Patent ID: 8623585

Claim:
A positive photoresist composition containing, as an essential component, a novolac phenolic resin (C) prepared by a method comprising: a first step of polycondensing an alkyl-substituted phenol (a1) with an aromatic aldehyde (a2) by heating at 60° C. to 140° C. in the presence of an acid catalyst, optionally using a solvent, to prepare an aromatic compound (A) represented by general formula (1) or (2): wherein R 1 , R 2 , and R 3 are each independently an alkyl group having 1 to 8 carbon atoms; m, n, and p are each independently an integer of 0 to 4; q is an integer of 1 to (5−p); and s is an integer of 1 to (9−p); a second step of isolating the aromatic compound (A) prepared in the first step from the reaction solution; and a third step of polycondensing the aromatic compound (A) isolated in the second step with an aliphatic aldehyde (B) by heating at 60° C. to 140° C. in the presence of an acid catalyst, optionally using a solvent.