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Device and method for obtaining a potential

外国特許コード F130007284
整理番号 KP09-052PCT-EP
掲載日 2013年4月9日
出願国 欧州特許庁(EPO)
出願番号 11750653
公報番号 2544016
公報番号 2544016
出願日 平成23年3月1日(2011.3.1)
公報発行日 平成25年1月9日(2013.1.9)
公報発行日 令和2年4月15日(2020.4.15)
国際出願番号 JP2011054635
国際公開番号 WO2011108543
国際出願日 平成23年3月1日(2011.3.1)
国際公開日 平成23年9月9日(2011.9.9)
優先権データ
  • 特願2010-044218 (2010.3.1) JP
  • 2011JP54635 (2011.3.1) WO
発明の名称 (英語) Device and method for obtaining a potential
発明の概要(英語) In a magnetic field obtaining apparatus, a measuring part (21) that is sufficiently longer than the width of an area to be measured is disposed on a measurement plane that satisfies z = ±, and scanning in an X' direction perpendicular to the longitudinal direction of the measuring part (21) is repeated while changing an angle ¸ formed by a predetermined reference direction on the measurement plane and the longitudinal direction of the measuring part (21) to a plurality of angles. Assuming that x' is a coordinate parameter in the X' direction, measured values f(x', ¸) obtained by repetitions of the scanning are Fourier transformed so as to obtain g(k x' , ¸) (where k x' is a wavenumber in the X' direction). Then, g(k x' , ¸) is substituted into a predetermined two-dimensional potential obtaining equation so as to obtain Æ (x, y, ±) that indicates a two-dimensional potential on the measurement plane. Accordingly, it is possible to perform high-resolution two-dimensional potential measurement as a result of using the measuring part (21) that is sufficiently larger than the width of an area to be measured.
従来技術、競合技術の概要(英語) Background Art
Conventionally, the distribution of a magnetic field has been obtained using a superconducting quantum interference device (hereinafter referred to as an "SQUID") or a magnetoresistive sensor, and for example, a defective (or short-circuited) portion of an electric circuit has been specified based on the magnetic field distribution. Since the resolution of the magnetic field measurement depends on the size of the SQUID coil or the magnetoresistive sensor, attempts are being made to reduce that size in order to improve the resolution of the measurement.
Obtaining the spatial distribution of a magnetic field has also been performed using magnetic force microscopy (hereinafter referred to as "MFM"). Japanese translation of PCT International Application Publication No. 2006-501484 suggests use of a carbon nanotube including a nanoscale ferromagnetic material as a cantilever in the MFM.
WO/2008/123432 (Document 2) discloses a technique for obtaining a three-dimensional potential distribution. With this technique, a magnetic force distribution on a specific measurement plane is obtained as a two-dimensional magnetic field distribution image, using an MFM above a sample having magnetic domains. An auxiliary magnetic field distribution image is also obtained by performing measurement on another measurement plane that is away from the above measurement plane by a small distance d, and a difference between these images is divided by the small distance d so as to obtain a two-dimensional magnetic field gradient distribution image. The magnetic field distribution image and the magnetic field gradient distribution image are Fourier transformed and substituted into a three-dimensional potential distribution obtaining equation derived from the general solution of the Laplace equation. It is thus possible to obtain an image that indicates a three-dimensional magnetic field distribution with high precision.
Incidentally, there is a limit to miniaturization of the SQUID coil or the magnetoresistive sensor because of the wavelength used in exposure technology, and thus there is also a certain limit to improvement in the resolution of the measurement. Moreover, although the radius of curvature of the tip of a silicon probe formed by anisotropic etching can be reduced to an extremely small value as small as several nanometers, it is necessary, when using the silicon probe in an MFM, to form a thin film of a magnetic material on the tip of the probe. This makes a magnetic force sensor that has a thickness equal to the "film thickness of the magnetic thin film + radius of curvature of the tip of the probe + the magnetic thin film". For example, if the film thickness of the magnetic thin film is 10 nm and the radius of curvature of the tip of the probe is 10 nm, the magnetic force sensor has a total diameter of 30 nm. At least there are no cases where the resolution of the measurement exceeds the radius of curvature of the tip of the probe. In addition, since it is difficult in practical use to cover only the tip portion of the probe with the magnetic thin film, the size of the effective magnetic force sensor is further increased.
