG. 5 or reflowing the resist in the same manner as in FIG. 3 can be adopted.

[Seventeenth Embodiment] A seventeenth embodiment of the present invention will be described with reference to FIG. FIG. 33 is a vertical sectional side view showing the configuration of the optical element 70 for an optical pickup of the present embodiment.

While the above-mentioned first objective lens 3 has a convex shape with respect to the surface of the substrate 2, the objective lens 14 of the present embodiment has a concave shape with respect to the surface of the substrate 2. At this time, the refractive index of the first objective lens 14 is set to be higher than the refractive index of the substrate 2. In comparison with the optical element 13 for an optical pickup shown in FIG. 6, the configuration is such that a second objective lens 62 is added.

[Eighteenth Embodiment] The eighteenth embodiment of the present invention will be described with reference to FIG. FIG. 34 is a vertical sectional side view showing the configuration of the optical pickup optical element 71 of the present embodiment.

The optical element 71 for an optical pickup of this embodiment is obtained by preparing the two first objective lenses 3a and 3b shown in the sixteenth embodiment and bonding them. . In comparison with the optical element 21 for an optical pickup shown in FIG. 8, the configuration is such that a second objective lens 62 is added. The bonding method is the optical element 2 for optical pickup.
It may be the same as the case of 1.

[Nineteenth Embodiment] A nineteenth embodiment of the present invention will be described with reference to FIG. FIG. 35 is a vertical sectional side view showing the configuration of the optical pickup optical element 72 of the present embodiment.

The optical element 72 for an optical pickup of the present embodiment is obtained by preparing two objective lenses 3 shown in the fifteenth embodiment and bonding them. In contrast to the optical element 22 for an optical pickup shown in FIG. 9, the configuration is such that a second objective lens 62 is added. The bonding method may be the same as that of the optical pickup optical element 22.

[Twentieth Embodiment] A twentieth embodiment of the present invention will be described with reference to FIGS. FIG. 34 is an optical pickup optical element 73 according to the present embodiment.
It is a longitudinal side view which shows a structure.

The optical element 73 for an optical pickup of the present embodiment comprises, like the optical element 61 for an optical pickup, etc., a first objective lens 3 having a function of condensing the light collimated by the optical system 4, The second objective lens 62, which is located close to an optical recording medium (not shown here), has the same optical axis as the first objective lens 3 and has a higher refractive index than the substrate 2, and a single substrate 2 It is the structure formed above.
In comparison with the optical element for an optical pickup 24 shown in FIG. 11, the configuration is such that a second objective lens 62 is added. That is, the minute opening 25 of the light shielding film 5 of the present embodiment is
It has a tapered shape in which the opening size decreases toward the optical recording medium side.

By doing so, the minute opening 25 can be manufactured more easily. In other words, the aperture size equal to or smaller than the diffraction limit is about 100 nm, which is a very difficult value even with the latest semiconductor processing process. However, this can be relatively easily realized by using the crystal axis anisotropic etching of single crystal silicon described later.

Further, by providing the second objective lens 62, the spot diameter on the surface of the second objective lens 62 becomes smaller as compared with the case where the second objective lens 62 is not provided. Along with this, the second objective lens 62 having a tapered hole
Even if the diameter of the side is reduced, the light use efficiency does not decrease. Second
By reducing the diameter of the objective lens 62 on the side of
As a result, the thickness of the light-shielding film 5 can be reduced, so that the processing accuracy of the opening diameter of the minute opening 25 can be improved.
That is, in the manufacturing method described with reference to FIG. 37, a tapered hole is formed by anisotropic etching of single crystal silicon. However, the diameter of the minute opening 25 on the recording medium side is smaller than the diameter of the hole on the second objective lens 62 side. It is determined by the thickness of the light shielding film (single crystal silicon film) 5. Since the absolute thickness accuracy increases as the thickness of the light-shielding film 5 decreases, the accuracy of the opening diameter of the minute opening 25 also improves.

FIG. 37 shows a method of manufacturing the optical element 73 for an optical pickup according to the present embodiment. The method is substantially the same as the method for manufacturing the optical element 24 for an optical pickup (FIG. 12), but the second objective lens 62 is previously manufactured on the glass substrate 30 to be joined in FIG. 37D by the method shown in FIG. Keep it. Subsequent steps are the same as those in FIG.

