F. Lison

Pattern generation with cesium atomic beams at nanometer scales

We have demonstrated that a cesium atomic beam can be used to pattern a gold surface using a self assembling monolayer (SAM) as a resist. A 12.5 μm period mesh was used as a proximity mask for the atomic beam. The cesium atoms locally change the wetability of the SAM, which allows a wet etching reagent to remove the underlying gold in the exposed regions. An edge resolution of better than 100 nm was obtained. The experiment suggests that this method can either be used as a sensitive position detector with nanometer resolution in atom optics, or for nanostructuring in a resist technique.

Atom Lithography with Cesium Atomic Beams

Optical lithography is the dominant method of manufacturing lateral microand nanostructures in nearly all areas of technology, but it is predicted to be limited to feature sizes of about 100 nm due to diffraction. At this scale the miniaturization is not yet impaired by quantum limits of the substrates and materials used for construction, i.e. transistors will still be governed by the same physical laws as the currently available components. Therefore nanofabrication of known devices may continue beyond this border without a conceptual change of important components involved, provided suitable lithographic processes with sub 100 nm resolution are available. According to the “roadmap” published by the semiconductor industry [1] it is expected that the technological 100 nm barrier will be reached by 2005. The applicability of sub 100 nm methods for nanostructure fabrication will not only be determined by technological and physical reasons, however, but more importantly by economical factors.

Lithography with cesium atomic beams

Summary form only given. To meet future demands for nanofabrication, lithographic systems with sub-100-nm resolution are required. Atoms with a velocity of several tens of meters per second have de Broglie wavelengths in the picometer regime, and hence, diffraction does not prevent focusing to a nanometer spot size. Atomic beams are therefore a natural candidate for generating nanostructures. Highly periodic one- and two-dimensional structures with linewidths well below 100 nm can be grown in a direct and parallel process by focusing atoms with standing-wave light fields onto a substrate. Our system consists of a self-assembled monolayer of thioles on top of a thin gold layer (30 nm).

Atom optical properties of magnetic components

Efficmt bear steering components far paramagnetic atoms CUI be manufacrured from permanent magnets. In contrast to atom optical components denved from light forces permanent magnetic components do not need any supplies, they have large apenures, and rpontilneous cmissroe is absent. Mayetic acceleration i s one ardor of magnitude smaller than typlcal accelerations by gpantaneous light farces, but the maximum momentum transfer can be increased through extended components or by loucrhg the longrludunal vclucity of the atoms. With strong rare carth permanent magnets we have built lenses [ I ] .ind nllrrors (fig. 1) for atomic bcams. Our lenses have ibcill lengths in the centimcler regims for sloniic ~elocillrs of abour 70 mis and a opening ofseveral miilimeters. Hexapolc I C ~ S C S can bc iiscd for fociising anid ~magmg with B monachromaric atomic beam 121. It is wll known 111 hght optics that minors haw fewer aberratrons thla lenses. A magnetic mirror for aloin 0pOcs has been constructed from B periodic airily of milgnctic slabs with alternating direction uf lhe magnetization. The dwice has a length of 90 mm and reilccts ces~um a t o m with B vclocicy component of up LO 5 nvs perpendicular to the mirror surface.