Photoacid generating polymers containing a urethane linkage for lithography

1. A photoacid generating polymer (PAG polymer), comprising:

a first repeat unit of formula (1):

wherein R a is an acid sensitive group and R b 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 R c is hydrogen or methyl, and Z′ 3 S ⊕ 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′-C(CF 3 ) 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;

wherein the first repeat unit, second repeat unit, and the third repeat unit are covalently bound repeat units of the PAG polymer.

2. The PAG polymer of claim 1 , wherein R a is selected from the group consisting of t-butyl, 1-ethyl-1-cyclopentyl, 1-methyl-1-cyclopentyl, 1-ethyl-1-cyclooctyl, 2-ethyl-2-adamantyl, 2-methyl-2-adamantyl, and combinations thereof.

3. The PAG polymer of claim 1 , wherein R b and R c are methyl.

4. The PAG polymer of claim 1 , wherein the third repeat unit is a mixture of structural isomers.

5. The PAG polymer of claim 1 , wherein the third repeat unit is a single structural isomer.

6. The PAG polymer of claim 1 , wherein the third repeat unit is a mixture of stereoisomers.

7. The PAG polymer of claim 1 , wherein the third repeat unit is a single stereoisomer.

8. The PAG polymer of claim 1 , wherein each Z′ is phenyl and Z′ 3 S ⊕ is a triphenylsulfonium ion (TPS ⊕ ).

9. The PAG polymer of claim 1 , wherein the third repeat unit has the formula (3):

wherein R d is hydrogen or methyl and L′ is a divalent linking group comprising at least one carbon.

10. The PAG polymer of claim 5 , wherein the norbornyl ring further comprises an alkyl and/or cycloalkyl substituent.

11. The PAG polymer of claim 1 , wherein the third repeat unit is:

12. The PAG polymer of claim 1 , wherein the first repeat unit is present in an amount of about 30 to about 45 mole percent based on total moles of repeat units in the PAG polymer.

13. The PAG polymer of claim 1 , wherein the second repeat unit is present in an amount of about 2.5 to about 8 mole percent based on total moles of repeat units in the PAG polymer.

14. The PAG polymer of claim 1 , wherein the third repeat unit is present in an amount of about 15 to about 55 mole percent based on total moles of repeat units in the PAG polymer.

15. The PAG polymer of claim 1 , comprising a fourth repeat unit of formula (5):

wherein R f is hydrogen or methyl.

16. The PAG polymer of claim 1 , comprising a fourth repeat unit of formula (6):

wherein R g is hydrogen or methyl.

17. The PAG polymer of claim 1 , comprising a fourth repeat unit comprising a pendant lactone.

18. The PAG polymer of claim 17 , wherein the fourth repeat unit is selected from the group consisting of

and combinations thereof.

19. A photoacid generating polymer (PAG polymer), comprising:

a first repeat unit of formula (1):

wherein R a is an acid sensitive group and R b 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 R c is hydrogen or methyl, and Z′ 3 S ⊕ 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 (CF 3 ), 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.

20. The PAG polymer of claim 19 , wherein the third repeat unit has the formula (4):

wherein R e is hydrogen or methyl and L′ is a divalent linking group comprising at least one carbon.

21. The PAG polymer of claim 19 , wherein the third repeat is:

22. 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 R a is an acid sensitive group and R b 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 R c is hydrogen or methyl, and Z′ 3 S ⊕ 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(CF 3 ) 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.

23. The method of claim 22 , wherein the third polymerizable monomer has the formula (9):

wherein R d is hydrogen or methyl and L′ is a divalent linking group comprising at least one carbon.

24. The method of claim 22 , wherein the third polymerizable monomer is NbHFAMA:

25. The method of claim 22 , wherein R a is selected from the group consisting of t-butyl, 1-ethyl-1-cyclopentyl, 1-methyl-1-cyclopentyl, 1-ethyl-1-cyclooctyl, 2-ethyl-2-adamantyl, and 2-methyl-2-adamantyl, and combinations thereof.

26. 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 R a is an acid sensitive group and R b 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 R c is hydrogen or methyl, and Z′ 3 S ⊕ 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 (CF 3 ), 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.

27. The method of claim 26 , wherein the third polymerizable monomer has the formula (10):

wherein each R e is hydrogen or methyl and L′ is a divalent linking group comprising at least one carbon.

28. The method of claim 26 , wherein the third polymerizable monomer is NbNHCF3SO2MA:

NbNHCF3SO2MA.

29. A photoresist composition, comprising the PAG polymer of claim 1 , a solvent, and an optional base quencher.

30. A photoresist composition, comprising the PAG polymer of claim 19 , a solvent, and an optional base quencher.

31. A lithographic process comprising:

disposing on a substrate a photoresist composition comprising the PAG polymer of claim 1 , a solvent, and an optional base quencher;

removing the solvent, thereby forming a photoresist layer disposed on the substrate;

optionally heating the photoresist layer in a post-application bake;

imagewise exposing the photoresist layer or the heated photoresist layer to a radiation, thereby forming an exposed photoresist layer comprising regions of exposed photoresist and regions of non-exposed photoresist;

optionally heating the exposed photoresist layer in a post-exposure bake;

treating the exposed photoresist layer or the heated exposed photoresist layer with a developer, thereby forming a relief pattern; and

optionally transferring the relief pattern to the substrate.

32. The process of claim 31 , wherein the developer is an aqueous base, and the developer removes regions of exposed photoresist.

33. A lithographic process comprising:

disposing on a substrate a photoresist composition comprising the PAG polymer of claim 19 , a solvent, and an optional base quencher;

removing the solvent, thereby forming a photoresist layer disposed on the substrate;

optionally heating the photoresist layer in a post-application bake;

imagewise exposing the photoresist layer or the heated photoresist layer to a radiation, thereby forming an exposed photoresist layer comprising regions of exposed photoresist and regions of non-exposed photoresist;

optionally heating the exposed photoresist layer in a post-exposure bake;

treating the exposed photoresist layer or the heated exposed photoresist layer with a developer, thereby forming a relief pattern; and

optionally transferring the relief pattern to the substrate.