Ultrasonic Force Microscopy: Nanometer Scale Mechanical Contrast
The mechanical sensitivity of acoustic microscopy and the spatial resolution of atomic force microscopy are combined in Ultrasonic Force Microscopy (UFM). To demonstrate the spatial resolution of this technique, UFM has been applied to map the mechanical compliance of thin films of silicon-germanium sandwiched between 50 nanometer (nm) layers of silicon. SiGe layers only 2.5 nm across have been identified for this system where the difference in the reduced modulii is less than 20 GPa. To interpret experimental results, extensive simulations of UFM measurements have also been performed for a wide variety of sample types. The contrast measured during UFM with a lock-in-amplifier is calculated and compared to experimental results. It is shown that UFM may be sensitive to the average mechanical properties within a 20 nm radius hemisphere that terminates at the surface.
KeywordsUltrasonic Vibration Mechanical Compliance SiGe Layer Acoustic Microscopy Cantilever Deflection
Unable to display preview. Download preview PDF.
- 4.D. A. Bonnell, Scanning Probe Microscopy and Spectroscopy2nd ed. (Wiley-VCH, New York2001).Google Scholar
- 5.B. D. Huey, R. M. Langford, G. A. D. Briggs et al.“Structural and Mechanical Implications of Focused Ion Beam Nano fabrication Characterized by Atomic and Ultrasonic Force Microscopies,”J. Vac. Sci. Tech. B (submitted 2001).Google Scholar
- 7.B. D. Huey, G. A. D. Briggs, and O. V. Kolosov, “Understanding the tip-surface interaction in ultrasonic force microscopy through experimental simulations,”J. Appl. Phys. (submitted 2001).Google Scholar