[Twenty-First Embodiment] A twenty-first embodiment of the present invention will be described with reference to FIG. In the present embodiment, each of the optical elements 61, 69, 70, 71, 72 for the optical pickup of each of the above-described embodiments will be described.
This shows a configuration example in which a minute opening 25 having a tapered shape is used instead of the minute opening 6.

[Twenty-second Embodiment] A twenty-second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the optical elements 61, 69, 70, 71, and 71 for the optical pickup of the twenty-first embodiment described above.
The high refractive index material 32 is filled in each of the small openings 25 in the tapered shape. Thereby, the light use efficiency is increased.

FIG. 40 shows an example of the manufacturing process in the case of the optical element 61 for an optical pickup shown in FIG. 39A, for example. Basically, it is the same as the case shown in FIG. 12, but in the step shown in FIG. 40C, a high refractive index material 32 is deposited on the tapered opening and flattened by etch back or the like.
Further, the silicon surface is exposed, and thereafter, FIG.
The following steps may be performed.

[Twenty-third Embodiment] A twenty-third embodiment of the present invention will be described with reference to FIGS. FIG. 41 is a longitudinal sectional side view showing the configuration of the optical element 81 for an optical pickup of the present embodiment. Here, FIG.
Has the same structure as the optical element 73 for an optical pickup shown in FIG. 1, but the shape of the probe portion 34 is a tapered projection structure in which the side facing the optical recording medium becomes thinner. In comparison with the optical element 33 for an optical pickup shown in FIG. 15, the configuration is such that a second objective lens 62 is added. That is, the material of the protruding probe portion 34 is the second
The same material as that of the objective lens 62 is used.

With such a structure, light incident on the probe portion 34 having the tapered projection structure is repeatedly reflected between the opposed tapered surfaces, and condensed on the tip of the projection.
Further, the presence of the second objective lens 62 reduces the light spot diameter at the bottom surface of the projection. Further, since the protrusion is also made of a high refractive index material, the wavelength in the protrusion becomes shorter. From these facts, light incident on the bottom surface of the projection can be used effectively, so that the light use efficiency is high. Near-field light 7 is emitted from the tip. Here, the optical element 81 for the optical pickup that emits the near-field light 7 has been described. However, by optimizing the shape of the protrusion by the completely same manufacturing method, both the near-field light and the propagating light are generated by the inter-mode interference. Can emit,
An optical element for an optical pickup with higher light use efficiency can be realized.

FIG. 42 shows an example of a method for manufacturing the optical element 81 for an optical pickup according to the present embodiment.

(A) First, the first and second objective lenses 3 and 62 are manufactured in the same manner as in the steps of FIGS. 31 (a) to 31 (l). The surface of the high refractive index material 82 is flattened by chemical mechanical polishing. (B) Thereafter, a pattern resin 35 is formed by photolithography at a position where the protruding probe section 34 is to be formed. (C) Using this as a mask, the projections 36 are formed on the high refractive index material 82 (transfer of the resin pattern) in the same manner as when the objective lens 62 was manufactured. (D) A light shielding film 5 is deposited on the protrusion side. (E) The light-shielding film 5 at the tip of the projection 36 is FIB
Alternatively, it is removed by a method such as chemical mechanical polishing.

In the present embodiment, an example in which a convex objective lens is formed on the surface of the substrate 2 with respect to the first objective lens 3 has been described as an example. However, the first objective lens 3 has various configurations as shown in FIG. Objective lenses 3 and 14 may be applied.

[Twenty-fourth Embodiment] A twenty-fourth embodiment of the present invention will be described with reference to FIGS. FIG. 43 is a vertical sectional side view showing a configuration of an optical element 83 for an optical pickup of the present embodiment. Here, FIG.
Has substantially the same structure as the optical element 81 for an optical pickup shown in FIG.
The material of the objective lens 62 is different, and the two are configured to have different refractive indexes. In contrast to the optical element 33 for an optical pickup shown in FIG.
2 is added. Preferably, it is preferred refractive index n ₂ of the protruding probe portion 34 is larger than the refractive index n ₁ of the second objective lens 62. In this case, FIG.
In the case of the optical element 81 for an optical pickup shown in (1), the wavelength in the projection is further shortened, and the light use efficiency is further increased.

