Long Coherence Length Far Ultraviolet Laser for High-Resolution Nano-Fabrication

Cost effective semiconductor processing tools that enable the high-resolution nano-fabrication of low-volume electronics are needed by the DOD. The printing of ultra-fine gratings on silicon wafers using interference immersion lithography is envisaged as a first maskless process step in the fabrication of advanced application specific integrated circuits. Next generation interference immersion lithography tools capable of rapidly printing grating structures with half-pitches down to 26 nm over large fields will require a new class of laser source that can provide both high spatial and temporal coherence as well as high power. Line narrowed ArF excimer lasers, while essential for high volume semiconductor production, are ill-suited to this interference lithography application due to their high costs and inherently poor spatial coherence. In this DARPA STTR we will develop a 1 MHz pulsed fiber laser and wavelength extension system that delivers greater than ¼ watt of average power in the far ultraviolet (near 193.4 nm) with a coherence length of 15 cm (2 GHz FWHM bandwidth).