Quantitative Short-pulse Acoustic Microscopy and Application to Materials Characterization

2000 ◽  
Vol 6 (1) ◽  
pp. 59-67
Author(s):  
Theodore E. Matikas
Keyword(s):  
Elastic Property ◽  
Acoustic Waves ◽  
Short Pulse ◽  
Surface Acoustic Waves ◽  
Tone Burst ◽  
Acoustic Microscopy ◽  
Near Surface ◽  
Microscopy Technique ◽  
Setup Phase ◽  
Additional Reference

Abstract A new acoustic microscopy method was developed for providing near-surface elastic property mapping of a material. This method has a number of advantages over the traditional V(z) technique. First, it enables one to perform measurements in an automated mode that only requires user intervention in the setup phase. This automated mode makes it feasible to obtain quantitative microscopy images of the elastic property over an area on the material being tested. Also, it only requires a conventional ultrasonic system operating in pulsed mode for collecting the data, rather than a specialized tone-burst system, which is needed in the traditional quantitative scanning acoustic microscopy technique. Finally, unlike the traditional method, the new experimental process does not require calibration of the systems electronics or additional reference data taken under hard-to-duplicate identical conditions from a material that does not exhibit surface acoustic waves.

Generating Near-THz Surface Acoustic Waves Using Picosecond Ultrasonics

2009 ◽  
Author(s):  
J. H. Lee ◽  
J. S. Sadhu ◽  
S. Sinha
Keyword(s):  
Rise Time ◽  
Acoustic Waves ◽  
High Frequency ◽  
Short Pulse ◽  
Surface Acoustic Waves ◽  
Grating Period ◽  
Critical Parameters ◽  
Generation Process ◽  
Short Pulse Laser ◽  
Substrate Properties

We present here a technique to generate high frequency SAW in non-piezoelectric substrate with nanostructure grating of period less than 100 nm fabricated on it. A short pulse laser (with rise time less than 100fs) incident on this structure creates a periodic thermal stress due to the differential absorption in the substrate and the grating. We show that this stress sets up a surface acoustic wave on the substrate that can be detected optically. Modeling the generation process and analysis of SAW spectrum reveals the critical parameters to be controlled for obtaining SAW of high frequency. We show that the grating period less than 50 nm, a laser pulse of rise time less than 100fs and substrate properties like high optical absorption and high Rayleigh velocity are necessary for generating surface acoustic waves in near-THz range. This work provides quantitative guidelines on the design of near THz phononics.

High-resolution picosecond acoustic microscopy for non-invasive characterization of buried interfaces

2006 ◽  
Vol 21 (5) ◽  
pp. 1204-1208 ◽  
Author(s):  
Shriram Ramanathan ◽  
David G. Cahill
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Integrated Circuit ◽  
Acoustic Waves ◽  
Spot Size ◽  
Acoustic Microscopy ◽  
Microscopy Technique ◽  
Fundamental Limitations ◽  
Buried Interfaces ◽  
Advanced Packaging

Non-destructive investigation of buried interfaces at high-resolution is critical for integrated circuit and advanced packaging research and development. In this letter, we present a novel non-contact microscopy technique using ultrahigh frequency (GHz range) longitudinal acoustic pulses to form images of interfaces and layers buried deep inside a silicon device. This method overcomes fundamental limitations of conventional scanning acoustic microscopy by directly generating and detecting the acoustic waves on the surface of the sample using an ultrafast pump-probe optical technique. We demonstrate our method by imaging copper lines buried beneath a 6-μm silicon wafer; the lateral spatial resolution of 3 μm is limited by the laser spot size. In addition to the high lateral spatial resolution, the technique has picosecond (ps) time resolution and therefore will enable imaging individual interconnect layers in multi-layer stacked devices.

