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STATE-OF-THE-ART OF FOCUSED ION BEAM NANOLITHOGRAPHY

K. Arshak1,* , M. Mihov2

Affiliation

  1. Electronic & Computer Engineering Dept., University of Limerick, Limerick, Ireland
  2. Materials & Surface Science Institute (MSSI), University of Limerick, Limerick, Ireland

Abstract

Finely-focused ion beams can be applied for advanced lithography, which provides some advantages over conventional direct-write electron beam technology. In focused ion beam technology, however, the ion penetration depth is limited, thus requiring the use of extremely thin resist layers or higher ion acceleration energies. These requirements are often undesirable for the current IC manufacturing processes. One solution to this problem is to exploit the Top Surface Imaging (TSI) technique for dry developed FIB lithography schemes. In this paper, we investigate a novel lithography process, which combines focused Ga+ ion beam (Ga+ FIB) exposure, silylation and oxygen dry etching. The Negative Resist Image by Dry Etching (NERIME) is a TSI scheme for DNQ/novolak based resists, and can result in either positive or negative resist images depending on the extent of the ion beam exposure dose. The mechanism of negative image formation in NERIME is studied by TEM, and is found to be due to the creation of a thin gallium oxide layer during the oxygen dry development. Energy dispersive X-ray spectrometry microanalysis shows that gallium is implanted into the SPR660 resist to a depth of 50 nm and the oxidised gallium layer has a thickness of approximately 15 nm. It is also shown that the NERIME process can resolve nanometer resist patterns down to 65 nm, and yet maintain a high aspect ratio of 15. The NERIME process could be a useful nanofabrication method, as an alternative to the current lithography processes..

Keywords

NERIME process, Nanolithography, Focused ion beams, Dry etching, TEM, EDS.

Submitted at: Dec. 9, 2004
Accepted at: Jan. 26, 2005

Citation

K. Arshak, M. Mihov, STATE-OF-THE-ART OF FOCUSED ION BEAM NANOLITHOGRAPHY, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 1, pp. 193-198 (2005)