JP2006302454A - Optical information recording medium, its manufacturing method and optical information processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium capable of highly efficiently recording and reproducing a signal of high quality when recording and reproduction are performed using a near field effect of light and to provide an optical information processor using the same. <P>SOLUTION: In the optical information recording medium 11 which is provided with a flat plate-shaped substrate and fine structures 12 each formed on the substrate and having a size shorter than the wavelength of recording light and wherein information is recorded in the fine structures 12 by using a probe 30 provided with a fine aperture 30a having a size shorter than the wavelength, the fine structure 12 has a layered structure having at least an optical recording layer and a metal layer (or the optical recording layer, a light absorbing layer and the metal layer). Thereby, the near field light is generated to the fine structure 12 by using the probe 30 provided with the fine aperture having the size shorter than the wavelength, recording can be performed in the optical recording layer by exciting plasmon in the metal layer and recording and reproduction of information of large capacity can be highly efficiently and stably performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical information recording medium having a fine structure with a size equal to or smaller than the wavelength of recording light and a method for producing the same, and further, using the optical information recording medium, the near-field optical effect is used to obtain data at an ultra-high density. The present invention relates to an optical information processing apparatus (optical information recording / reproducing apparatus) that performs recording or reproduction.

  In recent years, with the advancement to the multimedia era where various types of information such as audio and video motion picture files, text files, etc. are combined, the large capacity to quickly process and store a large amount of information There is a need for a medium for recording and storing such information. When bi-directional image communication such as high-definition video and VOD (Video-On-Demand), which is expected to become more popular in the future, is realized, the capacity of information recording media and storage media Will be further increased. In accordance with such a request, various recording and reproducing methods for recording media widely used at present are proposed. As one of such data recording / reproducing methods, recording on a recording medium using light is possible. There is a way to play.

As a typical example of a recording method using light, a method in which a specific refractive index is changed by irradiating a specific polymer material with predetermined light to change its molecular structure (for example, a phase change type). Recording method) and generally an amorphous alloy thin film made of rare earth metal and transition metal is irradiated with light in a predetermined magnetic field and locally heated above the Curie point or compensation point to change the local magnetization direction. (A magneto-optical recording method).
However, in these methods, the laser beam focused in the form of a spot by the lens optical system is irradiated onto the recording medium for recording or reproduction, so this laser spot diameter is important for determining the size of the recording mark. It has become a parameter.

  That is, the smaller the spot size of the laser beam, the more information can be recorded and reproduced on the optical recording medium, and the higher recording density can be achieved. The wavelength of light must be shortened and the numerical aperture (NA) of the objective lens of the optical pickup must be increased. However, the size of the laser beam spot that can be reduced by shortening the wavelength of the laser beam and increasing the numerical aperture of the objective lens is about the wavelength of the laser beam. For example, in order to shorten the wavelength of the laser beam, a blue semiconductor laser (up to 400 nm) is used instead of the red semiconductor laser (up to 660 nm) currently used as a light source of a DVD (digital versatile disk). When used as a light source, the amount of information that can be recorded per unit area of a DVD can be improved by about 2.5 times the amount of information on a recording medium when a red semiconductor laser is used. However, in such a method, the spot diameter of light is determined by the light diffraction limit, and there is a limit to improving the information recording density of the recording medium.

  Accordingly, in view of the above problems, near-field optics or volume holograms (Volume) are used as a technology based on a completely different principle from the above-described conventional technology when processing a terabyte (TB) class information amount. Ultra high density recording methods such as Hologram, photo-chemical hole burning, and three-dimensional optical recording have been proposed. However, the volume hologram and the photochemical hole burning have a drawback that it is difficult to put into practical use because there are significant restrictions on the usage environment of the recording medium.

In general, based on the light diffraction theory, the size (major axis) of the light focusing spot is determined by the wavelength of the light source and the numerical aperture, and the upper limit of the information recording density of the recording medium depends on the degree of reduction of the size of the light focusing spot. Is determined. In addition, the light diffraction phenomenon has the property that the beam becomes wider as the size of the light beam is reduced using a lens.
θ-λ / d (1)
It becomes. In the equation, θ represents the diffraction angle, d represents the diameter of the beam, and λ represents the wavelength of light. That is, based on the diffraction theory, the smaller the beam size using a lens, the larger the diffraction angle, and the beam size cannot be reduced below a predetermined value.

Therefore, the recording density limit of the optical recording medium is
d to 1.22λ · NA (2)
It is determined by the diffraction theory of light expressed approximately. Here, NA represents the numerical aperture of the objective lens. That is, the shorter the wavelength (λ) of the laser beam and the larger the numerical aperture (NA) of the lens, the smaller the size of the focused beam, and the recording surface density of the recording medium is the spot size. Due to the diffraction phenomenon due to the wave nature of light, the minimum size of information that can be recorded and reproduced per bit is approximately the wavelength of light.

Therefore, in such a conventional technique, the method of shortening the wavelength of light, reducing the size of the focused light spot using a lens having a large numerical aperture, and increasing the recording density is the best. The recording density obtained by this is expected to be limited to 20-30 Gbit / in ² . That is, in the conventional system, since light is used as an electromagnetic wave, when the recording density is improved, there is a problem that a restriction due to the diffraction limit is unavoidable.

  Therefore, in order to overcome such a diffraction limit, a method has been proposed in which light existing in the near field in the near field region (distance below the light wavelength from the surface of the substance) is used as a light source for the recording medium. That is, in principle, near-field light generated from an aperture smaller than the wavelength of light is not emitted. By recording and reproducing information on a recording medium using a method in which this near-field light interacts with a material located near the aperture, the diffraction limit is overcome and the information recording density of conventional optical recording There is a possibility that it can be improved dramatically.

  As a conventional technique for recording and reproducing information at high speed using this near-field light, a planar array type probe has been proposed (see Patent Document 1 and Patent Document 2). In this planar array type probe, a silicon substrate is anisotropically etched to produce minute openings in an array on the same substrate. Therefore, there are many probes in one element, and the sweep speed of the element itself does not need to be so high. The recording medium is arranged so as to rotate with respect to the probes arranged in a grid pattern, and the probes arranged on the two-dimensional plane pass through different points on the recording medium.

  In addition, these planar array type probes have a minute opening formed by digging a Si substrate by anisotropic etching. In this case, the part where the laser beam passes through the probe is a cavity, and when a more efficient light output (that is, for faster optical writing and reading) is required, It was necessary to fill with a material having a high refractive index and a high confinement effect.

  To solve this problem, a near-field optical probe has been proposed in which a truncated cone-shaped protrusion made of a high refractive index material is formed on a transparent substrate. In addition, in this method of manufacturing a near-field optical probe, it has been proposed to form a truncated cone-shaped protrusion made of the high refractive index material by dry etching (see Patent Document 3). Since this near-field optical probe has good dimensional controllability and a high refractive index, it has excellent reachability of light emitted from a minute aperture.

  In addition, as a method of forming a planar aperture probe having a plurality of micro aperture arrays and generating near-field light in the vicinity of the micro apertures for recording / reproducing on an optical recording medium, a photosensitive resin is formed on the substrate. A step of forming a film, a step of forming a latent image of a conical photosensitive resin pattern on a substrate using at least a photomask having a ring-shaped pattern and an exposure means having a diffused light component; Proposed a near-field optical probe in which a truncated cone-shaped protrusion is formed on a transparent substrate by developing the latent image of the conductive resin pattern and transferring the conical photosensitive resin pattern to the substrate by dry etching (See Patent Document 4, Patent Document 5, Patent Document 6, Patent Document 7, and Patent Document 8).

  An optical recording / reproducing medium suitable for a near-field recording method and a method for manufacturing the optical recording / reproducing medium, a cross section in a direction perpendicular to the guide groove of at least one of the concave portion or the convex portion in the concave and convex portions constituting the guide groove of the light spot. An optical recording / reproducing medium formed so as not to have a side perpendicular to the optical axis of the light spot, an optical recording / reproducing method improved by a tracking method using this optical recording / reproducing medium, and rectangular irregularities And a method of manufacturing an optical recording / reproducing medium in which the rectangular irregularities are deformed by heat treatment has been proposed (see Patent Document 9).

