Abstract: The present invention relates to a novolak type phenol resin, in particular a novolak type phenol resin for resists suitable for forming resist patterns. The novolak type phenol resin of the present invention is obtained by reacting at least a vinylphenol having a vinyl group and a phenolic hydroxyl group, such as parahydroxystyrene, or a polyvinylphenol, which is a polymer of the vinylphenol, a compound (A) such as 4,4′-methylenebis(2-hydroxymethyl-3,6-dimethylphenol) and/or a compound (B) such as 2,6-dihydroxymethyl-4-phenol, in a ratio of 1 to 40 moles of the compound (A) and/or compound (B) to 100 moles of the vinylphenol or 100 moles of structural unit of the vinylphenol contained in the polyvinylphenol in the presence of an acid and having a weight average molecular weight of 2,000 to 20,000. Such a novolak type phenol resin provides good pattern shape, heat resistance, resolution, and sensitivity in resists for lithography.

Abstract: The present invention relates to a phenol resin, in particular a phenol resin for resists suitable for forming resist patterns. The phenol resin of the present invention is obtained by reacting at least two components, i.e., a compound (A) such as 4-hydroxymethyl-2,6-dimethylphenol and a polymerizable phenol compound such as parahydroxystyrene or a polymer (B), which is a polymer of the polymerizable phenol compound, in a ratio of 1 to 50 moles of the compound (A) to 100 moles of the polymerizable phenol compound or 100 moles of structural unit of the polymerizable phenol compound contained in the polymer (B) in the presence of an acid and having a molecular weight of 2,000 to 20,000. Such a phenol resin provides good pattern shape, heat resistance, resolution, and sensitivity in resists for lithography.