×

Multiple frequency atomic force microscopy

  • US 7,603,891 B2
  • Filed: 10/05/2006
  • Issued: 10/20/2009
  • Est. Priority Date: 04/25/2006
  • Status: Active Grant
First Claim
Patent Images

1. A method of operating an atomic force microscope, comprising:

  • exciting a probe tip of a cantilever at or near a resonant frequency of the cantilever which forms a first eigenmode, while keeping the tip sufficiently far from a sample having a surface that said cantilever oscillates at a free amplitude A10 unaffected by the proximity of the cantilever to the sample surface and without making contact with the sample surface;

    changing the relative distance in a Z direction between a base of the cantilever and the sample surface to an amount where a detected amplitude A1 of the first eigenmode of the cantilever is affected by the proximity of the sample surface to the tip of the cantilever, without the tip of the cantilever making contact with the sample surface;

    scanning the sample by creating relative movement between the tip of the cantilever and the sample surface, while using a feedback loop to control the distance between the base of the cantilever and the sample surface so that the amplitude A1 of the first eigenmode of the cantilever is maintained at an essentially constant value;

    exciting the probe tip of the cantilever at or near a second eigenmode of the cantilever, where said second eigenmode of the cantilever is a different eigenmode than said first eigenmode, said scanning being at an amplitude A2 while keeping the first eigenmode drive and feedback loop with the same values and without using said second eigenmode in said feedback loop;

    adjusting the amplitude A2 of the second eigenmode of the cantilever until said amplitude A2 indicates the second eigenmode is interacting with the sample surface with predominantly repulsive forces;

    varying the amplitude A2 of the second eigenmode of the cantilever over a range of values while not including said amplitude A2 as an input to the feedback loop; and

    measuring the amplitude and phase of the first and second eigenmodes of the cantilever as measured characteristics of the sample.

View all claims
  • 5 Assignments
Timeline View
Assignment View
    ×
    ×