JP2000193580A - Optical waveguide type probe, light detecting head and production of them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide type probe and a light detecting head low in cost and high in reliability. SOLUTION: The optical waveguide type probe 1 is constituted so that a channel type waveguide 7 having a light incident tip end 7a sharpened so as to be a size of light wavelength or less and having a photodetector 6 and an optical coupling part between the tip end and terminal thereof is formed on a semiconductor substrate on which the photodetector 6 is formed so as to be held between clad layers having a refractive index lower than that of the channel type waveguide 7. This optical waveguide type probe 1 is mounted on a slider 2 to constitute a light detecting head 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup of an optical information reproducing apparatus for reproducing information recorded on a recording medium by using near-field light, and a method of manufacturing the same.

[0002]

2. Description of the Related Art An optical recording / reproducing apparatus represented by an optical disk apparatus has been attracting attention as a large-capacity interchangeable medium.

However, in recent years, the capacity of magnetic disk devices has been rapidly increasing.

[0004] Therefore, in order to further increase the density of the optical disk device, there are three directions: shorter wavelength of the light source, technology for forming minute information recording marks, and technology for accurately reproducing information recording marks smaller than the light spot diameter. Although research and development have been promoted since then, the problem is that light smaller than the wavelength cannot be collected due to the diffraction phenomenon.

As a method of overcoming this limitation and improving the recording density by two orders of magnitude from the current state, a near-field optical microscope (Scan) has been proposed.
ning Near-field Optical M
(microscope: SNOM, hereinafter abbreviated as SNOM)
An optical recording / reproducing method using the configuration described above has attracted attention.

[0006] This system generally includes Illumina.
one that emits near-field light from a small aperture called a Tion mode (hereinafter abbreviated as I mode);
A method of collecting near-field light appearing on the surface of a sample, which is called a “tion mode” (hereinafter abbreviated as “C mode”), with a probe is known, and a configuration called a hybrid mode having both functions is also known.

FIG. 9A shows the configuration of the I mode.

A probe 22 connected to a light source 21 faces a recording medium substrate 23 on which a recording film such as a phase change material is formed on a transparent substrate surface made of resin or glass and a recording mark 23a is formed. ing.

The probe is obtained by sharpening an optical fiber by heating, elongating, etching, or the like, forming a metal film 22b thereon, and removing the metal film only at the probe tip 22a. An opening is formed.

The distance between the probe tip 22a and the recording medium substrate 23 is maintained at several tens of nm.

With the recording medium substrate 23 interposed, the probe 22
The photodetector 24 is arranged on the opposite side of the photodetector 24.

Light generated by the light source 21 and guided to the probe 22 oozes as near-field light N at the probe tip 22a.

However, the recording medium substrate 23 on which the recording mark 23a is formed is present near the probe tip 22a, and a part of the exuded light is no longer near-field light, and is transmitted through the recording medium substrate 23. It becomes light.

When the propagating light generated from the near-field light N passes through the recording mark 23a, the recording mark 23a interacts with the light to cause a change in intensity and a phase. I do.

Since the photodetector 24 needs to receive light diverging through the recording medium substrate 23, a photodetector having a relatively large light receiving surface is required. There is a merit that the alignment with the probe tip 22a which is opposed to the other end becomes easy.

When a mark is recorded with the energy of near-field light, this I-mode is often adopted from the viewpoint of securing recording power.

FIG. 9B shows the configuration of the C mode.

The light source 21 is formed such that a recording film is formed on the surface of a transparent substrate made of resin or glass, and light is incident from the back surface of the recording medium substrate 23 on which the recording marks 23a are formed at an angle of a critical angle or more. Are located.

On the opposite side of the light source 21 across the recording medium substrate 23, a probe 22 connected to a photodetector 24 is arranged.

The distance between the probe tip 22a and the recording medium substrate 23 is maintained at several tens of nm.

The light emitted from the light source 21 enters from the back surface of the recording medium substrate 23, is totally reflected near the recording mark 23a, and is emitted to the outside again from the back surface side of the recording medium substrate.

At this time, near-field light N is seeping out on the surface of the recording medium substrate 23.

However, the probe tip 22 a exists near the recording medium substrate 23, and a part of the exuded light is no longer near-field light, but becomes propagation light guided to the probe 22.

The propagating light generated from the near-field light N interacts with the recording mark 23a when passing through the recording mark 23a, causing a change in intensity and a phase. Therefore, the photodetector connected to the probe 22 At 24, the signal can be read.

By making the optical coupling between the probe 22 and the photodetector 24 more efficient, the light receiving surface can be made smaller than that of the photodetector in the case of the I-mode.

In the I mode, light is irradiated only to a local region of the object to be measured, so that a chemical reaction, processing, physical property analysis, and the like can be performed in a minute region using the energy of near-field light.

For this reason, FIG.
There are relatively many studies and reports on the I mode shown in (a). For example, a probe 22 formed of an optical waveguide and integrated with a light source is proposed in JP-A-9-35318.

This will be described below with reference to FIGS. 10 and 11.
This will be described with reference to FIG.

