Process of imaging a deep ultraviolet photoresist with a top coating and materials thereof
View Patent ↗The present invention relates to a process for imaging deep ultraviolet (uv) photoresists with a topcoat using deep uv immersion lithography. The invention further relates to a topcoat composition comprising a polymer with at least one ionizable group having a pK a ranging from about −9 to about 11. The invention also relates to a process for imaging a photoresist with a top barrier coat to prevent contamination of the photoresist from environmental contaminants.
1. A barrier coating solution for a photoresist imaged with immersion lithography, where the barrier coating comprises an alkyl alcohol solvent and a polymer comprising an ionizable group, further where pKa of the ionizable group ranges from about −9 to about 11, and further where the barrier coating can be removed in an aqueous alkaline solution and the barrier coating has a dissolution rate of less than 1% of the film thickness while immersed for 30 seconds in water.
2. The composition of claim 1 , where the polymer has the structure
where, R is the polymeric backbone, W is a spacer group, ZH is the ionizable group, and t=0-5.
3. The composition of claim 2 , where R is selected from a multicyclic polymeric backbone, a monocyclic backbone, a linear aliphatic backbone, a branched aliphatic backbone, an aromatic backbone, a fluorinated alkyl backbone and mixtures thereof.
4. The composition of claim 2 , where ZH is selected from —C(C n F 2n+1 ) 2 OH (n=1-8), —PhOH, (SO 2 ) 2 NH, (SO 2 ) 3 CH, (CO) 2 H, SO 3 H, PO 3 H and CO 2 H.
5. The composition of claim 1 , where the solvent is selected from an alkyl alcohol with the structure HOC n H 2n+1 , where n is between 3 and 7.
6. The composition of claim 1 , where the solvent further comprises an n-alkane solvent with the structure C n H 2n+2 , where n is between 3 and 7.
7. The composition of claim 1 , further comprising a photoactive compound.
8. A process for imaging a photoresist comprising the steps of,
a) forming a coating of a photoresist on a substrate;
b) forming a barrier coating over the photoresist from a barrier coating solution of claim 1 ;
c) imagewise exposing the photoresist and the barrier coating using immersion lithography, further where the immersion lithography comprises an immersion liquid between the barrier coating and exposure equipment; and
d) developing the coatings with an aqueous alkaline solution.
9. The process of claim 1 , where the barrier coating is insoluble in the immersion liquid.
10. The process of claim 1 , where the immersion liquid comprises water.
11. The process of claim 1 , where the barrier coating is soluble in an aqueous alkaline solution.
12. The process of claim 1 , where the photoresist is sensitive to exposure wavelength between 150 nm and 450 nm.
13. The process of claim 1 , where the barrier coating further comprises a carboxylate solvent and a polymer comprising an ionizable group.
14. The process of claim 13 , where the polymer has the structure
where, R is a polymeric backbone, W is a spacer group, ZH is the ionizable group, and t=0-5.
15. The process of claim 14 , where R is selected from a multicyclic polymeric backbone, a monocyclic backbone, a linear aliphatic backbone, a branched aliphatic backbone, an aromatic backbone, a fluorinated alkyl backbone, and mixtures thereof.
16. The process of claim 14 , where ZH is selected from —C(C n F 2n+1 ) 2 OH (n=1-8), —PhOH, (SO 2 ) 2 NH, (SO 2 ) 3 CH, (CO) 2 NH, SO 3 H, PO 3 H and CO 2 H.
17. The process of claim 13 , where the barrier coating further comprises a photoactive compound.
18. The process of claim 13 , where the alkyl alcohol has the structure HOC n H 2n+1 , where n is between 3 and 12.
19. The process of claim 13 , where the solvent further comprises an n-alkane solvent with the structure C n H 2n+2 , where n is between 3 and 12.
20. The process of claim 1 , where the aqueous alkaline solution comprises tetramethyl ammonium hydroxide.
21. A process for imaging a deep UV photoresist to prevent environmental base contamination comprising the steps of,
a) forming a coating of a photoresist on a substrate;
b) forming a barrier coating over the photoresist from a barrier coating solution of claim 5 ;
c) imagewise exposing the photoresist and the barrier coating in a gaseous environment; and,
d) developing the coatings with an aqueous alkaline solution.
22. The process of claim 21 where the polymer has a pKa of less than 9.
23. The process of claim 21 where the barrier coating solution further comprises a photoactive compound.
24. The process of claim 21 where the exposure step is in air.
25. The process of claim 21 where the exposure is at 193 nm or 157 nm.
26. The process of claim 21 where the aqueous alkaline solution comprises tetramethyl ammonium hydroxide.
27. The process of claim 21 , where the solvent further comprises, an alkane or a carboxylate.