JP2002340773A - Proximity field optical probe, its manufacturing method, proximity field optical cantilever and optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a proximity field optical fiber probe exhibiting high dimensional controllability, and its manufacturing method, in which arrival of light emitted from a micro opening is enhanced by increasing the refractive index. SOLUTION: In the structure of a proximity field optical probe emitting proximity field light, truncated conical protrusions are formed of a high refractive index material on a transparent substrate. In the method for manufacturing a proximity field optical probe, the truncated conical protrusions are formed of a high refractive index material by dry etching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a near-field optical probe for emitting near-field light, and more particularly to a near-field optical probe used for a scanning near-field microscope and an optical recording apparatus, a method of manufacturing the same, and a near-field optical probe. The present invention relates to an optical cantilever and an optical pickup device.

[0002]

2. Description of the Related Art A scanning probe microscope represented by an atomic force microscope (AFM) or a scanning tunnel microscope (STM) is widely used as a method for observing fine irregularities on a sample surface. At present, this scanning probe microscope is applied not only to observation of surface shape but also to observation of characteristics of various minute regions such as surface potential, frictional force, magnetic force, and elastic modulus. As one of the scanning probe microscopes, there is a scanning near-field optical microscope (hereinafter, abbreviated as SNOM).

[0003] The near-field means that light incident from one of two media having different refractive indices under the condition of total reflection or more is totally reflected at a reflection boundary surface, but a non-propagating electromagnetic field component passes over a partial boundary surface. An area where only oozes out is formed, and refers to this non-propagating electromagnetic field area. Such a region can be formed by a so-called near-field optical probe having a minute aperture. This optical probe enables resolution smaller than the wavelength of the light to be introduced. It is said that this near field has a lateral spread only about the same size as the aperture size. Therefore, by reducing the size of the opening, an opening exceeding the diffraction limit of light is provided, and the near field seeps only near this opening.

[0004] SNOM generally means that a near-field optical fiber probe is raster-scanned while maintaining a certain distance from a sample to be measured, and at the same time as a topographic image (concavo-convex image) of the sample, the optical region of the micro-region is optically scanned. A device that measures characteristics.

[0005] As a conventional one related to the structure of a near-field optical probe that emits near-field light, there is one related to a near-field optical probe formed with pyramidal silicon (2000 Spring Institute of Applied Physics Tokyo Institute of Technology Yai Takashi).

According to this publication, an optical pickup having a pyramidal silicon shape on a glass substrate is manufactured. In this manufacturing method, an active silicon layer of an SOI substrate is anodically bonded to a glass substrate, and the substrate silicon layer is K
Perform wet etching with an OH solution or a TMAH solution. Thereafter, a resist pattern is formed on the silicon oxide film layer, and the resist pattern is used as a mask to etch with an HF solution. Using the patterned silicon oxide film layer as a mask, the active silicon layer is
Wet etching with a solution of PA creates a pyramidal silicon shape.

However, in this method, since it is formed by anisotropic wet etching using the crystal orientation of silicon, only a quadrangular pyramid or an octagonal pyramid can be formed at a constant gradient. Also, since the silicon shape is formed by undercutting the patterned silicon oxide film layer mask, there is a problem that dimensional controllability is poor.

Further, as shown in FIG. 10, a mask 11 made of a circular photoresist having a thickness of 5 μm and a diameter of 5 μm is formed on one surface of a flat substrate 1 made of quartz glass, and the temperature is higher than the photoresist mp deformation temperature. Is raised to 150 ° C. and baked for 30 minutes to form the mask 11 into a conical shape with a sharp tip, followed by dry etching using CF 4 until the mask 11 is eliminated to form the projection 21. (JP-A-6-331805). Then, the reflection film 2 is formed on the projection 21 and an electric probe having an opening with a diameter of about 20 nm at the tip of the projection 21 is formed by electric field etching. In this method, the same shape as that of the resist is transferred to the glass substrate while the resist pattern is retreated by dry etching. Since the probe shape is formed in the glass substrate, the refractive index is low, and the ratio of light reaching the vicinity of the opening is low.

The problem of the near-field optical probe is as follows.
The light emitted from the minute aperture is very weak. Generally, this emission efficiency is one of the incident light.
It is said to be around 1,000. Therefore, a method for efficiently generating a near field is being studied.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems and demands of the prior art, and has good dimensional controllability and a high refractive index to allow light to be emitted from a minute aperture. It is an object of the present invention to provide a near-field optical probe having excellent reachability and a method of manufacturing the same, and an optical pickup (optical pickup device) and an optical recording device using the same.