According to the configuration shown in FIG. 10, there are two flying sliders 25 and 26 which face each other across a recording medium substrate (described later with reference to FIG. 11), and the flying slider 25 is a light irradiation system and a flying slider. 26 is a light receiving system.

The flying slider 25 has a semiconductor laser 27
And a photodetector 2 for monitoring the output of the semiconductor laser 27
8, and a dielectric layer 29 are disposed.

A channel waveguide 30 is formed inside the dielectric layer 29, and its tip is sharpened to form a photon probe 31.

On the other hand, a prism 32 is arranged on the flying slider 26 of the light receiving system, and a photodetector which is hidden behind the prism 32 and cannot be seen is arranged near its mounting surface.

FIG. 11 shows a flying slider 25, a photon probe 31, a flying slider 26, and a floating slider 25 having the structure shown in FIG.
The cross section of the prism 32 and its peripheral portion is enlarged and displayed.

The flying slider 25 is provided with a groove 35, on the surface of which an insulating layer 38 is formed.

However, the width of the groove 35 in the direction perpendicular to the plane of the drawing is smaller than the width of the photodetector 28 and the semiconductor laser 27 in the direction perpendicular to the plane of the drawing.

The wiring 39 and the wiring 44 are attached to portions other than the groove 35 and the groove of the flying slider 25.

A pad 42 is attached to the surface of the photodetector 28 on the flying slider 25, and a pad 47 is attached to the surface of the semiconductor laser 27 on the flying slider 25.

The pad 42 and the wiring 39 are fixed by solder 43, and the pad 47 and the wiring 44 are fixed by solder 48, so that electrical connection is obtained.

The solder 48 also has a function of releasing heat generated by the semiconductor laser 27 to the flying slider 25.

The photodetector 28 has a pad 42 fixed to the solder 43 and a pad 40 attached to a surface opposite to the pad 42. When light from the semiconductor laser 27 enters the active layer 41, the active layer 41 is activated. A current flows through the internal PN junction, and the current is taken out by the pads 42 and 40.

The semiconductor laser 27 is provided with a pad 47 fixed by solder 48 and a pad 45 on the surface opposite to the pad 47. When a current flows through these, a laser beam is generated in the active layer 46. It has become so.

A part of the laser light is emitted from the end face of the semiconductor laser 27 on the side where the photodetector 28 is attached, and the signal intensity is measured by the photodetector 28.

Another part of the laser light is
The light exits from the end face opposite to the side on which the photodetector is mounted, and enters the sharpened portion 50.

The flying slider 25 has a dielectric layer 29a,
A dielectric layer 29b is attached, and a channel waveguide 30 is provided near these boundary surfaces.

A sharp portion 50 is provided on the end face of the channel waveguide 30 opposite to the end face on which the semiconductor laser 27 is mounted.

On the exposed surfaces of the dielectric layers 29a and 29b and the sharp portion, a light-shielding layer 49 is partially provided except for the opening 51.

A recording layer 34, a protective layer 33, and a lubricating layer 37a are attached to the surface of the recording medium substrate 36 on the above-described sharp portion 50 side, and a lubricating layer 37b is attached to the opposite surface.

Here, the protection layer 33 functions as a protection film for preventing the recording layer 34 from being oxidized or deteriorated, and when the flying slider 25 crashes.

A part of the guided light propagating through the channel waveguide 30 oozes out from the opening 51 as near-field light.

A lubricating layer 37a exists near the opening 51, and a part of the oozed light is no longer near-field light.
It becomes spatial light passing through the lubricating layer 37a, the protective layer 33, the recording layer 34, the recording medium substrate 36, and the lubricating layer 37b.

The spatial light generated from the near-field light is applied to the recording layer 3.
4, the recording layer 34 interacts with light to write and read information.

In the case of reading, the recording layer 34 on which information is written is irradiated with the emitted light through the opening 51.

A part of the irradiation light passes through the recording layer 34, and passes through the recording medium substrate 36 and the lubrication layer 37b.

The transmitted light 52 enters the prism 32 attached to the flying slider 26, is reflected inside, and
The light enters a photodetector 54 provided on the flying slider 26.

The transmitted light 52 is converted into an electric current by the photodetector 54, applied to a control device board (not shown) by the wirings 53a and 53b, and a signal is reproduced based on the detection signal.

On the other hand, regarding the configuration of the C mode shown in FIG. J. Appl. Phys. Vol
31 (1992) pp. Nano at 2282-2287
metric Scale Biosample Ob
Serving Using a Photon
Scanning Tunneling Micros
Although the relationship between the probe shape and the optical characteristics is described in the scope, there are fewer studies and reports than in the I mode, and as shown in FIG. Not done.

For example, JP-A-6-259821
In Japanese Patent Application Laid-Open Publication No. Hei 10 (1999), a hybrid mode configuration is proposed, in which a probe and an optical waveguide are combined via a grating coupler.

Hereinafter, this will be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 12 is a perspective view showing a recording / reproducing apparatus disclosed in JP-A-6-259821.