For example, as a material of the second objective lens 62, BK7 (refractive index 1.511 at a wavelength of 768.2 nm) is used.
5) was selected, and LaF ₂ was used as the material for the protruding probe.
(Refractive index 1.7335 at wavelength 768.2 nm) or SFS1 (refractive index 1.892 at wavelength 768.2 nm)
7) or silicon (the refractive index at a wavelength of 780 nm is about 3.6) is selected.

With such a structure, the light incident on the protruding tapered probe portion 34 is repeatedly reflected between the opposing tapered surfaces, and condensed on the tip of the protrusion.
Further, the presence of the second objective lens 62 reduces the light spot diameter at the bottom surface of the projection. Further, since the protrusion is also filled with the high refractive index material 37 and is made of a material having a higher refractive index than the second objective lens 62, the wavelength in the protrusion is further shortened. From these facts, the light incident on the bottom surface of the protrusion can be used effectively, so that the light use efficiency is further improved. Near-field light 7 is emitted from the tip. here,
The optical element 83 for the optical pickup that emits the near-field light 7 has been described. However, by optimizing the protrusion shape by the exactly same manufacturing method, it is possible to emit both the near-field light and the propagation light by the inter-mode interference. It is possible to realize an optical element for an optical pickup having higher light use efficiency.

FIG. 44 shows an example of a method of manufacturing the optical element 83 for an optical pickup according to the present embodiment.

(A) (b) First, FIGS.
Similarly to the process (l), the first and second objective lenses 3 and 62
Is prepared. The surface of the high refractive index material 82 is flattened by chemical mechanical polishing. (C) Further, a second high refractive index material 84 is deposited. (D) Thereafter, a pattern resin 35 is formed by photolithography at a position where the protruding probe portion 34 is to be formed. (E) Using this as a mask, the projections 36 are formed on the high refractive index material 84 (transfer of the resin pattern) in the same manner as when the objective lens 62 was manufactured. (F) A light-shielding film 5 is deposited on the protrusion side. (G) The light-shielding film 5 at the tip of the protrusion 36 is removed by a method such as FIB or chemical mechanical polishing.

In the present embodiment, an example in which a convex objective lens is formed on the surface of the substrate 2 with respect to the first objective lens 3 has been described as an example. Objective lenses 3 and 14 may be applied.

[Twenty-Fifth Embodiment] A twenty-fifth embodiment of the present invention will be described with reference to FIG. Regarding the optical element 85 for an optical pickup of the present embodiment, the configuration and manufacturing method of the probe section 41 thereof are basically the same as those shown in FIGS. That is, a second objective lens 62 is provided with respect to the probe unit 41 shown in FIG.
5 has the effect of improving the aperture diameter accuracy.

The tapered hole 42 provided in the light shielding film 5 has the same shape as that shown in FIGS. That is, the opening 42a on the bottom surface of the tapered hole 42
Has a so-called elongated shape such as an elliptical shape or a rectangular shape. As a result, similarly to the case shown in FIGS. 19 to 21, the small spot in the major axis direction of the substantially elliptical beam spot generated by the inter-mode interference, that is, the direction parallel to the polarization direction of the incident light. Can be realized. The dimensions of the bottom side of the tapered hole 42 with respect to the long side and the short side may be set in the same manner as in the case shown in FIGS.

[Twenty-Sixth Embodiment] A twenty-sixth embodiment of the present invention will be described with reference to FIG. With respect to the optical element 86 for an optical pickup of the present embodiment, the configuration and the manufacturing method of the probe section 41 are basically the same as the case shown in FIG. 24, but the same as in the case shown in FIG. With the second objective lens 62, the diameter of the light spot on the bottom surface of the projection is reduced. In addition, the projection is made of a high refractive index material
7, the wavelength in the protrusion becomes shorter. From these facts, light incident on the bottom surface of the projection can be used effectively, so that the light use efficiency is high.

The projection has a shape as shown in FIG. 25 as in the case shown in FIG. That is, the shape of the apex of the protruding tapered hole 42 is a so-called elongated shape such as an elliptical shape or a rectangular shape. This allows
As in the case of the above-described embodiment, it is possible to realize a small spot in the major axis direction of the substantially elliptical beam spot generated by the inter-mode interference, that is, in the direction parallel to the polarization direction of the incident light. it can. Opening 42 at the bottom of tapered hole 42
The dimension of the long side and the short side of the shape a may be set as appropriate.

