Fabrication of sub-100-nm linewidth periodic structures for study of quantum effects from interference and confinement in Si inversion layers

Two new types of Si metal-oxide-semiconductor field-effect transistor (MOSFET) devices have been fabricated and tested which involve a dual gate structure, the lower one being a W grating of 0.2 μm period, 0.1 μm linewidth. These devices, the lateral surface superlattice and the quasi-one-dimensional device, explore the regime where quantum mechanical effects become important. Fabrication techniques are described and projections made with regard to lithographic techniques for future electronic systems based on sub-100 nm linewidth devices. X-ray lithography at λ∼1 nm can provide linewidth control ≲10 nm and high pixel-transfer rate. The mask-to-substrate gap is constrained by diffraction. However, with a resist of sufficiently high contrast (and low sensitivity to avoid edge raggedness) linewidths of 50 nm should be feasible in high volume production at mask–substrate gaps of a few μm.