[0011]

As a method for efficiently generating the near field, the present inventor has proposed that the tip of the optical probe be formed as a truncated cone-shaped projection made of a material having a high refractive index. The effective wavelength of light propagating in a truncated cone-shaped silicon having a refractive index is represented by λ / n (λ; wavelength, n; refractive index). The efficiency of light reaching the micro tip can be increased, and the emission efficiency can be increased. In particular, as this high refractive index material,
By using silicon, the processing of the truncated cone shape becomes easy, so that the polarization plane of the emitted light can be sufficiently maintained against the polarization plane of the incident light, and the polarization direction can be freely changed. Have been found, and the present invention has been accomplished.

[0012] Further, as a manufacturing method thereof, dry etching is performed, and in particular, by using silicon as the high refractive index material, a uniform shape which can be easily manufactured and has almost no dimensional variation can be produced. It has also been found that the angle of inclination of the truncated cone can be easily changed by changing the etching conditions, leading to the present invention.

That is, a near-field optical probe and a method of manufacturing the same according to the present invention are described below and shown in structure.

(1) In the structure of a near-field light probe that emits near-field light, a near-cone light probe is characterized in that a truncated cone-shaped protrusion made of a high refractive index material is formed on a transparent substrate. .

(2) The near-field optical probe according to the above (1), wherein the substrate is covered with a high refractive index material film.

(3) The near-field optical probe according to (1) or (2), wherein silicon is used as the high refractive index material.

(4) In the method for manufacturing a near-field optical probe according to any one of the above (1) to (3), it is preferable that the truncated cone-shaped protrusions made of the high refractive index material are formed by dry etching. A method for manufacturing a near-field optical probe.

(5) S serving as a high refractive index material on the substrate
Firstly anodically bonding the active silicon layer side of the OI substrate, removing the substrate silicon layer and the silicon oxide film layer from the substrate sequentially to leave the active silicon layer on the substrate, A step of forming a resist pattern, a step of dry-etching a part or all of the active silicon layer using the mask of the resist pattern, a step of removing the resist, and a step of removing a metal on the substrate or the active silicon layer. A method of manufacturing a near-field optical probe according to the above (4), comprising a step of forming a film.

(6) S serving as a high refractive index material on the substrate
Firstly anodically bonding the active silicon layer side of the OI substrate; removing the substrate silicon layer from the substrate to leave a silicon oxide film layer and an active silicon layer on the substrate; A step of forming a resist pattern, a step of dry-etching the silicon oxide film layer and the active silicon layer using the mask of the resist pattern, a step of removing the resist, and a step of removing the resist and the silicon oxide film layer. The method for manufacturing a near-field optical probe according to the above (4), comprising a step of removing and a step of forming a metal film or a magnetic film on the substrate or the active silicon layer.

(7) S serving as a high refractive index material on the substrate
Firstly anodically bonding the active silicon layer side of the OI substrate, removing the substrate silicon layer and the silicon oxide film layer from the substrate sequentially to leave the active silicon layer on the substrate, A step of forming a resist pattern, a step of dry etching part or all of the active silicon layer using the resist pattern mask, a step of forming a metal film on the substrate or the active silicon layer, A method of manufacturing the near-field optical probe according to the above (4), comprising a step of removing the resist.

(8) S serving as a material having a high refractive index on the substrate
Firstly anodically bonding the active silicon layer side of the OI substrate; removing the substrate silicon layer from the substrate to leave a silicon oxide film layer and an active silicon layer on the substrate; A step of forming a resist pattern, a step of dry-etching the silicon oxide film layer and the active silicon layer using the resist pattern mask, and a step of forming a metal film on the substrate or the active silicon layer. Removing the resist and the silicon oxide film layer thereof. The method of manufacturing a near-field optical probe according to the above (4), further comprising the steps of:

(9) A near-field light cantilever used in a scanning near-field light microscope comprising the near-field light probe according to any one of the above (1) to (3).

(10) An optical pickup used in a near-field optical recording system, wherein the near-field optical probe according to any one of (1) to (3) is configured.

(11) An optical pickup for use in a near-field optical recording system comprising a plurality of near-field optical probes according to any one of (1) to (3).

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a near-field optical probe and a method of manufacturing the same according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments and examples.

