Optics and Lasers in Engineering 38 (2002)405 –415

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

a Laser Group, Department of Engineering, University of Liverpool, Brownlow Street, Liverpool L69 3GH, UK
b Laser Application Group, IMT Co. Ltd., Yongin P.O. Box 25, Kyunggi-Do 449-860, South Korea

 

Abstract: Laser removal of small 1 m sized copper,gold and tungsten particles from silicon wafer surfaces was carried out using ultraviolet radiation at 266 nm generated by Nd:YAG harmonic generation.Successful removal of both copper and gold particles from the surface was achieved whereas tungsten particles proved to be dif .cult to remove.The cleaning ef .ciency was increased with an increase of laser .uence.The optimum processing window for safe cleaning of the surface without any substrate damage was determined by measuring the damage threshold laser .uence on the silicon substrate and the required .uence for complete removal of the particles.The different cleaning ef .ciencies with particle type are discussed by considering the adhesion force of the particle on the surface and the laser-induced cleaning force for the three different particles.