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Date of Publication:2007-01-01

Journal:强激光与粒子束

Issue:9

Page Number:1561-1566

ISSN No.:1001-4322

Abstract:In the early stage of UV excimer laser ablation of semiconductor, plasma induced by laser ablation was assumed at local thermodynamic equilibrium. One-dimension hydrodynamic model is presented for the laser ablation of Ge in a background gas (He) at 133.32 Pa and the characteristics of plasma induced by Gaussian-shaped KrF laser pulse with wavelength of 248 nm, pulse width of 17 ns, and peak power of 4 × 108 W/cm2. The results show that the ablated depth arrives 55 nm after laser pulse irradiation. The background gas He is gradually pushed away by the Ge vapor, forming a compression shock wave. And the maximum temperature always locates at the front of the shock wave. Spatial distribution of ionization degrees at different time shows that the first-order ionization degree of Ge always dominates in the region close to the target surface. The second-order ionization degree of Ge is a little bit bigger than the first-order ionization degree of Ge during the pulse in the center part of plume. But after the pulse, the second-order ionization degree of Ge drops gradually and then the first-order ionization degree of Ge dominates again.

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