Furthermore, for processed products using photosensitive materials that form recesses or projections depending on the intensity of the irradiated light, the surface of the photosensitive material can be processed with fine light using a controlled intensity of light. By a light processing method, a fine concavo-convex shape or a binary or multi-value concavo-convex information recording bit is formed on a finely processed product or an optical recording medium easily and inexpensively by a single photosensitive material and optical system. A method has also been proposed (see Patent Document 10).
Further, a fine structure having a size smaller than the wavelength of light and a recording layer are formed on the recording medium, and recording on the recording medium is performed by near-field light radiated from a minute aperture of a planar probe having a minute aperture smaller than the wavelength of light. A method has been proposed in which information is recorded on a layer, and the coupling of near-field light emitted from a probe to a recording layer on a recording medium is enhanced to record and reproduce information efficiently and stably. Furthermore, by making the fine structure on the recording medium into a laminated structure, the coupling efficiency of the near-field light radiated from the probe to the recording medium is further improved, and information is recorded and reproduced with high efficiency and stability. Has been proposed (see Patent Document 11).

Japanese Patent No. 303085 JP-A-11-191238 JP 2002-340773 A JP 2003-317301 A JP 2003-322603 A JP 2004-5905 A JP 2004-39041 A JP 2004-61219 A JP 2000-322772 A JP 2003-39400 A JP 2003-308632 A

  As described above, various proposals have been made regarding optical information recording media and apparatuses that perform recording and reproduction using near-field light. However, the present invention is based on the above situation, and the near-field of light. An object of the present invention is to provide an optical information recording medium capable of recording and reproducing a high-efficiency and high-quality signal when performing recording or reproduction using the effect, and a method for manufacturing the same. It is another object of the present invention to provide an optical information processing apparatus capable of recording and reproducing a high-efficiency and high-quality signal using the optical information recording medium.

In order to achieve the above object, the present invention adopts the following means.
The first means of the present invention is a probe comprising a flat substrate and a microstructure having a size less than or equal to the wavelength of the recording light formed on the substrate, and a probe having a minute aperture having a size less than or equal to the wavelength. In an optical information recording medium in which information is recorded in a fine structure, the fine structure has a laminated structure having at least an optical recording layer and a metal layer (claim 1).
The second means of the present invention is a probe comprising a flat substrate and a fine structure having a size less than or equal to the wavelength of the recording light formed on the substrate, and having a minute aperture having a size less than or equal to the wavelength. In the optical information recording medium in which information is recorded in the fine structure, the fine structure has a laminated structure including at least an optical recording layer, a light absorbing layer, and a metal layer. In addition, since a light absorption layer absorbs light and generate | occur | produces heat, it is also called a heat | fever reaction layer.

According to a third means of the present invention, in the optical information recording medium of the first or second means, the fine structure has a dielectric layer on the metal layer.
According to a fourth means of the present invention, in the optical information recording medium of the third means, the dielectric layer is made of ZnSSiO ₂ .
Further, the fifth means of the present invention is characterized in that in the optical information recording medium of the third or fourth means, the thickness of the dielectric layer is thinner than the size of the fine structure. .

According to a sixth means of the present invention, in the optical information recording medium of any one of the first to fifth means, a protective layer is provided on the outermost surface of the fine structure.
According to a seventh means of the present invention, in the optical information recording medium according to any one of the first to sixth means, the metal layer is made of gold (Au), silver (Ag), aluminum (Al), platinum ( It is made of any one of Pt) and copper (Cu) (Claim 7).
Further, according to an eighth means of the present invention, in the optical information recording medium of any one of the first to seventh means, the size of the fine structure formed on the substrate is a minute aperture having a size equal to or smaller than the wavelength. It is equal to the opening dimension of the probe provided with (Claim 8).
According to a ninth means of the present invention, in the optical information recording medium of any one of the first to eighth means, the substrate surface has irregularities smaller than the wavelength of light. (Claim 9).

  A tenth means of the present invention is a method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate, and is provided on the entire surface of the flat glass substrate. Implanting ions capable of increasing the refractive index and forming fine irregularities with a resist on the surface; etching the glass substrate while retracting the resist; forming predetermined irregularities on the glass substrate surface; and resist Forming a laminated structure having at least an optical recording layer and a metal layer or a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer over the entire surface of the substrate, and a lift-off process for removing the resist. (Claim 10).

  The eleventh means of the present invention is a method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate, and is provided on the entire surface of the flat glass substrate. Implanting ions capable of increasing the refractive index, forming fine irregularities with a resist on the surface, etching the glass substrate while retracting the resist, forming predetermined irregularities on the glass substrate surface, And a step of removing the resist and a step of forming a laminated structure having at least an optical recording layer and a metal layer or a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer on the entire substrate surface. (Claim 11).

  A twelfth means of the present invention is a method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate, the resist being formed on the surface of the flat glass substrate. A step of forming fine irregularities, a step of etching the glass substrate while retracting the resist to form predetermined irregularities on the glass substrate surface, and at least the optical recording layer and the metal on the entire substrate surface while leaving the resist. And a lift-off step of removing the resist. The method further includes: a step of forming a layered structure having a layer; or a step of forming a layered structure having an optical recording layer, a light absorption layer, and a metal layer.

  A thirteenth means of the present invention is a method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate, the resist being formed on the surface of the flat glass substrate. Forming a fine unevenness, etching the glass substrate while retracting the resist to form a predetermined unevenness on the glass substrate surface, removing the resist, and optical recording at least over the entire substrate surface And a step of forming a laminated structure having a layer and a metal layer, or a laminated structure having an optical recording layer, a light absorbing layer and a metal layer.

  A fourteenth means of the present invention is a method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate, the surface of the glass substrate being coated with cobalt oxide. Forming a nano-glass thin film by a sputtering method, forming a fine unevenness with a resist on the surface, etching the glass substrate while retreating the resist, forming a predetermined unevenness on the glass substrate surface, Forming a laminated structure having at least an optical recording layer and a metal layer over the entire substrate surface while leaving the resist, or forming a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer, and a lift-off process for removing the resist (Claim 14).

  According to a fifteenth aspect of the present invention, there is provided a method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate, wherein the surface of the glass substrate is coated with cobalt oxide. Forming a nano-glass thin film by a sputtering method, forming a fine unevenness with a resist on the surface, etching the glass substrate while retreating the resist, forming a predetermined unevenness on the glass substrate surface, A step of removing the resist, and a step of forming a laminated structure having at least an optical recording layer and a metal layer or a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer on the entire substrate surface. (Claim 15).

  The sixteenth means of the present invention is a probe comprising a flat substrate and a fine structure having a size equal to or smaller than the wavelength of the recording light formed on the substrate, and a probe having a minute aperture having a size equal to or smaller than the wavelength. In an optical information recording medium in which information is recorded in a fine structure, the fine structure is produced by the production method of any one of the tenth to fifteenth means (claim 16).

According to a seventeenth means of the present invention, in the optical information recording medium of any one of the first to ninth and sixteenth means, diamond-like carbon is formed as a protective layer on the outermost surface of the fine structure. (Claim 17).
According to an eighteenth means of the present invention, in the optical information recording medium of any one of the first to ninth and sixteenth means, SiN is formed as a protective layer on the outermost surface of the fine structure. (Claim 18).

  According to a nineteenth aspect of the present invention, there is provided an optical information processing apparatus using the optical information recording medium of any one of the first to ninth and sixteenth to eighteenth means, and a minute aperture having a size equal to or smaller than a wavelength. A near-field light is generated with respect to the fine structure of the optical information recording medium by a probe provided with information recording or reproducing (claim 19).

