NANO-STRUCTURING OF SOLID SURFACE BY EUV Ar8+ LASER
K. Kolacek1, V. Prukner1, J. Schmidt1, O. Frolov1, J. Straus1, A. Shukurov2, J. Sobota3, T. Fort3
1 Institute of Plasma Physics, Academy of Sciences of the Czech Republic, v.v.i.
Department of Pulse Plasma Systems
2 Faculty of Mathematics and Physics, Charles University in Prague
Department of Macromolecular Physics
3 Institute of Scientific Instruments, Academy of Sciences of the Czech Republic, v.v.i.
Department of Electron Optics, Division of New Technologies
Abstract. Requirement of increased resolution is at present most loudly pronounced in microelectronics, which, following Moore´s law (doubling every two years the transistorcount that can be placed inexpensively on integrated circuit), commands a continuous upgrade of micro-/nano-lithography. Such upgrade indirectly influences processing speed, memory capacity, number and size of pixels in sensors, etc.
The submitted paper demonstrates our first attempt for “direct (i.e. ablation) patterning” of PMMA by pulse, high-current, capillary-discharge-pumped Ar8+ ion laser (λ = 46,9 nm). For focusing a long-focal spherical mirror (R = 2100 mm) covered by 14 double-layer Sc-Si coating was used. The ablated focal spots demonstrate not only that the energy of our laser is sufficient for such experiments, but also that the design of focusing optics must be more sophisticated: severe aberrations have been revealed – an irregular spot shape and strong astigmatism with astigmatic difference as large as 16 mm. Moreover, on the bottom of ablated spots a laserinduced periodic surface structure (LIPSS) has appeared. Finally, a direct patterning of quadratic hole 7,5x7,5 µm, standing in contact with PMMA substrate, has shown a strongly developed 2D diffraction pattern (period in the centre ~125 nm). In conclusion there will be shown the design of a new (grazing incidence) focusing optics, and a new “nano-patterning” tool – grazing incidence interferometer, which enable to ablate a regular, in advance defined pattern. It is believed that this is the first step to application of this technique not only to nanolithography,but also e.g. to study of electron dynamics in superlattices.
Acknowledgments:
This research has been supported by the Grant Agency of the Academy of Sciences CR (contract KAN300100702), and by the Ministry of Education, Youth, and Sports of the Czech Republic (contracts LA08024 and LC528).