FIGS. 1A to 1E are explanatory views showing manufacturing steps of a first embodiment of a near-field optical probe according to the present invention. FIGS. 2A to 2G are explanatory views showing the manufacturing steps of the second embodiment of the near-field optical probe according to the present invention.
FIGS. 3A to 3G are explanatory views showing the manufacturing steps of the third embodiment of the near-field optical probe according to the present invention. FIG. 4 is a view showing an SEM image of a truncated conical projection in the near-field optical probe according to the present invention. FIG. 5 is an image diagram showing a light intensity distribution emitted from the near-field optical probe according to the present invention. 6A to 6C are image diagrams showing light intensity distributions emitted from the near-field light probe according to the present invention when three different polarizations of light are incident. FIGS. 7A to 7G are explanatory views showing the manufacturing steps of the fourth embodiment of the near-field optical probe according to the present invention. FIGS. 8A to 8H
FIG. 14 is an explanatory view showing a manufacturing process of the fifth embodiment of the near-field optical probe according to the present invention. FIG. 9 is a view showing an SEM image of a truncated conical projection on which a plurality of near-field optical probes according to the present invention are formed.

In the near-field optical probe according to the present invention, a truncated cone-shaped protrusion made of a high refractive index material is formed on a transparent substrate.

By making the tip of the optical probe a truncated cone-shaped protrusion made of a high refractive index material, the effective wavelength of light propagating through the truncated cone-shaped protrusion is reduced. For this reason, the arrival efficiency of light to the minute tip portion is increased, and the emission efficiency can be effectively increased. In addition, by making the projection into a truncated cone shape, the polarization plane of the outgoing light can be sufficiently maintained with respect to the polarization plane of the incident light, and the polarization direction can be freely changed.

As such a structure, for example, FIG.
(E) As shown in FIGS. 2 (g) and 3 (g), a truncated cone-shaped projection 5 made of a high refractive index material is formed on the transparent substrate 2.

In the near-field optical probe according to the present invention, the substrate is preferably covered with a high refractive index material film.

For example, as shown in FIG. 1E, the high refractive index material 6 can be left on the transparent substrate 2. In this case, the manufacturing process shown in FIGS. 2 and 3 is also possible. By adjusting the etching time to be short, the high refractive index material 1c may be left on the substrate 2 to form a high refractive index material film.

By forming a high-refractive-index material film on a transparent substrate and forming a truncated-cone-shaped protrusion on the high-refractive-index material film with the same high-refractive-index material, the high-refractive-index film formed on the substrate is simply obtained. The adhesion between the substrate and the high-refractive-index material can be improved as compared with the protrusion of the material.

In the manufacturing method, wet etching using a BHF solution used for removing the side wall protective film is performed.
Peeling between the substrate and the truncated conical projection can be effectively prevented.

As the transparent substrate used for the near-field optical probe according to the present invention, quartz glass, alumina silicate glass,
Other known transparent substrates can be used.

As the high refractive index material, the following materials can be mentioned in addition to silicon nitride.

For example, Table 1 and the like are shown.

[Table 1]

In particular, it is desirable to use silicon as the high refractive index material. By using silicon of such an SOI wafer, a near-field optical probe can be easily manufactured, and the material is inexpensive. It can be easily obtained.

As the metal film covering the substrate of the near-field optical probe according to the present invention, a metal film which becomes a reflection film, for example, a conductive film of gold, silver, platinum or the like can be used. And a magnetic film such as CoTi.

Next, a method of manufacturing a near-field optical probe for generating a near-field according to the present invention will be described.

In the near-field optical probe, as shown in FIG. 1, a truncated cone-shaped projection made of the high refractive index material can be formed by dry etching.

A silicon nitride film 6 is formed on a transparent substrate (quartz substrate) 2 as a high refractive index material. As a method for forming this silicon nitride film, SiH ₄ and NH ₃
So-called high-temperature heat C which is thermally reacted at a high temperature of 0 to 1150 ° C
The film is formed by the VD method. Further, the film thickness is desirably 2 μm or more (FIG. 1A).

In this embodiment, silicon nitride is used as the high refractive index material.
Those listed above may be used.

A columnar resist pattern 3 is formed on a substrate having a silicon nitride film 6 formed on the quartz substrate 2 by using a photolithography technique of a semiconductor process. The columnar resist pattern 3 is formed in a region where a conical projection is formed (FIG. 1B). This resist pattern 3
Is used as a mask to dry-etch the silicon nitride film 6 (FIG. 1C). During this etching, the quartz substrate 2
Is used as a stopping layer, the near-field light probe 5 in which a truncated cone-shaped protrusion made of a high refractive index material is formed on a transparent substrate can be obtained. Also, as in this embodiment,
By performing the etching in a shorter time, the silicon nitride film 6 in the region without the resist pattern 3 is left on the transparent substrate 2 and the near-field optical probe 5 having the high refractive index material film is formed.
Can be made. The thickness of the silicon nitride film in the region where there is no resist pattern 3 is preferably 100 nm or more.