According to a twentieth means of the present invention, in the optical information processing apparatus of the nineteenth means, as the probe, a cylindrical resist pattern is formed on a quartz substrate on which a silicon nitride film is formed using a photolithographic technique of a semiconductor process. After the formation, the silicon nitride film is removed by dry etching using this resist pattern as a mask, and a flat probe having a projection made of a high refractive index material on an optically transparent quartz substrate using a quartz substrate as a stopper layer It is provided (claim 20).
According to a twenty-first means of the present invention, in the optical information processing apparatus of the twentieth means, the planar probe and the optical information recording medium are in a non-contact state, and the planar probe and the optical information recording The distance from the medium is held in an area that is less than or equal to the wavelength of the light source used (claim 21).

The twenty-second means of the present invention is the optical information processing apparatus according to any one of the nineteenth to twenty-first means, and is based on near-field light generated from a planar probe held close to the optical information recording medium. In an optical information processing apparatus for recording or reproducing desired information on or from the optical information recording medium, a light source that emits a laser beam having a predetermined wavelength, the laser beam is guided to an objective lens, and the laser is transmitted through the objective lens. An illumination optical system for irradiating the planar probe with a beam and a detection optical system for receiving light from the planar probe (claim 22).
According to a twenty-third means of the present invention, in the optical information processing apparatus of the twenty-second means, the laser beam of the planar probe opposed to the exit surface of the objective lens for condensing the light on the planar probe. An antireflective coating film is formed on the surface portion of the incident surface (claim 23).

In the optical information recording medium of the first means, the microstructure has a laminated structure having at least an optical recording layer and a metal layer, so that a large amount of information can be recorded and reproduced with high efficiency and stability.
In the optical information recording medium of the second means of the present invention, the fine structure is a laminated structure having at least an optical recording layer, a light absorbing layer (thermal reaction layer), and a metal layer. A large amount of information can be recorded and reproduced stably.

In the optical information recording medium of the third and fourth means, in addition to the configuration and effect of the first or second means, the microstructure has a dielectric layer on the metal layer. The layer makes it possible to concentrate light near the center of the fine structure, and information can be recorded and reproduced with better and high density.
Further, in the optical information recording medium of the fifth means, in addition to the configurations and effects of the third and fourth means, the thickness of the dielectric layer is smaller than the size of the fine structure, so that it is good for the optical recording layer. It is possible to combine near-field light with a high light distribution shape and high efficiency.

In the optical information recording medium of the sixth means of the present invention, in addition to the configuration and effect of any one of the first to fifth means, a protective layer is provided on the outermost surface of the fine structure, thereby Wear can be prevented, and reliability during recording and reproduction can be improved.
It is characterized by.
In the optical information recording medium of the seventh means of the present invention, in addition to the configuration and effect of any one of the first to sixth means, the metal layer is made of gold (Au), silver (Ag), aluminum ( Since it is made of any one of Al), platinum (Pt), and copper (Cu), it is possible to record and reproduce a large amount of information with higher efficiency and stability than in the past.
Further, in the optical information recording medium of the eighth means of the present invention, in addition to the configuration and effect of any one of the first to seventh means, the size of the fine structure formed on the substrate is less than the wavelength. Since it is equal to the aperture size of a probe having a small aperture, the light from the micro aperture provided at the tip of the probe can be coupled to the recording medium with high efficiency, the formation of a good recording mark, and a high SN ratio. Can be reproduced.
In the optical information recording medium of the ninth means of the present invention, in addition to the configuration and effect of any one of the first to eighth means, the substrate surface has irregularities smaller than the wavelength of light. Therefore, the light from the minute aperture provided at the probe tip can be coupled to the recording medium with higher efficiency, and it is possible to form a good recording mark and reproduce the signal with a high S / N ratio.

  In the method for producing an optical information recording medium of the tenth means of the present invention, a step of implanting ions capable of increasing the refractive index over the entire surface of a flat glass substrate, and forming fine irregularities with a resist on the surface; Etching the glass substrate while retracting the resist to form predetermined irregularities on the glass substrate surface, and a laminated structure having at least an optical recording layer and a metal layer on the entire substrate surface while leaving the resist, or an optical recording layer And a step of forming a laminated structure having a light absorption layer and a metal layer, and a lift-off step of removing the resist, it is possible to manufacture an optical information recording medium stably and inexpensively.

  In the method for producing an optical information recording medium of the eleventh means of the present invention, a step of implanting ions capable of increasing the refractive index over the entire surface of a flat glass substrate and forming fine irregularities with a resist on the surface; Etching the glass substrate while retracting the resist to form predetermined irregularities on the glass substrate surface; removing the resist; and a laminated structure having at least an optical recording layer and a metal layer on the entire substrate surface; or And a step of forming a laminated structure including an optical recording layer, a light absorbing layer, and a metal layer, so that an optical information recording medium can be manufactured stably and inexpensively.

  In a twelfth means for producing an optical information recording medium of the present invention, a step of forming fine irregularities with a resist on the surface of a flat glass substrate, and the glass substrate surface by etching the glass substrate while retracting the resist And forming a laminated structure having at least an optical recording layer and a metal layer or a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer on the entire substrate surface while leaving the resist. And a lift-off process for removing the resist, it is possible to manufacture an optical information recording medium stably and at a lower cost.

  According to a thirteenth means of the present invention for producing an optical information recording medium, a step of forming fine irregularities with a resist on the surface of a flat glass substrate, and a glass substrate by etching the glass substrate while retreating the resist. A step of forming predetermined irregularities on the surface, a step of removing the resist, and a laminated structure having at least an optical recording layer and a metal layer on the entire substrate surface, or a laminated structure having an optical recording layer, a light absorbing layer and a metal layer. Therefore, the optical information recording medium can be manufactured stably and at a lower cost.

  In the fourteenth means for producing an optical information recording medium of the present invention, a cobalt oxide nanoglass thin film is formed on the entire surface of a glass substrate by sputtering, and then fine irregularities are formed on the surface by a resist. Etching the glass substrate while retracting the resist to form predetermined irregularities on the glass substrate surface, and a laminated structure having at least an optical recording layer and a metal layer on the entire substrate surface while leaving the resist, or optical recording Since the method includes a step of forming a laminated structure including a layer, a light absorption layer, and a metal layer, and a lift-off step of removing the resist, an optical information recording medium can be manufactured stably and inexpensively.

  In the fifteenth means for producing an optical information recording medium of the present invention, a cobalt oxide nanoglass thin film is formed on the entire surface of a glass substrate by a sputtering method, and then fine irregularities are formed on the surface by a resist. Etching the glass substrate while retracting the resist to form predetermined irregularities on the surface of the glass substrate; removing the resist; a laminated structure having at least an optical recording layer and a metal layer on the entire substrate surface; Alternatively, the method includes a step of forming a laminated structure including an optical recording layer, a light absorbing layer, and a metal layer, so that an optical information recording medium can be manufactured stably and inexpensively.

  In the optical information recording medium of the sixteenth means of the present invention, since the fine structure is produced by the production method of any one of the tenth to fifteenth means, high-capacity information is recorded with high efficiency and stability. Therefore, an optical information recording medium that can be reproduced can be provided stably and inexpensively.

In the optical information recording medium of the seventeenth means of the present invention, in addition to the structure and effect of any one of the first to ninth and sixteenth means, diamond-like carbon is provided as a protective layer on the outermost surface of the fine structure. Since it is formed, it is possible to record and reproduce information with high reliability against surface abrasion.
In the optical information recording medium of the eighteenth means of the present invention, in addition to the structure and effect of any one of the first to ninth and sixteenth means, SiN is provided as a protective layer on the outermost surface of the fine structure. Since it is formed, it is possible to record and reproduce information with high reliability against surface abrasion.

  The optical information processing apparatus of the nineteenth means of the present invention uses the optical information recording medium of any one of the first to ninth and sixteenth to eighteenth means, and has a minute aperture having a size equal to or smaller than the wavelength. Since the probe generates near-field light with respect to the fine structure of the optical information recording medium and records or reproduces information, a large amount of information can be recorded and reproduced with high efficiency and stability. Further, it is possible to form a good recording mark and reproduce a signal with a high S / N ratio.

