Thermosetting iodine- and silicon-containing material, composition containing the material for forming resist underlayer film for EUV lithography, and patterning process

A composition for forming a silicon-containing resist underlayer film for EUV lithography, comprising:

• a thermosetting silicon-containing material;
• and
• a crosslinking catalyst, wherein
• the thermosetting silicon-containing material comprises:
• (i) one or more of
• a repeating unit shown by the following general formula (Sx-1),
• a repeating unit shown by the following general formula (Sx-2), and
• a partial structure shown by the following general formula (Sx-3),
• wherein R1 represents an iodine-containing organic group shown by the following general formula (Sx-R1):
• wherein R11 represents a single bond;
• R12 represents a monovalent organic group having 1 to 10 carbon atoms, a hydroxyl group, or a halogen atom other than iodine;
• n1 is 1, 2, or 3;
• and n2 is 0, 1, or 2;
• and R2 and R3 are each independently identical to R1, a hydrogen atom, or a monovalent organic group having 1 to 30 carbon atoms, and
• (ii) one or more of partial structures shown by the following formulae (Sx-x),