Zone-plate-array lithography in the deep ultraviolet

Abstract

We describe initial steps we have taken in the development of zone-plate-array lithography (ZPAL), a proposed new paradigm for sub-100 nm lithography. The optimal implementation of ZPAL would employ an undulator emitting soft x rays of 4.5 nm wavelength. However, we have opted to concentrate initially on the major uncertainties associated with ZPAL: (1) fabrication of a large array of zone plates with a center-to-center spacing accuracy finer than the minimum zone width, (2) multiplexing of input beams to the individual zone plates, and (3) coordination of that multiplexing with precision motion of a substrate stage. We fabricated arrays of pure-phase zone plates suitable for the 193 nm output of an ArF laser, and conducted exposure tests using a modified Michelson configuration for focusing the zone plate array on the substrate. We also show the first example of simplistic writing. We show that the micromirror array manufactured by Texas Instruments, for use in projection displays, has dimensions and switching characteristics close to those needed for an ultimate ZPAL system.