Laser cleaning of particles from silicon wafers : capabilities and mechanisms

Abstract

The preparation of surfaces free of particle contamination is one of the crucial prerequisites for a further increase in the integration density of ICs and for the progress in nanotechnology. Therefore the removal of sub-micron sized particles from silicon wafers is of great interest. For this purpose a variety of cleaning methods is currently under investigation.In semiconductor industry an ideal cleaning technique should be capable of removing particles with a diameter considerably below 100 nm, while a damage to the substrate has to be strictly avoided. Furthermore the process should be environmentally friendly and cost-effective. A promising approach which meets these requirements is called Laser Cleaning. So far two major approaches can be distinguished. The first one is called Dry Laser Cleaning (DLC), where the surface to be cleaned is simply irradiated by a short laser pulse [1,2,3]. In Steam Laser Cleaning (SLC) a thin layer of a liquid energy transfer medium is deposited on the surface prior to the laser pulse [1,2,4,5].In this paper we will present a short overview of these techniques followed by some of our recent results. The emphasis lies on the underlying mechanisms and an industrial applicability of both cleaning methods.