In this apparatus, a transparent probe 57 is provided at the tip of the cantilever 56, and information is recorded or reproduced by bringing the transparent probe 57 close to or in contact with the recording surface 55a of the disk 55.

When recording information, the laser light source 60
13 is converted into polarized light or circularly polarized light by a polarizer or a wave plate 61, and the light passes through a polarizing beam splitter 62 and a half-wave plate 63, and passes through an optical waveguide film 68 (FIG. 13) provided on a cantilever 56. Irradiates the recording surface 55a of the disk 55 via the transparent probe 57.

The disk 55 is formed by depositing a magnetic thin film having a multilayer structure of, for example, cobalt or platinum on a smooth glass or silicon substrate by sputtering.
By irradiating light from the tip of the transparent probe 57 as described above while applying a bias magnetic field in the vicinity of the transparent probe 57 by 4, information is recorded by magnetizing a minute portion corresponding to the light irradiation area. be able to.

For reproducing information, a laser beam having a smaller light amount than that at the time of recording is irradiated by the above-mentioned optical system, the reflected light is captured by the transparent probe 57, branched by the polarization beam splitter 62, and passed through the polarizer 65. By detecting with the detector 66, the rotation (Kerr effect) of the polarization angle of the reflected light according to the magnetization of the disk 55 can be detected.

FIG. 13 shows details of the cantilever 56. FIG. 13 (a) is a sectional view and FIG. 13 (b) is a plan view.

The cantilever 56 is provided with an optical waveguide film 68 made of silicon nitride on a silicon oxide film 67, and a movable probe of the cantilever 56 is provided with a transparent probe 57.

Here, the transparent probe 57 is provided at its tip with a small opening 74 sufficiently smaller than the wavelength of light, and the transparent probe 57 is covered with the light shielding film 75 except for the small opening 74. Covered.

Thus, it is possible to avoid inconvenience of irradiating extra light to the portion other than the tip portion of the transparent probe 57 and, conversely, to detect extra light, thereby performing highly accurate recording and reproduction. be able to.

The thickness and the refractive index of the optical waveguide film 68 are appropriately selected so that the wavefront is preserved with respect to the wavelength of the light to be used.

At the movable end of the cantilever 56, a substantially concentric grating 70 is provided around the axis 69 of the transparent probe 57 on the surface of the optical waveguide film 68. It constitutes a coupler connecting them.

Thus, the light that has passed through the optical waveguide film 68 can be efficiently guided to the transparent probe 57, and
The weak light detected in the near visual field at the tip of the transparent probe 57 can be efficiently guided to the optical waveguide film 68.

Also, by appropriately selecting the grating pitch for the wavelength of the light to be used, the transparent probe 5
Since the focus can be focused on the small aperture 74 of the seventh embodiment, high-density recording of information becomes possible.

At the fixed end of the cantilever 56, a transparent glass substrate 71 for fixing is adhered. On the surface of the optical waveguide film 68 located at this portion, the axis 69 of the transparent probe 57 is centered. A substantially concentric grating coupler 72 is provided.

When parallel light enters the grating coupler 72 from the direction 73 perpendicular to the optical waveguide film 68, the incident light is focused toward the axis 69 of the transparent probe 57 while maintaining the wavefront.

The guided light is transmitted to the transparent probe 5 described above.
It is led to 7.

[0075]

When a probe formed by processing an optical fiber is used, the processing of the probe is costly and is not suitable for mass production.

Therefore, it is desirable to form the probe with an optical waveguide and integrate it with the photodetector. However, regarding an optical system in which the optical waveguide with the probe is optically coupled to the photodetector, Had not been proposed.

In some cases, as a hybrid mode optical system, integration of a transparent probe and an optical waveguide film has been proposed, but integration of a photodetector has not been made.

Furthermore, the conventional sharp probe formed by processing a channel waveguide has a structure in which the tip still protrudes.

This is because the microscope is premised on measurement of irregularly sized projections or depressions, or the metal film is selectively removed to facilitate formation of an optical opening at the probe tip. However, there is a problem that the sharpened probe is easily broken.

An object of the present invention is to solve these problems and to provide a low-cost and highly reliable optical waveguide probe and light receiving head.

[0081]

According to a first aspect of the present invention, there is provided an optical waveguide probe comprising: a semiconductor substrate on which a photodetector is formed; The channel-type waveguide having the optical detector and the optical coupling portion therebetween is formed between cladding layers having a lower refractive index than the channel-type waveguide. The optical waveguide probe according to claim 1, wherein the output from the photodetector is provided on the same semiconductor substrate on which the channel type waveguide and the photodetector are formed. An IC to be processed is formed.

The optical waveguide probe according to claim 3 is
3. The optical waveguide probe according to claim 1, wherein the channel waveguide is formed via the semiconductor substrate and a silicon nitride film.

The optical waveguide probe according to the fourth aspect is
4. The optical waveguide probe according to claim 1, wherein a sharpened tip of the channel waveguide is covered with a dielectric material to form an optical opening, and the optical opening is substantially flat. It is characterized by being formed.

