A resist resin composition includes 100 parts by weight of a copolymer represented by Formula 3 below; 0.5 to 1.5 parts by weight of a photoacid generator and 700 to 1,500 parts by weight of a solvent: wherein R1, R2, and R3 are each independently a C1-30 alkyl group, a C3-30 cycloalkyl group, an ether group, an ester group, a carbonyl group, an acetal group, an epoxy group, a nitrile group, or an aldehyde group, R4, R5, and R6 are each independently hydrogen or a methyl group, and l, m, n, and o each independently refer to the number of repeating units in a main backbone and satisfy the conditions: l+m+n+o=1, 0≦l/(l+m+n+o)