Organometallic solution based high resolution patterning compositions and corresponding methods
Organometallic radiation resist compositions are described based on tin ions with alkyl ligands. Some of the compositions have branched alkyl ligands to provide for improved patterning contrast while maintaining a high degree of solution stability. Blends of compounds with distinct alkyl ligands can provide further improvement in the patterning. High resolution patterning with a half-pitch of no more than 25 nm can be achieved with a line width roughness of no more than about 4.5 nm. Synthesis techniques have been developed that allow for the formation of alkyl tin oxide hydroxide compositions with very low metal contamination.
1. A coating solution consisting essentially of volatile organic solvent and an organometallic composition comprising a first organometallic compound represented by the formula RSnO (3/2−x/2) (OH) x where (0<x<3) with from about 0.0025M to about 1.0M tin in the solution, where R is an alkyl group bonded to the tin at a secondary or tertiary carbon atom.
2. The coating solution of claim 1 wherein the first organometallic compound comprises tert-butyl tin oxide hydroxide (R=—C(CH 3 ) 3 ), iso-propyl tin oxide hydroxide (R=—CH(CH 3 ) 2 ), or mixtures thereof.
3. The coating solution of claim 1 wherein the organometallic composition further comprises a second organometallic compound distinct from the first organometallic compound and represented by the formula R′SnO (3/2−x/2) (OH) x where (0<x<3) and R′ is a linear or branched alkyl.
4. The coating solution of claim 1 wherein the organic solvent comprises an alcohol.
5. A coating solution consisting essentially of an organic solvent and an organometallic composition comprising a first organometallic compound represented by the formula RSnO (3/2−x/2) (OH) x where (0<x<3), where R is an alkyl group, where the alkyl group is bonded to the tin at a secondary or tertiary carbon atom, and a second organometallic compound distinct from the first organometallic compound and represented by the formula R′SnO (3/2−x/2) (OH) x where (0<x<3), where R′ is a linear or branched alkyl group and wherein R and R′ are not the same.
6. The coating solution of claim 5 wherein the first organometallic compound comprises tert-butyl tin oxide hydroxide (R=—C(CH 3 ) 3 ) or iso-propyl tin oxide hydroxide (R=—CH(CH 3 ) 2 ).
7. The coating solution of claim 5 wherein R and R′ are each independently branched alkyl groups.
8. The coating solution of claim 5 wherein the second organometallic compound represents at least about 8 mole percent of the organometallic compounds in the coating solution.
9. The coating solution of claim 5 wherein the organometallic composition further comprises a third distinct organometallic compound represented by the formula R″SnO (3/2−x/2) (OH) x where (0<x<3), where R″ is a linear or branched alkyl group wherein the third organometallic compound represents at least about 8 mole percent of the organometallic compounds in the coating solution.
10. The coating solution of claim 5 wherein the solvent comprises an alcohol and wherein the organometallic compounds result in a tin ion concentration from about 0.0025M to about1.5M and wherein the second organometallic compound represents at least about 8 mole percent of the organometallic compounds in the coating solution.
11. A method for patterning a film on a substrate, the method comprising:
exposing the film with patterned EUV doses of no more than about 80 mJ/cm 2 wherein the film has an average thickness from about 2 nm to about 50 nm and wherein the film comprises a first organometallic compound represented by the formula RSnO (3/2−x/2) (OH) x where (0<x<3), where R is an alkyl group bonded to the tin; and
developing the film to form features at half-pitch no more than about 25 nm and linewidth roughness no more than about 5 nm.
12. The method of claim 11 wherein the EUV dose is from about 12 mJ/cm 2 to about 75 mJ/cm 2 .
13. The method of claim 11 wherein the half-pitch is no more than about 18 nm.
14. The method of claim 11 wherein R is bonded to the tin at a secondary or tertiary carbon.
15. The method of claim 11 further comprising developing the film following exposure to form a negative image through the removal of unexposed portions of film.
16. The method of claim 11 further comprising developing the film following exposure to form a positive image through the removal of exposed portions of film.
17. A method for patterning an organometallic film on a substrate, the method comprising:
exposing the organometallic film to patterned EUV radiation at a dose-to-gel value of no more than about 15 mJ/cm 2 to obtain a contrast of at least about 6.
18. A patterned structure comprising a substrate having a surface and a coating associated with the surface wherein at least portions of the coating are represented by the formulation (R) z SnO 2−z/2−x/2 (OH) x (z>0, x>0, and 0 <(x+z)<4), where R is an alkyl group bonded to the tin at a secondary or tertiary carbon atom, wherein the coating has an average thickness of no more than about 50 nm.
19. The patterned structure of claim 18 wherein z is from about 0.25 to about 3.
20. The patterned structure of claim 18 wherein the substrate comprises polymer, elemental silicon, silica, and/or another inorganic material.
21. The patterned structure of claim 18 wherein the coating forms a pattern at least a portion of which forms features with a half-pitch of no more than about 25 nm.