Material Property Measurements Using Multiple Frequency Atomic Fore Microscopy
First Claim
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1. An atomic force microscope which processes a sample, comprising:
- a cantilever which has a probe tip which is moved relative to a surface of the sample;
a controller, controlling said cantilever to move, using a feedback loop to control a distance between the cantilever of the atomic force microscope and said surface, to maintain the probe tip of the cantilever in a pre-established relationship with respect to the surface of the sample while scanning the sample by creating relative movement between the probe tip of the cantilever and the sample and measuring values used to control said cantilever;
a cantilever exciter including first and second frequency synthesizer parts, creating first and second synthesized frequencies, and summing said first and second synthesized frequencies to create a multiple frequency exciting signal, and coupling said multiple frequency exciting signal for exciting the cantilever; and
a reference detection device receiving said synthesized frequencies as a reference signal;
said controller measuring cantilever values at said synthesized excitation frequencies; and
using said reference detection device and the measured cantilever values to provide information indicative of a surface of the sample.
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Abstract
Apparatus and techniques for extracting information carried in higher eigenmodes or harmonics of an oscillating cantilever or other oscillating sensors in atomic force microscopy and related MEMs work are described. Similar apparatus and techniques for extracting information using contact resonance with multiple excitation signals are also described.
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Citations
26 Claims
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1. An atomic force microscope which processes a sample, comprising:
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a cantilever which has a probe tip which is moved relative to a surface of the sample; a controller, controlling said cantilever to move, using a feedback loop to control a distance between the cantilever of the atomic force microscope and said surface, to maintain the probe tip of the cantilever in a pre-established relationship with respect to the surface of the sample while scanning the sample by creating relative movement between the probe tip of the cantilever and the sample and measuring values used to control said cantilever; a cantilever exciter including first and second frequency synthesizer parts, creating first and second synthesized frequencies, and summing said first and second synthesized frequencies to create a multiple frequency exciting signal, and coupling said multiple frequency exciting signal for exciting the cantilever; and a reference detection device receiving said synthesized frequencies as a reference signal; said controller measuring cantilever values at said synthesized excitation frequencies; and
using said reference detection device and the measured cantilever values to provide information indicative of a surface of the sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An atomic force microscope which processes a sample, comprising:
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a cantilever which has a probe tip which is moved relative to a surface of the sample; a controller, controlling said cantilever to move, using a feedback loop to control a distance between the cantilever of the atomic force microscope and said surface, to maintain the probe tip of the cantilever in a pre-established relationship with respect to the surface of the sample while scanning the sample by creating relative movement between the probe tip of the cantilever and the sample, said using a phase of the cantilever movement in the feedback loop, and using a frequency of the cantilever movement to maintain the phase substantially constant in the feedback loop; a cantilever exciter including first and second frequency synthesizer parts, creating first and second synthesized frequencies, and summing said first and second synthesized frequencies to create a multiple frequency exciting signal, and coupling said multiple frequency exciting signal for exciting the cantilever; and a reference detection device receiving said synthesized frequencies as a reference signal; said controller measuring cantilever values at the synthesized excitation frequencies; and
using said reference detection device and the measured cantilever values to provide information indicative of a surface of the sample. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An atomic force microscope which processes a sample, comprising:
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an atomic force microscope cantilever having a probe tip adapted to be located adjacent to a sample; a controller for said cantilever, using a feedback loop to control a distance between said probe tip, and a surface of the sample to maintain the probe tip of the cantilever in a pre-established relationship with respect to the surface of the sample while controlling scanning the sample by creating relative movement between the probe tip of the cantilever and the sample; a driver, creating two or more synthesized frequencies, summing together said two or more synthesized frequencies, and exciting a chip of the cantilever using said two or more synthesized frequencies; a lock-in amplifier, receiving each of said synthesized frequencies as a reference signal; and wherein said controller measuring cantilever values, including an amplitude and phase of the cantilever at the synthesized excitation frequencies and using the measured cantilever values to provide information indicative of a surface of the sample. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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Specification