In the optical information processing apparatus according to the twentieth means of the present invention, in addition to the structure and effects of the nineteenth means, a circle is formed on the quartz substrate on which a silicon nitride film is formed as the probe by using a photolithographic technique of a semiconductor process. After forming a columnar resist pattern, the silicon nitride film is removed by dry etching using this resist pattern as a mask, and a projection made of a high refractive index material is provided on an optically transparent quartz substrate using the quartz substrate as a stopper layer Since a flat probe is provided, fine recording marks can be recorded and reproduced with high density, high efficiency and stability.
In the optical information processing apparatus of the twenty-first means of the present invention, in addition to the configuration and effects of the twentieth means, the planar probe and the optical information recording medium are in a non-contact state, and the planar probe Since the distance between the optical information recording medium and the optical information recording medium is held in an area of the light source wavelength or less, fine recording marks can be recorded and reproduced with high density, high efficiency and stability.

In the optical information processing apparatus of the twenty-second means of the present invention, in addition to the configuration and effect of any one of the nineteenth to twenty-first means, proximity generated by a planar probe held in proximity to the optical information recording medium In an optical information processing apparatus that records or reproduces desired information on the optical information recording medium by using field light, a light source that emits a laser beam having a predetermined wavelength, and the laser beam is guided to an objective lens, and is passed through the objective lens. The illumination optical system for irradiating the planar probe with the laser beam and the detection optical system for receiving the light from the planar probe can be combined with the planar probe with high efficiency and stability. In addition, information can be recorded and reproduced with high efficiency and stability on a recording medium.
Further, in the optical information processing apparatus of the twenty-third means of the present invention, in addition to the structure and effect of the twenty-second means, the plane opposed to the exit surface of the objective lens for condensing light on the planar probe Since a non-reflective coating film is formed on the surface of the laser light incident surface of the probe, the laser beam can be coupled to the flat probe more efficiently and stably, and information can be sent to the recording medium. Recording and playback can be performed efficiently and stably.

  Hereinafter, the configuration and operation of an optical information recording medium according to the present invention, a manufacturing method thereof, and an optical information processing apparatus using the optical information recording medium will be described in detail based on the embodiments shown in the drawings.

  FIG. 1 is a schematic perspective view showing a main part of an optical information recording medium according to the present invention and an outline of a probe using near-field light. As shown in FIG. 1, in this embodiment, near-field light is generated from the tip of a probe 30 having a minute aperture 30a having a size sufficiently smaller than the incident wavelength, and is irradiated onto the optical information recording medium 11. On the substrate of the optical information recording medium 11, a microstructure 12 having substantially the same size as the minute opening 30a of the probe 30 is formed. By irradiating the microstructure 12 with near-field light from the tip of the probe 30, it is possible to reproduce information recorded in the microstructure 12 formed in advance on the optical information recording medium 11. Further, by forming a recordable material on the optical information recording medium 11, write-once type or rewritable type information recording is possible.

  FIG. 2 shows a configuration example of the optical information processing apparatus of the present invention. A portion corresponding to the near-field light probe 30 shown in FIG. 1 is formed in a protruding shape on the bottom surface of the substrate 29 of the planar probe 27. The protrusion-shaped probe 30 can be formed in a one-dimensional or two-dimensional array, and information from the optical information recording medium 11 can be reproduced sequentially or in parallel from the arrayed probes. is there. The probe 30 or a planar probe 27 having an array of probe portions formed on the bottom surface of the substrate 29 is supported by a holder 28 in the shape of a slider, and is moved over the moving or rotating optical information recording medium 11. The optical information recording medium 11 has a fine structure layer in which a fine structure 12 having a size equal to or smaller than the wavelength of recording light is formed on a flat plate (or disc-shaped) substrate 13, and a protective layer (not shown) is provided on the surface thereof. And is configured to withstand abrasion with the flat probe 27 that is run like a slider. The microstructure 12 has a laminated structure composed of a plurality of layers made of a plurality of substances. Details of the fine structure will be described later.

  In FIG. 2, laser light emitted from a semiconductor laser 21 as a light source is converted into a parallel light beam by a collimator lens 22 and enters a beam splitter 23. The light beam that has passed through the beam splitter 23 forms an image of a spot on the probe 30 formed on the bottom surface of the substrate 29 of the planar probe 27 by the objective lens 26, and generates near-field light from the tip of the protrusion of the probe 30. The generated near-field light is coupled to the fine structure 12 formed on the optical information recording medium 11. In the case of reproduction, the near-field light component reflected from the optical information recording medium 11 is detected by the probe 30 formed on the bottom surface of the substrate 29 of the flat probe 27. The detected near-field light is converted into a parallel light beam by the objective lens 26 through the probe portion, deflected by the beam splitter 23, and a spot is formed on the photodetector 25 by the imaging lens 24. The information recorded on the optical information recording medium 30 can be reproduced by the light intensity contrast on the photodetector.

  2, the optical information recording medium 11 is irradiated with near-field light generated by the probe 30 of the planar probe 27 and transmitted through the substrate 13 of the optical information recording medium 11 as shown in FIG. Information can also be recorded and reproduced by detecting the generated light with the imaging lens 24 and the photodetector 25. In this case, unlike the embodiment shown in FIG. 2, the beam splitter 23 is unnecessary, and the imaging lens 24 forms an image of the portion of the recording medium surface irradiated with the near-field light on the photodetector 25. To detect. The information recorded on the recording medium can be reproduced by the light intensity on the photodetector 25.

  In the present invention, by forming a columnar microstructure 12 as shown in FIG. 1 on the substrate surface of the optical information recording medium 11, for example, near-field light is efficiently emitted from the probe 30 having the minute aperture 30a. It is possible to use.

Next, an example of the fine structure 12 of the optical information recording medium 11 shown in FIG. 1 is shown in FIG. FIG. 4 is a schematic perspective view of an essential part showing an enlarged portion of the fine structure 12 of the optical information recording medium shown in FIG. Here, the size of the fine structure is equal to or smaller than the wavelength of the light source. For example, the diameter is 30 nm. Reference numeral 44 in the figure denotes fine structure protrusions formed on the substrate, glass or high-refractive index glass doped with ions, silicon compound materials such as SiO ₂ , SiON, and SiN, and sulfides such as ZnS, CaS, and BaS. It is composed of a material, a selenide material such as ZnSe or BaSe, a fluorine compound material such as CaF ₂ or BaF ₂ , ZnSSiO ₂ or the like. An optical recording layer 43, a metal layer 42, and a dielectric layer 41 are laminated on the fine structure protrusion 44.

As the dielectric layer 41, glass or ion-doped high refractive index glass, silicon compound material such as SiO ₂ , SiON, SiN, sulfide material such as ZnS, CaS, BaS, selenide material such as ZnSe, BaSe, Fluorine compound materials such as CaF ₂ and BaF ₂ , ZnSSiO _{2 and the} like can be used, and ZnSSiO ₂ is particularly preferable. When the thickness of the dielectric layer 41 is at least smaller than the diameter of the fine structure 12 and sufficiently smaller than the wavelength of incident light, the near-field light is coupled to the optical recording layer 43 with a good light distribution shape and high efficiency. can do.

The material of the optical recording layer 43 is a semiconductor material such as Si, Ge or GaAs, an intermetallic compound material containing a low melting point metal such as BiTe, BiIn, GaSb, GaP, InP, InSb, InTe, or SnSn, V ₂ O ₅ , Oxide materials such as Cr ₂ O ₃ , Mn ₃ O ₄ , Fe ₂ O ₃ , Co ₃ O ₄ , CuO, carbide materials such as C and SiC, nitride materials such as AlN, binary phases such as SbTe Examples thereof include change materials, ternary phase change materials such as GeSbTe, InSbTe, BiSbTe, and GaSbTe, and phase change materials such as quaternary materials such as AgInSbTe.
As the metal layer 42, it is desirable to use Au, Ag, Al, Cu, Pt or the like that can excite plasmons.