An optical waveguide probe according to a fifth aspect of the present invention
The optical waveguide probe according to claim 4, wherein the dielectric material is SOG (spin on glass).

The optical waveguide probe according to claim 6 is
The optical waveguide probe according to claim 4, wherein the dielectric material is silicon dioxide formed by CVD.

The optical waveguide probe according to claim 7 is
The optical waveguide probe according to any one of claims 3 to 6, wherein light other than guided light that is externally incident on at least one of the channel waveguide, the photodetector, and the IC is blocked. A light-shielding film is formed thereon.

The light receiving head according to the eighth aspect is the first aspect.
7. The optical waveguide probe according to any one of claims 1 to 7, wherein the optical waveguide probe is mounted on a slider, and when a recording medium on which information is recorded is irradiated with light from another optical system, near-field light generated near a recording mark is generated. The recorded information is reproduced by detecting with the optical waveguide type probe.

The light receiving head according to the ninth aspect provides the light receiving head according to the eighth aspect.
In the light receiving head described in (1), a plurality of the optical waveguide probes according to any one of claims 1 to 7 are formed on the same substrate to constitute a multi-probe.

According to a tenth aspect of the present invention, there is provided a method of manufacturing an optical waveguide type probe according to any one of the first to seventh aspects, wherein the sharpened tip portion of the channel type waveguide is provided. Forming an optical aperture by cleaving the semiconductor substrate on which the channel waveguide is formed.

The method of manufacturing an optical waveguide probe according to claim 11 is the method of manufacturing an optical waveguide probe according to any one of claims 1 to 7, wherein the sharpened tip portion of the channel type waveguide is provided. Forming an optical opening by dicing.

According to a twelfth aspect of the present invention, in the method of manufacturing an optical waveguide probe according to the seventh aspect, the light shielding film is formed by electroless plating.

According to a thirteenth aspect of the present invention, in the method for manufacturing a light receiving head according to the eighth or ninth aspect, the optical opening is formed at the tip portion of the optical waveguide type probe by the floating. It is characterized in that it is performed simultaneously with the surface processing of the mold slider.

[0093]

(Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of an optical waveguide type probe 1 according to the present invention and a light receiving head 3 configured by mounting the probe on an air floating type slider 2.

The light receiving head 3 is disposed on the side of the recording medium substrate 4 on which the recording mark 4a is formed.

On the opposite side of the recording medium substrate 4, a light irradiation system 5 including a light source and a lens is disposed.

The optical waveguide probe 1 has a photodetector 6
And a channel waveguide 7 optically coupled to the photodetector 6 and an IC 8 for signal processing are monolithically formed on the same element.

The tip of the channel waveguide 7 is sharpened below the wavelength of light, and constitutes the tip 7a.

The incident light L emitted from the light irradiation system 5 enters from the side of the recording medium substrate 4 where the recording marks 4a are not formed, and approaches the side of the recording medium substrate 4 where the recording marks 4a are formed. A field light N is generated.

At this time, since the incident light L passes through the recording mark 4a, if the recording mark 4a is recorded as a change in transmittance or refractive index, for example, the intensity of the near-field light N or seepage Changes the distance of the object.

On the surface of the recording medium substrate 4, the tip 7a of the channel waveguide 7 constituting the optical waveguide probe 1 is formed.
Is near a distance of several tens of nm, the near-field light N becomes propagation light and travels through the channel waveguide 7 to the photodetector 6.

The light propagating through the channel waveguide is photoelectrically converted by the photodetector 6, and the electric signal is
The signal is guided to a signal processing IC 8 constituting the optical waveguide probe 1 via a wiring on a semiconductor substrate 9 (not shown), and the information of the recording mark 4a is reproduced.

The optical waveguide type probe 1 detects the near-field light N generated in the vicinity of the recording mark 4a as an object to be measured by an optical probe and detects a signal.
NOM.

Next, the optical waveguide probe 1 of the present invention will be described with reference to FIG.

FIG. 2A is a plan view, and FIG. 2B is a sectional view.

The semiconductor substrate 9 has a photodetector 6 and an IC
8 are formed.

In the sectional view (b), only the photodetector 6 is shown.

Then, a silicon nitride film 10 is formed on the entire surface so as to cover the photodetector 6 and the IC 8.

The silicon nitride film 10 has a role of protecting the photodetector 6 and the IC 8 from damage during the later-described fabrication process, and from the waveguide material and impurity ions entering from the outside.

The silicon nitride film 10 is formed by low pressure CVD.
Suitable because the film is dense.

Further, a lower clad 11b,
Channel waveguide 7, upper cladding 11a, light shielding film 12,
The dielectric layers 13 are stacked in this order.

However, in the embodiment shown in FIG. 2, since the optical coupler of the tapered waveguide type is formed, the lower clad 11b is removed on the light receiving portion of the photodetector 6 to form an opening. .

The end of the channel waveguide 7 on the side opposite to the tip 7a is partially removed to form a termination 7b.

In this way, the light-shielding film 12 can be formed in the vicinity of the terminal end 7b, so that external light incident from the terminal end 7b can be blocked.

