Xk. Huang et al., NEW TECHNIQUE FOR COMPUTATION AND CHALLENGES FOR ELECTRON-BEAM LITHOGRAPHY, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 11(6), 1993, pp. 2565-2569
In this article, the basic concepts of our recently proposed computing
architecture based on Coulomb coupling of nanofabricated structures,
called quantum cellular automata (QCA) are reviewed and fabrication is
sues critical to the new technology are discussed. The QCA fabrication
will require an extremely high level of lithographic control. To this
end, the proximity effects in making very high density patterns with
poly(methylmethacrylate) (PMMA) and electron-beam lithography have bee
n experimentally investigated. A triple Gaussian model was used to sim
ulate the experimental data. By using a 50 keV electron beam, sub-40 n
m pitch gratings, double lines, and dot grids were successfully fabric
ated on Si and SiO2/Si bulk wafers with single-level PMMA and lift-off
.