  The near-field light coupled to the protrusions of the microstructure 12 having such a laminated structure from the probe 30 as shown in FIG. 1, FIG. 2, or FIG. By being generated, it is possible to bond to the microstructure 12 with high efficiency. The near-field light coupled to the metal layer 42 is coupled to the plasmon and enhanced in intensity, and then transferred to the optical recording layer 43 immediately below it. The optical recording layer 43 absorbs the combined near-field light and generates heat. If the optical recording layer 43 is a phase change material, information can be recorded by, for example, a phase change from a crystalline phase to an amorphous phase or from an amorphous phase to a crystalline phase due to heat generated by the combined near-field light. In addition, in a magneto-optical material, information can be recorded by applying a magnetic field during irradiation with near-field light.

  The dielectric layer 41 is formed to improve the spatial distribution in the fine structure of near-field light enhanced by plasmons generated in the metal layer 42. Here, the intensity distribution of the near-field light in the microstructure of the recording medium with and without the dielectric layer 41 in the microstructure is shown in FIG. When the dielectric layer 41 does not exist in the fine structure, a strong portion of near-field light is distributed at the edge portion of the fine structure orthogonal to the incident polarized light. However, the presence of the dielectric layer 41 makes the fine structure near the center of the fine structure. It becomes a shape having a single peak where a strong portion is located, and it is possible to concentrate near-field light in a narrower range. Therefore, information can be recorded / reproduced with good and high density by the laminated structure having the dielectric layer 41. Here, the thickness of the dielectric layer 41 needs to be sufficiently smaller than the wavelength of the incident light and at least smaller than the diameter of the fine structure 12.

Further, the same effect can be obtained with a structure as shown in FIG. FIG. 6 is a view showing another example of the fine structure, and is a schematic perspective view showing an enlarged main part of the fine structure 12 of the optical information recording medium shown in FIG. Here, the size of the fine structure is equal to or smaller than the wavelength of the light source. For example, the diameter is 30 nm. Reference numeral 55 in the figure is a fine-structure protrusion formed on the substrate, glass or high-refractive index glass doped with ions, silicon compound material such as SiO ₂ , SiOn, SiN, and sulfide such as ZnS, CaS, BaS. Material materials, selenide materials such as ZnSe and BaSe, fluorine compound materials such as CaF ₂ and BaF ₂ , ZnSSiO ₂ and the like. A thermal reaction layer 54, an optical recording layer 53, a thermal reaction layer (light absorption layer) 52, and a metal layer 51 are laminated on the fine structure protrusion 55.

Examples of the thermal reaction layers 52 and 54 include silicon compound materials such as SiO ₂ , SiOn, and SiN, sulfide materials such as ZnS, CaS, and BaS, selenide materials such as ZnSe and BaSe, and fluorine compounds such as CaF ₂ and BaF ₂ . Materials can be used.
The material of the optical recording layer 53 is a semiconductor material such as Si, Ge or GaAs, an intermetallic compound material containing a low melting point metal such as BiTe, BiIn, GaSb, GaP, InP, InSb, InTe, or SnSn, V ₂ O ₅ , Cr Oxide materials such as ₂ O ₃ , Mn ₃ O ₄ , Fe ₂ O ₃ , CoO ₄ , CuO, carbide materials such as C and SiC, nitride materials such as AlN, binary phase change materials such as SbTe, , Ternary phase change materials such as GeSbTe, InSbTe, BiSbTe, and GaSbTe, and quaternary phase change materials such as AgInSbTe.
The metal layer 51 is preferably made of Au, Ag, Al, Cu, Pt or the like that can excite plasmons.

  The near-field light coupled from the probe 30 as shown in FIG. 1, FIG. 2 or FIG. 3 to the protrusions of the microstructure 12 having such a laminated structure has the metal layer 41 in the microstructure, so By generating, it is possible to bond to the microstructure with high efficiency. The near-field light coupled to the metal layer 51 is coupled to the plasmon and enhanced in intensity, and then transferred to the thermal reaction layer (light absorption layer) 52 immediately below, and is absorbed by the heat reaction layer (light absorption layer). The heat generated in 52 is transferred to the optical recording layer 53. If the optical recording layer 53 is a phase change material, information can be recorded by, for example, a phase change from a crystalline phase to an amorphous phase, or from an amorphous phase to a crystalline phase. In addition, in a magneto-optical material, information can be recorded by applying a magnetic field during irradiation with near-field light. The thermal reaction layer 54 under the optical recording layer 53 is formed to confine heat generated in the optical recording layer 53. Although not shown, even in the case of a laminated structure as shown in FIG. 6, a dielectric layer can be provided on the metal layer 51 similarly to the structure shown in FIG. The spatial distribution in the fine structure of near-field light enhanced by plasmons generated in the layer 51 can be improved.

  By the way, in the optical information processing apparatus using the near-field light as shown in FIGS. 1 to 3, the size of the opening radius provided at the tip of the probe 30 having the minute opening 30a and the light irradiated with the near-field light. When the size of the fine structure 12 of the information recording medium 11 is substantially the same, the light intensity coupled from the tip of the opening to the recording medium is maximized. Therefore, when the fine structure 12 having the same size as the opening radius of the probe 30 is formed on the recording medium 11, light can be used with higher efficiency than in the case of a planar shape having no fine structure. It is desirable that the size of this is approximately the same as the opening radius of the probe 30, and the interval between the microstructures is preferably greater than or equal to the size of the microstructures.

  In this case, the distance between the probe 30 and the optical information recording medium 11 shown in FIG. 1 needs to be sufficiently closer than the wavelength of the incident light. Further, in this case, the flat probe 27 manufactured as shown in FIG. 2 is formed like a floating head, so that the distance between the minute openings of the optical information recording medium 11 and the flat probe 27 is kept constant and minute. It is possible to maintain a high density recording by forming a finer recording mark.

  The fine structure 12 on the optical information recording medium 11 side may be a structure in which the real part of the refractive index changes at a certain interval, or an imaginary part, that is, a structure in which the absorptance changes at a certain interval. Examples of the substrate 13 include chemically tempered glass (such as aluminosilicate glass) and quartz glass, and the thickness thereof is usually 0.5 to 1.5 mm, preferably 0.6 to 1.2 mm.

Further, the fine structure 12 on the optical information recording medium 11 side can be produced by, for example, the method described below.
As an example of a method for producing an optical information recording medium, as shown in FIG. 7, (a) ions that can increase the refractive index are implanted on the entire surface of a flat (square or disc-shaped) flat glass substrate 62. (B) forming fine irregularities on the surface thereof with the resist 63; (c) etching the glass substrate 62 while retracting the resist to form predetermined irregularities on the surface of the glass substrate; d) forming a laminated structure having at least the optical recording layer 67 and the metal layer 65 on the entire surface of the substrate while leaving the resist 63, or a laminated structure having the optical recording layer 67, the light absorbing layer 66, and the metal layer 65; (E) By performing the lift-off process of removing the resist 63, the optical information recording medium 61 having a fine laminated structure can be manufactured.

  More specifically, first, as shown in FIG. 7A, ions are implanted into the entire surface of the flat glass substrate 62 to form a high refractive index layer 64. Next, as shown in FIG. 7B, after forming cylindrical irregularities with a resist 63 on the surface thereof, as shown in FIG. 7C, the high refractive index of the glass substrate 62 while the resist 63 is retracted. The layer 64 is etched to form irregularities of the high refractive index layer 64 having a predetermined microstructure on the surface of the glass substrate. Further, as shown in FIG. 7D, an optical recording layer 67, a thermal reaction layer (light absorption layer) 66, and a metal layer 65 are laminated over the entire surface with the resist 63 remaining. Here, by forming a thermal reaction layer (light absorption layer) 66 next to the metal layer 65, the fine structure of the laminated structure shown in FIG. 6 can be formed. In this state, as shown in FIG. 7E, by removing the resist 63, a fine structure of a laminated structure including the metal layer 65, the thermal reaction layer (light absorption layer) 66, and the optical recording layer 67 is formed. The optical information recording medium 61 can be manufactured. In the above laminating step, a dielectric layer may be further laminated on the metal layer 65, and a thermal reaction layer may be provided below the optical recording layer 67.

