Photoacid generator and photoresist composition including the same

A photoacid generator represented by Formula IV below,

• wherein in Formula IV,
• L is S or I, and when L is I, R3 is omitted,
• R1, R2, and R3 are each independently a C1 to C10 alkyl group, a C1 to C10 alkoxy group, a C2 to C10 alkenyl group, a C2 to C10 alkynyl group, a C6 to C18 aryl group, a C7 to C18 arylalkyl group, or a C7 to C18 alkylaryl group, each of which is substituted with a heteroatom or intervened with a heteroatom,
• two of R1, R2, and R3 are bonded to each other to form a ring together with L,
• B1 includes three or more ester groups, and is a monovalent or divalent hydrocarbon group which is substituted with a heteroatom or intervened with a heteroatom,
• B2 and B3 are each independently a monovalent or divalent C1 to C20 hydrocarbon group which is substituted with a heteroatom or intervened with a heteroatom, and
• T1 and T2 are each independently an acid-sensitive group.

A photoresist composition, comprising:

• a photosensitive resin;
• a photoacid generator represented by Formula I, below;
• and
• a solvent capable of dissolving the photosensitive resin and the photoacid generator,
• wherein in Formula I,
• L is S or I, and when L is I, R3 is omitted,
• R1, R2, and R3 are each independently a C1 to C10 alkyl group, C1 to C10 alkoxy group, a C2 to C10 alkenyl group, a C2 to C10 alkynyl group, a C6 to C18 aryl group, a C7 to C18 arylalkyl group, or a C7 to C18 alkylaryl group, each of which is substituted with a heteroatom or intervened with a heteroatom,
• two of R1, R2, and R3 are bonded to each other to form a ring together with L,
• B1 includes two or more ester groups, and is a monovalent or divalent hydrocarbon group which is substituted with a heteroatom or intervened with a heteroatom,
• B2 is a monovalent or divalent C1 to C20 hydrocarbon group which is substituted with a heteroatom or intervened with a heteroatom, and
• T is an acid-sensitive group.