After the etching, the resist pattern 3 is subjected to resist ashing using oxygen plasma to remove the resist (FIG. 1D). The metal film 4 is formed by sputtering on the surface on which the truncated cone-shaped protrusions made of silicon nitride are formed. In this embodiment, gold (Au) is
A film having a thickness of about 40 nm was formed (FIG. 1E).

Further, in the method for manufacturing a near-field optical probe according to the present invention, a step of first anodically bonding an active silicon layer side of an SOI substrate to be a high refractive index material on the substrate; And sequentially removing the silicon oxide film layer to leave an active silicon layer on the substrate; forming a resist pattern on the substrate or the active silicon layer; and masking the resist pattern with the active silicon It is preferable to include a step of dry-etching a part or all of the layer, a step of removing the resist, and a step of forming a metal film on the substrate or the active silicon layer. Thereby, a near-field optical probe can be effectively formed.

As shown in FIG. 2, on a transparent substrate 2 (Corning # 7740; film thickness 250 μm), an active silicon layer 1c (film thickness 4 μm) / silicon oxide film layer 1b (film thickness
0.5 μm) / substrate silicon layer 1a (thickness 400 μm)
SOI (Silicon On Insulat)
or) The substrate 1 is bonded using anodic bonding. On this occasion,
What is bonded to the transparent substrate 2 is the active silicon layer 1c side of the SOI substrate (FIG. 2A).

In this embodiment, the transparent substrate is
Using # 7740 (250 μm thickness) manufactured by Corning,
The SOI substrate was bonded by anodic bonding. As this transparent substrate, a quartz substrate can be used. In the case of this quartz substrate, the quartz substrate and the active silicon layer of the SOI substrate can be joined by high-temperature direct joining. This high-temperature direct bonding can be performed by sufficiently cleaning the surface of the substrate, bonding them together, and performing a heat treatment at 900 ° C. or more in a nitrogen atmosphere. As another bonding method, there is a direct bonding at room temperature. In this method, the bonding surface of a quartz substrate and an SOI substrate to be bonded is mirror-polished and RCA-cleaned, and simultaneously irradiated with an FAB (Fast Atom Beam) of Ar for about 300 seconds in a chamber having a vacuum degree of 1 × 10 -9 Torr or less. And pressure bonding at a pressure of 10 MPa.

The bonding strength is 12 MPa or more.
Further, a transparent resin may be used as the transparent substrate.
The bonding method may also use a transparent adhesive.

The substrate silicon layer 1a of the SOI / transparent substrate is selectively removed using a KOH or TMAH solution (FIG. 2B).

Further, the silicon oxide film layer 1b is selectively removed using an HF solution to obtain a substrate having an active silicon layer 1c on a transparent substrate 2 (FIG. 2C).

A columnar resist pattern 3 is formed on the active silicon substrate 1c by using a photolithography technique of a semiconductor process. This cylindrical resist pattern 3
Is formed in the region where the conical silicon 5 is formed. The height of the resist pattern 3 needs to be 0.5 μm or more,
Desirably, it is 1 μm or more. In this embodiment, about 1 μm
m (FIG. 2 (d)).

Using this resist pattern 3 as a mask,
The active silicon layer 1c is dry-etched as described above (FIG. 2E). In this dry etching, a parallel plate type RIE (Reactive Ion Etchin) is used.
g) An apparatus was used. The etching conditions include gas; S
iCl4, RF power; 400 W, processing pressure; 50 m
Torr.

By using the transparent substrate 2 as a stopping layer at the time of this etching, a near-field optical probe in which a projection of active silicon having a truncated cone shape is formed on the transparent substrate can be obtained. Further, by performing etching in a shorter time, the active silicon layer 1c in the region where there is no resist pattern 3 is partially left on the transparent substrate 2 as described above, and a portion having a high refractive index material layer on the substrate surface is formed. Field light probes can be made. The thickness of the active silicon layer 1c in the region where the resist pattern 3 is not present is preferably 100 nm or more.

After the silicon etching, the resist pattern 3 is subjected to resist ashing using oxygen plasma to remove the resist. Further, the side wall protective film and the like adhered to the truncated cone side wall are removed using a BHF solution or the like (FIG. 2).
(F)).

FIG. 4 shows an example of an SEM image of the silicon-shaped truncated cone-shaped protrusion 5 formed under the dry etching conditions. As can be seen from this SEM image, it can be seen that silicon protrusions are formed in a truncated cone shape. The upper surface diameter of the truncated conical protrusion is about 500 nm, and the height is about 1.5.
00 nm.

