Material for forming underlayer film for lithography, composition for forming underlayer film for lithography, underlayer film for lithography and production method thereof, pattern forming method, resin, and purification method

A method for forming an underlayer film for lithography, comprising:

• forming an underlayer film on a substrate using a composition for forming an underlayer film, the composition including a solvent and a material for forming an underlayer film;
• and
• forming at least one photoresist layer on the underlayer film,
• the material for forming an underlayer film including at least any of a compound represented by following formula (1) or a resin including a structural unit derived from a compound represented by the following formula (1),
• wherein R1 represents a 2n-valent group having 1 to 60 carbon atoms, or a single bond, each R2 independently represents a halogen atom, a straigh, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a thiol group, a hydroxyl group, or a group where a hydrogen atom of a hydroxyl group is substituted with an acid-dissociable group, and may be the same or different in the same naphthalene ring or benzene ring, in which at least one R2 represents a group where a hydrogen atom of a hydroxyl group is substituted with an acid-dissociable group, n is an integer of 1 to 4, and structural formulae of n structural units in square brackets [ ] may be the same or different when n is an integer of 2 or more, X represents an oxygen atom, a sulfur atom, or a non-bridging group, each m2 is independently an integer of 0 to 7, provided that at least one m2 is an integer of 1 to 7, and each q is independently 0 or 1, wherein the compound has a group including an iodine atom.

A resist pattern forming method comprising:

• a step of forming an underlayer film on a substrate using a composition for forming an underlayer film, the composition including a solvent and a material for forming an underlayer film, the material for forming an underlayer film including at least any of a compound represented by following formula (1-1) or a resin including a structural unit derived from a compound represented by the following formula (1-1),
• wherein R1 represents a 2n-valent group having 1 to 60 carbon atoms, or a single bond, each R3 independently represents a halogen atom, a straight, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, or a thiol group, and may be the same or different in the same naphthalene ring or benzene ring, each R4 independently represents a hydrogen atom or an acid-dissociable group, in which at least one R4 represents an acid-dissociable group, n is an integer of 1 to 4, and structural formulae of n structural units in square brackets [ ] may be the same or different when n is an integer of 2 or more, each m5 is independently an integer of 1 to 6, each m6 is independently an integer of 0 to 5, m5 + m6 is an integer of 1 to 6, and each q is independently 0 or 1
• a step of forming at least one photoresist layer on the underlayer film, and
• a step of irradiating a predetermined region of the photoresist layer with radiation, and developing it.

A circuit pattern forming method comprising:

• a step of forming an underlayer film on a substrate using a composition for forming an underlayer film, the composition including a solvent and a material for forming an underlayer film, the material for forming an underlayer film including at least any of a compound represented by following formula (1-1) or a resin including a structural unit derived from a compound represented by the following formula (1-1),
• wherein R1 represents a 2n-valent group having 1 to 60 carbon atoms, or a single bond, each R3 independently represents a halogen atom, a straight, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, or a thiol group, and may be the same or different in the same napthalene ring of benzene ring, each R4 independently represents a hydrogen atom or an acid-dissociable group, in which at least one R4 represents an acid-dissociable group, n is an integer of 1 to 4, and structural formulae of n structural units in square brackets [ ] may be the same or different when n is an integer of 2 or more, each m5 is independently an integer of 1 to 6, each m6 is independently an integer of 0 to 5, m5 + m6 is an integer of 0 to 6, and each q is independently 0 or 1
• a step of forming an intermediate layer film on the underlayer film by using a silicon atom-containing resist intermediate layer film material,
• a step of forming at least one photoresist layer on an intermediate layer film,
• a step of irradiating a predetermined region of the photoresist layer with radiation, and developing it to form a resist pattern,
• a step of etching the intermediate layer film with the resist pattern as a mask, to form an intermediate layer film pattern,
• a step of etching the underlayer film with the intermediate layer film pattern as an etching mask, to form an underlayer film pattern, and
• a step of etching the substrate with the underlayer film pattern as an etching mask, to form a pattern on the substrate.

A purification method comprising:

• a step of providing a solution (A) by dissolving a compound represented by following formula (1-1) or a resin including a structural unit derived from a compound represented by the following formula (1-1) in a solvent, and
• a first extraction step of bringing the resulting solution (A) into contact with an acidic aqueous solution, to extract impurities in the solution (A), wherein
• the solvent to be used in the step of providing the solution (A) comprises an organic solvent optionally immiscible with water,
• wherein R1 represents a 2n-valent group having 1 to 60 carbon atoms, or a single bond, each R2 independently represents a halogen atom, a straight, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, or a thiol group, and may be the same or different in the same napthalene ring or benzene ring, each R4 independently represents a hydrogen atom or an acid-dissociable group, in which at least one R4 represents an acid-dissociable group, n is an integer of 1 to 4, and structural formulae of n structural units in square brackets [ ] may be the same or different when n is an integer of 2 or more, each m5 is independently an integer of 1 to 6, each m6 is independently an integer of 0 to 5, m5 + m6 is an integer of 1 to 6, and each q is independently 0 or 1.