Tapping atomic force microscope
First Claim
1. In a method of operating an atomic force microscope including a probe including a probe tip mounted on one end of a lever arm and wherein the probe tip is scanned across the surface of a sample and data resentative of the surface of the sample is gathered in relation to the positioning of the lever arm as the probe tip is scanned, the improvement comprising:
- oscillating the probe tip at or near a resonant frequency of the probe or a harmonic of said resonant frequency and with a free oscillation amplitude Ao sufficiently great so that the oscillating probe tip does not stick to the surface of the sample when the oscillating probe tip contacts the surface of the sample;
positioning the oscillating probe tip so that the oscillating probe tip repeatedly taps the surface of the sample with the probe tip repeatedly contacting and breaking contact with the surface of the sample without sticking to the surface of the sample;
translating the oscillating probe tip across the surface of the sample with the oscillating probe tip repeatedly tapping the surface of the sample so that the oscillation amplitude of the probe tip is stably affected due to changes in topography of the surface of the sample; and
producing signals indicative of variations in the topography of the surface of the sample in relation to changes in the oscillation of the oscillating probe tip upon repeated tapping of the oscillating probe tip against the surface of the sample during translation of the oscillating probe tip across the surface of the sample.
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Accused Products
Abstract
An atomic force microscope in which a probe tip is oscillated at a resonant frequency and at amplitude setpoint and scanned across the surface of a sample in contact with the sample, so that the amplitude of oscillation of the probe is changed in relation to the topography of the surface of the sample. The setpoint amplitude of oscillation of the probe is greater than 10 nm to assure that the energy in the lever arm is much higher than that lost in each cycle by striking the sample surface, thereby to avoid sticking of the probe tip to the sample surface. Data is obtained based either on a control signal produced to maintain the established setpoint or directly as a function of changes in the amplitude of oscillation of the probe.
202 Citations
28 Claims
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1. In a method of operating an atomic force microscope including a probe including a probe tip mounted on one end of a lever arm and wherein the probe tip is scanned across the surface of a sample and data resentative of the surface of the sample is gathered in relation to the positioning of the lever arm as the probe tip is scanned, the improvement comprising:
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oscillating the probe tip at or near a resonant frequency of the probe or a harmonic of said resonant frequency and with a free oscillation amplitude Ao sufficiently great so that the oscillating probe tip does not stick to the surface of the sample when the oscillating probe tip contacts the surface of the sample; positioning the oscillating probe tip so that the oscillating probe tip repeatedly taps the surface of the sample with the probe tip repeatedly contacting and breaking contact with the surface of the sample without sticking to the surface of the sample; translating the oscillating probe tip across the surface of the sample with the oscillating probe tip repeatedly tapping the surface of the sample so that the oscillation amplitude of the probe tip is stably affected due to changes in topography of the surface of the sample; and producing signals indicative of variations in the topography of the surface of the sample in relation to changes in the oscillation of the oscillating probe tip upon repeated tapping of the oscillating probe tip against the surface of the sample during translation of the oscillating probe tip across the surface of the sample. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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2. In an atomic force microscope (AFM) wherein a probe including a probe tip mounted on a lever arm is scanned across the surface of a sample and data reflecting the surface of the sample is gathered in relation to positioning of the lever arm as the probe tip is scanned, the improvement comprising:
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first transducer means for oscillating the probe tip with a free oscillation amplitude Ao sufficiently great, so that the oscillating probe tip does not stick to the surface of the sample'"'"'when the oscillating probe tip contacts the surface of the sample; second transducer means for positioning the oscillating probe tip so that the oscillating probe tip repeatedly taps the surface of the sample, thereby repeatedly contacting and breaking contact without sticking to the surface of the sample, and and for translating the oscillating probe tip across the surface of the sample with the oscillating probe tip repeatedly tapping the surface of the sample such that the amplitude of oscillation of the probe tip is affected by repeatedly tapping the sample surface; and means for monitoring the oscillation of the probe tip during translating of the oscillating probe tip to produce a signal indicative of variations in the topography of the surface of the sample in relation to changes in the oscillation of the oscillating probe tip during tapping against the surface of the sample and translation across the surface of the sample. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. In a method of operating an atomic force microscope including a probe including a probe tip mounted on one end of a lever arm and wherein the probe tip is scanned across a sample surface including a surface fluid layer, and data rpresentative of topography of the sample is gathered in relation to the positioning of the lever arm as the probe tip is scanned, the improvement comprising:
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oscillating the probe tip at a free oscillation amplitude A0 equal to or greater than 20 nanometers; interacting the oscillating probe tip with the sample surface so that the oscillating probe tip contacts and breaks contact with the sample surface without sticking to the sample surface to produce changes in the oscillation as a function of the topography of the sample; and producing signals representative of the topography of the sample in relation to the changes in the oscillation produced in said interacting step. - View Dependent Claims (14, 15, 16)
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17. In a method of operating an atomic force microscope including a probe including a probe tip mounted on one end of a lever arm and wherein the probe tip is scanned across the surface of a sample and data representative of the surface of the sample is gathered in relation to the positioning of the lever arm as the probe tip is scanned, the improvement comprising:
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oscillating the probe to produce a free oscillation amplitude Ao of the probe tip; providing a body of fluid on the surface of the sample with a depth sufficiently great to cover said oscillating probe; positioning the oscillating probe tip in the body of fluid so that the oscillating probe tip repeatedly taps the surface of the sample with the probe tip repeatedly contacting and breaking contact with the surface of the sample without sticking to the surface of the sample; translating the oscillating probe tip in said body of fluid across the surface of the sample with the oscillating probe tip repeatedly tapping the surface of the sample so that the oscillation amplitude of the probe tip is stably affected due to changes in topography of the surface of the sample; and
producing signals indicative of variations in the topography of the surface of the sample in relation to changes in the oscillation of the oscillating probe tip upon repeated tapping of the oscillating probe tip against the surface of the sample during translation of the oscillating probe tip across the surface of the sample. - View Dependent Claims (18, 19)
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Specification