Method for forming multi-layer film and patterning process

A method for forming a multi-layer film on a substrate, comprising the steps of:

• (1) forming an under layer film on the substrate by applying an under layer film material containing a resin having a repeating unit represented by the general formula (1) or (2) in which a fluorene structure is contained, and curing the same by heat treatment;
• (2) forming a metal oxide film on the under layer film by applying a metal oxide film material selected from a titanium oxide film material, a zirconium oxide film material, and a hafnium oxide film material;
• (3) forming a hydrocarbon film on the metal oxide film by applying a hydrocarbon film material;
• and
• (4) forming a silicon oxide film on the hydrocarbon film by applying a silicon oxide film material,
• wherein X represents a benzene ring, a naphthalene ring, or a carbazole ring;
• R1 represents a hydrogen atom, a glycidyl group, a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms;
• R2 represents a hydrogen atom, a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms;
• each R3 independently represents a single bond, an alkylene group having 1 to 20 carbon atoms, an alkenylene group having 2 to 20 carbon atoms, or an arylene group having 6 to 20 carbon atoms, and optionally contains one or more groups selected from an ether group, an ester group, a hydroxyl group, a carboxyl group, an alkoxy group, and a glycidylether group;
• R4 and R5 independently represent a benzene ring or a naphthalene ring, and a hydrogen atom(s) in the benzene ring or the naphthalene ring may be substituted by a hydrocarbon group having 1 to 6 carbon atoms;
• and “p” and “q” independently represent an integer of 0 to 2.