Sub-100-nm lithographic imaging with an EUV 10x microstepper

The capabilities of the EUV 10x microstepper have been substantially improved over the past year. The key enhancement was the development of a new projection optics system with reduced wavefront error (lambda(EUV)/20), reduced flare (<5%), and increased numerical aperture (0.088 round or 0.1x0.088 rectangular, interchangeable). These optics and concomitant developments in EUV reticles and photoresists have enabled dramatic improvements in EW imaging, illustrated by resolution of 70 nm dense (1:1) lines and spaces (L/S). CD linearity has been demonstrated for dense L/S over the range 200 nm to 80 nm, both for the imaging layer and for subsequent pattern transfer. For a +/-10% CD specification, we have demonstrated a process latitude of +/-0.8 mu m depth of focus and 10% dose range for dense 90 nm L/S, and +/-1 mu m depth of focus and 10% dose range for dense 100 nm L/S.