Photoacid generating polymers containing a urethane linkage for lithography

A photoacid generating polymer (PAG polymer), comprising:

• a first repeat unit of formula (1):
• wherein Ra is an acid sensitive group and Rb is hydrogen or methyl, wherein the first repeat unit is capable of reacting with a photogenerated acid to form a carboxylic acid containing repeat unit;
• a second repeat unit of formula (2):
• wherein Rc is hydrogen or methyl, and Z′3S⊕ is a triarylsulfonium counterion, and each Z′ is an independent monovalent aryl group, wherein the second repeat unit is capable of forming the photogenerated acid;
• and
• a third repeat unit comprising a norbornyl ester, wherein a norbornyl ring of the norbornyl ester comprises a monovalent substituent having the formula *-L′—NHS(═O)2(CF3), wherein L′ is a divalent linking group comprising at least one carbon and the starred bond of L′ is linked to the norbornyl ring;
• wherein the first repeat unit, the second repeat unit, and the third repeat unit are covalently bound repeat units of the PAG polymer.

A method of preparing a photoacid generating polymer (PAG polymer), comprising:

• forming a reaction mixture comprising:
• i) a solvent,
• ii) a polymerization initiator,
• iii) a first polymerizable monomer of formula (7):
• wherein Ra is an acid sensitive group and Rb is hydrogen or methyl, wherein the first polymerizable monomer is capable of forming a first repeat unit, the first repeat unit capable of reacting with a photogenerated acid to form a carboxylic acid containing repeat unit;
• iv) a second polymerizable monomer of formula (8):
• wherein Rc is hydrogen or methyl, and Z′3S⊕ is a triarylsulfonium counterion wherein each Z′ is an independent monovalent aryl group, and wherein the second polymerizable monomer is capable of forming a second repeat unit, the second repeat unit capable of forming the photogenerated acid;
• and
• v) a third polymerizable monomer comprising a norbornyl ester, wherein a norbornyl ring of the norbornyl ester comprises a monovalent substituent having the formula *-L′-C(CF3)2(OH), wherein L′ is a divalent linking group comprising at least one carbon and the starred bond of L′ is linked to the norbornyl ring, and wherein the third polymerizable monomer is capable of forming a third repeat unit comprising a norbornyl ester;
• and
• agitating and optionally heating the mixture, thereby forming the PAG polymer, wherein the first repeat unit, the second repeat unit, and the third repeat unit are covalently bound repeat units of the PAG polymer.

A method of preparing a photoacid generating polymer (PAG polymer), comprising:

• forming a reaction mixture comprising:
• i) a solvent,
• ii) a polymerization initiator,
• iii) a first polymerizable monomer of formula (7):
• wherein Ra is an acid sensitive group and Rb is hydrogen or methyl, wherein the first polymerizable monomer is capable of forming a first repeat unit, the first repeat unit capable of reacting with a photogenerated acid to form a carboxylic acid containing repeat unit;
• iv) a second polymerizable monomer of formula (8):
• wherein Rc is hydrogen or methyl, and Z′3S⊕ is a triarylsulfonium counterion wherein each Z′ is an independent monovalent aryl group, and wherein the second polymerizable monomer is capable of forming a second repeat unit, the second repeat unit capable of forming the photogenerated acid;
• and
• v) a third polymerizable monomer comprising a norbornyl ester, wherein a norbornyl ring of the norbornyl ester comprises a monovalent substituent having the formula *-L′—NHS(═O)2(CF3), wherein L′ is a divalent linking group comprising at least one carbon and the starred bond of L′ is linked to the norbornyl ring, and wherein the third polymerizable monomer is capable of forming a third repeat unit comprising a norbornyl ester;
• and
• agitating and optionally heating the mixture, thereby forming the PAG polymer, wherein the first repeat unit, the second repeat unit, and the third repeat unit are covalently bound repeat units of the PAG polymer.