Afm device and method
AssigneeNederlandse Organisatie voor toegepast-natuurwetenschappelijk onderzoek TNO
InventorsRoelof Willem HERFST, Maarten Hubertus VAN ES
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Abstract
An atomic force microscopy, AFM, device is provided herein of which the cantilever in operation of the AFM device has at least a first resonant mode with a first resonance frequency and a second resonant mode with a second resonance frequency that have the following relationship: ∃ N 1 , N 2 : F 2 - c . w 2 F 1 + c . w 1 < N 2 N 1 < F 2 + c . w 2 F 1 - c . w 1 wherein N1 are natural numbers, such that 0<N1<N2<15, w1 and w2 respectively are the full width half maximum (FWHM) values of the first and the second resonance band respectively, and wherein c is a constant equal to 3. Therewith a signal to noise ratio can be improved in a power efficient manner.
Claims20
An atomic force microscopy (AFM) device comprising:
- a cantilever having a tip, the cantilever in operation of the AFM device having at least a first resonant mode with a first resonance frequency (F1) and a second resonant mode with a second resonance frequency (F2) that is greater than the first resonance frequency (F1);
- a scanning system to provide for a relative movement of the tip along a surface of a sample;
- an excitation system to excite the cantilever with at least a first excitation signal and a second excitation signal, which first excitation signal has a first excitation frequency that is at least substantially equal to the first resonance frequency (F1) and the second excitation signal has a second excitation frequency that is at least substantially equal to the second resonance frequency (F2);
- a sensing system to provide a sensor signal (SD) indicative for a motion of the cantilever;
- a detection system to detect in the sensor signal (SD) at least a first physical property in a first frequency band centered around the first resonance frequency (F1) and to detect a second physical property in a second frequency band centered around the second resonance frequency (F2),
- wherein the first and the second resonance frequency have the following relationship:
- ∃
- N
-
- 1
- ,
- N
-
- 2
- :
- F
-
- 2
- -
- c
- .
- w
-
- 2
- F
-
- 1
- +
- c
- .
- w
-
- 1
- <
- N
-
- 2
- N
-
- 1
- <
- F
-
- 2
- +
- c
- .
- w
-
- 2
- F
-
- 1
- -
- c
- .
- w
-
- 1
- wherein N1 are natural numbers, such that 0<N1<N2<15, w1 and w2 respectively are the full width half maximum (FWHM) values of the first and the second resonance band respectively, and wherein c is a constant equal to 3, and
- wherein the first excitation signal is used to modulate a tip-sample force and in that the second excitation signal is used to dither the cantilever.
A method for performing atomic force microscopy comprising:
- providing a relative movement of a tip on a cantilever along a surface of a sample (smp), which cantilever while performing the method has at least a first resonant mode with a first resonance frequency (F1) and a second resonant mode with a second resonance frequency (F2) that is greater than the first resonance frequency;
- exciting the cantilever with at least a first excitation signal (SX1) and a second excitation signal (SX2), which first excitation signal has a first excitation frequency that is at least substantially equal to the first resonance frequency (F1) and which second excitation signal has a second excitation frequency that is at least substantially equal to the second resonance frequency (F2);
- providing a sensor signal (SD) indicative for a motion of the cantilever;
- detecting in the sensor signal (SD) at least a first physical property in a first frequency band centered around the first resonance frequency (F1) and a second physical property in a second frequency band centered around the second resonance frequency (F2),
- wherein the first and the second resonance frequency have the following relationship:
- ∃
- N
-
- 1
- ,
- N
-
- 2
- :
- (
- F
-
- 2
- -
- c
- .
- w
-
- 2
- )
- /
- (
- F
-
- 1
- +
- c
- .
- w
-
- 1
- )
- <
- N
-
- 2
- /
- N
-
- 1
- <
- (
- F
-
- 2
- +
- c
- .
- w
-
- 2
- )
- /
- (
- F
-
- 1
- -
- c
- .
- w
-
- 1
- )
- ,
- wherein N1 are natural numbers, such that 0<N1<N2<15, w1 and w2 respectively are the full width half maximum (FWHM) values of the first and the second resonance band respectively, and wherein c is a constant equal to 3, and
- wherein the first excitation signal is used to modulate a tip-sample force and in that the second excitation signal is used to dither the cantilever.
Dependencies are inferred from the claim text.