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Proceedings Paper

Design of an electron projection system with slider lenses and multiple beams
Author(s): Daniel Moonen; Peter L. H. Albertino Leunissen; Patrick W.H. de Jager; Pieter Kruit; Arno J. Bleeker; Karel D. Van der Mast
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Paper Abstract

The commercial applicability of electron beam projection lithography systems may be limited at high resolution because of low throughput. The main limitations to the throughput are: (i) Beam current. The Coulomb interaction between electrons result in an image blue. Therefore less beam current can be allowed at higher resolution, impacting the illuminate time of the wafer. (ii) Exposure field size. Early attempts to improve throughput with 'full chip' electron beam projection systems failed, because the system suffered from large off-axis aberrations of the electron optics, which severely restricted the useful field size. This has impact on the overhead time. A new type of projection optics will be proposed in this paper to overcome both limits. A slider lens is proposed that allows an effective field that is much larger than schemes proposed by SCALPEL and PREVAIL. The full width of the die can be exposed without mechanical scanning by sliding the beam through the slit-like bore of the lens. Locally, at the beam position, a 'round'-lens field is created with a combination of a rectangular magnetic field and quadruples that are positioned inside the lens. A die can now be exposed during a single mechanical scan as in state-of-the-art light optical tools. The total beam current can be improved without impact on the Coulomb interaction blur by combining several beams in a single lithography system if these beams do not interfere with each other. Several optical layouts have been proposed that combined up to 5 beams in a projection system consisting of a doublet of slider lenses. This type of projection optics has a potential throughput of 50 WPH at 45 nm with a resist sensitivity of 6 (mu) C/cm2.

Paper Details

Date Published: 1 July 2002
PDF: 12 pages
Proc. SPIE 4688, Emerging Lithographic Technologies VI, (1 July 2002); doi: 10.1117/12.472281
Show Author Affiliations
Daniel Moonen, Delft Univ. of Technology (Netherlands)
Peter L. H. Albertino Leunissen, Delft Univ. of Technology (Belgium)
Patrick W.H. de Jager, TNO Institute of Applied Physics (Netherlands)
Pieter Kruit, Delft Univ. of Technology (Netherlands)
Arno J. Bleeker, ASML (Netherlands)
Karel D. Van der Mast, ASML (Netherlands)

Published in SPIE Proceedings Vol. 4688:
Emerging Lithographic Technologies VI
Roxann L. Engelstad, Editor(s)

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