Atomic force microscope employing beam-tracking

• US 5,763,767 A
• Filed: 09/23/1996
• Issued: 06/09/1998
• Est. Priority Date: 02/03/1994
• Status: Expired due to Term

• Current Assignee: Keysight Technologies, Inc.
• Original Assignee: Molecular Devices
• Inventors: Jung, Pan S., Yaniv, Daphna R.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): LARKIN, DANIEL SEAN
• Application Number:
  US08/717,767
• Time in Patent Office: 624 Days
• Field of Search: 73/105, 250/306
• US Class Current: 73/105
• CPC Class Codes: G01Q 20/02 by optical means
• CPC Class Codes: Y10S 977/732 Nanocantilever
• CPC Class Codes: Y10S 977/849 with scanning probe
• CPC Class Codes: Y10S 977/851 Particular movement or positioning of scanning tip
• CPC Class Codes: Y10S 977/861 Scanning tunneling probe
• CPC Class Codes: Y10S 977/863 Atomic force probe
• CPC Class Codes: Y10S 977/868 with optical means
• CPC Class Codes: Y10S 977/869 Optical microscope
• CPC Class Codes: Y10S 977/87 Optical lever arm for reflecting light
• CPC Class Codes: Y10S 977/873 Tip holder
• CPC Class Codes: Y10S 977/875 with tip detail
• CPC Class Codes: Y10S 977/878 Shape/taper
• CPC Class Codes: Y10S 977/881 Microscopy or spectroscopy, e.g. sem, tem
• CPC Class Codes: Y10S 977/954 Of radiant energy

Abstract

A scanning probe microscope such as an atomic force microscope for measuring a feature of a sample surface with a sharp probe over an area of interest by means of a collimated light beam reflected from a reflective surface responsive to movement of the sharp probe relative to the sample surface, the movement detected by a position sensitive photodetector, includes a scanner having one end fixed and another end free and attached to the sharp probe for moving the sharp probe. Also fixed to the free end of the scanner is a mount for a beam tracking lens which is interposed into the collimated light beam to cause a focus spot of the light beam to track translational movement of the reflective surface caused by the scanner. In this way, a wide range of scanning ranges up to about 100×100 square micrometers is accommodated as is scanner head and scanner mode switching without the need to disturb the sample. Preferably the beam tracking lens is bi-convex and the source of the collimated light beam is a diode laser.

Claims

1. An atomic force microscope for examining surface properties of a sample surface, said atomic force microscope comprising:

a frame;

a sample stage;

a scanner element having a scanner end capable of motion relative to said frame in response to signals applied to said scanner element;

a cantilever having a reflective surface, a first cantilever end and a second cantilever end, said first cantilever end having a sharp probe tip extending therefrom toward said sample stage, said second cantilever end attached to said scanner;

at least one beam tracking element held in a fixed relationship to a portion of said scanner element;

a source of a collimated light beam, said source arranged to project said collimated light beam to said at least one beam tracking element and from said at least one beam tracking element to a focus at said reflective surface of said cantilever forming a reflected light beam emanating from said reflective surface; and

a position sensitive detector positioned to intercept said reflected light beam and produce a signal responsive to angular movement of said reflected light beam.

2. An atomic force microscope according to claim 1 wherein said position sensitive detector comprises a multi-cell photodetector.

3. An atomic force microscope according to claim 2 wherein said multi-cell photodetector is a bi-cell photodetector.

4. An atomic force microscope according to claim 1 wherein said scanner element is a piezoceramic scanner.

5. An atomic force microscope according to claim 4 wherein said piezoceramic scanner is a tube.

6. An atomic force microscope according to claim 5 wherein said tube is an S-shaped scanner.

7. An atomic force microscope according to claim 1 wherein said at least one beam tracking element comprises at least one lens.

9. An atomic force microscope according to claim 1 wherein said source includes a laser.

10. An atomic force microscope according to claim 9 wherein said laser is a diode laser.

11. An atomic force microscope according to claim 10 wherein said source further includes means for adjusting the position of said source with respect to said frame.

