Fabrication of nanometer-scale features by controlled isotropic wet chemical etching

An inexpensive fabrication technique for transferring the edges of a patter ned mask layer into an underlying, thin metal film is found in controlled u ndercutting by isotropic wet etching. This technique generates structures w ith critical dimensions as small as 50 nm (see Figure) in a thin film of ch romium or aluminum and it is useful for structures that do not require mult iple-level registration and that are tolerant of defects.