Scanning Near Field Ultrasound Holography
Scanning near-field ultrasound holography (SNFUH) is a method for performing nondestructive nano-scale high-resolution imaging of buried and embedded structures. SNFUH is critical for analysis of materials, structures and phenomena as they continue to shrink at the micro/nano scale. SNFUH is a type of scanning probe microscopy (SPM) technique that provides depth information as well as spatial resolution at the 10 to 100 nm scale. History Gajendra S. Shekhawat and Vinayak P. Dravid of Northwestern University (Evanston, IL, USA) developed SNFUH in 2005. Observing copper interconnect, copper damascene structures of a void in an opaque material was made possible by this technique. Technique Scanning near-field ultrasound holography combines atomic force acoustic microscopy and ultrasonic force microscopy. Two transducers producing high frequencies are used. Usually frequency is higher than the resonant frequency of the cantilever. One transducer is placed below the sample and the ...
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