One end of the channel waveguide 7 is sharpened so as to be smaller than the wavelength of light, and a light-shielding film 12 is also provided at this portion. However, the light-shielding film 12 is removed only at the tip 7a, and an optical aperture is formed. Is formed.

The periphery of the tip 7a and the top of the light-shielding film 12 are covered with a dielectric layer 13, so that the tip 7a does not protrude.

In the case of a photon microscope, the shape of the object to be measured is arbitrary, and it is necessary to scan the probe along the surface shape.

On the other hand, the surface of the recording medium substrate is almost flat, and does not need to move in the thickness direction.

Since the sharpened and protruded tip is easily damaged, the periphery of the tip is protected by covering with a dielectric material in the present invention.

The upper cladding 11a and the lower cladding 11b above and below the channel waveguide 7 are for preventing light transmitted through the inside of the waveguide from leaking to the outside, and include a transparent material having a smaller refractive index than the material of the optical waveguide. For example, silicon dioxide.

In FIG. 2B, the lower clad 11b
Gradually becomes thinner as it approaches the photodetector 6,
The tapered waveguide is formed by combining the channel waveguide 7 and the upper clad 11a laminated thereon.

Light incident from the tip 7a and propagating inside the channel waveguide 7 in the right direction in the figure gradually leaks toward the semiconductor substrate 9 as the thickness of the lower clad becomes thinner.

The light detector 6 is formed at a position where the light is received, and the light transmitted inside the channel waveguide 7 is efficiently guided to the light detector 6.

The incident angle of the light leaking to the photodetector 6 with respect to the photodetector 6 is designed so that, for example, 70 ° becomes the intensity peak of the incident light in consideration of the antireflection effect of the silicon nitride film 10 described later. ing.

By appropriately setting the thickness of the silicon nitride film 10 in consideration of these conditions, an anti-reflection structure for light guided to the photodetector 6 can be obtained.

The details of the antireflection function are described in Japanese Patent Application No. 9-063614 (“guided light detector and manufacturing method thereof”) previously proposed by the present applicants.

To quote this, for example, if the refractive index of the channel waveguide 7 is 1.53 and the refractive index of the lower cladding 11b is 1.45, the angle of light emitted from the waveguide is about 70 °. When the thickness of the silicon nitride film 10 having a refractive index of 1.9 is 450 to 550 nm with respect to the waveguide structure, an antireflection effect is exhibited for light having an incident angle of about 70 °.

Here, a method of manufacturing the above-described optical waveguide probe will be described with reference to FIGS. FIG.
As shown in (a), the semiconductor substrate 9 has a photodetector 6 in advance.
Is formed, and the silicon nitride film 10 is laminated thereon.

Although not shown in these cross-sectional views, an IC for signal processing is also formed in the same semiconductor substrate, and the IC is also covered with a silicon nitride film.

On the silicon nitride film 10, a lower clad 11b made of a dielectric film is laminated.

For forming the lower cladding 11b, a method such as sputtering or CVD can be used.

After application of SOG (Spin On Glass), baking may be performed.

Note that the etching rate of the lower clad is higher than that of the channel waveguide for later forming the probe.

Next, as shown in FIG. 3B, an optical coupler for coupling the guided light to the photodetector 6 is formed.

Here, the case of the above-described tapered waveguide is shown.

First, as a manufacturing process of the tapered waveguide, first,
The lower cladding 11b on the photodetector 6 is removed by etching, and this is polished to finish it in a gentle and smooth taper shape having a maximum inclination of 10 ° or less.

If the tapering shape is designed in advance in the etching step, the burden of the subsequent polishing process can be reduced, but the ridges and protrusions are quickly removed by the polishing, so this is not always necessary.

The formation of the taper by polishing is described in JP-A-9-152528.

It is desirable that the inclination of the taper be 10 ° or less, as described in the above-mentioned Japanese Patent Application No. 9-063614 (“guided light detector and manufacturing method thereof”).

Subsequently, as shown in FIG. 3C, a channel waveguide 7 is formed.

Specifically, a material having a higher refractive index than the upper and lower claddings, such as a glass sputtering film or a Si—O—N CVD film, is formed and patterned.

Here, the other end of the channel waveguide 7, which is not sharpened, is partially removed so that the end face 7b is exposed.

This is because the effect of the light-shielding film laminated in a later step is also used at the end of the channel waveguide 7 to block light entering from the outside.

The patterning may be etching using a resist pattern or lift-off.

In the step of forming the channel waveguide, the width of the channel waveguide in the depth direction is changed, and the tip of the channel waveguide 7 is sharpened in an in-plane direction in a wedge shape in a plan projection view.

Further, the upper clad 1
1a is laminated.

Each material is selected so that the etching rate of the upper clad is higher than that of the channel waveguide for later forming the probe.

Further, as shown in FIG. 3D, a resist layer 14 having an opening patterned at a portion where a probe is to be formed is formed. As shown in FIG. 3E, this pattern is used as a mask. The following layers are subjected to dry etching.

For this etching, ion milling with less side etching is suitable.

