Method and an apparatus for measuring the flying height with sub-nanometer resolution
First Claim
1. A method for measuring a distance between a sliding object and a transparent disk with sub-nanometer resolution, wherein the distance is regarded as a nanometer specimen, comprising steps of:
- a) providing a sampling light beam with adjustable initial polarization state by phase modulation, and with variable incident angles, which is controlled by an optical control subsystem, relative to said air film and forming a first reflected light beam of said sampling light beam relative to said air film;
b) guiding said first reflected light beam of said sampling light beam through said optical control subsystem to form a return light beam traveling in the opposite direction to said first reflected light beam, wherein said return light beam being incident to the specimen again at said detecting site, therefore a second reflected light beam of said returned light beam is formed, while said second reflected light beam exits from the said optical control subsystem in the opposite direction to the said sampling light beam, it is to form a signal light beam;
c) guiding said signal light beam through an analyzer and the detectors for detection of intensity and phase change of said signal light beam; and
d) partially dividing said signal light beam to form an observing light beam, which is guided to a microscope and used as a light source for observation of said detecting site on said specimen.
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Accused Products
Abstract
A method and apparatus is claimed for measuring the distance between a slider and a transparent disk with sub-nanometer resolution. The flying height is measured by applying ellipsometry. The measurement is done by: providing a sampling light beam with adjustable initial polarization state by phase modulation, and with variable incident angles relative to the air film and reflecting the sampling light off of the specimen at a detection site forming a reflected light beam that is then reflected at the detection site again and then guided to both detectors for detecting the intensity and phase change of the light beam to determine the gap'"'"'s thickness as well as passing some light to a microscope used for observation of the detecting site on the specimen.
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Citations
54 Claims
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1. A method for measuring a distance between a sliding object and a transparent disk with sub-nanometer resolution, wherein the distance is regarded as a nanometer specimen, comprising steps of:
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a) providing a sampling light beam with adjustable initial polarization state by phase modulation, and with variable incident angles, which is controlled by an optical control subsystem, relative to said air film and forming a first reflected light beam of said sampling light beam relative to said air film;
b) guiding said first reflected light beam of said sampling light beam through said optical control subsystem to form a return light beam traveling in the opposite direction to said first reflected light beam, wherein said return light beam being incident to the specimen again at said detecting site, therefore a second reflected light beam of said returned light beam is formed, while said second reflected light beam exits from the said optical control subsystem in the opposite direction to the said sampling light beam, it is to form a signal light beam;
c) guiding said signal light beam through an analyzer and the detectors for detection of intensity and phase change of said signal light beam; and
d) partially dividing said signal light beam to form an observing light beam, which is guided to a microscope and used as a light source for observation of said detecting site on said specimen. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for measuring a distance between a sliding object and a transparent disk with sub-nanometer resolution, wherein the distance is regarded as a nanometer specimen, comprising steps of:
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a) providing a sampling light beam with adjustable initial polarization state by phase modulation, and with variable incident angles, which is controlled by an optical control subsystem, relative to said air film and forming a first reflected light beam of said sampling light beam relative to said air film;
b) guiding said first reflected light beam of said sampling light beam through said optical control subsystem to form a return light beam traveling in the opposite direction to said first reflected light beam, wherein said return light beam being incident to the specimen again at said detecting site, therefore a second reflected light beam of said returned light beam is formed, while said second reflected light beam exits from the said optical control subsystem in the opposite direction to the said sampling light beam, it is to form a signal light beam;
c) guiding said signal light beam through an analyzer and the detectors for detection of intensity and phase change of said signal light beam;
d) partially dividing said signal light beam to form an observing light beam, which is guided to a microscope and used as a light source for observation of said detecting site on said specimen;
e) partially dividing said sampling light beam to form a reference light beam, which is guided to a reference light beam analyzer for measuring light intensity and phase change of said reference light beam as a calibration reference of non-linear phase retardation and non-uniform absorption in said phase modulator; and
f) providing a polarization state control method utilizing intensity and phase change of said reference light beam as parameters to accurately control the polarization state of said sampling light beam. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An apparatus for measuring the distance between a sliding object and a transparent disk with sub-nanometer resolution, wherein the distance is regarded as a nanometer specimen, comprising:
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a linear polarizing light source subsystem of which light intensity is to be tuned and initial linear polarization state is provided thereof to form a sampling light beam;
a phase modulator for the control of phase change of said sampling light beam to vary initial polarization state of said linear polarizing light source;
an optical control subsystem, which comprises a beam-bending element for guiding said sampling light beam incident to the detecting site in various angles, a carrier carrying and moving the said beam-bending element, and an optical component set comprising a focusing element and a normal reflection element, wherein said focusing element is used to guide said sampling light beam passing through said transparent disk to form a first reflected light beam at a detecting site of said specimen, and wherein said normal reflection element is used to normally reflect said first reflected light beam to form a return light beam traveling along the same path but in the direction opposite to said sampling light beam, therefore, a second reflected light beam of said return light beam at said detecting site is formed, while said second reflected light beam exits from the said optical control subsystem in the opposite direction to the said sampling light beam, it is to form a signal light beam; and
a signal analysis subsystem for detecting light intensity and phase change of said signal light beam. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. An apparatus for measuring a distance between a sliding object and a transparent disk with sub-nanometer resolution, wherein the distance is regarded as a nanometer specimen, comprising:
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a linear polarizing light source subsystem of which light intensity is to be tuned and initial linear polarization state is provided thereof to form a sampling light beam;
a phase modulator for the control of phase change of said sampling light beam to vary initial polarization state of said linear polarizing light source;
an optical control subsystem, which comprises a beam-bending element for guiding said sampling light beam incident to the detecting site in various angles, a carrier carrying and moving the said beam-bending element, and an optical component set comprising a focusing element and a normal reflection element, wherein said focusing element is used to guide said sampling light beam passing through said transparent disk to form a first reflected light beam at a detecting site of said specimen, and wherein said normal reflection element is used to normally reflect said first reflected light beam to form a return light beam traveling along the same path but in the direction opposite to said sampling light beam, therefore, a second reflected light beam of said return light beam at said detecting site is formed, while said second reflected light beam exits from the said optical control subsystem in the opposite direction to the said sampling light beam, it is to form a signal light beam;
a signal analysis subsystem for detecting light intensity and phase change of said signal light beam;
a reference analysis subsystem for detection of light intensity and polarization state variation of said reference light beam and calibration of non-linear phase retardation and non-uniform absorption in said phase modulator to accurately control said polarization state of said sampling light beam; and
a transfer function calibration device for detection of unknown ellipsometric parameters of said optical system. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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Specification