Bismide compound, acid generator and resist composition each containing the same, and method of forming pattern from the composition

A bisimide compound shown by the general formula [1]:

• wherein two R's are each independently a hydrogen atom or a group shown by the general formula [2]:
• —SO2R1 [2]
• wherein R1 is an alkyl group having 1 to 12 carbon atoms, a haloalkyl group having 1 to 12 carbon atoms, or an aryl group, an aralkyl group or an aromatic heterocyclic group, which may have a substituent selected from the group consisting of a halogen atom, an alkyl group, a haloalkyl grou having 1 to 4 carbon atoms, an alkoxy group, a haloalkoxy group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, a nitro group, an N,N-dimethylamino group and an acetamide group, a camphor group or a naphthoquinonediazide group;
• A1 is a tetra-valent alicyclic hydrocarbon group having 4 to 10 carbon atoms, a tetra-valent bridged alicyclic hydrocarbon group having 7 to 8 carbon atoms, a tetra-valent aromatic hydrocarbon group having 6 to 14 carbon atoms or a group shown by the general formula [3]:
• wherein A2 is a direct-linkage, an —O— group or a —C(CF3)2— group[[)]], and provided that A, is a group shown by the general formula [3] when R is a hydrogen atom, an alkyl group shown by R1 in the general formula [2] is one having 6 to 12 carbon atoms when A1 is a tetra-valent bridged alicyclic hydrocarbon group having 7 to 8 carbon atoms, and one having 3 to 12 carbon atoms when A1 is a tetra-valent aromatic hydrocarbon group having 6 to 14 carbon atoms;
• and a haloalkyl group shown by R1 is one having 3 to 12 carbon atoms when A1 is a group shown by the general formula [3];
• and further an alkyl group as a substituent of an aryl group which may have a substituent, shown by R1 is one having 2 to 12 carbon atoms when A2 in the general formula [3] is an —O— group.