12. An atomic force microscope according to claim 1 wherein said position sensitive detector further includes means for adjusting the position of said position sensitive detector with respect to said frame.

8. An atomic force microscope according to claim wherein said at least one lens is bi-convex.

13. An atomic force microscope for examining the surface properties of a sample surface, said atomic force microscope comprising:

a frame;

a sample stage;

a piezoceramic tube scanner element having a scanner end capable of motion relative to said frame in response to signals applied to said scanner element;

a cantilever having a reflective surface, a first cantilever end and a second cantilever end, said first cantilever end having a sharp probe tip extending therefrom toward said sample stage;

at least one beam tracking lens fixed in operation to a portion of said scanner element;

a source of a collimated light beam including a diode laser module, said source fixed in operation to said frame, said source arranged to project said collimated light beam through said at least one beam tracking lens and to a focus at said reflective surface of said cantilever forming a reflected light beam emanating from said reflective surface; and

a position sensitive photodetector fixed in operation to said frame and positioned to intercept said reflected light beam and produce a signal responsive to angular movement of said reflected light beam.

14. An atomic force microscope according to claim 13 wherein said position sensitive photodetector further includes means for adjusting the position of said position sensitive detector with respect to said frame.

15. An atomic force microscope according to claim 13 wherein said source further includes means for adjusting the position of said source with respect to said frame.

16. An atomic force microscope for examining the surface properties of a sample surface, said atomic force microscope comprising:

a frame;

a sample stage disposed under a portion of said frame;

a piezoceramic tube scanner element having a scanner end capable of motion relative to said frame in response to said scanner element;

at least one beam tracking element held in a fixed relationship to a portion of said scanner element;

a cantilever having a reflective surface, a first cantilever end and a second cantilever end, said first cantilever end having a sharp probe tip extending therefrom toward said sample stage;

a source of a collimated light beam, said source fixed in operation to said frame, said source arranged to project said collimated light beam to a focus at said reflective surface of said cantilever forming a reflected light beam emanating from said reflective surface; and

a position sensitive photodetector fixed in operation to said frame and positioned to intercept said reflected light beam and produce a signal responsive to angular movement of said reflected light beam.

17. An atomic force microscope for examining the surface properties of a sample surface, said atomic force microscope comprising:

a frame;

a sample stage having an upper surface for supporting a sample, said sample stage disposed under a portion of said frame wherein said upper surface of said sample stage is not in contact with said frame;

a piezoceramic tube scanner element having a scanner end capable of motion relative to said frame in response to said scanner element;

at least one beam tracking element held in a fixed relationship to a portion of said scanner element;

an atomic force cantilever probe for interacting with the sample surface disposed on said sample stage, said probe suspended from said piezoceramic tube scanner, a source of a collimated light beam, said source fixed in operation to said frame, said source arranged to project said collimated light beam to a focus at said reflective surface of said cantilever forming a reflected light beam emanating from said reflective surface; and

a position sensitive photodetector fixed in operation to said frame and positioned to intercept said reflected light beam and produce a signal responsive to angular movement of said reflected light beam.

18. An atomic force microscope for examining surface properties of a sample surface, said microscope comprising:

a frame;

a sample stage;

a scanner element having a scanner end capable of motion relative to said frame in response to signals applied to said scanner element;

a cantilever having a reflective surface, a first cantilever end and a second cantilever end, said first cantilever end having a sharp probe tip extending therefrom toward said sample stage, said second cantilever end attached to said scanner;

at least one beam tracking element held in a fixed relationship to a portion of said scanner element;

a source of a beam of radiant energy, said source arranged to project said beam of radiant energy to said at least one beam tracking element and from said at least one beam tracking element to a focus at said reflective surface of said cantilever forming a reflected beam of radiant energy emanating from said reflective surface; and

a position sensitive detector positioned to intercept said reflected beam of radiant energy and produce a signal responsive to angular movement of said reflected beam of radiant energy.

