Microwave impedance microscopy using a tuning fork
First Claim
1. A microwave impedance microscope, comprising:
- a support having a support surface for supporting a sample to be tested;
a tuning fork which has two tines extending parallel to a fork axis with a gap there between and being caused to vibrate with respect to the fork axis in response to an oscillatory signal applied thereto;
a probe electrode formed from a metal member having a tapered probe tip extending parallel to a probe axis generally perpendicular to the support surface for a height H between a rim and an apex of the tapered probe tip and having an aspect ratio AR of at least 3 between the height H and a rim diameter DR of the rim, wherein at least a portion of the metal member including the tapered probe tip is fixed to one of the two tines and projects to the sample along the probe axis; and
microwave circuitry for impressing an incident microwave signal to the tapered probe tip, for receiving a reflected microwave signal from an interaction of the incident microwave signal with the sample, and for producing at least one output signal representing an electrical characteristic of the sample.
1 Assignment
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Accused Products
Abstract
A microwave impedance microscope including a tuning fork having a high-aspect ratio etched metal tip electrode extending transversely to one tine of the fork and having a high aspect ratio to thereby reduce parasitic capacitance. The metal tip may be electrochemically etched from a wire, then bonded to the tine. The fork is slightly inclined from the surface of the sample and the tip electrode projects transversely to the fork. A microwave signal is impressed on the tip. Microwave circuitry receives microwave signals reflected from the sample back into the tip and demodulates the reflected signal according to the impressed signal. Further circuitry further demodulates the reflected signal according to the lower-frequency signal causing the fork to oscillate at its mechanically resonant frequency. A multi-wavelength matching circuit interposed between the microwave circuitry and the probe includes a coaxial cable of length half a fundamental microwave wavelength.
12 Citations
20 Claims
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1. A microwave impedance microscope, comprising:
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a support having a support surface for supporting a sample to be tested; a tuning fork which has two tines extending parallel to a fork axis with a gap there between and being caused to vibrate with respect to the fork axis in response to an oscillatory signal applied thereto; a probe electrode formed from a metal member having a tapered probe tip extending parallel to a probe axis generally perpendicular to the support surface for a height H between a rim and an apex of the tapered probe tip and having an aspect ratio AR of at least 3 between the height H and a rim diameter DR of the rim, wherein at least a portion of the metal member including the tapered probe tip is fixed to one of the two tines and projects to the sample along the probe axis; and microwave circuitry for impressing an incident microwave signal to the tapered probe tip, for receiving a reflected microwave signal from an interaction of the incident microwave signal with the sample, and for producing at least one output signal representing an electrical characteristic of the sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A microwave impedance microscope, comprising:
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a probe having an electrode probe tip extending towards a sample to be tested;
microwave circuitry for impressing an incident microwave signal to the electrode probe tip, for receiving a reflected microwave signal from an interaction of the incident microwave signal with the sample, and for producing at least one output signal representing an electrical characteristic of the sample, the microwave circuitry including a microwave source capable of producing the incident microwave signal at a fundamental microwave frequency and at least one harmonic frequency thereof; anda matching circuit disposed between the microwave circuitry and the probe electrode probe tip and that is resonant at the fundamental microwave frequency and at the at least one harmonic frequency. - View Dependent Claims (14, 15, 16)
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17. A microwave impedance microscope, comprising:
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a support having a support surface for supporting a sample to be tested; a tuning fork which has two tines extending parallel to a fork axis with a gap there between and being caused to vibrate with respect to the fork axis in response to an oscillatory signal applied thereto, wherein the fork axis extends from distal ends of the two tines upwardly at no more than 25°
from a plane parallel to the support surface;a probe electrode having a probe tip extending parallel to a probe axis generally perpendicular to the support surface and fixed to one of the tines and projects along the probe axis to the sample; and microwave circuitry for impressing an incident microwave signal to the probe tip, for receiving a reflected microwave signal from an interaction of the incident microwave signal with the sample, and for producing at least one output signal representing an electrical characteristic of the sample. - View Dependent Claims (18, 19, 20)
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Specification