Maskless, microlens euv lithography system with grazing-incidence illumination optics

Abstract

An EUV lithography system achieves high-resolution printing without the use of photomasks, projection optics, multilayer mirrors, or an extremely high-power EUV source. The system comprises a xenon laser-produced-plasma (LPP) illumination source (requiring 93 W hemispherical EUV emission in the wavelength range 10–12 nm), all-ruthenium optics (grazing-incidence mirrors and microlenses) and spatial light modulators comprising MEMS-actuated microshutters. Two 300-mm wafers are simultaneously exposed with a single 10 kHz LPP source to achieve a throughput of 6 wafers per hour, per LPP source. The illumination is focused by the microlens arrays onto diffraction-limited (42-nm FWHM) spots on the wafer plane, and the spots are intensity-modulated by the microshutters as they are raster-scanned across the wafer surface to create a digitally synthesized exposure image. The optical path between the source and the microlenses traverses seven grazing-incidence mirrors (two collimator elements and five fold mirrors), which have high reflection efficiency and essentially unlimited wavelength bandpass.