Patterning process and composition for forming silicon-containing film usable therefor

A patterning process for forming a negative pattern by lithography, comprising at least the steps of:

• using a composition for forming silicon-containing film, containing a silicon-containing compound (A) and an organic solvent (B), to form a silicon-containing film;
• wherein the silicon-containing compound (A) is obtained by hydrolytically condensing a mixture comprising:
• one or more kinds selected form a hydrolyzable silicon compound represented by the following general formula (A-1), a hydrolyzate of the compound, a condensate of the compound, and a hydrolysis condensate of the compound;
• and one or more kinds of compounds each selected from a group consisting of a hydrolyzable silicon compound represented by the following general formula (A-2-1), a hydrolyzate of the compound, a condensate of the compound, a hydrolysis condensate of the compound, a reactive compound represented by the following general formula (A-2-2), a hydrolyzate of the compound, a condensate of the compound, and a hydrolysis condensate of the compound,
• (R2)m2(OR3)(3-m2)Si—R1—Si(R4)m4(OR5)(3-m4) (A-1)
• R11m11R12m12R13m13Si(OR14)(4-m11-m12-m13) (A-2-1)
• U(OR21)m21(OR22)m22(O)m23/2 (A-2-2)
• , wherein
• R1 represents a single bond, or a divalent organic group having 1 to 20 carbon atoms,
• each R2 and R4 independently represent a hydrogen atom, or a monovalent organic group having 1 to 20 carbon atoms,
• each R3 and R5 independently represent a hydrogen atom, or an alkyl group having 1 to 6 carbon atoms, and
• m2 and m4 represent integers satisfying that 0≦m2+m4≦2;
• each R11, R12, and R13 independently represent a hydrogen atom, or a monovalent organic group having 1 to 30 carbon atoms,
• each m11, m12, and m13 independently represent 0 or 1, and satisfy that 0≦m11+m12+m13≦3, and
• R14 represents a hydrogen atom, or an alkyl group having 1 to 6 carbon atoms;
• and
• each R21 and R22 independently represent a hydrogen atom, or an organic group having 1 to 30 carbon atoms,
• m21+m22+m23/2 represents a valence to be determined by a kind of U,
• each m21, m22, and m23 independently represent an integer of 0 or more, and
• U represents one of elements belonging to the III group, IV group, and V group in the periodic table, except for carbon and silicon;
• using a silicon-free resist composition to form a photoresist film on the silicon-containing film;
• heat-treating the photoresist film, and
• subsequently exposing the photoresist film to a high energy beam;
• and
• using a developer comprising an organic solvent to dissolve an unexposed area of the photoresist film, thereby obtaining a negative pattern.