Patent ID: 6869744

Claim:
A chemically amplified positive resist composition for forming a resist film on a substrate having a chromium film deposited thereon and for exposure to electron beam, comprising as a base polymer a resin having the following unit (A) soluble in aqueous alkaline solution, in which acid labile acetal or ketal groups of the following general formula (1)-1, (1)-2 or (1)-3 replace at least some of the hydrogen atoms on the phenolic hydroxyl groups of the unit (A) so that the resin becomes insoluble or substantially insoluble in alkali, and as another base polymer a resin having the following unit (B) soluble in aqueous alkaline solution, in which acid labile tertiary hydrocarbon groups of the following general formula (2)-1 replace at least some of the hydrogen atoms of the carboxyl groups of the unit (B) so that the resin becomes insoluble or substantially insoluble in alkali: wherein R 31 and R 32 each are hydrogen or a straight, branched or cyclic alkyl or fluorinated alkyl group of 1 to 10 carbon atoms; x is an integer of 1 to 4; wherein R 1 and R 2 each are hydrogen or a straight, branched or cyclic alkyl group of 1 to 20 carbon atoms, which may contain a hetero atom, R 3 is a straight, branched or cyclic alky group of 1 to 20 carbon atoms or aryl or aralkyl group of 6 to 20 carbon atoms, which may contain a hetero atom, or a pair of R 1 and R 2 , R 1 and R 3 , or R 2 and R 3 , taken together, may form a ring; wherein R 19 and R 20 each are hydrogen or a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms, or R 19 and R 20 , taken together, may form a ring, and R 19 and R 20 are straight or branched alkylene groups of 1 to 8 carbon atoms when they form a ring; R 21 is a straight, brached or cyclic alkylene group of 1 to 10 carbon atoms; “b” and “c” are 0 or integers of 1 to 10; A is a (a+1)-valent aliphatic or alicyclic saturated hydrocarbon group, aromatic hydrocarbon group or heterocyclic group having 1 to 50 carbon atoms, which may be separated by a hetero atom or in which some of the hydrogen atoms attached to carbon atoms may be substituted with hydroxyl, carboxyl, carbonyl or fluorine; B is —CO—O—, —NHCO—O— or —NHCONH—, and “a” is an integer of 1 to 7; wherein R 4 to R 6 each are a straight, branched or cyclic alkyl group of 1 to 20 carbon atoms or aryl group of 6 to 20 carbon atoms, at least one of R 4 , R 5 and R 6 is a cyclic alkyl group of 5 to 20 carbon atoms or aryl group of 6 to 20 carbon atoms, which may contain a hetero atom or a pair of R 4 , R 5 and R 6 , taken together, may form a ring of 5 to 30 carbon atoms, which may contain hetero atom, the total number of carbon atoms in R 4 , R 5 and R 6 together is from 6 to 30.