METHOD FOR PRODUCING NOVOLAC-TYPE PHENOLIC RESIN, NOVOLAC-TYPE PHENOLIC RESIN, AND PHOTORESIST COMPOSITION

摘要

PROBLEM TO BE SOLVED: To provide a novolac-type phenolic resin which can allow a photoresist composition having high heat resistance, high sensitivity, a high residual film rate and high resolution well-balancedly to be provided and to provide a method for producing the novolac-type phenolic resin stably.SOLUTION: The method for producing the novolac-type phenolic resin comprises a polycondensation reaction step of subjecting a phenol component (a) and an aldehyde component (b) to a polycondensation reaction. The aldehyde component (b) contains aromatic dialdehyde (b1) and formaldehyde (b2). The polycondensation reaction step comprises: a first step of condensation-polymerizing the phenol component (a) and a part of the aldehyde component (b) containing one of the aromatic dialdehyde (b1) and the formaldehyde (b2) in the presence of an acid catalyst; and a second step of condensation-polymerizing a reaction mixture obtained at the first step and the remainder of the aldehyde component (b) containing the other of the aromatic dialdehyde (b1) and the formaldehyde (b2). The novolac-type phenolic resin contains a blocked segment including an aromatic dialdehyde (b1)-derived unit or a formaldehyde (b2)-derived unit, at the least, in one molecule thereof. The photoresist composition contains one of these novolac-type phenolic resins.