[27th Embodiment] The 20th embodiment of the present invention
A seventh embodiment will be described with reference to FIG. Of this implementation
The optical pickup 87 in the form
The configuration and manufacturing method of the lobe part 41 are basically
Similar to the case shown in FIG. 27, but in the case shown in FIG.
Has the second objective lens 62 in the same manner as
The spot diameter is configured to be small. Also,
The material of the projection type probe section 41 and the second objective lens 62
Different materials and different refractive indexes
ing. Preferably, the refractive index of the protruding probe 41 side
n₂Is the refractive index n on the second objective lens 62 side ₁Greater than
Is more preferred. In this case, the embodiment shown in FIG.
The wavelength in the protrusion is shorter than in the case
Efficiency is increased.

For example, as the material of the second objective lens 62,
BK7 (refractive index 1.511 at wavelength 768.2 nm)
5) is selected, and L is used as the material of the projection type probe portion 41.
aF ₂(Refractive index at a wavelength of 768.2 nm: 1.7335)
Alternatively, SFS1 (refractive index 1.8 at a wavelength of 768.2 nm)
927) or silicon (the refractive index at a wavelength of 780 nm is
Select about 3.6).

The projection 41 has the same shape as that shown in FIGS. 27 and 28. That is, the protrusion 41
Has a so-called elongate shape such as an elliptical shape or a rectangular shape. Thus, similarly to the case of FIG. 27, it is possible to realize a small spot in the major axis direction of the substantially elliptical beam spot generated by the inter-mode interference, that is, in the direction parallel to the polarization direction of the incident light. it can. The dimensions of the long side and the short side of the shape of the opening 42a on the bottom surface of the tapered hole 42 may be set similarly to the case of FIG.

[28th Embodiment] A 28th embodiment of the present invention will be described with reference to FIG. FIG.
1 shows a configuration example of an optical element 100 for an optical pickup of the present embodiment, in which (a) is a plan view and (b) is a longitudinal side view thereof.

This optical pickup optical element 100 is
The flying slider 101 has a structure for flying above the optical recording medium 46. On this flying slider 101, for example, a semiconductor laser 102 for emitting a laser beam as coherent light, a collimator lens 103 for shaping (collimating) the laser beam emitted from the semiconductor laser 102 into a parallel beam, and a semiconductor laser 102 A polarizing beam splitter 104 for separating a parallel beam from the optical recording medium 46 and a reflected beam from the optical recording medium 46;
05 and the photodiode 10 to which the reflected light from the optical recording medium 46 is input via the polarization beam splitter 104.
6 and a reflecting prism 107 that reflects a parallel beam and makes it incident on the first objective lens 3. In addition,
The semiconductor laser 102, the collimator lens 103, the polarizing beam splitter 104, the quarter-wave plate 105, and the photodiode 106 are installed on a holder 108 that supports them.

Further, a convex first objective lens 3 and a second objective lens 62 for converging a parallel beam from the quarter-wave plate 105, and a spot less than the diffraction limit from the converged laser beam Protruding near-field optical probe unit 10 that generates near-field light 7 having a diameter (or near-field light and propagation light)
9 (corresponding to the protruding probe section 34 and the like) are formed on the flying slider 101. The first objective lens 3, the second objective lens 62, and the protruding near-field optical probe unit 109 are manufactured using the semiconductor manufacturing process as described in each of the above-described embodiments (this embodiment). The embodiment shows an application example of the type shown in FIG. 46).

[0202] Also, the whole is stored in a case 110,
This case 110 is fixed to the tip of a suspension 111.

With such a structure, the optical pickup optical system can be reduced in size and thickness. Also,
Since the weight is reduced, the seek time is shortened, and the operation of recording, reproducing, or erasing information on the optical recording medium 46 is accelerated. Further, the objective lenses 3 and 6 on the flying slider 101
2 and other optical components 10 constituting an optical pickup optical system
Since the elements 2 to 107 are integrated, there is no need to perform a recording, reproducing or erasing operation while tracking them as in the related art, unlike when they are separated. The reflecting prism 107 having a simple shape reflects the parallel beam toward the objective lenses 3 and 62 and the protruding near-field optical probe unit 109 and makes it incident. Therefore, unlike the prior art 1, there is no need for a solid immersion mirror having an aspherical curved surface or the like, and there is no technically difficult problem of aspherical polishing.

[Twenty-Ninth Embodiment] A twenty-ninth embodiment of the present invention will be described with reference to FIG. FIG.
1A shows a configuration example of an optical element 112 for an optical pickup of the present embodiment, FIG. 1A is a plan view, and FIG. 1B is a longitudinal side view thereof.

