Scanning laser ultrasonics experiments for in situ nondestructive analysis of integrated circuits

Scanning experiments on a very large scale integrated (VLSI) circuit are presented using the picosecond ultrasonics technique. This optical nondestructive technique is based on ultrasound generation and detection by ultrashort laser pulses. The experimental setup and methodology are described. The influence of the protection layer for passivated circuits on the experimental results is described and illustrated by experimental data. In order to help in the interpretation of the experimental analysis of microelectronic devices, a simulation tool was developed.