Photoresist composition and method of forming a photoresist pattern using the same

A method of forming a photoresist pattern comprising:

• forming a photoresist film on an object by coating the object with a photoresist composition comprising a cross-linking agent including at least one epoxy group and/or at least two hydroxyl groups, a photosensitive material, an organic solvent, and a compound having a chemical structure represented by formulae (1) or (2),
• wherein in formulae (1) and (2), R1 is a triol moiety obtained by removal of three hydrogen atoms from three hydroxyl groups of a triol, R2, R3 and R4 are independently dicarboxylic acid moieties obtained by removal of two hydrogen atoms from two carboxylic groups of a dicarboxylic acid, R5, R6 and R7 are independently a tert-butyl group, a tetrahydropyranyl group or a 1-ethoxyethyl group, R8 is a tricarboxylic acid moiety obtained by removal of three hydrogen atoms from three carboxylic groups of a tricarboxylic acid, and X1 to X6 are independently a hydrogen atom or a hydroxyl group;
• exposing the photoresist film to light;
• and
• partially removing the photoresist film from the object to form the photoresist pattern.