  As another example of a method for producing an optical information recording medium, as shown in FIG. 8, (a) a flat refractive index is increased over the entire surface of a flat (square or disc-shaped) glass substrate 72. (B) a step of forming fine irregularities on the surface thereof with a resist 73, and (c) etching the glass substrate 72 while retracting the resist to form predetermined irregularities on the surface of the glass substrate. A step, a step of removing the resist 73, and (d) a laminated structure having at least the optical recording layer 77 and the metal layer 75 on the entire substrate surface from which the resist is removed, or the optical recording layer 77, the light absorption layer 76, and the metal layer 75. The optical information recording medium 71 having a fine laminated structure can be manufactured by performing the step of forming a laminated structure having

  More specifically, first, as shown in FIG. 8A, ions are implanted into the entire surface of the glass substrate 72 to form a high refractive index layer 74. Next, as shown in FIG. 8B, after forming cylindrical irregularities with a resist 73 on the surface thereof, the high refractive index of the glass substrate 72 while the resist 73 is retracted as shown in FIG. 8C. The layer 74 is etched to form irregularities of the high refractive index layer 74 having a predetermined microstructure on the surface of the glass substrate. Next, after removing the resist 73, as shown in FIG. 8D, an optical recording layer 77, a thermal reaction layer (light absorption layer) 76, and a metal layer 75 are laminated over the entire substrate surface. Here, by forming the thermal reaction layer (light absorption layer) 76 next to the metal layer 75, the fine structure of the laminated structure shown in FIG. 6 can be formed. Further, in the optical information recording medium 71 of FIG. 8D, the protrusions of the above-mentioned laminated structure are formed on the surface. If the protrusions are removed by polishing the surface from this state, the same as FIG. 7E. In addition, an optical information recording medium having a flat surface can be produced. In the above laminating step, a dielectric layer may be further laminated on the metal layer 65, and a thermal reaction layer may be provided below the optical recording layer 67.

  In the manufacturing method shown in FIGS. 7 and 8, the high refractive index layers 64 and 74 are formed on the glass substrates 62 and 72. However, without forming the high refractive index layers 64 and 74, the substrate 62, After performing photolithography directly on 72 and etching the glass substrate itself, the same fine structure was obtained by performing the steps of FIGS. 7B to 7E or FIGS. 8B to 8D. An optical information recording medium can be manufactured.

  That is, as an example of the manufacturing method in that case, in FIG. 7, a process of forming fine irregularities directly on the surface of the flat glass substrate 62 with the resist 63 without performing ion implantation into the glass substrate 62, Etching the glass substrate 62 while retracting the resist 63 to form predetermined irregularities on the glass substrate surface, and a laminated structure having at least the optical recording layer 67 and the metal layer 65 on the entire substrate surface while leaving the resist 63 left. Alternatively, a step of forming a laminated structure including the optical recording layer 67, a light absorption layer (thermal reaction layer) 66, and a metal layer 65 and a lift-off step of removing the resist 63 are performed, thereby performing the same process as in FIG. A laminated structure can be produced.

  As another example, in FIG. 8, a process of forming fine irregularities with a resist 73 directly on the surface of the flat glass substrate 72 without performing ion implantation into the glass substrate 72 and the resist 73. Etching the glass substrate 72 while being retracted to form predetermined irregularities on the surface of the glass substrate; removing the resist 73; and a laminated structure having at least the optical recording layer 77 and the metal layer 75 on the entire substrate surface; Alternatively, by performing a step of forming a laminated structure including the optical recording layer 77, the light absorbing layer (thermal reaction layer) 76, and the metal layer 75, a laminated structure similar to FIG.

  Examples of the glass substrate used in the manufacturing method described above include chemically tempered glass (such as aluminosilicate glass) and quartz glass, and the thickness thereof is usually 0.5 to 1.5 mm, preferably 0.6 to 1. .2 mm. Examples of the impurity include sodium, potassium, lithium, magnesium, thallium, and the like, and ions having a high polarizability or ions having a high polarization ability are particularly preferable. As the former, Tl (thallium) is preferable. As the latter, Li (lithium) is preferable. Further, in order to selectively implant ions into the substrate surface, the former Tl having a large ion radius is preferable. Examples of the ion implantation include an ion implantation method, an ion exchange method, and an electro float method, and the ion implantation method is particularly preferable. In this case, the refractive index is increased by increasing the ion concentration to be implanted. Therefore, the refractive index of the convex portion can be easily changed by changing the type of ions to be implanted and the amount of implanted dope.

  In addition, there are various substances introduced to increase the refractive index described above. For example, in the case of the ion exchange method, the mobility in the high-temperature glass must be sufficiently high in order to perform ion exchange efficiently. Monovalent ions are selected based on such conditions as not to be necessary and that the properties are not impaired even if the glass is doped in a large amount. Furthermore, in order to improve the performance of an optical probe (for example, an optical fiber probe or a planar probe), ions having an effect of increasing the refractive index as much as possible are desired. Considering this, thallium ions (Tl +) and cesium ions (Cs +) are appropriate. The thallium ion (Tl +) has a non-rare glass type (18 + 2) structure in the outer shell electron arrangement, is easily diffused in high-temperature glass, and can be added to the glass in a large amount as a glass stitch modifying ion, and has a large refractive index. Change can be obtained. The metal layer 65 can be formed by any method such as metal vapor deposition, sputtering, plating, and electrodeposition. Examples of the metal include aluminum (Al), gold (Au), silver (Ag), platinum (Pt), copper (Cu), etc., but those having low oxidizability are particularly preferable.

In addition to the above, a cobalt oxide nanoglass thin film may be formed in place of the high refractive index layers 64 and 74 shown in FIGS. That is, it is possible to form a Co ₃ O ₄ thin film on the glass substrate 62 by forming a thin film of cobalt oxide (eg, Co ₃ O ₄ ) at room temperature by a commonly used high frequency sputtering method.
As an example of a method for producing the optical information recording medium in this case, in FIG. 7, instead of ion implantation into the glass substrate 62, a cobalt oxide nanoglass thin film is formed on the entire surface of the glass substrate 62 by sputtering. After that, a step of forming fine irregularities with the resist 63 on the surface, and a step of forming predetermined irregularities on the glass substrate surface by etching the cobalt oxide nanoglass thin film of the glass substrate 62 while retracting the resist 63 And a laminated structure having at least the optical recording layer 67 and the metal layer 65 on the entire substrate surface while leaving the resist 63, or a laminated structure having the optical recording layer 67, the light absorbing layer (thermal reaction layer) 66, and the metal layer 65. By performing the forming step and the lift-off step of removing the resist 63, a stacked structure similar to that shown in FIG. It can be.

  As another example of the manufacturing method, in FIG. 8, instead of ion implantation into the glass substrate 72, a cobalt oxide nanoglass thin film is formed on the entire surface of the glass substrate 72 by a sputtering method, and then on the surface. A step of forming fine irregularities with the resist 73, a step of etching the cobalt oxide nanoglass thin film on the glass substrate while retracting the resist 73 to form predetermined irregularities on the glass substrate surface, and removing the resist 73 And a step of forming a laminated structure having at least the optical recording layer 77 and the metal layer 75 or a laminated structure having the optical recording layer 77, the light absorbing layer (thermal reaction layer) 76, and the metal layer 75 on the entire substrate surface. By performing the above, a stacked structure similar to that shown in FIG. 8 can be manufactured.

Since the optical information recording medium of the present invention has a fine structure produced by any one of the above production methods, the optical information recording medium capable of stably recording and reproducing a large amount of information with high efficiency can be stably produced. And it can be provided at low cost.
In the optical information processing apparatus of the present invention, the optical information recording medium 11 having the microstructure 12 having the laminated structure described above is used, and a minute aperture 30a having a size equal to or smaller than the wavelength as shown in FIGS. Since the probe 30 provided generates near-field light to the fine structure 12 of the optical information recording medium 11 to record or reproduce information, it is possible to record and reproduce large-capacity information with high efficiency and stability. .

