Thickening composition, method for manufacturing thickened resist pattern, and method for manufacturing processed substrate

A thickening composition comprising:

• a polymer (A) comprising a repeating unit (A1) represented by the formula (a1) and a solvent (B):
• wherein
• L1, L2 and L3 are each independently a single bond, C1-10 linear alkylene, C3-10 branched alkylene or C3-10 cyclic alkylene;
• R1, R2 and R3 are each independently H, C1-10 linear alkyl, C3-10 branched alkyl, C3-10 cyclic alkyl, C6-15 aryl or C6-15 aralkyl;
• R4 is C1-15 linear alkyl, C3-15 branched alkyl, C3-15 cyclic alkyl, C6-15 aryl, C6-15 aralkyl or a combination of any of these;
• wherein at least one of hydrogen atoms in R4 can be replaced with C1-5 linear alkyl—COOH or —OH;
• wherein at least one of non-adjacent methylene (—CH2—) in L1, L2, L3, R1, R2, R3 and R4 can be replaced with —O—, —S—,—CO—, —CO—O—, —O—CO—, —O—CO—O—, -CR5=CR6- or —C≡C—;
• R5 and R6 are each independently H or C1-6 linear alkyl;
• X is O or S;
• and
• n is 0 or 1.