JP4293283B2 - Information reproducing apparatus and information reproducing method - Google Patents

Description

The present invention relates to an information reproducing apparatus and information reproducing method capable of performing ultra-high density recording / reproducing of image information, large-capacity data, and the like.

With the development of computer networks, the amount of information processed by a computer has increased rapidly, and the need for an information recording / reproducing apparatus with a very large capacity has increased. Semiconductor memory or a HDD (hard disk drive), in an optical disc system, in surface recording density (recording amount per unit area) is currently highest in HDD, at product level ^{50Gbit / in 2 (Gbit / in} 2: 1 Recording density is achieved (10 ⁹ bits per square inch).

However, in magnetic recording such as HDD, it is very difficult to stably realize a recording density exceeding 100 Gbit / in ² due to a magnetization reversal phenomenon due to thermal fluctuation. In the current optical disk system in which the recording density is limited by the diffraction limit of light, the recording density of about ²⁰ Gbit / in ² is the limit when the light source is in the visible light range.

  The surface recording density of a semiconductor memory is inferior to that of an HDD or an optical disk system, and a minimum processing line width of about 10 nm is required to obtain a recording density equivalent to these. As described above, in the information recording system using magnetism or light, there is a limit to the minimum pit size that determines the recording density, and it is necessary to significantly advance the microfabrication technology even in the semiconductor memory.

  In place of the conventional information recording apparatus whose recording density is reaching its limit, a new information recording method with a different recording / reproducing method has been studied. One of them is an information recording system using a scanning probe microscope (SPM) technique using a microprobe.

For example, an ultra-high density information recording system of several hundred Gbit / in ² using an atomic force microscope (AFM) has been developed (see, for example, Patent Document 1). In this system, a cantilever with a microprobe as used in AFM is used to form a small depression (pit) with a diameter of several tens of nanometers on an organic recording medium, and the pit is read by the same cantilever (non-patent) Reference 1).

  That is, in this system, a very sharp microprobe having a radius of curvature of less than 20 nm and a heater for heating the probe are formed at the tip of the cantilever fixed to the support base. When a current is passed through the heater through the two wires while the tip of the probe is lightly in contact with the surface of the recording medium, the organic recording medium in contact with the tip of the probe is locally melted, and the diameter of 30 to 40nm minute pits are formed (Thermomechanical Writing).

  On the other hand, pit reading is performed by applying a pulse current to the same heater as in pit formation, but the current value is slightly smaller than that during recording so that pits are not formed. In this state, when scanning is performed while the microprobe is in contact with the recording medium, the distance between the heater and the recording medium varies depending on the presence or absence of pits. When the distance changes, the thermal conductivity from the heater to the recording medium changes, and the heater temperature changes.

Finally, the presence or absence of pits is detected by measuring the temperature change of the heater as the change in heater current (Thermomechanical Reading). Recording / reproducing operation at a recording density of 100 to 200 Gbit / in ² has been demonstrated in an array in which 32 × 32 AFM cantilevers with heaters are integrated using a micro electro mechanical system (MEMS) fabrication technique. (See Non-Patent Document 2).

US Pat. No. 5,835,477 P. Vettiger et al., IBM Journal of Research and Development, 1999, Vol. 44, No. 3, 323 M.I.Lutwyche et. Al., Appl.Phys.Lett.2000, Vol.77, No.20, 3299

  Unlike the recording method using magnetism or light, the recording method for forming topological pits using this microprobe has the advantage that there is no lower limit of pit size in principle. However, the Thermomechanical system in which the probe is heated, minute pits are formed on the recording medium in contact with the probe, and the presence or absence of the pits is detected has three problems related to heat. The first is large power consumption, the second is the problem of tracking irregularities due to temperature changes, and the third is the problem of thermal time constant.

  In the conventional information recording / reproducing apparatus, only 2% of the electric power supplied to the heater is used for pit formation. Moreover, since a heater current is required not only during recording but also during reproduction, the power consumed by the entire two-dimensional array becomes very large. Furthermore, since the heat utilization efficiency is poor, the temperature of the array rises due to the heat generated by the heater.

  This rising temperature varies depending on the power consumption of the heater. In this system, 32 AFM cantilevers belonging to the same row of the two-dimensional array are operated in parallel, so that the overall heater current varies greatly depending on the data pattern to be recorded during recording (current is applied only to the heater of the cantilever forming the pit). Flow).

