Topcoat compositions containing fluorinated thermal acid generators
Provided are topcoat compositions that include: a matrix polymer; a surface active polymer; an ionic thermal acid generator comprising an anion and a cation, wherein the anion, the cation, or the anion and the cation are fluorinated; and a solvent. Also provided are coated substrates and pattern-forming methods which make use of the topcoat compositions. The invention has particular applicability in photolithographic processes as a photoresist topcoat layer in the manufacture of semiconductor devices.
1. A topcoat composition, comprising:
a matrix polymer;
a surface active polymer;
an ionic thermal acid generator comprising an anion and a cation, wherein the anion, the cation, or the anion and the cation are fluorinated, wherein the cation is of the general formula (I):
(BH) + (I)
which is the monoprotonated form of a nitrogen-containing base B; and
a solvent.
2. The topcoat composition of claim 1 , wherein the anion is fluorinated.
3. The topcoat composition of claim 1 , wherein the cation is fluorinated.
4. The topcoat composition of claim 1 , wherein the anion is polycyclic.
5. The topcoat composition of claim 1 , wherein the ionic thermal acid generator comprises a fluorinated alcohol group comprising a fluorine atom bonded to a carbon at the alpha position of the hydroxyl group and/or or a fluorinated group bonded pendant to a carbon at the alpha position of the hydroxyl group.
6. The topcoat composition of claim 5 , wherein the fluorinated alcohol group is bonded to an aromatic ring of the anion through an ester group.
7. The topcoat composition of claim 6 , wherein the anion comprises a plurality of fluorinated alcohol groups bonded to the aromatic ring through a respective ester group.
8. The topcoat composition of claim 1 , wherein the ionic thermal acid generator comprises a nitrogen-containing cation.
9. The topcoat composition of claim 1 , further comprising a photoacid generator.
10. The topcoat composition of claim 1 , wherein the solvent comprises a mixture of organic solvents comprising a first organic solvent having a boiling point of from 120 to 140° C., a second organic solvent having a boiling point of from 140 to 180° C. and a third organic solvent having a boiling point of from 170 to 200° C.
11. The topcoat composition of claim 1 , wherein the base has a pKa from 0 to 5.0.
12. The topcoat composition of claim 1 , wherein the cation is a substituted or unsubstituted C3-30 aryl amine.
13. A coated substrate, comprising: a semiconductor substrate; a photoresist layer over the semiconductor substrate; and a topcoat layer over the photoresist layer, wherein the topcoat layer is formed from a topcoat composition of claim 1 .
14. A pattern-forming method, comprising:
(a) forming a photoresist layer over a substrate;
(b) forming a topcoat layer over the photoresist layer, wherein the topcoat layer is formed from a topcoat composition of claim 1 ;
(c) exposing the topcoat layer and the photoresist layer to activating radiation; and
(d) contacting the exposed topcoat layer and photoresist layer with a developer to form a photoresist pattern.
15. The pattern-forming method of claim 14 , wherein the base has a pKa from 0 to 5.0.
16. The pattern-forming method of claim 14 , wherein the cation is a substituted or unsubstituted C3-30 aryl amine.
17. The pattern-forming method of claim 14 , wherein the ionic thermal acid generator comprises a fluorinated alcohol group comprising a fluorine atom bonded to a carbon at the alpha position of the hydroxyl group and/or or a fluorinated group bonded pendant to a carbon at the alpha position of the hydroxyl group.
18. The pattern-forming method of claim 17 , wherein the fluorinated alcohol group is bonded to an aromatic ring of the anion through an ester group.
19. The pattern-forming method of claim 18 , wherein the anion comprises a plurality of fluorinated alcohol groups bonded to the aromatic ring through a respective ester group.