Laser sputtering. Part I. On the existence of rapid laser sputtering at 193 nm

Abstract

Irradiation, i.e.bombardment, with 193 nm laser pulses having an energy fluence of 2.5 J cm2 and a duration of ~12 ns leads to rapid sputtering with Au, Al2O3, MgO, MgO. Al2O3, SiO2, glass and LaB6, relatively slow sputtering with MgF2 and diamond, and mainly thermal-stress cracking with W. Scanning electron microscopy (SEM) suggests that the mechanism for the sputtering of Au in either vacuum or air is one based on the hydrodynamics of molten Au, while an SEM-derived surface temperature estimate confirms that thermal sputtering (which might have been expected) is not possible. SEM with W shows that the near total lack of material removal is due to the thermal-stress cracking not leading to completed exfoliation, together with the surface temperature being too low for either hydrodynamical or thermal processes. Corresponding SEM with Al2O3 shows, in the case of specimens bombarded in vacuum, topography of such a type that all mechanisms except electronic ones can be ruled out. The topography of Al2O3 or other oxides bombarded in air through a mask is somewhat different, showing craters as for vacuum bombardments but ones which have a cone-like pattern on the bottom. © 1985.