Materialography of Micro-Nano-Structured Surfaces 
ITRS- 
r- und F._Miicklich, Zhongfan Liu, T. Recktenwald 
ch der Funktionswerkstoffe, Universitit des Saarlandes 
schung, : ) hp 
nd sich Dedicated to Prof. Giinter Petzow on the occasion of his 75" birthday 
heuer Abstract 
alische 
Zukunft The 3D design of microstructures is one of the key tools to tailor materials properties. But on 
in-line- the surface, a two dimensional section through this bulk microstructure appears. Thus, the 
tnahme properties which are influenced by local interactions with this surface microstructure scatter. 
\nalytik This scattering could be reduced by the additional tailoring and the lateral formation of the 
surface microstructure. Biological systems take advantage of such effects. namely in terms of 
composite effects. 
sen die By the interference of 2, 3 and more coherent Laser beams it is shown, how periodic patterns 
un g der of sufficient high power can be directly transformed into various kinds of surface 
ng von microstructure modifications. While the lateral periodicity of lines or dots can be chosen from 
nn 200 nanometer up to 20 micrometer, the surface modifications may consist in defined 
digitale geometrical depth profiling, as well as structural and/or chemical modifications. depending on 
werden the material and the Laser parameters chosen. 
Einsatz 
{. Introduction 
| Heiko In biological systems the surface microstructures are often “designed” by periodical pattem 
[Mei95]. These pattern are often formed by more tough layers alternating with more strength 
he und ones. This well known composite effect combines both advantages. Consequently a 
olkmann remarkable strength enhancement is achieved without any loss of thoughness [Fra01]. If the 
paration feature size of these pattern decreases, this effect becomes more emphasized. This calls for a 
nd Uwe technical realization of such surface pattern in the micrometer scale. 
Laser interference nano-microstructuring is a newly developed method for laser material 
surface modification, by which various interference patterns can be transformed directly, 
. quickly, permanently, and in a large scale to the surface of different kinds of materials. 
calischer Among them are semiconductors, metals, ceramics, and polymers. Although there are many 
in der techniques for surface modification , laser interference nano-microstructuring is proved to be 
an immediate approach with good prospects also for technical application to produce micro- 
national structures with resolution from micro- to nano-meter scale. It takes fully advantage of the 
specialty of the laser beam, namely, high energy density, high coupling efficiency especially 
2001 in the UV range, strong coherency, and very good spatial and temporal selectivity. In view of 
risierung the technical efficiency it is a single-step and parallel process, with a broad range of material 
en fiir selection. and therefore is a good extension of the current lithographic techniques. 
Compared with traditional laser material processing it is in the scale from micrometer down to 
nano-meter, due to interference and non-linear behavior of the process. Especially due to the 
large photo energy available with UV ns-pulsed laser it can modify the material surface 
electron directly through interactions between photon and atoms or molecules, therefore various 
mechanisms i.e., melting, evaporation, crystallization, photo-decomposition, photochemical 
alysis of reaction and ablation can be exploited for material surface modification or functionalization. 
1 process 
2 (2001) 
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