The structure of the optical pickup optical element 112 of this embodiment is basically the same as that of the optical pickup optical element 100 shown in FIG. 48, but the first objective lenses 3a and 3b are (Type as shown in FIG. 39 (e)), and the upper surface of the flying slider 113 is formed as a complete plane.

Therefore, according to the present embodiment, the reflecting prism 107 can be solidly attached to the upper surface of the flying slider 113 immediately above the first objective lenses 3a and 3b. Thereby, the easiness of adhesion of the reflection prism 107, the strength after adhesion, and the stability are improved.

[Thirtieth Embodiment] A thirtieth embodiment of the present invention will be described with reference to FIG. 50A and 50B show a configuration example of the optical element 114 for an optical pickup of the present embodiment, wherein FIG. 50A is a plan view and FIG.

The structure of the optical pickup optical element 114 of this embodiment is basically the same as that of the optical pickup optical element 112 shown in FIG. Optical recording medium 4 of light shielding film 5
The surface on the sixth side and the tip end surface of the projection-type probe 109 are processed so as to be in the same plane.

In this case, since the entire slider including the optical system is flattened, the handling of the slider is facilitated because there is no protrusion, or the entire slider and the optical recording medium 4 can be easily read.
6 are hardly damaged.

In addition to the protruding type probe 109 shown in the twenty-seventh to twenty-ninth embodiments, various near-field optical probes as described in the above-described embodiments or particularly the Other types of near-field probes that are not illustrated as a form may be used. Further, the embodiment having the second objective lens 62 has been described as an embodiment, but a configuration having only the first objective lens 3 or 14 may be employed without this. Further, regarding the first objective lens 3,
Various lenses as exemplified in the above-described embodiments can be used. Even if it is a lens other than the exemplified type, the point is that if it is a lens that is integrally formed on the slider,
Anything is fine.

[0211]

According to the optical pickup device of the first aspect of the present invention, the objective lens for condensing the collimated light is formed on the substrate, and is formed at or near the converging point of the objective lens. Since the probe section that generates the near-field light or the near-field light and the propagation light is formed, precise and advanced dynamic alignment (tracking) between the probe section and the focal point can be unnecessary, and recording, The reproducing or erasing operation can be performed stably and at high speed.

According to the second aspect of the present invention, in the optical element for an optical pickup according to the first aspect, the probe portion is formed by forming a minute opening in a film that is deposited on the substrate and does not transmit coherent light. Has been
Precise and advanced dynamic positioning (tracking) between the probe section and the focal point can be dispensed with, and the recording, reproducing, or erasing operation can be performed stably and at high speed.

According to the third aspect of the present invention, in the optical element for an optical pickup according to the first aspect, the probe portion is formed on a film which is deposited on the substrate and does not transmit coherent light, and has a minute opening on the medium facing surface side. It is formed by a hole penetrated in a tapered shape so that the probe section and the focal point can be precisely and highly dynamically aligned (tracking).
Can be eliminated, and the recording, reproducing or erasing operation can be performed stably and at high speed.

According to the fourth aspect of the present invention, in the optical element for an optical pickup according to the first aspect, the probe portion is formed as a tapered projection whose material facing side is made thin by a material that transmits coherent light. This eliminates the need for precise and sophisticated dynamic alignment (tracking) between the probe unit and the focal point, and enables stable, high-speed recording, reproduction, or erasing operations.

According to the fifth aspect of the present invention, in the optical element for an optical pickup according to the first aspect, since the probe portion is formed of the same material as that of the substrate and formed as a tapered projection having a narrower medium-facing side. Precise and advanced dynamic positioning (tracking) between the probe section and the focal point can be dispensed with, and the recording, reproducing, or erasing operation can be performed stably and at high speed.

According to the sixth aspect of the present invention, in the optical element for an optical pickup according to the first aspect, the probe portion is formed as a tapered projection whose material facing side is made narrower by a material having a higher refractive index than the substrate material. Because it is formed, precise and advanced dynamic alignment (tracking) between the probe section and the focal point is not required, and recording,
The reproducing or erasing operation can be performed stably and at high speed.