19. An atomic force microscope according to claim 18 wherein said position sensitive detector comprises a multi-cell photodetector.

20. An atomic force microscope according to claim 19 wherein said multi-cell photodetector is a bi-cell photodetector.

21. An atomic force microscope according to claim 18 wherein said scanner element is a piezoceramic scanner.

22. An atomic force microscope according to claim 21 wherein said piezoceramic scanner is a tube.

23. An atomic force microscope according to claim 22 wherein said tube is an S-shaped scanner.

24. An atomic force microscope according to claim 18 wherein said at least one beam tracking element comprises at least one lens.

25. An atomic force microscope according to claim 24 wherein said at least one lens is bi-convex.

26. An atomic force microscope according to claim 18 wherein said source includes a laser.

27. An atomic force microscope according to claim 26 wherein said laser is a diode laser.

28. An atomic force microscope according to claim 27 wherein said source further includes means for adjusting the position of said source with respect to said frame.

29. An atomic force microscope according to claim 18 wherein said position sensitive detector further includes means for adjusting the position of said position sensitive detector with respect to said frame.

30. An atomic force microscope for examining the surface properties of a sample surface, said atomic force microscope comprising:

a frame;

a sample stage;

a tube scanner element having a scanner end capable of motion relative to said frame in response to signals applied to said scanner element;

a cantilever having a reflective surface, a first cantilever end and a second cantilever end, said first cantilever end having a sharp probe tip extending therefrom toward said sample stage;

at least one beam tracking lens fixed in operation to a portion of said scanner element;

a source of a beam of radiant energy including a diode laser module, said source fixed in operation to said frame, said source arranged to project said beam of radiant energy through said at least one beam tracking lens and to a focus at said reflective surface of said cantilever forming a reflected beam of radiant energy emanating from said reflective surface; and

a position sensitive photodetector fixed in operation to said frame and positioned to intercept said reflected beam of radiant energy and produce a signal responsive to angular movement of said reflected beam of radiant energy.

31. An atomic force microscope according to claim 30 wherein said position sensitive photodetector further includes means for adjusting the position of said position sensitive detector with respect to said frame.

32. An atomic force microscope according to claim 30 wherein said source further includes means for adjusting the position of said source with respect to said frame.

33. An atomic force microscope for examining the surface properties of a sample surface, said atomic force microscope comprising:

a frame;

a sample stage disposed under a portion of said frame;

a tube scanner element having a scanner end capable of motion relative to said frame in response to said scanner element;

at least one beam tracking element held in a fixed relationship to a portion of said scanner element;

a cantilever having a reflective surface, a first cantilever end and a second cantilever end, said first cantilever end having a sharp probe tip extending therefrom toward said sample stage;

a source of a beam of radiant energy, said source fixed in operation to said frame, said source arranged to project said beam of radiant energy to a focus at said reflective surface of said cantilever forming a reflected beam of radiant energy emanating from said reflective surface; and

a position sensitive photodetector fixed in operation to said frame and positioned to intercept said reflected beam of radiant energy and produce a signal responsive to angular movement of said reflected beam of radiant energy.

34. An atomic force microscope for examining the surface properties of a sample surface, said atomic force microscope comprising:

a frame;

a sample stage having an upper surface for supporting a sample, said sample stage disposed under a portion of said frame wherein said upper surface of said sample stage is not in contact with said frame;

a tube scanner element having a scanner end capable of motion relative to said frame in response to said scanner element;

at least one beam tracking element held in a fixed relationship to a portion of said scanner element;

a cantilever-type reflective atomic force probe for interacting with the sample surface disposed on said sample stage, said probe suspended from said tube scanner,

a source of a collimated light beam, said source fixed in operation to said frame, said source arranged to project said collimated light beam to a focus at said reflective surface of said cantilever forming a reflected light beam emanating from said reflective surface; and

a position sensitive photodetector fixed in operation to said frame and positioned to intercept said reflected light beam and produce a signal responsive to angular movement of said reflected light beam.