CHARACTERIZATION OF AZ PN114 RESIST FOR SOFT-X-RAY PROJECTION LITHOGRAPHY

Using 14-nm wavelength illumination, we have imaged 0.1-mum-wide lines and spaces in single-layer thin films of the highly sensitive, negative, chemically amplified resist AZ PN114 by using both a Schwarzschild 20 x camera and an Offner ring field 1x optical system. For soft-x-ray projection lithography the approximate 0.2-mum absorption length in resists at 14-nm wavelength necessitates a multilayer resist system. To explore further the requirements of the imaging layer of such a system, we have transferred patterns, exposed by a high-resolution electron beam in a 60-nm-thick layer of AZ PN114, into the underlying layers of a trilevel structure. Significant pattern edge noise and resist granularity were found. It remains to be determined whether the observed noise is dominated by statistical fluctuations in dose or by resist chemistry. We also investigated pinhole densities in these films and found them to increase from 0.2 cm-2 for 380-mm-thick films to 15 cm-2 for 50-nm-thick films.