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.