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Atom Lithography

Atom lithography, shooting sculpted beams of atoms at a substrate, can create lines of deposited atoms with widths as narrow as 50 nm. Two groups in Holland have separately carried out experiments in which atoms, heated in an oven, released through a baffle, "cooled" by laser rays striking the beam at right angles, and then focused in optical microlenses consisting of opposing laser beams.

In the case of physicists at Eindhoven University of Technology (contact Ton van Leeuwen, 31-40-2474094, k.a.h.v.leeuwen@tue.nl) the best resulting grid of iron atoms had lines only 50 nm wide and spaced consistently 186 nm apart (see figure at www.aip.org/png).

The researchers expect to achieve 10-nm lines, but their chief aim is to move from producing simple grid patterns to making more elaborate patterns with holographic and other techniques. They are also pursuing a "single-point writer" option, in which the full atomic beam will be focused to a single, very intense spot.

What is the advantage of such slow atom-beam approach to lithography? Mainly it is the directness of the method for inscribing microcircuitry (no etching or use of masks) and exercising great control over line width and spacing.

The researchers also admit that there are imposing technological hurdles to using this approach on an industrial scale. Short-term applications would most likely be for making MEMS-like structures (teSligte et al., Applied Physics Letters, 8 November 2004; text at www.aip.org/physnews/select; lab website at www.phys.tue.nl/aow).

The other Dutch group, at Radboud University Nijmegen have laid down their own grid of iron atoms with lines 95 nm in width, 186 nm apart, and covering an area of 1.6 x .4 mm^2. (Myszkiewicz et al., Applied Physics Letters, 25 Oct; contact Theo Rasing, 31-24-3653102) The two groups are now working together on some joint ventures.