The metal film 4 is formed by sputtering on the surface on which the truncated conical projections 5 are formed. In this embodiment, gold (Au) was deposited to a thickness of about 40 nm (FIG. 2).
(G)).

FIG. 5 shows a light intensity distribution emitted from the near-field optical probe manufactured as described above. For this measurement,
As the light source, an LD having a wavelength of 780 nm is used, and the diameter of the upper surface of the truncated cone of the near-field optical probe is about 150 nm.
As can be seen from the light intensity distribution diagram of FIG. 5, it can be seen that a light spot corresponding to the diameter of the upper surface of the truncated cone is emitted. Thus, it can be seen that a minute beam spot having a wavelength of 1/4 or less can be created.

The upper surface diameter of frustoconical silicon is about 900 nm.
FIG. 6 shows how the intensity distribution of emitted light changes when three different polarizations of light enter the near-field optical probe. As can be seen from FIG. 6, it can be seen that the pattern changes greatly depending on the incident polarization direction. The state of this change also changes depending on the shape of the silicon. for that reason,
By using the frustoconical silicon projection in the near-field optical probe according to the present invention, unlike the pyramid-shaped one, even when the polarization direction is rotated, the angle of the silicon inclined surface with respect to the polarization plane is kept constant. Therefore, an emission pattern in which only the pattern is rotated can be obtained.

Further, in the near-field optical probe according to the present invention, the transparent substrate 2 is covered with the same silicon film as the projections, and a truncated cone-shaped silicon projection is formed on the silicon film, so that the transparent substrate 2 is transparent. The adhesion between the transparent substrate and the silicon can be improved as compared with the case where the frustum-shaped silicon is formed on a simple substrate. Further, in the above-described manufacturing method, the silicon substrate and the truncated cone-shaped silicon can be prevented from being peeled off by the wet etching using the BHF solution used for removing the sidewall protective film.

Further, in order to form the truncated conical silicon projection, it can be formed only by the dry etching method according to the present invention. That is, KOH or T
In the wet etching using the MAH solution, since the shape is formed based on the crystal orientation of the silicon crystal, only a quadrangular pyramid (pyramid shape) or an octagonal pyramid silicon shape can be formed. Also, the angle of the slope is uniquely determined. However, by using dry etching, the taper angle can be set arbitrarily in the truncated silicon shape, and the upper surface diameter of the truncated cone-shaped silicon can be finished with almost no variation.

Further, in the method for manufacturing a near-field optical probe according to the present invention, a step of removing a substrate silicon layer from the substrate to leave a silicon oxide film layer and an active silicon layer on the substrate; A step of forming a resist pattern on the silicon oxide film layer, a step of dry-etching a part or all of the active silicon layer using the resist pattern mask, and a step of removing the resist and the silicon oxide film layer And a step of forming a metal film on the substrate or the active silicon layer.

By using the process shown in FIG. 2 as a method of manufacturing a near-field optical probe having a truncated conical projection according to the present invention, a near-field optical probe can be effectively formed. Although a high refractive index material can be formed on a transparent substrate by such a method, formation of a film having a thickness of several μm may take too long in terms of manufacturing.

As shown in FIG. 3, an active silicon layer 1c (4 μm) / a silicon oxide film layer 1b (0.5 μm) / a transparent substrate 2 (Corning # 7740, 250 μm thick)
SOI (S) composed of substrate silicon layer 1a (400 μm)
An icon (Inicon On Insulator) substrate 1 is bonded using anodic bonding. At this time, the active silicon layer 1c of the SOI substrate is bonded to the transparent substrate 2 (FIG. 3A).

SOI / Transparent Substrate Silicon Layer 1a
Is selectively removed using a KOH or TMAH solution, and the silicon oxide film layer 1b is exposed on the surface (FIG. 3).
(B)).

A columnar resist pattern 3 is formed on the silicon oxide film layer 1b by using a photolithography technique of a semiconductor process. The columnar resist pattern 3 is formed in a region where conical silicon is to be formed (FIG. 3).
(C)).

Using the resist pattern 3 as a mask, the silicon oxide film 1b is dry-etched (FIG. 3).
(D)).

For dry etching, a parallel plate type RI is used.
An E (Reactive Ion Etching) apparatus was used. As etching conditions, gas; CHF ₃ and O
₂ , RF power; 100 W, processing pressure; 100 mT
orr. Further, using the resist pattern 3 and the silicon oxide film layer 1b as a mask, the active silicon substrate layer 1c
Is dry-etched (FIG. 3E).