JP 2007 271465 A solves the problem of providing a magnetic field distribution measuring instrument that has high resolution and that simplifies the position control of a probe. The solution is a magnetic field distribution measuring instrument which comprises the probe having a thin-film magnetometric sensor for detecting magnetic field distribution very close to a measured object as an output signal of voltage or current, an actuator for one-dimensionally translation-scanning the probe in the thickness direction of the thin-film magnetometric sensor, a rotating mechanism for making the measured object rotate in the horizontal plane, an angle sensor for detecting the rotation angle of the measured object, and a magnetic field distribution reconstructing means for reconstructing the magnetic field distribution, based on the output signal from the probe, the position signal of the probe output from the actuator, and a rotation angle signal output from the angle sensor.
The problem of the present application is therefore related to improving the resolution of universal two-dimensional potential measurements and calculating the three-dimensional potentials formed at least in the periphery of an object.
This problem is solved by the independent claims. Preferred embodiments are given by the dependent claims.
特許請求の範囲(英語) [claim1]
1. A potential obtaining apparatus (1, 1a to 1c) for, assuming that φ(x, y, z) is a potential function that indicates a three-dimensional potential formed at least in the periphery of an object (9, 9a, 9c) due to the presence of said object, where x, y, and z are coordinate parameters of a rectangular coordinate system defined in mutually perpendicular X, Y, and Z directions that are set for said object, obtaining φ(x, y, α) on a measurement plane (91, 92) that is set outside said object and satisfies z = α, where α is an arbitrary value,
said apparatus comprising:
a measurement unit in which a plurality of linear areas that extend in a longitudinal direction parallel to said measurement plane that is parallel to an XY plane are set so as to be arranged in an X' direction perpendicular to said longitudinal direction on said measurement plane, and that is for obtaining, by a sensor extending in said longitudinal direction, a measured value derived from said three-dimensional potential in each of said plurality of linear areas in a state in which an angle θ formed by the Y direction and said longitudinal direction has been changed to a plurality of angles; and
a computing part (61, 63) for, assuming that x' is a coordinate parameter in the X' direction, where an origin is on a Z axis, obtaining φ(x, y, α) on the measurement plane (91, 92) using the measured values f(x', θ) obtained by said measurement unit from Equation 24,
ϕxyα=∬∫fx′,θexp-ikx′x′dx′expikx′xcosθ+ysinθkx′dkx′dθ
where kx' is a wavenumber in the X' direction,
wherein said measurement unit includes:
a measuring part (21, 21a to 21c) which is said sensor, said measuring part being a thin-film element that spreads in said longitudinal direction and the Z direction and being configured to generate a signal derived from said three-dimensional potential;
an angle changing part (32, 32a) for changing said angle θ formed by the Y direction and said longitudinal direction of said measuring part;
a moving mechanism (33, 33a) for moving said measuring part in the X' direction relative to said object on said measurement plane such that scanning is performed in which said measuring part is adapted to pass through over a measurement area of said object; and
a control part (4, 62, 62a) for controlling said angle changing part and said moving mechanism such that said scanning is repeated while said angle θ is changed to a plurality of angles,
wherein said measurement unit is adapted to obtain measured values f(x', θ) by repetitions of said scanning,
wherein the potential obtaining apparatus further comprises:
another moving mechanism (34, 34a) for moving said measuring part in the Z direction relative to said object,
wherein said three-dimensional potential satisfies the Laplace equation,
wherein said control part is adapted to obtain φ(x, y, 0) on said measurement plane that satisfies z = 0 as a two-dimensional first image (71), and after said measuring part is moved by a small distance in the Z direction relative to said object, to obtain a two-dimensional intermediate image (72) using a technique similar to that used to obtain said first image, and
said computing part is adapted to obtain a difference image between said first image and said intermediate image, to divide said difference image by said small distance so as to obtain a differential image as a second image, to Fourier transform φ(x, y, 0) serving as said first image and φz(x, y, 0) serving as said second image so as to obtain ψ (kx, ky) and ψz(kx, ky), where kx and ky are respectively wavenumbers in the X direction and the Y direction, and then to obtain φ(x, y, z) from Equation 25 using ψ (kx, ky) and ψz(kx, ky).
ϕxyz=∬expikxx+ikyy12ψkxky+ψzkxkykx2+ky2expzkx2+ky2+12ψkxky-ψzkxkykx2+ky2exp-zkx2+ky2dkxdky

