PHOTORESIST PATTERN TRIMMING METHODS
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 free acid having fluorine substitution and a solvent, the trimming composition being free of cross-linking agents. The coated semiconductor substrate is heated to cause a change in polarity of the resist 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, a free acid having fluorine substitution and a solvent, and wherein the trimming composition is free of cross-linking agents;
(d) heating the coated semiconductor substrate, 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 solvent of the photoresist trimming composition is chosen from water, organic solvents and mixtures thereof.
3 . The method of claim 2 , wherein the solvent of the photoresist trimming composition is chosen from alkanes, alcohols, ethers, esters, ketones and mixtures thereof.
4 . The method of claim 1 , wherein the matrix polymer of the photoresist trimming composition is soluble in aqueous alkaline developer.
5 . The method of claim 1 , wherein the developing solution is an aqueous tetramethylammonium hydroxide solution.
6 . The method of claim 1 , wherein the matrix polymer contains functional groups selected from —OH, —COOH, —SO3H, —SiOH, hydroxyl styrene, hydroxyl naphthalene, sulfonamide, hexafluoroisopropyl alcohol, anhydrate, lactone, ester, ether, allylamine, pyrolidone.
7 . 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.
8 . 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.
9 . The method of claim 8 , wherein the plurality of features of the photoresist pattern comprise a plurality of posts.
10 . The method of any 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.