  On the other hand, in reproduction, a heater current is passed through all 32 cantilevers belonging to the same row, but each heater current is smaller than that during recording. Therefore, the temperature of the array differs between recording and reproduction.

  This temperature change causes expansion or contraction according to the coefficient of thermal expansion of the array material. If the temperature of the array is different between recording and reproduction, the pit position at the time of recording and the probe position at the time of reproduction are shifted, making it impossible to reproduce information.

  In a conventional information recording / reproducing apparatus, in order to prevent tracking errors due to thermal expansion / contraction, a heater and a temperature sensor are built in the array, and the temperature of the array is adjusted to be constant with an accuracy of ± 1 ° C. As a result, the control circuit becomes complicated, and there is a drawback that the power consumption is further increased by the heater.

  Further, in this information recording / reproducing apparatus, since the thermal time constant is as slow as several μs, the recording / reproducing speed of one cantilever is limited to about 100 kHz. The thermal time constant is determined by the size and shape of the heater, but the heater size cannot be made too small due to mechanical strength constraints. Therefore, high-speed recording / reproduction is difficult with the Thermomechanical method using heating by a heater.

  The present invention has been made to solve such problems. That is, the present invention includes a scanning probe type information reproducing apparatus, information reproducing method, information recording or reproducing apparatus, and information recording or reproducing method, including means for generating an elastic wave instead of a heating means for a microprobe. The information is recorded by forming a shape pit (indentation) on the recording medium using the energy of the elastic wave emitted from the microprobe. In addition, by using the energy of the elastic wave emitted from the microprobe, information is reproduced based on the presence or absence of a pit on the recording medium close to the tip of the microprobe.

  In the present invention, since the heating means for the microprobe is not provided, it is possible to solve the problems related to heat that the Thermomechanical system has. That is, pit formation by elastic waves has low energy consumption because of high energy utilization efficiency. Further, since no heating means is used, the amount of heat generation is small, and thermal expansion / contraction due to this is small. Furthermore, since the propagation speed of elastic waves is fast, the time constant is small, and high-speed recording / reproduction is possible.

  According to the present invention, in a scanning probe type information recording / reproducing apparatus provided with means for generating elastic waves and a microprobe, the elastic wave generated from the tip of the microprobe is used to form a non-circular shape on the recording medium. By using a reversible pit forming method, power consumption is low, heat generation is small, and high-speed information recording is possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram for explaining an information recording / reproducing apparatus according to the present embodiment. That is, this information recording / reproducing apparatus records and reproduces information by scanning the surface of the recording medium 24 with the probe 21a (protruding end) of the microprobe 21 that is a cantilever. The microprobes 21 are arranged on the array chip 210 in a matrix of, for example, 32 × 32 (omitted to 5 × 5 in FIG. 1), and the probes 21 a of the microprobes 21 face the recording medium 24. It is in a state to do.

  The recording medium 24 is placed on a drive 25, and the drive 25 moves in the XYZ directions so that the relative position with each microprobe 21 can be adjusted. The recording medium 24 is provided with subfields corresponding to the contact range of one microprobe 21 and micropits are formed in each subfold. Recording is performed by forming minute pits by contact with the minute probe 21, and reproduction is performed by detecting the minute pits with the minute probe 21.

  In this embodiment, elastic wave generating means is used as means for applying energy to the cantilever, and a depression is formed on the surface of the recording medium at the position of the probe by the elastic wave applied from the elastic wave generating means to the cantilever. The information is recorded and the information is reproduced by reading the presence or absence of the depression.

  Next, an example of the microprobe portion applied in the present embodiment will be described.

<First embodiment>
FIG. 2 schematically shows an example of an information recording / reproducing apparatus according to the first embodiment. An elastic wave generating element (elastic wave generating means) 22 is integrally formed on the support base 23, and a microprobe 21 is integrally formed thereon, and a recording medium 24 is installed in the vicinity of the tip of the probe. The elastic wave generated by the elastic wave generating element 22 is irradiated onto the surface of the recording medium 24 through the microprobe 21.

  The region irradiated with the elastic wave is limited to the vicinity of the tip of the microprobe 21 and vibration is locally applied to the region. A depression (pit) is formed by heating with it. By using, for example, a resin material having a low softening temperature as the recording medium 24, pits can be formed with small elastic wave energy.

  In the example shown in FIG. 2, the pit is formed by bringing the tip of the microprobe 21 close to the resin surface of the recording medium 24 without contacting it, but the elastic wave is efficiently only from the tip of the microprobe 21. Therefore, if the distance between the tip of the minute probe 21 and the resin surface is small, minute pits can be formed.

