This article reports on sub-0.25 mum electron-beam lithography using a new positive-tone chemically amplified resist system called KRS. Unlike conventional chemically amplified resist systems, KRS is immune to N-methylpyrolidone contamination and does not require a postexposure bake step. The resist is aqueous developable and shows a contrast figure of about 10 and a sensitivity of about 12 muC/cm2 at 50 kV. A 0.15 mum feature size with a shaped-beam system in 0.8 mum thick resist on silicon with -0.05 mum print bias was achieved. Sub-100 nm features are resolved in 0.3 mum thick KRS using a high-resolution Gaussian-beam system. The resist was found to be extremely suitable for patterning densely packed, high resolution, and high aspect ratio structures. As examples, the application of this resist for fabricating high resolution x-ray masks and very high performance 0.1 mum gate-length n-metal-oxide-semiconductor field effect transistors are reported.