Extremely Low Ablation Rate of Metals Using XeCl Excimer Laser

Ablation thresholds for the metallic elements Ti, Mo, Pt, Au, and Al were investigated using a XeCl excimer laser in the fluence range of 0.1–20 J/cm2. The ablation thresholds were estimated from the dependence of the ablation rate and the diameter of the crater produced by the laser irradiation on laser fluence. Two ablation thresholds obtained from the ablation rate dependence on fluence agreed well with those obtained from the diameter dependence. The lower ablation threshold is related to the threshold calculated using a one-dimensional thermal diffusion model. The results suggest that even at such extremely low ablation rates, melting plays an essential role in excimer laser ablation.