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Proceedings Paper

Molecular dynamics simulation of heat-affected zone of copper metal ablated with femtosecond laser
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Paper Abstract

Femtosecond laser ablation of materials with high thermal conductivity is of paramount importance, because the chemical composition and properties of the area ablated with femtosecond laser are kept unchanged. The material processing by femtosecond laser can well control the heat-affected zone, compared to nanosecond laser ablation. We report on the heat-affected zone of crystalline copper (Cu) by use of femtosecond laser experimentally and theoretically. Laser ablation of Cu is investigated theoretically by two temperature model and molecular dynamics (MD) simulation. The MD simulation takes into account of electron temperature and thermal diffusion length calculated by two temperature model. The dependence of lattice temperature on time and depth is calculated by the MD simulation and two temperature model. The heat-affected zone estimated from the temperature is mainly studied and calculated to be 3 nm at 0.02 J/cm2 which is below the threshold fluence of 0.137 J/cm2. In addition, the thickness of heat-affected zone of copper crystal ablated with femtosecond Ti:sapphire laser is experimentally studied. As a result of X-ray diffraction (XRD) of the ablated surface, the surface crystallinity is partially changed into disordered structure from crystal form. The residual energy left in the metal, which is not used for ablation, will induce liquid phase, leading to the amorphous phase of the metal during resolidification. The thickness of heat-affected zone depends on laser fluence and is experimentally measured to be less than 1 μm at higher laser fluences than the ablation threshold.

Paper Details

Date Published: 21 March 2005
PDF: 12 pages
Proc. SPIE 5714, Commercial and Biomedical Applications of Ultrafast Lasers V, (21 March 2005); doi: 10.1117/12.589513
Show Author Affiliations
Yoichi Hirayama, Keio Univ. (Japan)
Minoru Obara, Keio Univ. (Japan)


Published in SPIE Proceedings Vol. 5714:
Commercial and Biomedical Applications of Ultrafast Lasers V
Joseph Neev; Christopher B. Schaffer; Andreas Ostendorf; Stefan Nolte, Editor(s)

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