Acoustic Characterization of Mesoscale Objects

Chinn, D ; Huber, R ; Chambers, D ; Cole, G ; Balogun, O ; Spicer, J ; Murray, T

关键词: ACOUSTICS;    DETECTION;    EXCITATION;    LASERS;    MICHELSON INTERFEROMETER;    PENETRATION DEPTH;    RESOLUTION;    SILICON;    SPATIAL RESOLUTION;    ULTRASONIC WAVES;   

DOI  :  10.2172/969531
RP-ID  :  UCRL-TR-229835
PID  :  OSTI ID: 969531
Others  :  TRN: US201002%%363

美国|英语

来源: SciTech Connect

【 摘 要 】

This report describes the science and engineering performed to provide state-of-the-art acoustic capabilities for nondestructively characterizing mesoscale (millimeter-sized) objects--allowing micrometer resolution over the objects entire volume. Materials and structures used in mesoscale objects necessitate the use of (1) GHz acoustic frequencies and (2) non-contacting laser generation and detection of acoustic waves. This effort demonstrated that acoustic methods at gigahertz frequencies have the necessary penetration depth and spatial resolution to effectively detect density discontinuities, gaps, and delaminations. A prototype laser-based ultrasonic system was designed and built. The system uses a micro-chip laser for excitation of broadband ultrasonic waves with frequency components reaching 1.0 GHz, and a path-stabilized Michelson interferometer for detection. The proof-of-concept for mesoscale characterization is demonstrated by imaging a micro-fabricated etched pattern in a 70 {micro}m thick silicon wafer.