Acid generators and photoresists comprising same

1. A photoresist composition, comprising:

(i) a polymer;

(ii) a first non-polymeric onium salt acid generator that produces a first acid upon exposure of the photoresist composition to activating radiation; and

(iii) a second onium salt acid generator that 1) comprises a covalently bound acid-labile moiety and 2) produces a second acid upon exposure of the photoresist composition to activating radiation;

wherein the first acid and second acid have pKa values that differ by at least 1; and

the acid-labile moiety of the second onium salt acid generator is a group of the formula —C(═O)O(CH 2 ) n (C═O)O-ALG, where n is an integer of from 1 to 12 and ALG is a group that results in an acid labile moiety.

2. The photoresist composition of claim 1 wherein the pKa value of the first acid is lower than the pKa value of the second acid.

3. A method for providing a photoresist relief image, comprising:

a) applying a coating layer of a photoresist composition of claim 1 on a substrate; and

b) exposing the photoresist composition layer to activating radiation and developing the exposed photoresist composition coating layer.

4. The method of claim 3 wherein the photoresist composition layer is exposed to EUV or e-beam radiation.

5. The photoresist composition of claim 1 wherein the first onium salt acid generator and the second onium salt acid generator are each not bound to a polymer.

6. The photoresist composition of claim 1 wherein at least one of the first onium salt acid generator and the second onium salt acid generator comprises a thioxanthone moiety.

7. The photoresist composition of claim 1 wherein at least one of the first onium salt acid generator and the second onium salt acid generator comprises a dibenzothiophene moiety.

8. The photoresist composition of claim 1 wherein the first acid and second acid have pKa values that differ by at least 1.5.

9. The photoresist composition of claim 1 wherein the first acid and second acid have pKa values that differ by at least 2.

10. The photoresist composition of claim 1 wherein the first acid and second acid have pKa values that differ by at least 3.

11. The photoresist composition of claim 1 wherein the first acid and second acid have pKa values that differ by at least 4.

12. The photoresist composition of claim 1 wherein both the first onium salt acid generator and the second onium salt acid generator are sulfonium compounds.

13. A photoresist composition of claim 1 further comprising a non-photo-destroyable base.

14. A photoresist composition, comprising:

(i) a polymer;

(ii) a first non-polymeric onium salt acid generator that produces a first acid upon exposure of the photoresist composition to activating radiation; and

(iii) a second onium salt acid generator that 1) comprises a covalently bound acid-labile moiety and 2) produces a second acid upon exposure of the photoresist composition to activating radiation;

wherein the first acid and second acid have pKa values that differ by at least 1;

wherein at least one of the first onium salt acid generator and the second onium salt acid generator comprises a thioxanthone moiety; and

wherein the first onium salt acid generator and the second onium salt acid generator are each not bound to a polymer.

15. A photoresist composition of claim 14 further comprising a non-photo-destroyable.

16. A photoresist composition of claim 14 wherein the acid-labile moiety of the second onium salt acid generator is a group of the formula —C(═O)O(CH 2 ) n (C═O)O-ALG, where n is an integer of from 1 to 12 and ALG is a group that results in an acid labile moiety.