Laser removal of copper particles from silicon wafers using UV, visible and IR radiation

Laser removal of small copper particles from silicon wafer surfaces was carried out using Nd:YAG laser radiation from near-infrared (1064 nm) through visible (532 nm) to ultraviolet (266 nm). It has been found that both 266 nm and 532 nm are successful in removing the particles from the surface whereas 1064 nm was shown to be ineffective in the removal of particles. The damage-threshold laser fluence at 266 nm was much higher than other wavelengths which provides a much wider regime for safe cleaning of the surface without causing any substrate damage. The cleaning efficiency was increased with a shorter wavelength. The effect of laser wavelength in the removal process is discussed by considering the adhesion force of the particle on the surface and the laser-induced cleaning forces for the three wavelengths. Received: 31 May 2000 / Accepted: 14 July 2000 / Published online: 20 June 2001