Fabrication of 2-nm-wide silicon quantum wires through a combination of a partially-shifted resist pattern and orientation-dependent etching

This article proposes a nanofabrication technique for fabricating quantum wires with dimensions in the sub-10 nm regime. This technique consists of partially shifted resist-pattern formation and orientation-dependent Si etching that takes advantage of the difference in the crystallographic properties of the {111} planes and the other planes. When {110} Si substrates are etched using a partially shifted pattern as a mask, the etching generates a smooth {111} side plane and eventually forms a straight Si line pattern whose width is equal to the difference between the size of the shift and the originally exposed linewidth. Therefore, line patterns smaller than the beam diameter of lithographic tools can be formed. We show the effectiveness of this technique by fabricating a 2-nm-wide Si line. The electrical conductance characteristics of the Si nanoline formed by this technique are also shown.