Positive resist composition comprising a mixture of two

Abstract

Disclosed is an improved, chemically-amplifying positive resist composition for radiations, especially UV rays, deep-UV rays, excimer laser beams, X-rays, electron beams. The composition comprises (A) a resin component whose solubility in an alkaline aqueous solution is increased by the action of acids, (B) a compound which generates an acid when exposed to radiations, and (A) a resin component, (B) an acid-generating agent and (C) an organic carboxylic acid compound, in which said resin component (A) is a mixture comprising (a) a polyhydroxystyrene where from 10 to 60 mol % of the hydroxyl groups have been substituted by residues of a general formula (I): ##STR1## wherein R.sup.1 represents a hydrogen atom or a methyl group, R.sup.2 represents a methyl group or an ethyl group, and R.sup.3 represents a lower alkyl group having 1 to 4 carbon atoms; and (b) a polyhydroxystyrene where from 10 to 60 mol % of the hydroxyl groups have been substituted by tert-butoxycarbonyloxy groups. The composition has a high sensitivity, a high resolution, high heat resistance, good width characteristic in focus depth and good post-exposure storage stability, has good storage stability as a resist solution, and gives resist patterns with good profiles, without depending on the substrate to which it is applied. The composition is useful for forming fine patterns in producing ultra-LSIs.