According to the optical element for an optical pickup of the present invention, the first element for collecting the collimated light is provided.
And a second objective lens coaxial with the optical axis of the first objective lens and further condensing the light condensed by the first objective lens on the substrate. Since the probe section for generating near-field light or near-field light and propagation light is formed at or near the focal point of the lens, the light source is realized while achieving the objects of the above-mentioned inventions. Light utilization efficiency can be improved.

According to the eighth aspect of the present invention, in the optical element for an optical pickup according to the seventh aspect, the light use efficiency of the light source can be improved.

According to the ninth aspect of the present invention, in the optical element for an optical pickup according to the seventh aspect, the light use efficiency of the light source can be improved.

According to the tenth aspect, the seventh aspect is provided.
In the optical element for an optical pickup described above, the light use efficiency of the light source can be improved.

According to the eleventh aspect, according to the seventh aspect,
In the optical element for an optical pickup described above, the light use efficiency of the light source can be improved.

According to the twelfth aspect, the seventh aspect is provided.
In the optical element for an optical pickup described above, the light use efficiency of the light source can be improved.

According to the thirteenth aspect, the third aspect is provided.
Or, in realizing the invention described in 9, since the minute opening at the tip of the hole is elongated, higher recording density can be realized.

According to the fourteenth aspect of the present invention, there is provided an optical element for an optical pickup according to the fourth, fifth, sixth, tenth, eleventh or twelfth aspect. In realizing the present invention, since the apex of the tapered projection is elongated, higher recording density can be realized.

According to the fifteenth aspect, the first aspect is provided.
In the optical element for an optical pickup according to any one of the above items 14 to 14, since another optical component constituting an optical system for recording, reproducing or erasing information on an optical recording medium together with an objective lens is mounted on the substrate. Therefore, an optical system can be configured on the slider without using a technically difficult solid immersion mirror as in the prior art 1, thereby providing excellent features of low cost and high reliability. It is possible to provide an optical element for an optical pickup suitable for high-density recording that achieves miniaturization and weight reduction of a device, high-speed operation, and high reliability while achieving the above.

According to the sixteenth aspect, it is possible to provide a manufacturing method suitable for the optical element for an optical pickup as described above.

[Brief description of the drawings]

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

FIG. 2 is a vertical sectional side view showing a state in which a deviation occurs between a minute aperture and an optical system.

FIG. 3 is a process chart showing the manufacturing steps in the order of steps.

FIG. 4 is a vertical sectional side view showing a configuration of an optical element for an optical pickup according to a second embodiment of the present invention.

FIG. 5 is a plan view showing a photomask used in the manufacturing process.

FIG. 6 is a vertical sectional side view showing a configuration of an optical element for an optical pickup according to a third embodiment of the present invention.

FIG. 7 is a process chart showing the manufacturing steps in the order of steps.

FIG. 8 is a vertical sectional side view showing a configuration of an optical element for an optical pickup according to a fourth embodiment of the present invention.

FIG. 9 is a longitudinal sectional side view showing a configuration of an optical element for an optical pickup according to a fifth embodiment of the present invention.

FIG. 10 is a vertical sectional side view showing a configuration of each optical pickup optical element according to a sixth embodiment of the present invention.

FIG. 11 is a vertical sectional side view showing a configuration of an optical element for an optical pickup according to a seventh embodiment of the present invention.

FIG. 12 is a process chart showing the manufacturing steps in the order of steps.

FIG. 13 is a longitudinal sectional side view showing a configuration of each optical pickup optical element according to an eighth embodiment of the present invention.

FIG. 14 is a vertical sectional side view showing a configuration of each optical pickup optical element according to a ninth embodiment of the present invention.

FIG. 15 is a vertical sectional side view showing a configuration of an optical element for an optical pickup according to a tenth embodiment of the present invention.

FIG. 16 is a process chart showing the manufacturing steps in the order of steps.

FIG. 17 is a longitudinal sectional side view showing a configuration of an optical element for an optical pickup according to an eleventh embodiment of the present invention.

FIG. 18 is a process chart showing the manufacturing steps in the order of steps.

FIG. 19 is a schematic perspective view showing a configuration of a probe section of an optical element for an optical pickup according to a twelfth embodiment of the present invention.

20A is a sectional view taken along line AA of FIG. 19, and FIG. 20B is a sectional view taken along line BB of FIG.

21A and 21B show an optical element for an optical pickup, wherein FIG. 21A is a vertical front view, and FIG. 21B is a vertical side view.

FIG. 22 is an explanatory diagram showing a beam spot shape.

