Composition for forming photosensitive resist underlayer film

A method for forming a photoresist pattern to be used in a production of a semiconductor device, the method comprising:

• applying a composition for forming a resist underlayer film on a semiconductor substrate followed by baking to form a resist underlayer film;
• forming a photoresist film on the resist underlayer film;
• exposing the semiconductor substrate coated with the resist underlayer film and the photoresist film;
• and
• developing the photoresist film and the resist underlayer film after the exposure to be removed concurrently without dry etching,
• wherein the composition for forming a resist underlayer film comprises:
• a polymer (B) containing unit structures of Formula (1) and Formula (2):
• wherein in above Formula (1) and Formula (2), each of R1 and R4 is a hydrogen atom or a methyl group;
• in Formula (1), R2 is a monovalent organic group, R3 is a hydrogen atom or a C1-12 alkyl group or acyl group, p is an integer of 0 to 3, q is an integer of 1 to 3, and (p+q) is an integer of 1 to 5;
• and in Formula (2), R5 is an acid-cleavable group);
• the polymer (B) being a polymer in which the unit structure of Formula (1) has a ratio of mole number (a) within a range of 0.20≦a≦0.90, and the unit structure of Formula (2) has a ratio of mole number (b) within a range of 0.05≦b≦0.6, when a total mole number of all unit structures constituting the polymer is 1.0, and the polymer (B) having a weight average molecular weight of 3,000 to 100,000;
• a polymer (C) containing unit structures of Formula (1) and Formula (3):
• wherein in above Formula (1) and Formula (3), each of R1 and R6 is a hydrogen atom or a methyl group;
• in Formula (1), R2 is a monovalent organic group, R3 is a hydrogen atom or a C1-12 alkyl group or acyl group, q is an integer of 1 to 3, p is an integer of 0 to 3, and (p+q) is an integer of 1 to 5;
• and in Formula (3), each of R7 and R8 is independently a hydrogen atom, or a substituted or unsubstituted C1-12 alkyl group, or R7 and R8 are bonded to each other to form, together with a nitrogen atom bonded thereto, a group having a three- to fifteen-membered ring structure, and R7 and R8 are not a hydrogen atom at the same time;
• the polymer (C) being a polymer in which the unit structure of Formula (1) has a ratio of mole number (a) within a range of 0.20≦a≦0.90, and the unit structure of Formula (3) has a ratio of mole number (c) within a range of 0.001≦c≦0.40, when a total mole number of all unit structures constituting the polymer is 1.0, and the polymer (C) having a weight average molecular weight of 3,000 to 100,000;
• a crosslinkable compound (D) being a compound of Formula (4):
• wherein in Formula (4), R9 is a *—(CH2)nO— group or a *—(CH2O)n- group (where the linkage with * is bonded to an ether moiety), and n is an integer of 1 to 10;
• a photoacid generator (E);
• a solvent (F);
• and
• a basic compound (G), wherein
• a ratio of the polymer (B) and the polymer (C) is 1:0.01 to 1:1 by weight,
• the crosslinkable compound (D) is used in an amount ranging from 10% by mass to 70% by mass based on the total mass of the polymer (B) and the polymer (C), and
• the composition includes 0.001 to 5 parts by mass of the basic compound (G) with respect to 100 parts by mass in a total mass of the polymer (B) and the polymer (C).