Fluorinated copolymer process for its production and resist composition containing it

A fluorinated copolymer (A2) having units derived from a monomer unit formed by cyclopolymerization of a fluorinated diene represented by the following formula (1) and units derived from a monomer unit formed by polymerization of an acrylic monomer represented by the following formula (3):

• CF2═CFCH2CH(CH2C(CF3)2(OR1))CH2CH═CH2 (1)
• wherein R1 is a hydrogen atom, an alkyl group having at most 20 carbon atoms, which may have an etheric oxygen atom, an alkoxycarbonyl group having at most 15 carbon atoms, or CH2R2 (wherein R2 is an alkoxycarbonyl group having at most 15 carbon atoms), and the alkyl group and the alkoxycarbonyl group for R1, and R2 may have some or all of their hydrogen atoms substituted by fluorine atoms;
• CH2═CR5COOR6 (3)
• wherein R5 is a hydrogen atom, a fluorine atom, an alkyl group having at most 3 carbon atoms, or a fluoroalkyl group having at most 3 carbon atoms, R6 is an alkyl group having at most 20 carbon atoms, and some of hydrogen atoms of the alkyl group may be substituted by fluorine atoms, alkyl groups or fluoroalkyl groups.

A method for producing a fluorinated copolymer (A1) characterized by radical copolymerizing a fluorinated diene represented by the following formula (1) and a functional group-containing fluorinated diene represented by the following formula (2) (provided that a fluorinated diene represented by the formula (1) is excluded):

• CF2═CFCH2CH(CH2C (CF3)2(OR1))CH2CH═CH2 (1)
• wherein R1 is a hydrogen atom, an alkyl group having at most 20 carbon atoms, which may have an etheric oxygen atom, an alkoxycarbonyl group having at most 15 carbon atoms, or CH2R2 (wherein R2 is an alkoxycarbonyl group having at most 15 carbon atoms), and the alkyl group and the alkoxycarbonyl group for R1, and R2 may have some or all of their hydrogen atoms substituted by fluorine atoms;
• CF2═CR3-Q-CR4═CH2 (2)
• wherein each of R3 and R4 which are independent of each other, is a hydrogen atom, a fluorine atom, an alkyl group having at most 3 carbon atoms, a fluoroalkyl group having at most 3 carbon atoms, or a cyclic aliphatic hydrocarbon group, and Q is an alkylene group, an oxyalkylene group, a fluoroalkylene group or an oxyfluoroalkylene group, having a functional group or a functional group-containing side chain group.

A method for producing a fluorinated copolymer (A2) having a cyclic structure in its main chain, characterized by radical copolymerizing a fluorinated diene represented by the following formula (1) and an acrylic monomer represented by the following formula (3):

• CF2═CFCH2CH(CH2C(CF3)2(OR1))CH2CH═CH2 (1)
• wherein R1 is a hydrogen atom, an alkyl group having at most 20 carbon atoms, which may have an etheric oxygen atom, an alkoxycarbonyl group having at most 15 carbon atoms, or CH2R2 (wherein R2 is an alkoxycarbonyl group having at most 15 carbon atoms), and the alkyl group and the alkoxycarbonyl group for R1, and R2 may have some or all of their hydrogen atoms substituted by fluorine atoms;
• CH2═CR5COOR6 (3)
• wherein R5 is a hydrogen atom, a fluorine atom, an alkyl group having at most 3 carbon atoms, or a fluoroalkyl group having at most 3 carbon atoms, R6 is an alkyl group having at most 20 carbon atoms, and some of hydrogen atoms of the alkyl group may be substituted by fluorine atoms, alkyl groups or fluoroalkyl groups.