Poly{4-hydroxystyrene-co-2(4-methoxybutyl)-2-adamantyl methacrylate} was synthesized and initially evaluated as a new KrF as a prelude to developing a high performance extreme UV (EUV) chemically amplified resist. Incorporation of 2-(4-methoxybutyl)-2-adamantyl groups as protecting groups in the matrix polymers enabled enhanced dry-etch resistance, and excellent lithographic performance was obtained. The resist system formulated with this polymer resolved 120 nm line and space patterns using a KrF excimer laser scanner (0.60NA), and 50 nm line patterns (pitch 180 nm) using an EUV lithography tool. The dry-etch resistance of this resist for a CF4-based plasma was 1.1 times better than that of poly(4-hydroxystyrene).