Zone-plate array lithography (ZPAL): A new maskless approach

This paper reviews recent progress in our development of a new maskless lithography scheme which utilizes an array of Fresnel zone plates to write arbitrary patterns on a wafer. Maskless, zone-plate-array lithography (ZPAL) should be capable of producing 25 nm feature sizes at a throughput of 1 cm(2)/second using 4.5 nm radiation from an undulator on a compact synchrotron. This wavelength will allow a large depth-of-focus with essentially no proximity effect at a large gap between the zone-plate array and the substrate. We present a detailed ZPAL system design, and show calculations and simulations which address issues of resolution, contrast, throughput, source characteristics, and micromechanical modulation schemes for x-ray beamlets in ZPAL. We review our experimental efforts in ZPAL in the x-ray and ultraviolet regions.