Abstract: A radiation-sensitive resin composition containing an alkali-soluble resin, comprising a polyhydroxy compound having the following formula: ##STR1## or a quinonediazidesulfonate of the polyhydroxy compound. The radiation-sensitive resin composition is suitable for use as a positive type photoresist which has such excellent developability as to inhibit effectively the generation of scum in the formation of a photoresist pattern, has high sensitivity and is excellent in heat resistance and remained thickness ratio upon development.

Abstract: A positive type radiation-sensitive resin composition comprising an alkali-soluble novolac resin and a 1,2-quinonediazide compound, characterized in that said alkali-soluble novolac resin is a resin produced by condensing a carbonyl compound and a phenol mixture comprising 6 to 94 mole % of m-cresol and 94 to 6 mole % of at least one compound represented by the formula (I) other than m-cresol: ##STR1## wherein X is --CH.sub.3, --C.sub.2 H.sub.5, --C(CH.sub.3).sub.3, --CO.sub.2 CH.sub.3 or --CO.sub.2 C.sub.2 H.sub.5 ; n is an integer satisfying 3.gtoreq.m.gtoreq.1; and m is an integer satisfying 3.gtoreq.m.gtoreq.1, in which resin when the polystyrene-reduced molecular weight is determined by a gel permeation chromatography using a monodisperse polystyrene as the standard, maximum values a, b and c present, respectively, in the molecular weight ranges of 6,300 to 25,000, 2,500 to 6,000 and 150 to 900 in the molecular weight distribution curve obtained satisfy the following relationships: a/b=0-1.5 and c/b=1.