X-ray diffraction from perfect silicon crystals distorted by surface acoustic waves

2000 ◽  
Vol 33 (4) ◽  
pp. 1019-1022 ◽  
Author(s):  
R. Tucoulou ◽  
R. Pascal ◽  
M. Brunel ◽  
O. Mathon ◽  
D. V. Roshchupkin ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Acoustic Waves ◽  
Crystal Surface ◽  
Source Region ◽  
Surface Acoustic Waves ◽  
X Ray Diffraction ◽  
Zno Film ◽  
Near Surface ◽  
X Ray

High-resolution X-ray diffraction measurements were carried out on ZnO/Si devices under surface acoustic wave excitation and revealed some very clear satellite diffraction peaks that are obtained from the sinusoidal modulation of the near-surface region. This experiment shows that the propagation of a Rayleigh surface acoustic wave in a perfect crystal acts as a dynamical diffraction grating. The variation of the acoustic velocity has been followed across the crystal surface from the acoustic source region (beneath the ZnO film) to the far field region (not covered by the ZnO film).

Non-invasive high-resolution acoustic microscopy technique using embedded nanostructures

2007 ◽  
Vol 1019 ◽  
Author(s):  
Daniel Wulin ◽  
Shriram Ramanathan
Keyword(s):  
High Resolution ◽  
Acoustic Waves ◽  
High Frequency ◽  
Acoustic Microscopy ◽  
Biological Applications ◽  
Acoustic Oscillations ◽  
Non Invasive ◽  
Microscopy Technique ◽  
First Time

AbstractAn opto-acoustic system capable of operating at frequencies greater than 1 GHz with novel biological applications is proposed for the first time. Metallic spheres with radii on the order of hundreds of nanometers dispersed inside a bio-matrix can be used to generate in-situ ultra-high frequency acoustic waves whose normal mode frequencies can be calculated using Lamb's theory for acoustic oscillations of elastic spheres. The frequency and amplitude of the resulting acoustic waves can be related to the physical properties of the metallic spheres and the surrounding bio-matrix: the acoustic waves produced by the metallic spheres are well-suited to high resolution acoustic imaging. We anticipate that our approach will open up new nanoscale techniques to study cells non-invasively.

Scanning electron acoustic microscopy and its applications

1986 ◽  
Vol 320 (1554) ◽  
pp. 243-255 ◽  
Keyword(s):  
Acoustic Waves ◽  
Magnetic Domain ◽  
Depth Resolution ◽  
Acoustic Microscopy ◽  
Polycrystalline Materials ◽  
Sound Waves ◽  
Near Surface ◽  
Manufacturing Defects ◽  
Electron Acoustic ◽  
Scanning Electron

Scanning electron acoustic microscopy (SEAM) is a relatively new technique for imaging and characterization of thermal and elastic property variations on the scale of a few micrometres. A megahertz-chopped, focused electron beam in a scanning electron microscope (SEM) generates sound waves in the sample, and the signal from a transducer attached to the specimen is used to form a scanned image in parallel with the normal SEM image. Although the acoustic wavelengths are typically several millimetres, lateral and depth resolution may be only a few micrometres. This is because image contrast is mainly derived from the micrometre-sized acoustic generation volume just under the beam. In this generation volume, both elastic variations and thermal scattering of the critically damped ‘thermal waves’, with wavelength of a few micrometres (due to the periodic beam heating), may lead to contrast. There is also evidence for non-thermoelastic contrast generation mechanisms, and these show finer resolution, SEAM shows both advantages and drawbacks compared to conventional scanning acoustic microscopy (SAM). Although understanding of the detailed contrast mechanisms in seam is at present only at a qualitative level, it is clear that they are generally different from those in SAM. The technique is now beginning to attract commercial attention, and applications include imaging of cracks and voids, grains and grain boundaries and second phases in polycrystalline materials, regions of plastic deformation, and magnetic domain structures. Images can be obtained from ics and semiconductor materials which show doped and implanted regions, near-surface manufacturing defects, and even individual dislocations. The acoustic waves excite vibrational patterns in the specimen, and these can be used as low-resolution probes of, for example, bonding integrity.

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