  Of course, by contacting the tip of the microprobe 21 and the resin surface of the recording medium 24, the energy of the elastic wave can be more efficiently given to the recording medium, and the intensity is smaller than the elastic wave intensity required in the case of non-contact. A pit can be formed.

  The load of the microprobe 21 applied to the recording medium 24 is appropriately adjusted according to the intensity of the elastic wave on the surface of the recording medium 24. Typically, a pit having a sufficient depth and radius is formed with a load of about 0.1 μN. Can be formed. Since the elastic wave is efficiently emitted only from the tip of the microprobe 21, the smaller the radius of the tip, the smaller the pits can be formed and the recording density can be increased.

  In the present embodiment, a method of forming a shape pit on the surface of the recording medium 24 by applying elastic waves to the surface of the recording medium 24 via the microprobe 21 is used. It is necessary to maintain its shape for a sufficient amount of time. For this reason, the intensity of the elastic wave applied to the surface of the recording medium has a magnitude necessary for the pits to remain even after the supply of the elastic wave is cut off.

  The magnitude of the elastic wave necessary for the pits to remain even after the supply of the elastic wave is cut off is the elastic wave generation method, the coupling efficiency between the elastic wave generating element 22 and the microprobe 21, the microprobe 21 and Depending on the distance from the recording medium 24, the material / shape / size of the microprobe 21, the material of the recording medium 24, etc., in order to reduce the power consumption in the recording operation, the generation of elastic waves with high energy conversion efficiency It is desirable to use the method. There are piezoelectric, magnetostrictive, electromagnetic, electrostatic, etc. methods for generating elastic waves. From the viewpoint of ease of integration and energy conversion efficiency, a piezoelectric elastic wave generation method using the piezoelectric effect is used. Is desirable.

  The piezoelectric elastic wave generating element 22 includes a length-extensional mode vibrator with field perpendicular to length, a thickness-extensional mode vibrator, and a thickness shear mode vibrator. However, a bulk acoustic resonator suitable for microfabrication is suitable.

  FIG. 3 schematically shows the structure of a thin film bulk acoustic wave resonator including a microprobe. The basic structure of the thin film bulk acoustic wave resonator is a three-layer structure including a lower electrode 35 and an upper electrode 37 sandwiching the piezoelectric thin film 36.

  When a voltage is applied between the lower electrode 35 and the upper electrode 37, the piezoelectric thin film 36 contracts in the film thickness direction, and a bulk acoustic wave propagating in the thickness direction is generated. The thin film bulk acoustic wave resonator is formed on the support base 33 via the insulating film 34. The support base 33 is used to maintain the mechanical strength of the entire element.

  A microprobe 31 whose tip is directed downward is formed on the lower surface of the support base 33 via an insulating film 32. Since the microprobe 31 is formed in the window region 38 from which a part of the support base 33 is removed, the elastic wave generated from the thin film bulk acoustic wave resonator is passed through the insulating films 32 and 34 and the microprobe 31. Is transmitted with high efficiency.

  4 to 5 are schematic cross-sectional views showing a method for producing the structure shown in FIG. As shown in FIG. 4A, an SOI (Silicon on Insulator) substrate having a thermal oxide film 44 formed on the surface is used as the substrate. In the figure, reference numerals 41 and 43 denote Si layers, and 42 denotes a buried oxide film layer (BOX layer: Buried Oxide layer).

First, in order to form a microprobe, as shown in FIG. 4B, the upper insulating film 44 corresponding to the position of the microprobe is formed by photolithography and reactive ion etching (RIE). ) To form a circle. As a gas used for etching, for example, a mixed gas of CF ₄ and O ₂ is used.

Next, using the patterned insulating film 44 as a mask, the Si layer 43 underneath is subjected to reactive ion etching with a mixed gas of SF ₆ and O ₂ to etch only Si and directly under the etching mask. Leave the Si in a conical shape.

  Thereafter, only the etching mask is removed with, for example, a BHF (Buffered Hydrogen Fluoride) solution, and the remaining conical Si tip is sharpened, and thermal oxidation and removal of the oxide film are repeated several times.

  The surface of the cone-shaped Si is covered with an oxide film due to thermal oxidation, and removing it removes the entire cone, but the tip has a very sharp tip shape because the oxidation progresses slowly due to residual stress. Is obtained. As shown in FIG. 4C, the microprobe 43 manufactured in this way is buried with an appropriate protective film 45 to protect the tip.

