Method and Device of Using a Scanning Probe Microscope

Patent metadata

Field	Value
Publication number	US-2018106830-A1
Application number	US-201615573137-A
Country	US
Kind code	A1
Filing date	May 11, 2016
Priority date	May 11, 2015
Publication date	Apr 19, 2018
Grant date	—

Abstract

a scanning probe microscope for high-speed imaging and/or nanomechanical mapping. The microscope comprises a scanning probe comprising a cantilever with a tip at the distal end; and means for modulating a tip-sample distance separating the tip from an intended sample to be viewed with the microscope, the means for modulating being adapted to provide a direct cantilever actuation.

First claim

1 - 17 . (canceled)

18 : A method for characterising a surface of a sample using atomic force microscopy with a cantilever acting as both actuator and sensor, the method comprising the steps of:
generating an oscillating motion between a probe of the cantilever of the atomic force microscope and the surface of the sample by direct cantilever actuation; recording a deflection of the cantilever as a first signal as a function of time; extracting a tip-sample interaction as a second function of time from the first signal, by subtracting a background signal as a function of time; determining a peak force from the extracted tip-sample interaction; comparing the peak force to a predetermined setpoint force to determine an error signal; generating a control signal from the error signal; and actuating a z-actuator using the control signal to maintain the peak force at the predetermined setpoint force.

19 : The method of claim 18 , wherein the background signal includes a signal of the deflection of the direct cantilever actuation to generate tip-sample distance modulation.

20 : The method of claim 18 , wherein the step of generating the oscillating motion is performed by a modulation device that includes at least one of a photothermal device, electrothermal device, electrostatic device, magnetic device, and piezoelectric device.

21 : The method of claim 18 , wherein the step of recording the cantilever signal includes a step of reading a light beam.

22 : The method of claim 18 , wherein the step of recording the cantilever signal includes using a piezoresistive cantilever detection mechanism.

23 : The method of claim 21 , wherein the step of generating the oscillating motion uses a photothermal device as a modulation, and both a device generating the light beam and the photothermal device include a single laser.

24 : The method of claim 18 , wherein the step of generating the oscillating motion is performed by a modulation device configured to provide a deformation of an entirety of the cantilever.

25 : The method of claim 18 , wherein the step of generating the oscillating motion is performed by a modulation device configured to provide a partial deformation of the cantilever.

26 : The method of claim 18 , wherein the step of generating the oscillating motion is configured to achieve a predefined motion.

27 : The method of claim 26 , wherein the predefined motion compensates for a background signal.

28 : The method of claim 18 , further comprising the step of:
thermally bending the cantilever to provide a feedback motion for a scanning.

29 : The method of claim 28 , wherein the step of thermally bending is configured to enable the feedback motion to be achieved by a combination of a piezo scanner and the bending of the cantilever by splitting a feedback signal by frequency to prevent the feedback signal from causing scanner resonances.

30 : An atomic force microscope configured to perform the method of claim 18 .

31 : An atomic force microscope cantilever comprising:
a first material; a second material; the first material having a thermal expansion coating of the second material; the second material configured to absorb a larger amount of light to locally heat the cantilever than the first material; the second material having a different thermal expansion coefficient than the first material; and the second material configured to reflect strongly at an intended readout laser wavelength and to absorb more at the actuation laser wavelength.

32 : A method for calibrating a cantilever deflection sensitivity due to a direct cantilever actuation, the cantilever being used to measure a sample, the method comprising the steps of:
deflecting the cantilever through a direct actuation until the cantilever touches a surface of the sample, at a point of contact; calculating the cantilever deflection sensitivity at the contact point by increasing the direct actuation; changing a z-position of the sample by a predetermined amount; repeating the step of deflecting and the step of calculating for a total of at least two times; and extracting the direct cantilever actuation deflection sensitivity by regression.

Assignees

• Ecole Polytechnique Fed Lausanne Epfl

Inventors

• Fantner Georg Ernest
• Adams Jonathan David
• Nievergelt Adrian Pascal

Classifications

• G01Q10/065

  Feedback mechanisms, i.e. wherein the signal for driving the probe is modified by a signal coming from the probe itself · CPC title

• G01Q20/02 Primary

  by optical means · CPC title

• G01Q60/32

  AC mode · CPC title

• G01Q10/045 Primary

  Self-actuating probes, i.e. wherein the actuating means for driving are part of the probe itself, e.g. piezoelectric means on a cantilever probe · CPC title