POSITIVE TYPE PHOTORESIST COMPOSITION

PURPOSE:To obtain the superior positive type photoresist composition excellent in sensitivity, resolution, heat resistance and dry etching resistance by incorporat ing the specified ratio of a polyhydric phenol compound which is condensation reaction product of the specific phenols with aldehydes and a quinon diazide compound. CONSTITUTION:In the compound, 50-99 wt.pts. of a polyhydric phenol compound which is a condensation reaction product of phenols in which ortho-cresol and at least one kind selected from 2.5-dimethlphenol, 3,5-dimethylphenol are mixed at the mol ratio of (95/5)-(5/95) with aldehydes, and 1-50 wt.pts of quinon diazide compound are incorporated. Here the ratio of ortho-cresol and dimethylphenol is preferably used at the mol ratio of (90/10)-(10/90). The molecular weight of the polyhydric phenol used for this is 300-2000 of a number average molecular weight determined by GPC chromatography, preferably >=1500. Thus the positive type photo resist composition excellent in the sensitivity, resolution, heat resis tance, and dry etching resistance is obtained.