Abstract

The response of insulating solids to excimer light excitation is being studied to gain more detailed understanding of the ablative decomposition of insulators undergoing laser etching. The response is detected through deflection of a He–Ne laser beam from the surface displacement caused by the excitation. The basic technique of photothermal displacement measurements has been presented previously.^1,2 In our experiments, a He-Ne laser probe beam is focused to a spot ~350 μm in diameter. The reflected beam is directed onto a silicon position sensitive detctor with a rise time of 17 ns. Sample excitation at 193 nm (ArF) and 248 nm (KrF) from a pulsed excimer laser is focused to spot sizes of 1–1.2 mm in diameter. The excitation spot is moved with respect to the sample both vertically and horizontally via micrometer motion of a 10-cm quartz focusing lens. Observations were made generally below the ablation threshold for samples of polyimide, PMMA, glass, and Al₂O₃.

© 1986 Optical Society of America