Laser removal of nanosized particles from a silicon wafer using green laser

Abstract

As semiconductor device technology moves toward higher densities and smaller dimensions, a wafer surface cleaning of sub-100 nm sized particles becomes one of the most important processes. This paper presents the laser removal of nanosized particles from a silicon wafer. We collected the 100 nm sized NaCl particles on a silicon wafer by using scanning mobility particle sizer (SMPS). The collected NaCl particles were removed by irradiation of a 532 nm green laser which from 2nd harmonic generation of Nd:YAG laser. The silicon wafer surfaces were measured by a scanning electron microscopy (SEM) and the number of NaCl particles before and after laser irradiation were compared each other. Over 90% particle removal efficiency was found at output energy of 200 mJ/cm2 and pulse duration of 4.5 ns. We confirmed that laser cleaning processes are induced by fast thermal expansion of NaCl particles and/or silicon wafer surfaces irradiated by laser.As semiconductor device technology moves toward higher densities and smaller dimensions, a wafer surface cleaning of sub-100 nm sized particles becomes one of the most important processes. This paper presents the laser removal of nanosized particles from a silicon wafer. We collected the 100 nm sized NaCl particles on a silicon wafer by using scanning mobility particle sizer (SMPS). The collected NaCl particles were removed by irradiation of a 532 nm green laser which from 2nd harmonic generation of Nd:YAG laser. The silicon wafer surfaces were measured by a scanning electron microscopy (SEM) and the number of NaCl particles before and after laser irradiation were compared each other. Over 90% particle removal efficiency was found at output energy of 200 mJ/cm2 and pulse duration of 4.5 ns. We confirmed that laser cleaning processes are induced by fast thermal expansion of NaCl particles and/or silicon wafer surfaces irradiated by laser.