FIG. 23 is a plan view for explaining the effect of the elongated minute opening.

FIG. 24 is a schematic perspective view showing a configuration of a probe section of an optical element for an optical pickup according to a thirteenth embodiment of the present invention.

25A is a sectional view taken along line AA of FIG. 24, and FIG. 25B is a sectional view taken along line BB of FIG. 24.

26A and 26B show an optical element for an optical pickup, where FIG. 26A is a longitudinal front view, and FIG. 26B is a longitudinal side view.

FIG. 27 is a schematic perspective view showing a configuration of a probe section of an optical element for an optical pickup according to a fourteenth embodiment of the present invention.

28A is a sectional view taken along line AA of FIG. 27, and FIG. 28B is a sectional view taken along line BB of FIG. 27;

29A and 29B show an optical element for an optical pickup, in which FIG. 29A is a vertical sectional front view, and FIG. 29B is a vertical sectional side view.

FIG. 30 is a vertical sectional side view showing a configuration of an optical element for an optical pickup according to a fifteenth embodiment of the present invention.

FIG. 31 is a process chart showing the manufacturing steps in the order of steps.

FIG. 32 is a longitudinal sectional side view showing a configuration of an optical element for an optical pickup according to a sixteenth embodiment of the present invention.

FIG. 33 is a longitudinal sectional side view showing a configuration of an optical element for an optical pickup according to a seventeenth embodiment of the present invention.

FIG. 34 is a vertical sectional side view showing a configuration of an optical element for an optical pickup according to an eighteenth embodiment of the present invention.

FIG. 35 is a vertical sectional side view showing a configuration of an optical element for an optical pickup according to a nineteenth embodiment of the present invention.

FIG. 36 is a vertical sectional side view showing a configuration of an optical element for an optical pickup according to a twentieth embodiment of the present invention.

FIG. 37 is a process chart showing the manufacturing steps in the order of steps.

FIG. 38 is a longitudinal sectional side view showing the configuration of each optical pickup optical element according to the twenty-first embodiment of the present invention.

FIG. 39 is a longitudinal sectional side view showing a configuration of each optical pickup optical element according to a twenty-second embodiment of the present invention.

FIG. 40 is a process chart showing the manufacturing process in order of process.

FIG. 41 is a vertical sectional side view showing the configuration of each optical pickup optical element according to the twenty-third embodiment of the present invention.

FIG. 42 is a process chart showing the manufacturing process in order of process.

FIG. 43 is a longitudinal sectional side view showing the configuration of each optical pickup optical element according to the twenty-fourth embodiment of the present invention.

FIG. 44 is a process diagram showing the manufacturing process in order of process.

45A and 45B show an optical element for an optical pickup according to a twenty-fifth embodiment of the present invention, wherein FIG. 45A is a longitudinal front view, and FIG.

46A and 46B show an optical element for an optical pickup according to a twenty-sixth embodiment of the present invention, wherein FIG. 46A is a vertical front view, and FIG.

FIGS. 47A and 47B show an optical element for an optical pickup according to a twenty-seventh embodiment of the present invention, wherein FIG. 47A is a longitudinal front view, and FIG.

FIGS. 48A and 48B show an optical element for an optical pickup according to a twenty-eighth embodiment of the present invention, wherein FIG. 48A is a plan view and FIG.

FIGS. 49A and 49B show an optical element for an optical pickup according to a twenty-ninth embodiment of the present invention, wherein FIG. 49A is a plan view, and FIG.

FIGS. 50A and 50B show an optical element for an optical pickup according to a thirtieth embodiment of the present invention, wherein FIG. 50A is a plan view and FIG.

[Explanation of symbols]

 Reference Signs List 1 optical pickup optical element 2 substrate 3 objective lens, first objective lens 5 film that does not transmit coherent light 6 micro aperture 7 near-field light 11, 13 optical pickup optical element 14 objective lens, first objective lens 21 , 22 Optical pickup optical element 23 High refractive index film 24 Optical pickup optical element 25 Tapered hole 32 High refractive index material 33 Optical pickup optical element 34 Probe section with tapered projection 37 High refractive index material Reference Signs List 40 optical pickup optical element 41 probe unit 46 optical recording medium 61 optical pickup optical element 62 second objective lens 69 to 73 optical pickup optical element 81 optical pickup optical element 82 high refractive index material 83 optical pickup optical element 85-87 Optical element for optical pickup 100 Light Optical elements 102 to 107 other optical components 108 and 109 probes 112, 114 optical pickup for an optical element for Kkuappu