  Further, in the present invention, as shown in FIG. 2 or FIG. 3, desired information is transmitted to the optical information recording medium 11 by the near-field light generated by the flat probe 27 held in proximity to the optical information recording medium 11. In an optical information processing apparatus for recording or reproducing, a light source 21 that emits a laser beam of a predetermined wavelength, a laser beam from the light source 21 is guided to an objective lens 26, and the planar probe 27 is irradiated with the laser beam via the objective lens 26. The illumination optical systems 22 and 23 and the detection optical systems 24 and 25 that receive the light from the planar probe 27, so that the laser beam can be coupled to the planar probe 27 with high efficiency and stability. 11 can be recorded and reproduced with high efficiency and stability.

  The semiconductor laser (laser diode: LD) 21 that is the light source shown in FIGS. 2 and 3 is preferably linearly polarized light. In order to obtain linearly polarized light, a polarizing plate may be inserted. However, since a semiconductor laser (LD) or the like has linearly polarized light itself, it can be easily generated as it is or in combination with a polarizing plate. Further, by arranging a quarter wavelength plate and a polarization beam splitter above the minute opening of the probe portion 30 of the flat probe 27 and rotating the polarization planes of incident light and signal light by 90 degrees, the signal light is made higher. It is possible to detect by the S / N ratio. In this case, the return light to the semiconductor laser 21 can be suppressed, the laser oscillation state can be kept good, a good recording mark can be formed, and the reproduction signal can be formed. Can be detected stably.

In addition, the outermost surface of the optical information recording medium 11 is moved at a high speed by moving the planar probe 27 for near-field light to a distance equal to or shorter than the wavelength, so that the recording layer (metal layer, thermal reaction layer, A protective layer is necessary to prevent wear of the laminated structure layer comprising an optical recording layer. Since the near-field light oozes out from the probe 30 at a wavelength or less, in order to make the distance to the recording layer as close as possible, the protective layer is preferably made of a material that is thin and hardly absorbs light. In this example, diamond-like carbon was used as one of the materials satisfying the above conditions. This protective layer can be formed by a film forming apparatus such as sputtering, ion beam sputtering, or CVD. More specifically, in this example, diamond-like carbon was produced by CVD as a protective layer on the outermost surface of the recording medium.
As another example of the protective layer, silicon nitride (SiN) can be used. This SiN protective layer can also be formed by a film forming apparatus such as sputtering, ion beam sputtering, or CVD.

As the planar probe 27 for generating near-field light used in the optical information processing apparatus of the present invention, a planar probe array in which protruding probes 30 are arrayed one-dimensionally or two-dimensionally can also be used. An example of a method for producing this planar probe array is shown in FIG.
First, a silicon nitride (SiN) film 86 is formed as a high refractive index material on a transparent substrate (quartz substrate) 82 as shown in FIG. This silicon nitride film can be formed by a high temperature thermal CVD method in which SiH ₄ and NH ₃ are thermally reacted at a high temperature of 700 to 1100 degrees. The thickness of this silicon nitride film is desirably 2 μm or more. Here, a silicon nitride film is used as the high refractive index material, but there is no problem with other high refractive index materials. For example, after sputtering SiO ₂ on quartz glass (about 1 μm from the substrate surface), an intrusion layer of N atoms or C atoms is produced. In the case of C atoms, ions are implanted into quartz glass by an ion implantation method using CH ₄ as a source gas. In the case of N atoms, SiO ₂ is deposited by a thermal decomposition CVD method using SiH ₄ and N ₂ O as raw materials. A high refractive index layer can be formed by forming a film.

This high refractive index layer can be formed not only by the above method but also by other CVD, vacuum deposition, sputtering or the like or a thermal diffusion method. Also, a substrate called a SOI substrate in which a silicon oxide buffer layer is formed on a silicon single crystal substrate is used, and electrodes are provided on the SOI substrate and the glass substrate, and an appropriate voltage is applied in a temperature atmosphere of about 300 degrees. A high refractive index material can be formed on the quartz substrate by bonding the SOI substrate and the glass substrate by application. As another method, the surfaces of the quartz substrates to be bonded can be sufficiently cleaned, the active silicon layers of the SOI substrate can be bonded together, and bonded by heat treatment at 900 ° C. or higher in a nitrogen atmosphere. Also, the bonded surfaces of the quartz substrate and the SOI substrate to be bonded are mirror-polished and cleaned by RCA, and argon (Ar) FAB (Fast Atom Beam) is simultaneously applied for about 300 seconds in a vacuum chamber of 1 × 10 ⁻⁹ Torr or less. Irradiation and bonding are performed by pressure bonding at a pressure of 10 MPa.

  As shown in FIG. 9B, a cylindrical resist pattern 83 is formed on a substrate in which a silicon nitride film 86 is formed on the quartz substrate 82 by using a photolithography technique of a semiconductor process. This cylindrical resist pattern 83 is formed in a region where a silicon protrusion is formed. Next, as shown in FIG. 9C, the silicon nitride film 86 is removed by dry etching using the resist pattern 83 as a mask. When this etching is performed, the quartz substrate 82 is used as a stopper layer, and as shown in FIG. 9D, the near-field light probe 85 made of a protrusion of a high refractive index material on the optically transparent quartz substrate 82. Can be formed in an array. Further, by adjusting the etching time, the silicon nitride film 86 in the region where the resist pattern 83 does not exist on the quartz substrate 82 is left on the substrate, and the near-field light made of a high refractive index material protrusion is formed on the quartz substrate 82. A plurality of probes 85 can be formed in an array. Thereafter, as shown in FIG. 9E, the surface of the substrate 82 is coated with an antireflection film 84 by sputtering or the like, and further, as shown in FIG. By coating the antireflection film 87, a planar probe having a probe array composed of a plurality of protruding probes 85 can be formed.

  Here, by changing the dry etching conditions, the shape of the formed silicon nitride protrusion can be changed. For the dry etching, a parallel plate type RIE (Reactive Ion Etching) apparatus was used. Here, various types of silicon nitride protrusions can be formed by changing the gas type, processing pressure, and RF power to optimum conditions. By using the transparent substrate 82 as a stopping layer during this etching, a near-field optical probe made of a cylindrical or conical silicon protrusion can be formed on the transparent substrate.

By the way, an antireflection film 87 as shown in FIG. 9F, for example, is formed on the upper surface side of the planar probe 27 shown in FIGS. When this antireflection film 87 is formed, the reflectance can be reduced as compared with the case where there is no antireflection film. For example, when an MgF ₂ antireflection film is formed to 140 nm, the reflectance can be reduced from 4% to 1.4%. In addition to MgF ₂ , SiO, CeF ₃ or the like can be used as a single-layer thin film for forming the antireflection film 87. Accordingly, the near-field light can be efficiently generated as much as the reflectivity is reduced, so that signals can be detected with high efficiency and high speed.

Also, by changing the antireflection film 87 from a single layer film to a multilayer film, it is possible to obtain a lower reflectance in a wider wavelength region than in the case of a single layer film. For example, a first dielectric film made of MgF _{2 having a} thickness of 140 nm is formed on a planar probe having an aperture sufficiently smaller than the incident wavelength, and a thickness of CeO ₂ is formed thereon as a _second dielectric film. When a thin film of 96 nm is formed and a thin film made of SiO having a thickness of 108 nm is further formed thereon as a third dielectric film, a multilayer film is formed. And a non-reflective coating can be applied to the planar probe. By applying the non-reflective coating in this manner, the laser beam can be coupled to the planar probe 27 more efficiently and stably, and information can be recorded and reproduced on the recording medium 11 with high efficiency and stability. be able to.

  The thickness of the antireflective coating film may be 100 nm or more, and has a sufficient mechanical strength and is stable, so that a laser beam can be coupled to a planar probe with high efficiency and stability. It can be accurately tracked in a minute guide groove, and information can be recorded and reproduced with high efficiency and stability on a recording medium.

