Abstract

X-ray lithography is a promising technology for the production of VLSI microeiectric circuits on Si wafers with sub-0.5-μm features. Recently it has been shown¹ that soft x rays between 4.4 and 8.0 nm generated by a high-repetition 1.06-μm NdrYAG laser-produced plasma can be used for lithography when using polyimide masks. Such masks have a transmissive window on the long-wavelength side of the carbon K-edge at 4.4 nm. It is well known from iaser-plasma interaction physics that soft x rays can be generated more efficiently from plasmas produced by a laser at 249 nm rather than 1.06 μm. The purpose of the work was to demonstrate this improved performance and expose x-ray resists using a plasma x-ray source generated by using a low-energy commercially available 249-nm KrF laser (Lambda Physik EMG 150ES).

© 1986 Optical Society of America