Chemical cleaning has been used from several decades as a surface preparation technique for diffusion bonding. Here we present a theoretical investigation that examines the effect of changes in the process parameters when a laser is used as an alternative to chemical cleaning for surface contaminant removal. In the first part the prerequisites for successful diffusion bonding are discussed in brief. In the second part a theoretical model is described that includes laser beam attenuation in the plasma plume and its effect on evaporation of the material. Using the model, a comprehensive analysis of the effect of different fluences and other parameters for a KrF Excimer laser is presented. Calculations were carried out for a range of peak fluxes from below the ablation threshold to fluxes of the order of 9 x 1012 W/ m2. The predicted effects on evaporation, melt depth and surface temperature are reported, illustrated by a number of surface topographic images from preliminary experiments. Finally, optimal parameters for cleaning according to the theoretical investigation are proposed.
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