REMOVAL OF SUBMICRON PARTICLES FROM NICKEL-PHOSPHORUS SURFACES BY PULSED-LASER IRRADIATION

Pulsed laser cleaning was demonstrated to be an efficient way for remo ving submicron particles from the nickel-phosphorus (NiP) surface both experimentally and theoretically. Experimentally, it is found that us ing KrF excimer laser with a pulse width of 23 ns the cleaning thresho ld is about 20 mJ/cm(2) for removing quartz particles from the NiP sur face and laser cleaning efficiency increases rapidly with increasing l aser fluence. The theoretical analysis shows that the peak cleaning fo rce (per unit area) is larger than the adhesion force (per unit area) for submicron quartz particles on the NiP surface when it is irradiate d by excimer laser with a fluence above 10 mJ/cm(2). Therefore, it is possible to remove submicron quartz particles from NiP surfaces by las er irradiation. The difference between the cleaning force (per unit ar ea) and the adhesion force (per unit area) increases with increasing l aser fluence, leading to a higher cleaning efficiency for quartz parti cles on the NiP surface. (C) 1997 Elsevier Science B.V.