Then, as shown in FIG. 3F, if isotropic etching is performed in this state with an acid solution containing hydrofluoric acid or the like, the upper cladding 11 having a large etching rate can be obtained.
a and the lower cladding 11b are etched first so that the channel waveguide 7 remains.

At this time, the accumulated time during which the end face of the channel waveguide contacts the etchant varies depending on the speed of the side etching of the upper clad 11a and the lower clad 11b. Therefore, by appropriately controlling the etching time, FIG. The shape can be sharpened as shown in f).

Thereafter, as shown in FIG. 4A, the resist layer 14 is removed to form the light shielding film 12.

Metal is suitable for the light-shielding film, and since a light-shielding film is provided on the wall surface of the etching groove G formed in FIG. 3E, electroless plating is suitable as a method.

In the vapor deposition, the metal particles are not sufficiently wrapped around the shaded portion, and cannot be applied to this step.

From above, a dielectric layer 13 is formed as shown in FIG.

Since the burying depth is about several tens of μm, it is preferable to form a silicon dioxide film by applying and firing SOG or CVD.

In the case of film formation by CVD, TEOS is used as a raw material.
The use of (ethyl silicate) improves the step coverage.

Finally, as shown in FIG. 4C, by dividing the semiconductor substrate 9, an optical aperture smaller than the wavelength of light is formed at the tip 7a of the channel waveguide. It is made.

Since it is necessary to align the divided portion with the tip 7a of the channel waveguide, a groove is formed by etching from the back surface of the semiconductor substrate 9 and the semiconductor substrate can be divided by cleaving using the groove.

When the cleavage is used, the semiconductor substrate can be divided along a plane according to the crystal plane of the semiconductor substrate, so that the flatness of the end face is improved.

As another method, dry etching may be performed from the front side using the patterned resist as a mask, and etching may be performed beyond the dielectric layer 13.

Since it is difficult to divide the semiconductor substrate 9 only by dry etching, it is preferable to previously thin the portion of the semiconductor substrate 9 from the rear surface with an alkaline solution to make it thinner.

As another method, dicing performed in the production of a normal semiconductor device can be used. For example, the cut portion may be cut with a fine diamond blade.

In this case as well, it is difficult to cut the semiconductor substrate 9 with only a fine blade, so it is preferable to previously thin the cut portion of the semiconductor substrate 9 with an alkaline solution from the back surface.

It is also effective to use different blades, for example, dicing most with a coarse blade and then cutting with a fine blade.

In FIG. 2, a tapered waveguide is taken as an example of the optical coupler for coupling the guided light to the photodetector 6, but the end face mirror type shown in FIG. The grating type shown in b) may be used.

In FIG. 5A, light incident from the tip 7a of the channel waveguide 7 becomes guided light, propagates through the channel waveguide 7, is reflected by the end face mirror 15, and is formed on the semiconductor substrate 9. The light is guided to the photodetector 6 and photoelectrically converted.

The end face mirror 15 may be a critical angle mirror utilizing total reflection of light or a mirror made of a metal film.

Also, by making the reflecting surface concave, it is possible to suppress the divergence of the light guided to the photodetector.

On the other hand, in FIG. 5B, light incident from the tip 7a of the channel waveguide 7 becomes guided light, propagates through the channel waveguide 7, is diffracted by the grating 16, and is formed on the semiconductor substrate 9. The photodetector 6 is guided to the photodetector 6 and photoelectrically converted.

The grating 16 is manufactured by providing a lattice shape on the channel waveguide 7, for example. The channel waveguide 7 may be laminated with a different material, or the channel waveguide 7 may be dug and processed.

If the grating 16 is formed into a curved line or the pitch is changed to form a condensing grating coupler, the divergence of the light guided to the photodetector can be suppressed.

In the embodiment shown in FIGS. 5A and 5B, since the incident angle of the light guided to the photodetector 6 changes, the thickness of the silicon nitride film 10 is optimized corresponding to each of them, and an antireflection effect is obtained. It is.

If the optical waveguide probe 1 shown in FIG. 4C is fixed to a flying slider, the light receiving head 3 of the present invention shown in FIG. 1 can be obtained. The optical waveguide probe of the present invention can be formed on a substrate. The manufacturing process in this case will be described with reference to FIGS.

FIG. 6A shows a ceramic substrate 17 constituting the flying slider 2.

This material is determined in consideration of workability, heat dissipation, thermal expansion coefficient, etc., and for example, calcium titanate is used.

As shown in FIG. 6B, a semiconductor material 9 ′ is laminated on the ceramic substrate 17.

As a method, an amorphous semiconductor film may be formed. However, in order to improve the performance of a photodetector manufactured in a subsequent step, it is better to bond a single crystal substrate.

For example, the ceramic substrate 17 having a mirror-finished surface and the semiconductor material 9 ′ are further ion-etched in a vacuum vessel to activate the surface, and are pressed as they are in a vacuum vessel to perform room temperature bonding. .

For the room temperature bonding, see, for example,
One example is described in Japanese Patent No. 92702.

