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An acoustic micrometer and its application to layer thickness measurements
Y Tsukahara1, N Nakaso, J I Kushibiki
1Toppan Printing Co. Ltd., Saitama.
Summary
This study introduces an acoustic micrometer for precise thickness measurements. The system demonstrates excellent stability and accuracy for thin gold layers, crucial for microelectronics applications.
Area of Science:
- Materials Science
- Metrology
- Acoustics
Background:
- Accurate measurement of thin film thickness is critical in microelectronics and materials science.
- Existing metrology techniques may have limitations in resolution, accuracy, or non-contact capabilities.
Purpose of the Study:
- To describe the principle and system of an acoustic micrometer.
- To evaluate the performance characteristics of the acoustic micrometer, including stability, accuracy, spatial resolution, and temperature dependence.
- To demonstrate the application of the acoustic micrometer for measuring electroplated gold layers.
Main Methods:
- The study details the operational principle and system design of the acoustic micrometer.
- Gold layers (1-20 µm thickness) electroplated on 42% Ni-Fe alloy substrates were used as test specimens.
- Measurements were conducted using a frequency range of 10-200 MHz.
Main Results:
- The acoustic micrometer system demonstrated high stability within +/-0.2%.
- Accuracy of the measurements achieved was within +/-1%.
- The system effectively measured gold layer thicknesses ranging from 1 to 20 µm.
Conclusions:
- The acoustic micrometer is a viable tool for precise thickness measurements of thin films.
- The system exhibits excellent performance metrics suitable for demanding applications.
- Further research can explore its application to a wider range of materials and thicknesses.
