Chemically amplified negative resist composition and patterning process

A pattern forming process comprising the steps of:

• applying a negative resist composition onto a processable substrate to form a resist film,
• exposing the film patternwise to high-energy radiation, and
• developing the exposed film with an alkaline developer to form a resist pattern;
• wherein the negative resist composition is a chemically amplified negative resist composition comprising a polymer, adapted such that the polymer may turn insoluble in alkaline developer by reacting with a crosslinker and/or a recurring unit having a crosslinkable functional group in the polymer under the catalysis of an acid generated upon exposure to high-energy radiation, to form crosslinks between polymer molecules,
• said polymer consisting of:
• 0.5 to 10 mol % of recurring units of the general formula (1),
• 50 to less than 99.5 mol % of a sum total of recurring units of at least one type selected from the general formulae (2), (3), and (4),
• greater than 0 mol % and up to 39.5 mol % of recurring units of general formula (5),
• greater than 0 mol % and up to 39.5 mol % of a sum total of recurring units of at least one type selected from the general formulae (6) and (7), and
• 0 to 20 mol % of recurring units of the general formula (M-1) or (M-2);
• wherein A is a single bond or a C1-C10 alkylene group which may be separated by ethereal oxygen,
• Rf is each independently hydrogen, fluorine, trifluoromethyl, or pentafluoroethyl, with the proviso that not all Rf's are hydrogen,
• B is a C1-C10 divalent hydrocarbon group in which some or all hydrogen atoms may be replaced by fluorine and in which a methylene moiety at a position other than α- and β-positions relative to the ester oxygen atom may be replaced by oxygen,
• C is a single bond or a C1-C10 alkylene group which may be separated by ethereal oxygen,
• R1 is hydrogen, fluorine, methyl, or trifluoromethyl,
• R2, R3, and R4 are each independently a straight, branched or cyclic C1-C10 alkyl or alkoxy group,
• R5 is a substituted or unsubstituted, straight, branched or cyclic C1-C30 alkyl group which may contain an ether bond, or a substituted or unsubstituted C6-C14 aryl group,
• R6 is each independently a C1-C8 alkyl group,
• R7 is each independently a C1-C8 alkyl group,
• k, m and n are each independently an integer of 0 to 3, a is an integer of 0 to 4, b is an integer of 1 to 5, c and d each are an integer of 1 to 4, e is an integer of 0 to (4-c), f is an integer of 0 to (4-d), p is independently 0 or 1, and t is an integer of 0,
• wherein D is a single bond or a C1-C10 alkylene group which may be separated by ethereal oxygen, R1 is as defined above, R8 is each independently halogen, an optionally halo-substituted C1-C8 alkyl or alkoxy group, a C6-C20 aromatic ring-containing hydrocarbon group, or an optionally halo-substituted C1-C12 acyloxy group, g is an integer of 0 to 5, q is 0 or 1, and s is an integer of 0 to 2,
• wherein R9 is independently halogen, an optionally halo-substituted C1-C12 acyloxy group, an optionally halo-substituted C1-C8 alkyl group, or an optionally halo-substituted C1-C8 alkoxy group, and h is an integer of 0 to 4,
• wherein R1 is hydrogen, fluorine, methyl, or trifluoromethyl, R10 is hydrogen of or a straight, branched or cyclic C1-C8 monovalent hydrocarbon group, R11 is each independently a straight, branched or cyclic C1-C8 monovalent hydrocarbon group which may contain oxygen, or halogen, i is an integer of 0 to 4, and u is an integer of 0 to 2,
• wherein the recurring units of formula (1) account for 0.5 to 10 mol % and the sum of recurring units of formulae (2), (3), and (4) accounts for 50 to 99.5 mol %, recurring units of formula (5) account for 39.5 mol %, recurring units of formulae (6) or (7) account for up to 39.5 mol %, and recurring units of formulae (M-1) or (M-2) account for up to 20 mol %, based on the entire recurring units of the polymer.