Title :
Interferometric detection in picosecond ultrasonics for nondestructive testing of submicrometric opaque multilayered samples: TiN/AlCu/TiN/Ti/Si
Author :
Rossignol, Clement ; Perrin, Bernard
Author_Institution :
Lab. de Mecanique Physique, Bordeaux I Univ., Talence, France
Abstract :
An experimental investigation of nanometric thin films by a picosecond ultrasonic technique is presented. A photoelastic model is used with an interferometric device, combined with ultrafast optical pump and probe setup, to measure the thicknesses of submicrometric layers made of TiN, Ti, and AlCu deposited on silicon (Si) wafers. The results are in good agreement with ellipsometry measurements showing that the picosecond ultrasonic technique can give accurate results even when the reflectance signal is very low. Additional important results are first, that the adhesion of the TiN surface film is probed by processing both the frequency and the damping of the oscillation of a resonance acoustic mode; and second, the presence of a thin buried TiN layer under an opaque AlCu film is highlighted by the interferometric setup.
Keywords :
acoustic wave interferometry; adhesion; aluminium alloys; copper alloys; high-speed optical techniques; multilayers; photoelasticity; thickness measurement; titanium; titanium compounds; ultrasonic materials testing; Si; TiN-AlCu-Ti; adhesion; buried TiN layer; ellipsometry measurement; interferometric detection; nanometric thin films; nondestructive testing; photoelastic model; picosecond ultrasonics; reflectance signal; submicrometric opaque multilayered samples; thickness measurement; ultrafast optical pump; Nondestructive testing; Optical devices; Optical films; Optical interferometry; Photoelasticity; Semiconductor device modeling; Semiconductor thin films; Tin; Ultrasonic imaging; Ultrasonic variables measurement;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2005.1509794