In this dry etching, a parallel plate type RIE (Reactive Ion E)
tching) apparatus was used. The etching conditions are as follows: gas; SiCl ₄ , RF power; 400 W, processing pressure: 50 m Torr.

After the silicon etching, the resist pattern 3 is removed by performing ashing with oxygen plasma. Further, a silicon oxide film layer 1b remaining on the side wall protective film attached to the frustoconical side wall and the frustoconical silicon protrusion 5
Is removed using an HF solution (FIG. 3 (f)).

The metal film 4 is formed by sputtering on the surface on which the frustoconical silicon protrusions 5 are formed. In this example, gold (Au) was deposited to a thickness of about 40 nm (FIG. 3).
(G)).

By forming the truncated-cone-shaped silicon projection by such a manufacturing method, the height of the truncated-cone-shaped silicon projection 5 can be increased as compared with the manufacturing method shown in FIG. That is, using only the resist shown in FIG. 2 as a mask,
This is because the resist pattern 3 and the silicon oxide film layer 1b of the SOI substrate are used as a mask as compared with the case where the active silicon layer is etched. Further, when the silicon oxide film layer of the SOI substrate is removed, the side wall protective film can be removed at the same time, which leads to a reduction in manufacturing time.

A method of manufacturing a near-field optical probe according to the present invention comprises the steps of first anodically bonding the active silicon layer side of an SOI substrate which is to be a high refractive index material on the substrate, and the steps of: A step of sequentially removing the oxide film layer to leave an active silicon layer on the substrate, a step of forming a resist pattern on the active silicon layer, and a part or a part of the active silicon layer using the resist pattern mask It is preferable to include a step of dry-etching the whole, a step of forming a metal film on the substrate or the active silicon layer, and a step of removing the resist.

As shown in FIG. 7, on a transparent substrate 2 (Corning # 7740, 250 μm thick), an active silicon layer 1c (4 μm) / silicon oxide film layer 1b (0.5 μm) /
SOI (S) composed of substrate silicon layer 1a (400 μm)
An icon (Inicon On Insulator) substrate 1 is bonded using anodic bonding. At this time, the active silicon layer 1c of the SOI substrate is bonded to the transparent substrate 2 (FIG. 7A).

The SOI / transparent substrate silicon layer 1a is selectively removed using a KOH or TMAH solution (FIG. 7B).

Further, the silicon oxide film layer 1b is selectively removed using an HF solution to form a substrate having the active silicon layer 1c on the transparent substrate 2 (FIG. 7 (c)).

A columnar resist pattern 3 is formed on the active silicon substrate 1c by using a photolithography technique of a semiconductor process. This cylindrical resist pattern 3
Is formed in the region where the conical silicon 5 is formed. The height of the resist pattern 3 needs to be 0.5 μm or more,
Desirably, it is 1 μm or more. In this embodiment, about 1 μm
m (FIG. 7 (d)).

Using this resist pattern 3 as a mask,
The active silicon layer 1c is dry-etched as described above (FIG. 7E). For this dry etching, a parallel plate type RIE (Reactive Ion Etching) apparatus was used. Etching conditions include gas; SiCl
4, RF power; 400 W, processing pressure: 50 mTorr
r. By using the transparent substrate 2 as a stopping layer at the time of this etching, a near-field optical probe having a truncated-cone-shaped silicon protrusion formed on the transparent substrate can be obtained. Also, by etching in a shorter time, the active silicon layer 1 in a region where there is no resist pattern 3 is formed.
By leaving c on the transparent substrate 2, a near-field optical probe having a high refractive index material layer can be similarly formed. The thickness of the active silicon layer 1c in the region where the resist pattern 3 is not present is preferably 100 nm or more.

After the silicon etching, a metal film 4 is formed on the etched surface by sputtering. Gold (Au) was deposited to a thickness of about 40 nm (FIG. 7F). Gold (A
u) After film formation, ultrasonic cleaning is performed in an acetone solution for about 10 minutes. The resist is removed by the ultrasonic cleaning of acetone (lift-off method) (FIG. 7G).

According to this manufacturing method, a near-field optical probe in which a part other than the silicon upper surface in the shape of a truncated cone is covered with a gold (Au) film can be obtained.

By forming the truncated-cone-shaped silicon projections by such a manufacturing method, there is no metal film on the upper surface of the frustum-shaped silicon. Therefore, compared to the manufacturing method shown in FIGS.
Further, the emission efficiency can be increased.

