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R. Catrin, C. Gachot, G. Marchand, U. Schmid, F. Mücklich:
"Selective wet chemical etching of metallic thin films designed by Laser Interference Metallurgy (LIMET)";
Vortrag: SPIE Europe: Microtechnologies for the New Millennium, Dresden, Deutschland; 04.05.2009 - 08.05.2009; in: "Proceedings of SPIE", Society of Photo-Optical Instrumentation Engineers (SPIE, 7362-7366 (2009).

The physical and chemical behaviour of materials is strongly correlated with their microstructure. Therefore, much effort
is invested in the advanced microstructural design of metallic thin films. Laser Interference Metallurgy (LIMET) is used to locally tune the grain architecture of metallic thin films from the nano to the microscale. This means a defined size and orientation of the grains with lateral periodicity, by interfering on the sample surface two or more laser beams of a high power nanosecond pulsed Nd:YAG laser. This technique enables the local nucleation and crystallization of amorphous or nanocrystalline metallic thin films, thus combining nano- and microcrystalline regions ordered in periodic line- or lattice-like arrangements in a composite architecture. After having locally modified the microstructure of e-beam evaporated Pt and Au thin films by laser irradiation a wet chemical etching procedure was induced in hot aqua regia. Doing so, a selective etching is achieved without using conventional lithography. Due to the laser-induced recrystallization in periodic structures, these microcrystalline zones
of specific oriented grains show a higher resistance against the wet chemical etchant than the as-deposited, nanocrystalline areas, which are completely removed down to the substrate. Therefore, this procedure may have the potential to be an alternative, low cost approach to conventional lithographic techniques and provides a novel method for a straight-forward patterning of metallic thin films.

Laser Interference Metallurgy (LIMET), wet chemical etching, metallic thin films, microstructural design, grain architecture, Nd:YAG pulse laser, recrystallization, aqua regia.

http://dx.doi.org/10.1117/12.821333