Appl.Phys.A73,219–224(2001)

J.M. Lee, C. Curran, K.G. Watkins

Laser Group, Department of Engineering, University of Liverpool, Brownlow Street,
Liverpool L69 3GH, UK

 

Abstract: Laser removal of small copper particles from sili-con wafer surfaces was carried out using Nd:YAG laser radi-ation 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 sur-face without causing any substrate damage. The cleaning effi-ciency was increased with a shorter wavelength. The effect of laser wavelength in the removal process is discussed by con-sidering the adhesion force of the particle on the surface and the laser-induced cleaning forces for the three wavelengths.