Rossignol Clément, Perrin Bernard
Laboratoire de Mécanique, Physique, Université Bordeaux 1, 351 cours de la Liberation, 33405 Talence, Cedex, France.
IEEE Trans Ultrason Ferroelectr Freq Control. 2005 Aug;52(8):1354-9. doi: 10.1109/tuffc.2005.1509794.
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.
本文介绍了利用皮秒超声技术对纳米薄膜进行的实验研究。采用光弹性模型与干涉仪装置相结合，并结合超快光泵浦和探测装置，来测量沉积在硅（Si）晶片上的由氮化钛（TiN）、钛（Ti）和铝铜（AlCu）制成的亚微米层的厚度。结果与椭偏测量结果吻合良好，表明即使反射信号非常低，皮秒超声技术也能给出准确的结果。另外两个重要结果是：其一，通过处理共振声模振荡的频率和阻尼来探测TiN表面膜的附着力；其二，干涉仪装置突出显示了不透明AlCu膜下存在一层薄的掩埋TiN层。