[claim2]
2. The potential obtaining apparatus according to claim 1, wherein
φ(x, y, z) corresponds to a function derived by differentiating said three-dimensional potential one or more times with respect to the Z direction.

[claim3]
3. The potential obtaining apparatus according to claim 1, wherein
a film thickness of said thin-film element gradually decreases in a direction along a surface of said thin-film element, the direction being perpendicular to said longitudinal direction.

[claim4]
4. The potential obtaining apparatus according to any one of claims 1 to 3, wherein
said three-dimensional potential is a potential derived from a magnetic potential, an electric potential, or a temperature field.

[claim5]
5. A magnetic field microscope (1) comprising:
the potential obtaining apparatus according to claim 1 for obtaining a function derived by differentiating a magnetic potential once or more times with respect to the Z direction, as φ(x, y, z),
wherein said computing part is adapted to substitute a value that indicates either a position of a surface of said object or a position close to said surface into z of φ(x, y, z).

[claim6]
6. An inspection apparatus (1a) using nuclear magnetic resonance, comprising:
the potential obtaining apparatus according to claim 1 for obtaining a function derived by differentiating a magnetic potential once or more times with respect to the Z direction, as φ (x, y, z); and
means (11, 12) for sequentially inducing nuclear magnetic resonance inside said object on a plurality of planes located at a plurality of positions in the Z direction,
wherein said control part is adapted to obtain φ(x, y, z) when nuclear magnetic resonance is induced on each plane included in said plurality of planes, and
said computing part is adapted to substitute a value that indicates a position of said each plane into z of φ (x, y, z) obtained for said each plane.

[claim7]
7. A potential obtaining method for, assuming that φ(x, y, z) is a potential function that indicates a three-dimensional potential formed at least in the periphery of an object (9, 9a, 9c) due to the presence of said object, where x, y, and z are coordinate parameters of a rectangular coordinate system defined in mutually perpendicular X, Y, and Z directions that are set for said object, obtaining φ(x, y, α) on a measurement plane (91, 92) that is set outside said object and satisfies z = α, where α is an arbitrary value,
said method comprising the steps of:
a) (S11 to S13) setting a plurality of linear areas that extend in a longitudinal direction parallel to said measurement plane that is parallel to an XY plane such that said plurality of linear areas are arranged in an X' direction perpendicular to said longitudinal direction on said measurement plane, and obtaining, by a sensor extending in said longitudinal direction, a measured value derived from said three-dimensional potential in each of said plurality of linear areas in a state in which an angle θ formed by the Y direction and said longitudinal direction has been changed to a plurality of angles; and
b) (S14) assuming that x' is a coordinate parameter in the X' direction, where an origin is on a Z axis, obtaining φ(x, y, α) on the measurement plane (91, 92) using the measured values f(x', θ) obtained in said step a) from Equation 26,
ϕxyα=∬∫fx′,θexp-ikx′x′dx′expikx′xcosθ+ysinθkx′dkx′dθ
where kx' is a wavenumber in the X' direction,
wherein said step a) includes the steps of:
a1) (S11) moving a measuring part (21, 21a to 21c) in the X' direction relative to said object on said measurement plane such that scanning is performed in which said measuring part is adapted to pass through over a measurement area of said object, said measuring part being said sensor and being a thin-film element that spreads in said longitudinal direction and the Z direction and generates a signal derived from said three-dimensional potential; and
a2) (S12 to S13) obtaining measured values f(x', θ) by repetitions of said step a1) while changing said angle θ formed by the Y axis and said longitudinal direction of said measuring part to a plurality of angles,
wherein said three-dimensional potential satisfies the Laplace equation and said measurement plane satisfies z = 0,
wherein φ(x, y, 0) is obtained as a two-dimensional first image (71) in said steps a) and b), and
wherein said potential obtaining method comprises the steps of:
c) (S22) after said measuring part is moved by a small distance in the Z direction relative to said object, obtaining a two-dimensional intermediate image (72) using a method similar to that used to obtain said first image;
d) (S23) obtaining a difference image between said first image and said intermediate image and dividing said difference image by said small distance so as to obtain a differential image as a second image;
e) (S24) Fourier transforming φ(x, y, 0) serving as said first image and φz(x, y, 0) serving as said second image so as to obtain ψ(kx, ky) and ψz(kx, ky), where kx and ky are respectively wavenumbers in the X direction and the Y direction; and
f) (S25) obtaining φ(x, y, z) from Equation 27 using ψ (kx, ky) and ψz(kx, ky).
ϕxyz=∬expikxx+ikyy12ψkxky+ψzkxkykx2+ky2expzkx2+ky2+12ψkxky-ψzkxkykx2+ky2exp-zkx2+ky2dkxdky

[claim8]
8. The potential obtaining method according to claim 7, wherein
φ(x, y, z) corresponds to a function derived by differentiating said three-dimensional potential once or more times with respect to the Z direction.

[claim9]
9. The potential obtaining method according to any one of claims 7 and 8, wherein
said three-dimensional potential is a potential derived from a magnetic potential, an electric potential, or a temperature field.
  • 出願人(英語)
  • NATIONAL UNIVERSITY CORPORATION KOBE UNIVERSITY
  • 発明者(英語)
  • KIMURA KENJIRO
国際特許分類(IPC)
指定国 Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
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