Subsequently, a thin film bulk acoustic wave resonator is manufactured. First, in order to remove a part of the Si layer 41 of the SOI substrate and form a window region, an SiO ₂ film 46A is formed on the entire back surface of the SOI substrate by, for example, PE-CVD (Plasma-Enhanced Chemical Vapor Deposition).

In order to remove a portion corresponding to the opening in the SiO ₂ film, the Si substrate is anisotropically etched using, for example, a TMAH (Tetramethylammonium Hydroxide) solution. TMAH is a Si selective etchant, and as shown in FIG. 4D, an inclined window with the BOX layer 42 left is formed. Subsequently, the SiO ₂ film 46 is removed, and an SiO ₂ film 46B is formed on the back surface by PE-CVD again for insulation (see FIG. 5).

As shown in FIG. 5, the lower electrode 47, the piezoelectric thin film 48, and the upper electrode 49 of the thin film bulk acoustic wave resonator are patterned on the SiO ₂ film 46B formed on the entire surface, and the lower electrode 47 and the upper electrode 49 are patterned. A wiring region for applying a voltage from the outside is formed in between.

The upper electrode 49 and the lower electrode 47 are both made of a two-layer film of Ni—Cr and Au, for example, and are patterned by electron beam evaporation and lift-off methods. For example, if ZnO is used, the piezoelectric thin film 48 is formed by a reactive sputtering method using Zn as a target and a mixture of Ar and O ₂ , and using a photoresist as a mask, CH ₃ COOH: H ₃ PO ₄ : Patterned by etching the ZnO film with a mixture of H ₂ O = 1: 1: 10.

Finally, the protective film 45 of the microprobe is removed using an appropriate means (for an organic film, plasma etching using O ₂ ). By applying an alternating current or a short pulse voltage between the electrodes of the thin film bulk acoustic wave resonator including the microprobe thus fabricated, an elastic wave is emitted from the tip of the microprobe.

  Fine pits can be formed on the surface of the recording medium by applying this elastic probe close to or in contact with an appropriate recording medium (for example, polymethylmethacrylate) and applying an elastic wave. If the thickness of the piezoelectric thin film used in the thin film bulk acoustic wave resonator is half the wavelength of the generated acoustic wave in the piezoelectric thin film, the maximum acoustic wave generation efficiency can be obtained at that frequency ( Standing wave condition). Therefore, the thickness of the piezoelectric film should be appropriately adjusted according to the frequency of the elastic wave to be used, and is not particularly defined in the present invention.

  Although FIGS. 2 to 5 show an apparatus and a manufacturing method including a single microprobe, a one-dimensional or two-dimensional array structure including a plurality of microprobes may be used. By operating a plurality of microprobes in parallel using the array structure, it is possible to obtain a higher operating speed than an apparatus having a single microprobe. In this case, an element for applying an elastic wave may be provided for each microprobe, or a structure for applying an elastic wave from a single elastic wave generating element to a plurality of microprobes may be employed.

<Second embodiment>
Next, a second embodiment of the microprobe will be described. FIG. 6 is a diagram for explaining the microprobe according to the second embodiment. FIG. 6B is a plan view seen from the microprobe side, and FIG. 6A is a line AA ′ of this plan view. The cross section in is shown. The BOX layer 52 of the SOI substrate is removed over the entire window region 50 except for the strip-shaped portion 52A supporting the microprobe 53.

  Further, the layer 56 provided for insulation from the Si substrate 51 is removed over the entire window region 50 including the lower portion of the microprobe 53. Therefore, a gap corresponding to the thickness of the insulating layer 56 is formed between the BOX layer 52A that supports the microprobe 53 and the lower electrode 57 of the thin film bulk acoustic wave resonator.

  At this time, since both ends of the microprobe 53 are supported on the Si substrate 51 by the strip-shaped BOX layer 52A, when the recording medium is brought into contact with the microprobe 53, the strip-shaped BOX layer 52A is bent. An excessive load is not applied to the microprobe 53.

  By providing a gap between the microprobe and the thin film bulk acoustic wave resonator as described above, even when a recording method in which the microprobe and the recording medium are brought into contact with each other, the load applied to the microprobe is not affected. It can be prevented from being added to the thin film bulk acoustic wave resonator.

  The shape of the strip-shaped BOX layer 52A is not limited to a structure in which both ends are fixed, and an arbitrary structure of a cantilever (cantilever) or multipoint support can be employed. The displacement (spring constant) of the beam per unit load can be designed by the length, width, thickness of the beam, or the Young's modulus of the material.

