Si(100) WAFERS CLEANED BY LASER ABLATION

Abstract

A quick and relatively simple technique for stripping off Si wafers of its native oxide and carbon impurities, using pulsed laser ablation at room temperature, is presented. In a chamber at 10-10 Torr, an oxidized Si (100) surface is ablated with 248 nm UV radiation from a KrF excimer laser. Experiments using 200 pulses of different laser energy densities were performed until a clean surface, at 600 mJ/cm 2, was obtained as determined by Auger electron spectroscopy and ellipsometry measurements. The slightly out of focus laser beam is scanned over the selected area leaving an atomically 1×1 feceted Si surface, as shown by RHEED. The familiar 1×2 reconstructed Si surface may be obtained through a post annealing process.