Then, as shown in FIG. 6C, the photodetector 6 is formed on the semiconductor material 9 ', and further, the structure from the silicon nitride film 10 to the dielectric layer 13 in FIG. I do.

That is, the manufacturing process of the portion above the semiconductor material 9 'is the same as the method described with reference to FIGS. 3 and 4, and the state of FIG. 6C corresponds to the state of FIG. are doing.

However, the silicon nitride film 10, the upper clad 11a, and the lower clad 11b in FIG. 6 are not shown.

Thereafter, as shown in FIG. 6D, the ceramic substrate 17 is cut in accordance with the shape of the flying slider 2 to form a cut product 18.

In this state, the tip 7 of the channel waveguide 7
In a, no optical aperture has been formed yet.

FIG. 7A is a perspective view of the cut product 18.

Finally, as shown in FIG. 7B, necessary shapes such as the notch 19 and the groove 20 are processed, and the surface is polished to complete the light receiving head 3.

At the time of this polishing, the tip of the channel waveguide 7
An optical aperture smaller than the wavelength of light is formed in a.

As described above, by forming the optical opening at the tip portion of the optical waveguide type probe at the same time as the surface processing of the flying type slider, the optical opening at the tip portion of the floating type slider and the optical waveguide type probe is formed. Since the alignment in the height direction is not required, the fabrication becomes easy.

Embodiment 2 Another embodiment of the present invention will be described with reference to FIG.

The optical waveguide probe 1 'shown in FIG. 8 includes a plurality of photodetectors 6' and a channel waveguide 7 'optically coupled to the photodetectors 6'. Is composed.

Further, an IC for signal processing is provided on the same element.
8 'is formed monolithically.

The channel waveguide 7 'has a tip which is sharpened below the wavelength of light to form a tip 7a'.

By forming a light receiving head in which the optical waveguide type probe 1 'is mounted on the above-mentioned flying type slider and reproducing information on a plurality of tracks simultaneously by the multi-probe, the reproduction speed is improved.

It is also possible to use this multi-probe for tracking servo.

For example, a tracking error signal can be detected from the output of the photodetector 6 'optically coupled to the outer two channel waveguides 7', and servo similar to the three-beam method can be performed. is there.

[0197]

According to the first aspect of the present invention, on the semiconductor substrate on which the photodetector is formed, the front end on which light is incident is sharpened below the wavelength of light, and the light detection is performed between the front end and the end. The channel-type waveguide having the optical coupler and the optical coupling portion is formed between the cladding layers having a lower refractive index than that of the channel-type waveguide, whereby high-density information can be reproduced using near-field light. As a result, it is possible to reproduce a large amount of recorded information composed of minute marks.

According to the second aspect of the present invention, an IC for processing an output from the photodetector is formed on the same semiconductor substrate on which the channel type waveguide and the photodetector are formed. Accordingly, since the wiring can be shortened and the photoelectric conversion and the signal processing can be performed in the same element, the influence of signal crosstalk and disturbance noise is reduced, and the element characteristics are improved.

According to the third aspect of the present invention, the channel type waveguide is formed through the semiconductor substrate and the silicon nitride film, so that the photodetector and the IC can be connected to external impurities or impurities. Since it can be protected from processing damage, the element characteristics are stabilized and the reliability is improved.

According to the fourth aspect of the present invention, the tip of the channel-type waveguide processed to be thinner than the wavelength of light is covered with a dielectric material, and the optical opening is formed substantially in a plane. Since the tip of the probe can be protected, reliability is improved.

According to the fifth and sixth aspects of the present invention, since the dielectric material is made of silicon dioxide by SOG or CVD, the embedding in the groove becomes good, so that the tip of the channel type waveguide is formed. Can be easily coated with the dielectric material, which leads to cost reduction and improvement in reliability.

According to the seventh aspect of the present invention, a light shielding film is formed so as to block light other than externally guided light incident on one of the channel type waveguide, photodiode and IC. As a result, unnecessary external light can be blocked, so that the element characteristics are improved.

According to the eighth aspect of the present invention, the optical waveguide probe is mounted on an air-floating slider to form a light receiving head, so that the head can be downsized. Becomes possible.

According to the ninth aspect of the present invention, in the light receiving head, by forming a plurality of optical waveguide type probes on the same substrate to constitute a multi-probe, the information reproducing speed is increased. Information can be reproduced.

According to the tenth aspect of the present invention, the formation of the optical opening at the tip portion of the channel-type waveguide is performed by cleaving the semiconductor substrate on which the channel-type waveguide is formed. Since the opening can be formed on a plane conforming to the crystal plane, the end face treatment such as polishing is not required, which leads to cost reduction.

According to the eleventh aspect of the present invention, by forming the optical opening at the tip portion of the channel type waveguide by dicing, the number of processing steps can be reduced, so that the cost can be reduced. Can be

According to the twelfth aspect of the present invention, by forming the light-shielding film by electroless plating, it becomes possible to form a film in a region shadowed by the groove, so that the device characteristics are stabilized. Reliability is improved.

