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Proceedings Paper

Experimental investigation of Fang's Ag superlens suitable for integration
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Paper Abstract

We report on experimental realization of the Fang Ag superlens structure [1] suitable for further processing and integration in bio-chips by replacing PMMA with a highly chemical resistant cyclo-olefin copolymer, mr-I T85 (Micro Resist Technology, Berlin, Germany). The superlens was able to resolve 80 nm half-pitch gratings when operating at a free space wavelength of 365 nm. Fang et al. used PMMA since it enables the presence of surface plasmons at the PMMA/Ag interface at 365 nm and because it planarizes the quartz/chrome mask. If the superlens is to be integrated into a device where further processing is needed involving various organic polar solvents, PMMA cannot be used. We propose to use mr-I T85, which is highly chemically resistant to acids and polar solvents. Our superlens stack consists of a quartz/chrome grating mask, a 40 nm layer of mr-I T85, 35 nm Ag, and finally 70 nm of the negative photoresist mr-UVL 6000 (Micro Resist). A 50 nm layer of aluminium on top of the quartz/chrome mask reflected all light that did not penetrate through the mask openings thereby reducing waveguiding in the top resist layer. The exposures took place in a UV-aligner at 365 nm corresponding to the excitation wavelength of the surface plasmons at the mr-I T85/Ag interface. Supporting COMSOL simulations illustrate the field intensity distribution inside the resist as well as the presence of surface plasmons at the mr-I T85/Ag boundary. AFM scans of the exposed structure revealed 80 nm gratings.

Paper Details

Date Published: 2 September 2009
PDF: 7 pages
Proc. SPIE 7395, Plasmonics: Nanoimaging, Nanofabrication, and their Applications V, 73951I (2 September 2009); doi: 10.1117/12.825940
Show Author Affiliations
Claus Jeppesen, Technical Univ. of Denmark (Denmark)
Rasmus B. Nielsen, Technical Univ. of Denmark (Denmark)
Purdue Univ. (United States)
Sanshui Xiao, Technical Univ. of Denmark (Denmark)
Niels Asger Mortensen, Technical Univ. of Denmark (Denmark)
Alexandra Boltasseva, Purdue Univ. (United States)
Anders Kristensen, Technical Univ. of Denmark (Denmark)


Published in SPIE Proceedings Vol. 7395:
Plasmonics: Nanoimaging, Nanofabrication, and their Applications V
Satoshi Kawata; Vladimir M. Shalaev; Din Ping Tsai, Editor(s)

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