A semiconductor photoresist composition includes an organometallic compound represented by Chemical Formula 1, an organometallic compound represented by Chemical Formula 2, and a solvent, and a method of forming patterns using the same. When the semiconductor photoresist composition is irradiated with e.g., extreme ultraviolet light, radical crosslinking between Sn-containing units may occur via Sn—O—Sn bond formation, and a photoresist polymer providing excellent sensitivity, small or reduced line edge roughness, and/or excellent resolution may be formed.