Radiation-sensitive composition and method for forming resist pattern

3:

• The radiation-sensitive composition according to claim 1, wherein the compound (B) comprises a structure in which an iodo group is bound to an aromatic ring.

6:

• The radiation-sensitive composition according to claim 1, further comprising an onium salt compound which can generate an acid having an acidity lower than an acidity of an acid generated by the compound (B) and which differs from the compound (B).

7:

• The radiation-sensitive composition according to claim 1, further comprising an onium salt compound which can generate an acid having an acidity higher than an acidity of an acid generated by the compound (B) and which differs from the compound (B).

8:

• The radiation-sensitive composition according to claim 1, wherein the compound (B) comprises a first onium salt compound, and a second onium salt compound which can generate an acid having an acidity lower than an acidity of an acid generated by the first onium salt compound.

9:

• The radiation-sensitive composition according to claim 1, wherein the cation comprises a sulfonium cation structure or an iodonium cation structure.

10:

• The radiation-sensitive composition according to claim 9, wherein the cation comprises an aromatic ring bound to a sulfonium cation or an iodonium cation, and at least one group selected from the group consisting of a fluoroalkyl group, a fluoro group excepting a fluoro group in the fluoroalkyl group, and an iodo group is bound to the aromatic ring.

11:

• The radiation-sensitive composition according to claim 1, wherein the polymer (A) further comprises a structural unit comprising an acid-dissociable group.

12:

• The radiation-sensitive composition according to claim 1, wherein the polymer (A) further comprises a structural unit comprising an aromatic group and a hydroxy group bound to the aromatic ring.

13:

• The radiation-sensitive composition according to claim 1, wherein the polymer (A) further comprises a structural unit comprising a fluorine atom.

14:

• The radiation-sensitive composition according to claim 13, wherein the polymer (A) comprises the structural unit comprising a fluorine atom in an amount, with respect to all the structural units forming the polymer (A), of 45 to 99 mol %.

15:

• The radiation-sensitive composition according to claim 13, wherein an amount of the polymer (A), with respect to the entire amount of the composition excepting the solvent, is 0.1 to 20 mass %.

16:

• The radiation-sensitive composition according to claim 1, wherein the polymer (A) comprises the structural unit represented by the formula (1) in an amount, with respect to all the structural units forming the polymer (A), of 1 to 55 mol %.

17:

• The radiation-sensitive composition according to claim 1, further comprising
• (C) a polymer comprising a structural unit which comprises an acid-dissociable group and the polymer (C) being different from the polymer (A), wherein
• the polymer (A) has a fluorine atom content by mass higher than a fluorine atom content of the polymer (C).

19:

• The radiation-sensitive composition according to claim 1, wherein D− in the formula (1) is —COO−, —SO3−, —PO3−, —POO−, or —O−.