Imaging Interior Planes by Acoustic Microscopy
It has been recently demonstrated that the acoustic microscope can visualize image planes relatively deep beneath the surface with a lateral resolution approaching one acoustic wavelength in the solid. This has been achieved using mercury or gallium as the medium connecting the acoustic lens to the object. These liquids with their solid-like impedance better improve the acoustic power penetrating in the object and minimize the aberration effects caused by refraction at the liquid-solid interface. In this paper we discuss on the suitability of both liquids devoting a large place to imaging with mercury. We present some unique features of this kind of microscopy such as test of bonding of two silicon wafers with indium when temperature is changed or studies of electrical breakdown of layers of indium and gold through a wafer of glass or silicon.
KeywordsSilicon Wafer Acoustic Image Acoustic Beam Acoustic Microscope Scanning Acoustic Microscopy
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