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15 March 1998 Silicon wafer temperature monitoring using all-fiber laser ultrasonics
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Laser-ultrasonics is a very attractive technique for in-line process control in the semiconductor industry as it is compatible with the clean room environment and offers the capability to inspect parts at high-temperature. We describe measurements of the velocity of laser-generated Lamb waves in silicon wafers as a function of temperature using fiber- optic laser delivery and all-fiber interferometric sensing. Fundamental anti-symmetric Lamb-wave modes were generated in 5 inches < 111 > silicon wafers using a Nd:YAG laser coupled to a large-core multimode fiber. Generation was also performed using an array of sources created with a diffraction grating. For detection a compact fiber-optic sensor was used which is well suited for industrial environments as it is compact, rugged, stable, and low-cost. The wafers were heated up to 1000 degrees C and the temperature correlated with ultrasonic velocity measurements.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jorge J. Alcoz and Charles E. Duffer "Silicon wafer temperature monitoring using all-fiber laser ultrasonics", Proc. SPIE 3399, Process Control and Sensors for Manufacturing, (15 March 1998);

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