Composition for forming resist underlayer film with improved film density

A method for producing a semiconductor device, the method comprising:

• a step of forming a resist underlayer film from a resist underlayer film-forming composition on a semiconductor substrate;
• a step of forming a resist film on the resist underlayer film;
• a step of forming a resist pattern through irradiation with light or an electron beam and development;
• a step of etching the underlayer film with the formed resist pattern;
• and
• a step of processing the semiconductor substrate with the patterned underlayer film,
• wherein the resist underlayer film-forming composition comprises a novolak resin having a repeating unit structure consisting of the following formula (1):
• wherein a group A is an organic group that includes a ring structure comprising an aromatic ring selected from the group consisting of benzene, naphthalene and diphenylamine and a group B is each independently an organic group that includes a ring structure comprising an aromatic ring, a condensed aromatic ring, or a condensed aromatic hetero ring, wherein the repeating unit structure of formula (1) further includes two or more same or different mono- or divalent chemical groups selected from the group consisting of
• chemical group (a) that is sulfide group,
• chemical group (b) that is amino group, carboxyl group, a carboxylic acid alkyl ester group, nitro group, hydroxy group, ether group, or a combination thereof, with a proviso that chemical group (b) does not include a secondary amino group, and
• chemical group (c) that is a fluoroalkyl group,
• by way of the mono- or divalent chemical groups each being substituted for a hydrogen atom bonded to a carbon atom in the ring structure of the group A and/or of the group B;
• wherein, in the two or more mono- or divalent chemical groups, at least one is selected from the chemical group (b);
• wherein if the group A is diphenylamine:
• the amino group of the diphenylamine is one of the two or more mono- or divalent chemical groups;
• chemical group (a) is a sulfide group;
• chemical group (b) is a carboxylic acid alkyl ester group, an ether group, or a combination thereof;
• and
• chemical group (c) is a fluoroalkyl group.

A method for producing a semiconductor device, the method comprising:

• a step of forming a resist underlayer film from a resist underlayer film-forming composition on a semiconductor substrate;
• a step of forming a hard mask on the resist underlayer film;
• a step of further forming a resist film on the hard mask;
• a step of forming a resist pattern through irradiation with light or an electron beam and development;
• a step of etching the hard mask with the formed resist pattern;
• a step of etching the underlayer film with the patterned hard mask;
• and
• a step of processing the semiconductor substrate with the patterned resist underlayer film,
• wherein the resist underlayer film-forming composition comprises a novolak resin having a repeating unit structure consisting of the following formula (1):
• wherein a group A is an organic group that includes a ring structure comprising an aromatic ring selected from the group consisting of benzene, naphthalene and diphenylamine and a group B is each independently an organic group that includes a ring structure comprising an aromatic ring, a condensed aromatic ring, or a condensed aromatic hetero ring, wherein the repeating unit structure of formula (1) further includes two or more same or different mono- or divalent chemical groups selected from the group consisting of
• chemical group (a) that is sulfide group,
• chemical group (b) that is amino group, carboxyl group, a carboxylic acid alkyl ester group, nitro group, hydroxy group, ether group, or a combination thereof, with a proviso that chemical group (b) does not include a secondary amino group, and
• chemical group (c) that is a fluoroalkyl group,
• by way of the mono- or divalent chemical groups each being substituted for a hydrogen atom bonded to a carbon atom in the ring structure of the group A and/or of the group B;
• wherein, in the two or more mono- or divalent chemical groups, at least one is selected from the chemical group (b);
• wherein if the group A is diphenylamine:
• the amino group of the diphenylamine is one of the two or more mono- or divalent chemical groups;
• and
• chemical group (a) is a sulfide group;
• chemical group (b) is a carboxylic acid alkyl ester group, an ether group, or a combination thereof;
• and
• chemical group (c) is a fluoroalkyl group.