Photothermal deflection microscope with linear-motor-drive and its applications to NDE of microdevices

A photoacoustic and photothermal deflection imaging apparatus was fabricated using linear-motor-driven slide stages as the scanning tool. It achieved both high-resolution scanning (0.1 mu m step), fast scan (40mm/sec) and random access. In gas-microphone photoacoustic microscope (PAM) operation. the reduction of acoustic noise about 30dB compared that with pulse-motor-driven pulse stages was achieved Photothermal deflection microscope (PTM) using a high-resolution position sensitive device realized both comparable resolution of thermal image as that of PAM and the open-air environment for nondestructive inspection of solid specimen in common operating software as PAM Applications of the PAM and PTM to nondestructive evaluation of both surface and undersurface defects of the solid specimens including semiconductor microdevices and a simulated subsurface defect are also demonstrated. Achieved resolution of the thermal images of an integrated circuit fabricated on a silicon substrate obtained using both PAM and PTM was up to 8-12 mu m.