Thermal measurements using multiple frequency atomic force microscopy

• US 8,677,809 B2
• Filed: 10/21/2010
• Issued: 03/25/2014
• Est. Priority Date: 06/16/2008
• Status: Active Grant

• Current Assignee: Oxford Instruments Afm Inc
• Original Assignee: Oxford Instruments Afm Inc, Oxford Instruments PLC
• Inventors: Proksch, Roger, Gannepalli, Anil
• Primary Examiner(s): LARKIN, DANIEL SEAN
• Application Number:
  US12/925,442
• Publication Number:
  US 20110154546A1
• Time in Patent Office: 1,251 Days
• Field of Search: 731/05, 850/1, 850/5, 850/37, 850/50, 850/63
• US Class Current: 73/105
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• 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 60/32 AC mode

Abstract

Apparatus and techniques for extracting information carried in higher eigenmodes or harmonics of an oscillating cantilever or other oscillating sensors in atomic force microscopy and related MEMs work are described. Similar apparatus and techniques for extracting information from piezoelectric, polymer and other materials using contact resonance with multiple excitation signals are also described.

Claims

1. A method of operating an atomic force microscope which includes a cantilever probe specialized for thermal measurements through providing two separate legs culminating at a tip and allowing a current to heat the tip, comprising:

heating the tip of the cantilever probe until the onset of local melting;

using a feedback loop to control a distance between a base of said cantilever probe and a surface of a sample to maintain the tip of the cantilever probe in contact with the surface in the Z direction;

exciting a chip of the cantilever probe at two or more different synthesized frequencies that have been summed together by a circuit element;

providing each synthesized frequency as a reference signal to a lock-in amplifier; and

measuring amplitude, frequency and/or phase of the cantilever at the different excitation frequencies.

2. The method according to claim 1, comprising:

displaying the measured amplitude, frequency and phase of the cantilever.