Excimer laser photoablation of silicon

The ultraviolet and visible emission spectra from excimer laser-produced silicon plasmas were studied and the ablation rate measured as a function of laser energy density and wavelength. A spectroscopic investigation of the laser-produced plasma showed Si I, Si II, and Si III spectral lines with higher laser intensity causing a higher degree of ionization in the plasma. Both timeintegrated and time-resolved spectroscopic studies showed electronic transitions superimposed on a weak continuum over the entire range from 250 to 640 nm. The photoablation rate of Si was independent oflaser wavelength (193 or 248 nm), and had an energy density threshold of;:::; 1.3 J/ cm2• The threshold was almost independent of the buffer gas pressure between vacuum and 1000 Torr. These results are described in the framework recently developed for excimer laser ablation of metals.