1 is a schematic perspective view of a main part showing an outline of a fine structure of an optical information recording medium according to the present invention and a probe using near field light. It is a schematic block diagram of the optical information processing apparatus which shows one Example of this invention. It is a schematic block diagram of the optical information processing apparatus which shows another Example of this invention. It is a schematic principal part perspective view which shows an example of the fine structure of the optical information recording medium shown in FIG. It is a figure which shows intensity distribution of the near field light in a fine structure with and without a dielectric layer in the fine structure of an optical information recording medium. It is a schematic principal part perspective view which shows another example of the fine structure of the optical information recording medium shown in FIG. It is process explanatory drawing which shows an example of the manufacturing process of the fine structure of an optical information recording medium. It is process explanatory drawing which shows another example of the manufacturing process of the fine structure of an optical information recording medium. It is process explanatory drawing which shows an example of the preparation methods of a planar probe array.

Explanation of symbols

11: Optical information recording medium 12: Fine structure 13: Planar substrate 21: Semiconductor laser (LD)
22: Collimator lens 23: Beam splitter 24: Imaging lens 25: Optical detector 26: Objective lens 27: Planar probe 28: Holder 29: Planar substrate 30: Projection-shaped probe 30a: Microscopic aperture

Claims (23)

Light in which information is recorded on the fine structure by a probe having a flat substrate and a fine structure having a size less than or equal to the wavelength of the recording light formed on the substrate and having a minute aperture having a size less than or equal to the wavelength In an information recording medium,
2. The optical information recording medium according to claim 1, wherein the microstructure has a laminated structure having at least an optical recording layer and a metal layer. Light in which information is recorded on the fine structure by a probe having a flat substrate and a fine structure having a size less than or equal to the wavelength of the recording light formed on the substrate and having a minute aperture having a size less than or equal to the wavelength In an information recording medium,
2. The optical information recording medium according to claim 1, wherein the microstructure has a laminated structure including at least an optical recording layer, a light absorption layer, and a metal layer. The optical information recording medium according to claim 1 or 2,
2. The optical information recording medium according to claim 1, wherein the microstructure has a dielectric layer on the metal layer. The optical information recording medium according to claim 3.
The optical information recording medium in which the dielectric layer is characterized by comprising the ZnSSiO _2. The optical information recording medium according to claim 3 or 4,
An optical information recording medium, wherein a thickness of the dielectric layer is thinner than a size of the fine structure. In the optical information recording medium according to any one of claims 1 to 5,
An optical information recording medium comprising a protective layer on the outermost surface of the fine structure. In the optical information recording medium according to any one of claims 1 to 6,
An optical information recording medium, wherein the metal layer is made of any one of gold (Au), silver (Ag), aluminum (Al), platinum (Pt), and copper (Cu). In the optical information recording medium according to any one of claims 1 to 7,
An optical information recording medium characterized in that the size of the fine structure formed on the substrate is equal to the aperture size of a probe having a micro aperture having a size equal to or smaller than the wavelength. In the optical information recording medium according to any one of claims 1 to 8,
The optical information recording medium, wherein the substrate surface has irregularities smaller than the wavelength of light. A method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate,
Implanting ions capable of increasing the refractive index over the entire surface of the flat glass substrate, and forming fine irregularities with a resist on the surface;
Etching the glass substrate while retreating the resist to form predetermined irregularities on the glass substrate surface;
Forming a laminated structure having at least an optical recording layer and a metal layer over the entire substrate surface while leaving the resist, or forming a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer;
A lift-off step of removing the resist;
A method for producing an optical information recording medium, comprising: A method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate,
Implanting ions capable of increasing the refractive index over the entire surface of the flat glass substrate, and forming fine irregularities with a resist on the surface;
Etching the glass substrate while retreating the resist to form predetermined irregularities on the glass substrate surface;
Removing the resist;
Forming a laminated structure having at least an optical recording layer and a metal layer over the entire surface of the substrate, or a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer;
A method for producing an optical information recording medium, comprising: A method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate,
Forming fine irregularities with a resist on the surface of a flat glass substrate;
Etching the glass substrate while retreating the resist to form predetermined irregularities on the glass substrate surface;
Forming a laminated structure having at least an optical recording layer and a metal layer over the entire substrate surface while leaving the resist, or forming a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer;
A lift-off step of removing the resist;
A method for producing an optical information recording medium, comprising: A method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate,
Forming fine irregularities with a resist on the surface of a flat glass substrate;
Etching the glass substrate while retreating the resist to form predetermined irregularities on the glass substrate surface;
Removing the resist;
Forming a laminated structure having at least an optical recording layer and a metal layer over the entire surface of the substrate, or a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer;
A method for producing an optical information recording medium, comprising: A method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate,
Forming a cobalt oxide nanoglass thin film on the entire surface of the glass substrate by sputtering, and then forming fine irregularities on the surface with a resist;
Etching the glass substrate while retreating the resist to form predetermined irregularities on the glass substrate surface;
Forming a laminated structure having at least an optical recording layer and a metal layer over the entire substrate surface while leaving the resist, or forming a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer;
A lift-off step of removing the resist;
A method for producing an optical information recording medium, comprising: A method for producing an optical information recording medium having a fine structure having a size equal to or smaller than the wavelength of recording light on a flat substrate,
Forming a cobalt oxide nanoglass thin film on the entire surface of the glass substrate by sputtering, and then forming fine irregularities on the surface with a resist;
Etching the glass substrate while retreating the resist to form predetermined irregularities on the glass substrate surface;
Removing the resist;
Forming a laminated structure having at least an optical recording layer and a metal layer over the entire surface of the substrate, or a laminated structure having an optical recording layer, a light absorbing layer, and a metal layer;
A method for producing an optical information recording medium, comprising: Light in which information is recorded on the fine structure by a probe having a flat substrate and a fine structure having a size less than or equal to the wavelength of the recording light formed on the substrate and having a minute aperture having a size less than or equal to the wavelength In an information recording medium,
An optical information recording medium, wherein the fine structure is produced by the production method according to claim 10. In the optical information recording medium according to any one of claims 1 to 9, and 16,
An optical information recording medium, wherein diamond-like carbon is formed as a protective layer on the outermost surface of the fine structure. In the optical information recording medium according to any one of claims 1 to 9, and 16,
An optical information recording medium, wherein SiN is formed as a protective layer on the outermost surface of the fine structure.   A near field with respect to the microstructure of the optical information recording medium using the optical information recording medium according to any one of claims 1 to 9 and 16 to 18 with a probe having a minute aperture having a size equal to or smaller than a wavelength. An optical information processing apparatus that generates light and records or reproduces information. The optical information processing apparatus according to claim 19, wherein
As a probe, a cylindrical resist pattern is formed on a quartz substrate on which a silicon nitride film is formed using a photolithographic technique of a semiconductor process, and then the silicon nitride film is removed by dry etching using the resist pattern as a mask, An optical information processing apparatus comprising a planar probe having a quartz substrate as a stopper layer and a projection made of a high refractive index material provided on an optically transparent quartz substrate. The optical information processing apparatus according to claim 20,
An optical device characterized in that the planar probe and the optical information recording medium are in a non-contact state, and the distance between the planar probe and the optical information recording medium is held in a region of a light source wavelength or less. Information processing device. The optical information processing apparatus according to any one of claims 19 to 21, wherein desired information is recorded by near-field light generated from a planar probe held close to the optical information recording medium. In an optical information processing apparatus for recording or reproducing on a medium,
A light source that emits a laser beam of a predetermined wavelength; an illumination optical system that guides the laser beam to an objective lens; and irradiates the planar probe with the laser beam through the objective lens; and light from the planar probe An optical information processing apparatus having a detection optical system for receiving light. The optical information processing apparatus according to claim 22,
A non-reflective coating film is formed on the surface portion of the laser light incident surface of the planar probe, which is opposed to the exit surface of the objective lens for condensing light on the planar probe. Optical information processing device.

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