Laser cleaning of silicon surface with deposition of different liquid films

Laser cleaning can efficiently remove tiny particles from a silicon surface on which a liquid film has been previously deposited when the laser fluenc e is large enough. The cleaning force is due to the high pressure of stress wave generated through the rapid growth of vapor bubbles inside the superh eated liquid. The behaviors of this type of laser cleaning are theoreticall y described with deposition of two kinds of liquid film: acetone and ethano l. The cleaning threshold of laser fluence is different for these two kinds of liquids for some differences in their thermodynamic properties. For rem oval of alumina particles with a size of 1 mu m, the lower cleaning thresho ld of laser fluence is obtained with deposition of acetone because of its l ower boiling point and volume heat capacity. The theoretical result also in dicates that the cleaning force with deposition of ethanol increases more q uickly along with laser fluence than with acetone. This phenomenon is much useful for removal of smaller particles and can lead to high cleaning effic iency. (C) 1999 published by Elsevier Science B.V. All rights reserved.