Further, in the method for manufacturing a near-field optical probe according to the present invention, the S
Firstly anodically bonding the active silicon layer side of the OI substrate; removing the substrate silicon layer from the substrate to leave a silicon oxide film layer and an active silicon layer on the substrate; A step of forming a resist pattern, a step of dry-etching a part or all of the silicon oxide film layer and the active silicon layer using the mask of the resist pattern, and forming a metal film on the substrate or the active silicon layer. It is preferable to include a step of forming a film and a step of removing the resist and the silicon oxide film layer.

As shown in FIG. 8, an active silicon layer 1 was placed on a transparent substrate 2 (Corning # 7740, 250 μm thick).
SOI (Si) composed of c (4 μm) / silicon oxide film layer 1 b (0.5 μm) / substrate silicon layer 1 a (400 μm)
(icon on insulator) substrate 1 is bonded using anodic bonding. At this time, what is bonded to the transparent substrate 2 is the active silicon layer 1c of the SOI substrate (FIG. 8A).

SOI / Transparent Substrate Silicon Layer 1a
Is selectively removed using a KOH or TMAH solution, and the silicon oxide film layer 1b is exposed on the surface (FIG. 8).
(B)).

A columnar resist pattern 3 is formed on the silicon oxide film layer 1b by using a photolithography technique of a semiconductor process. This columnar resist pattern 3 is formed in a region where conical silicon is formed (FIG. 8).
(C)).

Using the resist pattern 3 as a mask, the silicon oxide film layer 1b is dry-etched (FIG. 8).
(D)).

For dry etching, a parallel plate type RI
An E (Reactive Ion Etching) apparatus was used. As etching conditions, gas; CHF ₃ and O
₂ , RF power; 100 W, processing pressure; 100 mT
orr. Further, using the resist pattern 3 and the silicon oxide film layer 1b as a mask, the active silicon substrate layer 1c
Is dry-etched (FIG. 8E).

In this dry etching, a parallel plate type RIE (Reactive Ion E)
tching) apparatus was used. The etching conditions are as follows: gas; SiCl ₄ , RF power; 400 W, processing pressure: 50 m Torr.

After the silicon etching, a metal film 4 is formed on the etched surface by sputtering. Gold (Au) was deposited to a thickness of about 40 nm (FIG. 8F). Gold (A
u) After film formation, ultrasonic cleaning is performed in an acetone solution for about 10 minutes. The resist is removed by the ultrasonic cleaning of acetone (lift-off method) (FIG. 8G).

Further, the silicon oxide film layer 1b remaining on the truncated conical silicon protrusion 5 is removed using an HF solution (FIG. 8).
(H)).

According to this manufacturing method, a near-field optical probe in which a portion other than the upper surface of the silicon protrusion having the shape of a truncated cone is covered with a gold (Au) film can be obtained.

By forming the truncated cone-shaped silicon projection by such a manufacturing method, there is no metal film on the upper surface of the truncated cone-shaped silicon projection, so that the emission efficiency is further increased similarly to the manufacturing method shown in FIG. Can be increased. FIG.
The resist residue that cannot be removed by the ultrasonic cleaning of acetone by the manufacturing method described in (1) can be completely removed by the subsequent HF solution in the silicon oxide film removing step. In addition, since the active silicon layer is etched using the resist and the silicon oxide film layer as a mask, the height of the truncated cone-shaped silicon projection can be increased.

The near-field light probe obtained by the method for manufacturing a near-field light probe manufactured as described above can be a near-field light cantilever used in a scanning near-field light microscope.

The near-field optical cantilever described above can measure optical characteristics with high sensitivity as a near-field probe having high light emission efficiency. In addition, since the cantilever can be manufactured without variation, the measurement can be performed with high accuracy and without variation as a cantilever.

The near-field probe obtained by the method for manufacturing a near-field optical probe according to the present invention can be an optical pickup used for a near-field optical recording system.

By using it as an optical pickup,
Fine mark recording exceeding the diffraction limit of light becomes possible,
This is effective for high-density recording.

Further, an optical pickup for use in a near-field optical recording system in which a plurality of near-field optical probes obtained by the method for manufacturing a near-field optical probe according to the present invention can be provided.

The transfer rate can be effectively increased by forming a plurality of the above probes and processing them in parallel. FIG. 9 shows an example (SEM image) of an optical pickup including a plurality of such near-field optical probes. As shown in FIG. 9, it can be seen that several near-field optical probes are formed uniformly with almost no variation.

[0098]

As described above, according to the near-field optical probe and the method of manufacturing the same according to the present invention, in the structure of the near-field optical probe that emits near-field light, a high-refractive-index material is provided on a transparent substrate. Since the truncated-cone-shaped protrusions made of are formed, and in the method of manufacturing the near-field optical probe, the truncated-cone-shaped protrusions made of the high-refractive-index material are formed by dry etching, so that dimensional controllability is good. In addition, by increasing the refractive index, it is possible to improve the reach of light and the like emitted from the minute aperture.

