Photoresist pattern trimming methods
View Patent ↗Provided are methods of trimming photoresist patterns. The methods involve coating a photoresist trimming composition over a photoresist pattern, wherein the trimming composition includes a matrix polymer, a thermal acid generator and a solvent, the trimming composition being free of cross-linking agents. The coated semiconductor substrate is heated to generate an acid in the trimming composition from the thermal acid generator, thereby causing a change in polarity of the matrix polymer in a surface region of the photoresist pattern. The photoresist pattern is contacted with a developing solution to remove the surface region of the photoresist pattern. The methods find particular applicability in the formation of very fine lithographic features in the manufacture of semiconductor devices.
1. A method of trimming a photoresist pattern, comprising, in sequence:
(a) providing a semiconductor substrate comprising one or more layers to be patterned on an upper surface thereof;
(b) forming a photoresist pattern on the one or more layers to be patterned, wherein the photoresist pattern comprises a plurality of features and is formed from a chemically amplified photoresist composition, the photoresist pattern comprising a matrix polymer having acid labile groups;
(c) coating a photoresist trimming composition over the photoresist pattern, wherein the trimming composition comprises a matrix polymer comprising one or more group chosen from —OH, hydroxyl styrene, hydroxyl naphthalene, hexafluoroisopropyl alcohol and combinations thereof, a thermal acid generator and a solvent, and wherein the trimming composition is free of cross-linking agents;
(d) heating the coated semiconductor substrate to generate an acid in the trimming composition from the thermal acid generator, thereby causing a change in polarity of the photoresist matrix polymer in a surface region of the photoresist pattern; and
(e) contacting the photoresist pattern with a developing solution to remove the surface region of the photoresist pattern.
2. The method of claim 1 , wherein the acid generated by the thermal acid generator is fluorine-substituted.
3. The method of claim 1 , wherein the matrix polymer of the photoresist trimming composition is soluble in aqueous alkaline developer.
4. The method of claim 1 , wherein the developing solution is an aqueous tetramethylammonium hydroxide solution.
5. The method of claim 1 , wherein the trimming composition further comprises a compound comprising functional groups chosen from —OH, —NH, —SH, ketones, aldehydes, —SiX wherein X is chosen from halogens, vinyl ethers and combinations thereof, and combinations thereof.
6. The method of claim 1 , wherein the plurality of features of the photoresist pattern comprise a plurality of lines or posts having a duty ratio of 1:1 or more before trimming and 1:3 or less sense after trimming.
7. The method of claim 1 , further comprising:
(f) forming sidewall spacers on the trimmed photoresist pattern after contacting the photoresist pattern with the developing solution; and
(g) removing the trimmed photoresist pattern, leaving sidewall spacers on the one or more layers to be patterned.
8. The method of claim 1 , wherein the thermal acid generator generates an aromatic acid.
9. The method of claim 1 , wherein the thermal acid generator generates a sulfonic acid.
10. The method of claim 1 , wherein the solvent is chosen from alcohols, ethers and mixtures thereof.
11. The method of claim 1 , wherein the thermal acid generator generates a non-aromatic acid.
12. The method of claim 11 , wherein the non-aromatic acid has at least one fluorine substituent at the alpha position of the acid group.
13. A method of trimming a photoresist pattern, comprising, in sequence:
(a) providing a semiconductor substrate comprising one or more layers to be patterned on an upper surface thereof;
(b) forming a photoresist pattern on the one or more layers to be patterned, wherein the photoresist pattern comprises a plurality of features and is formed from a chemically amplified photoresist composition, the photoresist pattern comprising a matrix polymer having acid labile groups;
(c) coating a photoresist trimming composition over the photoresist pattern, wherein the trimming composition comprises a matrix polymer, a thermal acid generator and a solvent chosen from alcohols, ethers and mixtures thereof, wherein the trimming composition is free of cross-linking agents;
(d) heating the coated semiconductor substrate to generate an acid in the trimming composition from the thermal acid generator, thereby causing a change in polarity of the photoresist matrix polymer in a surface region of the photoresist pattern; and
(e) contacting the photoresist pattern with a developing solution to remove the surface region of the photoresist pattern.
14. The method of claim 13 , wherein the acid generated by the thermal acid generator is fluorine-substituted.
15. The method of claim 13 , wherein the thermal acid generator generates an aromatic acid.
16. The method of claim 13 , wherein the thermal acid generator generates a sulfonic acid.
17. The method of claim 13 , wherein the matrix polymer comprises one or more group chosen from —OH, hydroxyl styrene, hydroxyl naphthalene, hexafluoroisopropyl alcohol and combinations thereof.
18. The method of claim 13 , wherein the thermal acid generator generates a non-aromatic acid.
19. The method of claim 18 , wherein the non-aromatic acid has at least one fluorine substituent at the alpha position of the acid group.