  For example, the spring constant can be reduced by making the beam longer, reducing the width, or making it thinner. If the spring constant is reduced, the load applied to the microprobe can be reduced for the same displacement, so that wear and destruction of the microprobe can be reduced. However, the self-resonant frequency of the beam also decreases at the same time. If the resonance frequency is too low, the response speed of the beam due to the elastic wave is lowered, and high-speed recording operation becomes difficult. Unlike the propagation of heat, the propagation of elastic waves in solids with negligible viscosity is essentially a small time constant. Therefore, a beam structure with an appropriate resonance frequency should be designed so as not to sacrifice this small time constant.

  7 to 8 show a method for manufacturing the structure shown in FIG. As the substrate, an SOI substrate having a thermal oxide film 64 formed on the surface is used as shown in FIG. In the figure, reference numerals 61 and 63 denote Si layers, and 62 denotes a BOX layer.

First, in order to form a microprobe, as shown in FIG. 7B, a portion of the upper SiO ₂ film 64 corresponding to the position of the microprobe is patterned into a circle using photolithography and the RIE method. To do. As a gas used for etching, for example, a mixed gas of CF ₄ and O ₂ is used. Next, using the patterned insulating film 64 as a mask, the Si layer 63 underneath is subjected to reactive ion etching with a mixed gas of SF ₆ and O ₂ , and only Si is isotropically etched. Leave Si in a cone.

  Thereafter, only the etching mask is removed with, for example, a BHF solution, and thermal oxidation and removal of the oxide film are repeated several times in order to sharpen the remaining conical Si tip. As shown in FIG. 7C, the microprobe 63 produced in this way is buried with an appropriate protective film 65 to protect the tip.

Subsequently, a thin film bulk acoustic wave resonator is manufactured. First, in order to remove a part of the Si substrate 61 and form a window region, an SiO ₂ film 66A is formed on the entire back surface of the SOI substrate by, eg, PE-CVD (see FIG. 7D). In order to remove the portion corresponding to the window in the SiO ₂ film 66A in a circular shape, the Si substrate is anisotropically etched using, for example, a TMAH solution. As a result, as shown in FIG. 7D, an inclined window with the BOX layer 62 left is formed.

Subsequently, the SiO ₂ film 66A is removed, and an insulating film 66B is formed on the entire surface. As shown in FIG. 8A, the lower electrode 67, the piezoelectric thin film 68, and the upper electrode 69 of the thin film bulk acoustic wave resonator are patterned on the insulating film 66B, and the space between the lower electrode 67 and the upper electrode 69 is patterned. A wiring region for applying a voltage from the outside is formed.

The upper electrode 69 and the lower electrode 67 are both made of, for example, a two-layer film of Ni—Cr and Au, and are patterned by electron beam evaporation and a lift-off method. The piezoelectric thin film 68 is patterned by using, for example, ZnO and etching only the ZnO film with a mixed solution of CH ₃ COOH: H ₃ PO ₄ : H ₂ O = 1: 1: 10 using a photoresist as a mask. The

Then, the protective film 65 of the microprobe is removed using an appropriate means (for organic films, plasma etching using a mixed gas of CF ₄ and O ₂ ) (see FIG. 8B). Further, the support structure 52A (see FIG. 6B) of the microprobe 63 is patterned on the BOX film 62 using photolithography and RIE.

As a gas used for etching, for example, a mixed gas of CF ₄ and O ₂ is used. Finally, the insulating film 66B in the window portion is selectively removed (see FIG. 8C). At this time, an organic material is preferably used for the insulating film 66B so that the Si substrate 61, the microprobe 63, and the BOX layer 62 are not affected. In this way, only the insulating film 66B can be selectively removed by dry etching using an organic material stripping solution or O ₂ gas.

  By applying an alternating current or a short pulse voltage between the electrodes of the thin film bulk acoustic wave resonator having the microprobe thus fabricated, the elastic wave emitted from the thin film bulk acoustic wave resonator is It propagates to the microprobe 63 through the gap below the needle 63 and an elastic wave is emitted from the tip.

