A CO2 laser-based system was used to provoke the vapor-assisted removal of contaminating particles from different kinds of surfaces. Particles of alumina, silicon carbide, boron carbide, and cerium dioxide, with a size as small as 0.1 μm, have been efficiently removed from silicon, gold, and silicon dioxide surfaces. The dependence of the cleaning efficiency on the laser fluence was investigated; a threshold was found at 0.65 J/cm2 and the efficiency was highest for a fluence ranging from 2.9 to 3.2 J/cm2 for silicon, and 3.2 J/cm2 for gold and silicon dioxide surfaces. The amount of the water vapor which condenses at the surface was also found to play a major role, the best results being obtained with a condensed thickness calculated to be 6 μm. The zeta potential value of the contaminant particles with respect to that of the surface greatly influences the cleaning process.

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Deep level transient spectroscopy is used to determine the deep levels introduced by tungsten in the silicon band gap. The experimental results indicate that tungsten creates three defect centers, with levels at Ev+0.22 eV, Ev+0.33 eV, and Ec−0.59 eV. The shape of the concentration profiles indicates that W does not diffuse by a simple mechanism in Si.