Method and apparatus of operating a scanning probe microscope

Patent metadata

Field	Value
Publication number	US-9810713-B2
Application number	US-201615057963-A
Country	US
Kind code	B2
Filing date	Mar 1, 2016
Priority date	Nov 13, 2008
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

Methods and apparatuses are provided for automatically controlling and stabilizing aspects of a scanning probe microscope (SPM), such as an atomic force microscope (AFM), using Peak Force Tapping (PFT) Mode. In an embodiment, a controller automatically controls periodic motion of a probe relative to a sample in response to a substantially instantaneous force determined, and automatically controls a gain in a feedback loop. A gain control circuit automatically tunes a gain based on separation distances between a probe and a sample to facilitate stability. Accordingly, instability onset is quickly and accurately determined during scanning, thereby eliminating the need of expert user tuning of gains during operation.

First claim

We claim:

1. A method for monitoring effectiveness of a scanning probe microscope (SPM), the method comprising:
providing relative motion between a probe and a sample and controlling that motion using a feedback loop in peak force tapping (PFT) mode;
detecting an attractive force between the probe and the sample; and
comparing the attractive force to a predetermined threshold in real time with operation of the controlling step.

2. The method of claim 1 , wherein the attractive force substantially results from an adhesion force between the probe and the sample.

3. The method of claim 2 , wherein the adhesion force is determined according to a maximum adhesion force.

4. The method of claim 2 , wherein the adhesion force is determined according to an integration of a work of adhesion with respect to a departure point from and a return point to a non-interacting zero force baseline.

5. The method of claim 1 , wherein the attractive force substantially results from van der Waals forces.

6. The method of claim 5 , wherein the van der Waals forces are determined according to a slope with respect to a non-interacting zero force baseline.

7. A method for monitoring tip health of a probe of a scanning probe microscope (SPM) during SPM operation, the method comprising:
providing relative motion between a probe and a sample and controlling the motion using peak force tapping (PFT) mode;
providing relative scanning motion between the probe and the sample so the controlling step is performed at multiple pixels along a scan line;
generating a force curve at each pixel; and
automatically determining tip health at each pixel in real time with the controlling step.

8. The method of claim 7 , further comprising detecting an attractive force between the probe and the sample; and
comparing the attractive force to a predetermined threshold.

9. The method of claim 8 , wherein the attractive force substantially results from an adhesion force between the probe and the sample.

10. The method of claim 9 , wherein the adhesion force is determined according to a maximum adhesion force.

11. The method of claim 9 , wherein the adhesion force is determined according to an integration of a work of adhesion with respect to a departure point from and a return point to a non-interacting zero force baseline.

12. The method of claim 8 , wherein the attractive force substantially results from van der Waals forces.

13. The method of claim 12 , wherein the van der Waals forces are determined according to a slope with respect to a non-interacting zero force baseline.

14. The method of claim 13 , wherein the determining step is performed at least every 300 microseconds.

15. The method of claim 7 , further comprising determining a slope of a portion of the force curve corresponding to an attractive force, wherein the slope is indicative of tip health.

16. The method of claim 15 , wherein the attractive force is caused by van der Waals force.

Assignees

• Bruker Nano Inc

Inventors

• Shi Jian
• Hu Yan
• Hu Shuiqing
• Ma Ji
• Su Chanmin

Classifications

• G01Q60/34

  Tapping mode · CPC title

• G01Q20/00 Primary

  Monitoring the movement or position of the probe · CPC title

• G01Q60/32

  AC mode · CPC title

• G01Q60/30

  Scanning potential microscopy · CPC title

• G01Q60/24 Primary

  AFM [Atomic Force Microscopy] or apparatus therefor, e.g. AFM probes · CPC title