  By bringing the microprobe 63 into contact with an appropriate recording medium (for example, polymethylmethacrylate), minute pits can be formed on the surface of the recording medium. (If the thickness of the piezoelectric thin film used in the thin film bulk acoustic wave resonator is half the wavelength of the generated acoustic wave in the piezoelectric thin film, the maximum acoustic wave generation efficiency can be achieved at that frequency.) . Therefore, the thickness of the piezoelectric film should be appropriately adjusted according to the frequency of the elastic wave to be used, and is not particularly defined in the present invention.

  Although FIGS. 6 to 8 show an apparatus and a manufacturing method including a single microprobe, a one-dimensional or two-dimensional array structure including a plurality of microprobes may be used. By operating a plurality of microprobes in parallel using the array structure, it is possible to obtain a higher operating speed than an apparatus having a single microprobe. In this case, an element for applying an elastic wave may be provided for each microprobe, or a structure for applying an elastic wave from a single elastic wave generating element to a plurality of microprobes may be employed.

  In the above examples, the information recording / reproducing apparatus has been described as an apparatus capable of both recording and reproducing information. However, the information recording / reproducing apparatus may be configured as separate apparatuses, that is, an information recording apparatus and an information reproducing apparatus. Good.

It is a schematic diagram explaining the information recording / reproducing apparatus which concerns on this embodiment. It is a schematic diagram explaining an example of the information recording / reproducing apparatus based on 1st Example. It is a schematic diagram explaining the structure of the thin film bulk acoustic wave resonator provided with the microprobe. FIG. 6 is a schematic cross-sectional view (No. 1) for explaining the method of manufacturing the information recording / reproducing apparatus in the first example. It is a schematic cross section (the 2) explaining the manufacturing method of the information recording / reproducing apparatus which concerns on 1st Example. It is a schematic diagram explaining an example of the information recording / reproducing apparatus which concerns on 2nd Example. It is a schematic cross section explaining the manufacturing method of the information recording and reproducing apparatus which concerns on 2nd Example (the 1). It is a schematic cross section explaining the manufacturing method of the information recording and reproducing apparatus which concerns on 2nd Example (the 2).

Explanation of symbols

  21 ... microprobe, 22 ... elastic wave generating element, 23 ... support base, 24 ... recording medium

Claims (12)

In an apparatus for reproducing information by scanning a microprobe on the surface of a recording medium in which a concave shape corresponding to recording information is formed in a subfield on the surface by scanning the microprobe,
Elastic wave generating means for applying an elastic wave that is high-frequency vibration to the microprobe, and using the elastic wave transmitted from the elastic wave generating means to the microtip tip , the tip of the microprobe and An information reproducing apparatus, wherein information on the presence or absence of a depression on the surface of the recording medium at a close position is read by the microprobe. The microprobe is arranged in a plurality of matrixes corresponding to a plurality of subfields of the recording medium , and for each microprobe, the presence or absence of the depressions in the corresponding subfield is read. 1. An information reproducing apparatus according to 1. The information reproducing apparatus according to claim 1, wherein the elastic wave generating means is a piezoelectric element. The information reproducing apparatus according to claim 1, wherein the elastic wave generating means is a bulk acoustic wave resonator. The information reproducing apparatus according to claim 1, wherein the microprobe is disposed between the elastic wave generating unit and the recording medium. The information reproducing apparatus according to claim 1, wherein the microprobe is integrally formed on the elastic wave generating means. The information reproducing apparatus according to claim 1, wherein the microprobe is formed on the elastic wave generating means via a predetermined gap. The microprobe is formed on the bulk acoustic wave resonator via a predetermined gap, and is supported by a part other than the thin film vibrator of the bulk acoustic resonator. 4. The information reproducing apparatus according to 4. In a method of reproducing information by scanning a microprobe on the surface of a recording medium in which a shape-like depression corresponding to recording information is formed in a subfield on the surface by scanning the microprobe,
By applying an elastic wave that is high-frequency vibration to the microprobe and using the elastic wave transmitted to the tip of the microprobe, information on the presence or absence of depressions on the surface of the recording medium at a position close to the tip is obtained. An information reproduction method characterized by reading with a probe. The microprobe is arranged in a plurality of matrixes corresponding to a plurality of subfields of the recording medium , and for each microprobe, the presence or absence of the depressions in the corresponding subfield is read. 9. The information reproducing method according to 9. A drive for mounting the recording medium and moving in the X, Y, and Z directions is provided.
The information reproducing apparatus according to any one of claims 1 to 8. The thickness of the piezoelectric thin film used for the bulk acoustic wave resonator is half the wavelength of the generated acoustic wave in the piezoelectric thin film.
The information reproducing apparatus according to claim 4.

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