Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 17: Poster Session I (Nanostructures at Surfaces; Metal Substrates: Epitaxy and Growth; Methods: Scanning Probe Techniques; Phase Transitions)

O 17.71: Poster

Montag, 26. März 2007, 17:30–20:30, Poster C

Steam laser cleaning with infrared pulses — •Pascal Frank, Florian Lang, Paul Leiderer, and Johannes Boneberg — Fachbereich Physik, Universität Konstanz, Fach M676, 78457 Konstanz

Steam Laser Cleaning is a powerful technique for removing very small contaminating particles from sensitive surfaces like Si wafers. The traditional concept of this method is to adsorb a thin liquid film (e.g. water or isopropanol) on the sample surface and then heat the sample with a short laser pulse. Heat transfer from the substrate to the liquid leads to explosive evaporation of the adsorbed film, connected with a removal of the particles. We have investigated here an alternative route by not heating the substrate, but rather the liquid layer directly with an appropriate laser pulse. For this purpose we use an optical parametric oscillator which generates light at 2.94 um, right at the maximum of the OH stretching mode in water and isopropanol. The absorption depth is around 1 micron. First experiments with model contaminants (PS colloid spheres between 200 and 1000nm diameter) show that cleaning of Si as well as glass surfaces is possible, both by irradiation from the front or the back side of the sample. This holds a number of advantages compared to the commonly used technique.