Method And Apparatus Of Tuning A Scanning Probe Microscope

• US 20130125269A1
• Filed: 11/12/2012
• Published: 05/16/2013
• Est. Priority Date: 11/11/2011
• Status: Active Grant

• Current Assignee: Bruker Nano, Inc. (Bruker Corporation)
• Original Assignee: Bruker Nano, Inc. (Bruker Corporation)
• Inventors: Su, Chanmin, Huang, Lin, Pittenger, Bede, Hu, Shuiqing, Silva, Paul
• Granted Patent: US 8,997,259 B2
• Time in Patent Office: Days
• US Class Current: 850/8
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• CPC Class Codes: G01Q 30/00 Auxiliary means serving to assist or improve the scanning probe techniques or apparatus, e.g. display or data processing devices
• CPC Class Codes: G01Q 30/04 Display or data processing devices
• CPC Class Codes: G01Q 40/00 Calibration, e.g. of probes
• CPC Class Codes: G01Q 60/24 AFM [Atomic Force Microscopy] or apparatus therefor, e.g. AFM probes
• CPC Class Codes: G01Q 60/34 Tapping mode

Abstract

An apparatus and method of automatically determining an operating frequency of a scanning probe microscope such as an atomic force microscope (AFM) is shown. The operating frequency is not selected based on a peak of the amplitude response of the probe when swept over a range of frequencies; rather, the operating frequency is selected using only peak data corresponding to a TIDPS curve.

Claims

1. A method of operating a scanning probe microscope (SPM) comprising:

tuning the SPM to determine an operating frequency of a drive of the SPM without detecting an amplitude response of an oscillating probe over a range of frequencies.

2. The method of claim 1, wherein said tuning step includes generating a thermally induced displacement power spectrum (TIDPS) of the SPM to generate a TIDPS curve, and identifying the operating frequency based only on a peak associated with the TIDPS curve.

3. The method of claim 2, wherein the peak of the TIDPS curve corresponds to a fundamental resonant frequency of the oscillating probe.

4. The method of claim 2, wherein the generating step includes a high speed data capture (HSDC) to generate HSDC data.

5. The method of claim 4, wherein the high speed data capture includes using FPGA architecture.

6. The method of claim 5, wherein the high speed data capture includes a capture rate greater than 1 MHz and a duration less than 500 ms.

7. The method of claim 6, wherein the capture rate is greater than 5 MHz and the duration is less than 250 ms.

8. The method of claim 4, wherein the generating step includes executing a Fast Fourier Transform on the HSDC data to generate FFT data.

9. The method of claim 8, further comprising curve fitting the FFT data.

10. The method of claim 9, wherein the curve fitting step includes using a simple harmonic oscillator (SHO) over a first range of frequencies to generate a curve fitted plot, wherein the curve fitted plot includes the peak.

11. The method of claim 10, further comprising a second curve fitting step over a second range of frequencies, the second range of frequencies being smaller than the first range of frequencies and spanning a selected amount relative to a frequency at the peak.

12. The method of claim 2, further comprising using a peak offset value to determine the operating frequency of the SPM drive.

13. The method of claim 12, wherein the peak offset value is input by an SPM operator via a user interface of the SPM.

14. The method of claim 13, further comprising generating oscillatory motion in a probe over a range of frequencies, and plotting an amplitude response of the probe over the range of frequencies so as to determine an amplitude and a phase of the drive.

15. The method of claim 14, wherein the amplitude response includes at least one peak, and wherein the operating frequency does not correspond to any peak of the at least one peak.

16. A scanning probe microscope (SPM) comprising:

a probe that deflects in response to thermal energy;

a detector that detects the deflection;

a fast thermal spectrum module coupled to the detector to generate a TIDPS curve; and

wherein an operating frequency of the SPM is determined based only on the TIDPS curve.

17. The SPM of claim 16, wherein the fast thermal spectrum (FTS) module includes a high speed data capture (HSDC) module that acquires thermal data from the detector.

18. The SPM of claim 17, wherein the HSDC module includes FPGA-based architecture.

19. The SPM of claim 18, wherein the HSDC module acquires data at a sampling rate that is between about 5 MHz and 50 MHz, and a sampling duration greater than 10 ms and less than 1000 ms.

20. The SPM of claim 17, wherein the FTS module includes a FFT module that runs a FFT on data output by the HSDC module, and further comprising a signal processing block that runs a curve fit on the output of the FFT module.