[Brief description of the drawings]

FIGS. 1A to 1E are explanatory views showing manufacturing steps of a first embodiment of a near-field optical probe according to the present invention.

FIGS. 2A to 2G are explanatory views showing manufacturing steps of a second embodiment of the near-field optical probe according to the present invention.

FIGS. 3 (a) to 3 (g) are explanatory views showing manufacturing steps of a third embodiment of the near-field optical probe according to the present invention.

FIG. 4 is a view showing an SEM image of a truncated conical projection in the near-field optical probe according to the present invention.

FIG. 5 is an image diagram showing a light intensity distribution emitted from a near-field optical probe according to the present invention.

6 (a) to 6 (c) are image diagrams showing light intensity distributions emitted from the near-field optical probe according to the present invention when three different polarized lights are incident.

FIGS. 7A to 7G are explanatory views showing manufacturing steps of a fourth embodiment of the near-field optical probe according to the present invention.

FIGS. 8A to 8H are explanatory views showing manufacturing steps of a fifth embodiment of the near-field optical probe according to the present invention.

FIG. 9 is a view showing an SEM image of a truncated conical projection on which a plurality of near-field optical probes according to the present invention are formed.

10 (a) to 10 (e) are explanatory views showing steps for manufacturing a conventional optical probe.

[Description of Signs] 2 Transparent substrate 3 Resist 4 Metal film 6 High refractive index material layer

Claims (11)

[Claims] 1. A near-field light probe comprising a near-field light probe that emits near-field light, wherein a truncated cone-shaped protrusion made of a high refractive index material is formed on a transparent substrate. 2. The near-field optical probe according to claim 1, wherein the substrate is covered with a high refractive index material film. 3. The near-field optical probe according to claim 1, wherein silicon is used as said high refractive index material. 4. The method for manufacturing a near-field optical probe according to claim 1, wherein the truncated cone-shaped protrusions made of the high refractive index material are formed by dry etching. Manufacturing method of field light probe. 5. A step of first anodically bonding an active silicon layer side of an SOI substrate to be a high refractive index material on the substrate, and removing the substrate silicon layer and the silicon oxide film layer from the substrate in order, Leaving an active silicon layer on the active silicon layer; forming a resist pattern on the active silicon layer; dry etching a part or all of the active silicon layer using the resist pattern mask; The method for manufacturing a near-field optical probe according to claim 4, comprising a step of removing and a step of forming a metal film on the substrate or the active silicon layer. 6. An anodic bonding step on an active silicon layer side of an SOI substrate which is to be a high refractive index material on said substrate, and a silicon oxide film layer and a silicon oxide film layer are removed on said substrate by removing said substrate silicon layer from said substrate. Leaving an active silicon layer; forming a resist pattern on the silicon oxide film layer; dry etching the silicon oxide film layer and the active silicon layer using the resist pattern mask; 5. The method for manufacturing a near-field optical probe according to claim 4, further comprising: a step of removing the silicon oxide film layer; and a step of forming a metal film or a magnetic film on the substrate or active silicon layer. . 7. A step of first anodically bonding an active silicon layer side of an SOI substrate to be a high refractive index material on the substrate, and sequentially removing the substrate silicon layer and the silicon oxide film layer from the substrate to form on the substrate Leaving an active silicon layer on the active silicon layer; forming a resist pattern on the active silicon layer; dry etching a part or all of the active silicon layer using the resist pattern mask; 5. The method for manufacturing a near-field optical probe according to claim 4, further comprising: a step of forming a metal film on the active silicon layer; and a step of removing the resist. 8. A step of first anodic bonding the active silicon layer side of the SOI substrate to be a high refractive index material on the substrate, removing the substrate silicon layer from the substrate, and forming a silicon oxide film layer on the substrate. Leaving an active silicon layer; forming a resist pattern on the silicon oxide film layer; dry etching the silicon oxide film layer and the active silicon layer using a mask of the resist pattern; 5. The method according to claim 4, further comprising: forming a metal film on the active silicon layer; and removing the resist and its silicon oxide film layer. 9. A near-field light cantilever for use in a scanning near-field light microscope comprising the near-field light probe according to claim 1. 10. An optical pickup device for use in a near-field optical recording system, wherein the near-field optical probe according to claim 1 is configured. 11. An optical pickup device for use in a near-field optical recording system, comprising a plurality of near-field optical probes according to claim 1.