Laser generated guided waves and finite element modeling for the thickness gauging of thin layers.
In this paper, nondestructive testing has been performed on a thin gold layer deposited on a 2 in. silicon wafer. Guided waves were generated and studied using a laser ultrasonic setup and a two-dimensional fast Fourier transform technique was employed to obtain the dispersion curves. A gold layer thickness of 1.33 microm has been determined with a +/-5% margin of error using the shape of the two first propagating modes, assuming for the substrate and the layer an uncertainty on the elastic parameters of +/-2.5%. A finite element model has been implemented to validate the data post-treatment and the experimental results. A good agreement between the numerical simulation, the analytical modeling and the experimentations has been observed. This method was considered suitable for thickness layer higher than 0.7 microm.
Lefevre
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F
Département Opto-Acousto-Electronique (UMR CNRS 8520), Institut d'Electronique de Microélectronique et de Nanotechnologie, Université de Valenciennes, Le Mont Houy, 59313 Valenciennes Cedex 09, France.
Jenot
F
F
Ouaftouh
M
M
Duquennoy
M
M
Ourak
M
M