A CLEANING MODEL FOR REMOVAL OF PARTICLES DUE TO LASER-INDUCED THERMAL-EXPANSION OF SUBSTRATE SURFACE

Taking Van der Waals force and cleaning force due to fast thermal expa nsion of substrate surface induced by pulsed laser irradiation into ac count, a cleaning model was established for removal of tiny particles from substrate surfaces. The cleaning condition and cleaning threshold can be obtained from this model. Theoretical predictions have been ve rified by the experimental results for removing quartz particles from silicon substrate. For laser-induced removal of quartz particles from silicon substrate surfaces, the cleaning threshold is about 135 mJ/cm( 2) Cleaning efficiency increases with increasing laser fluence, and la rge particles can be removed more easily than small ones.