Claims (16)

[Claims] 1. Coherent light having a predetermined wavelength is incident, the light is collimated, and the collimated light is condensed as a minute spot on an optical recording medium to record information on the optical recording medium. In an optical element for an optical pickup for performing reproduction or erasing, an objective lens for condensing the collimated light is formed on a substrate, and near-field light or near-field light is formed at or near a converging point of the objective lens. An optical element for an optical pickup, wherein a probe portion for generating light and propagation light is formed. 2. The optical pickup optical device according to claim 1, wherein the probe section is formed by forming a minute opening in a film that is deposited on the substrate and does not transmit the coherent light. element. 3. The probe section is formed by a hole deposited on the substrate and impermeable to the coherent light through a tapered shape so that the medium facing surface side has a minute opening. The optical element for an optical pickup according to claim 1, wherein: 4. The optical element for an optical pickup according to claim 1, wherein the probe section is formed as a tapered protrusion having a medium-facing side narrowed by a material through which the coherent light is transmitted. 5. The optical element for an optical pickup according to claim 1, wherein the probe portion is formed of a same material as that of the substrate, and is formed as a tapered projection having a medium facing side narrowing. 6. The optical pickup optical device according to claim 1, wherein the probe portion is formed of a material having a refractive index higher than that of the substrate material, and is formed as a tapered protrusion having a medium-facing side narrowed. element. 7. Coherent light having a predetermined wavelength is incident, the light is collimated, and the collimated light is condensed on the optical recording medium as a minute spot, thereby recording information on the optical recording medium. In an optical element for an optical pickup for performing reproduction or erasing, a first objective lens for condensing the collimated light, and condensed by the first objective lens coaxially with an optical axis of the first objective lens. A second objective lens for further condensing the reflected light on the substrate, and generates near-field light or near-field light and propagating light at or near the focal point of the second objective lens. An optical element for an optical pickup, wherein a probe portion is formed. 8. The apparatus according to claim 7, wherein the probe section is formed by forming a minute opening in a film that is deposited on the second objective lens and does not transmit the coherent light. Optical element for optical pickup. 9. The probe section is formed in a film deposited on the second objective lens and not penetrating the coherent light by a hole penetrating in a tapered shape so that the medium facing surface side has a minute opening. The optical element for an optical pickup according to claim 7, wherein: 10. The apparatus according to claim 7, wherein the probe section is formed on the second objective lens as a tapered projection whose side facing the medium is made narrower by a material transmitting the coherent light. Optical element for optical pickup. 11. The apparatus according to claim 7, wherein the probe section is formed on the second objective lens as a tapered protrusion having a medium facing side tapered from the same material as the second objective lens. An optical element for an optical pickup according to the above. 12. The probe section is formed on the second objective lens as a tapered projection whose surface facing the medium is made narrower with a material having a higher refractive index than the material of the second objective lens. The optical element for an optical pickup according to claim 7, wherein: 13. The small opening at the tip of the hole penetrated in a tapered shape is elongated.
Or the optical element for an optical pickup according to 9. 14. The tapered projection according to claim 4, wherein an apex of the projection has an elongated shape.
13. The optical element for an optical pickup according to 0, 11 or 12. 15. recording information on the optical recording medium;
15. The optical element for an optical pickup according to claim 1, wherein another optical component that forms an optical system for performing reproduction or erasure together with the objective lens is mounted on the substrate. 16. Recording of information on the optical recording medium by injecting coherent light having a predetermined wavelength, collimating the light, and condensing the collimated light as a minute spot on the optical recording medium. A method for manufacturing an optical element for an optical pickup for performing reproduction or erasing by using a semiconductor manufacturing process, wherein a first objective lens for condensing the collimated light is provided on a substrate. Forming, forming a concave curved surface on the side opposite to the first objective lens formed on the substrate, depositing a material having a higher refractive index than the substrate on the concave curved surface, Forming a second objective lens for further condensing the light condensed by the first objective lens at a position coaxial with the optical axis of the first objective lens; Forming a tapered protruding probe for generating near-field light or near-field light and propagation light on the second objective lens by processing a material having a higher refractive index than the substrate deposited on the second objective lens. And a method for producing an optical element for an optical pickup.