According to the thirteenth aspect of the present invention, the formation of the optical opening at the tip portion of the channel type waveguide is performed simultaneously with the surface processing of the floating type slider, so that the floating type slider and the optical waveguide type are formed. Since it is not necessary to align the tip of the channel type waveguide of the probe with the optical aperture in the height direction, the fabrication is easy and the cost is reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIGS. 2A and 2B are a plan view and a sectional view showing an embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a manufacturing process according to an example of the present invention.

FIG. 4 is a cross-sectional view illustrating a manufacturing process according to an example of the present invention.

FIG. 5 is a sectional view showing another embodiment of the present invention.

FIG. 6 is a sectional view showing a manufacturing process of another embodiment of the present invention.

FIG. 7 is a perspective view showing a manufacturing process of another embodiment of the present invention.

FIG. 8 is a plan view showing another embodiment of the present invention.

FIG. 9 is a configuration diagram showing a conventional technique.

FIG. 10 is a perspective view showing a conventional example.

FIG. 11 is a sectional view showing a conventional example.

FIG. 12 is a perspective view showing another conventional example.

FIG. 13 is a sectional view and a plan view showing another conventional example.

[Explanation of symbols]

 1, 1 'Optical waveguide probe 2 Slider 3 Light receiving head 4 Recording medium substrate 4a Recording mark 5 Light irradiation system 6, 6' Photodetector 7, 7 'Channel waveguide 7a, 7a' Channel waveguide tip 7b Channel Type waveguide termination 8, 8 'IC 9 Semiconductor substrate 9' Semiconductor material 10 Silicon nitride film 11a Upper cladding 11b Lower cladding 12 Light shielding film 13 Dielectric layer 14 Resist 15 End face mirror 16 Grating 17 Ceramic substrate 18 Cutout 19 Notch 20 Groove 21 Light source 22 Probe 22a Probe tip 22b Metal film 23 Recording medium substrate 23a Recording mark 24 Photodetector L Incident light L 'Guided light N Near-field light G Etching groove

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H01L 27/14 H01L 27/14 D 31/0232 31/02 DF term (reference) 2H037 AA04 BA11 CA34 CA40 DA06 2H047 KA03 KA13 KA15 KB08 MA07 PA04 PA05 PA21 PA24 QA04 RA04 TA05 TA27 TA44 4M118 AA10 AB10 BA02 CA02 EA01 GA09 GB11 5D119 AA11 AA22 BA01 CA05 CA06 CA11 DA01 DA05 FA05 JA37 JA64 KA02 MA06 5F088 BA15 BB10 EA06 HA10 HA12

Claims (13)

[Claims] 1. A semiconductor substrate having a photodetector formed thereon,
A channel type waveguide having a photodetector and an optical coupling portion between the end where light is incident is sharpened to a wavelength equal to or less than the wavelength of light and the end is formed in a cladding layer having a lower refractive index than the channel type waveguide. Characterized by being sandwiched and formed,
Optical waveguide probe. 2. An IC for processing an output from the photodetector is formed on the same semiconductor substrate on which the channel type waveguide and the photodetector are formed. The optical waveguide probe according to claim 1. 3. The optical waveguide probe according to claim 1, wherein the channel waveguide is formed via the semiconductor substrate and a silicon nitride film. 4. A sharpened tip of the channel type waveguide is covered with a dielectric material to form an optical opening, and the optical opening is formed substantially in a plane.
The optical waveguide probe according to claim 1. 5. The method according to claim 1, wherein the dielectric material is SOG (spin
5. The method according to claim 4, wherein
2. The optical waveguide probe according to claim 1. 6. The optical waveguide probe according to claim 4, wherein said dielectric material is silicon dioxide formed by CVD. 7. The channel waveguide, the photodetector,
The optical waveguide according to any one of claims 3 to 6, wherein a light-shielding film is formed so as to block light other than guided light incident on at least one of the ICs from the outside. Type probe. 8. An optical waveguide probe according to claim 1, wherein said probe is mounted on a slider, and when a recording medium on which information is recorded is irradiated with light from another optical system, a recording mark is formed. A light-receiving head, wherein near-field light generated in the vicinity is detected by the optical waveguide probe to reproduce recorded information. 9. The light receiving device according to claim 8, wherein a plurality of the optical waveguide type probes according to claim 1 are formed on the same substrate to constitute a multi-probe. head. 10. The method of manufacturing an optical waveguide probe according to claim 1, wherein an optical opening is formed in a sharpened tip portion of the channel waveguide.
A method for producing an optical waveguide probe, wherein the method is performed by cleaving the semiconductor substrate on which the channel waveguide is formed. 11. The method of manufacturing an optical waveguide probe according to claim 1, wherein an optical opening is formed in a sharpened tip portion of the channel waveguide.
A method for producing an optical waveguide probe, which is performed by dicing. 12. The method of manufacturing an optical waveguide probe according to claim 7, wherein the light shielding film is formed by electroless plating. 13. The method for manufacturing a light receiving head according to claim 8, wherein the optical opening of the tip portion of the optical waveguide probe is formed simultaneously with the surface processing of the floating slider. , A method of manufacturing a light receiving head.