Pitch multiplication using self-assembling materials
Self-assembling materials, such as block copolymers, are used as mandrels for pitch multiplication. The copolymers are deposited over a substrate and directed to self-assemble into a desired pattern. One of the blocks forming the block copolymers is selectively removed. The remaining blocks are used as mandrels for pitch multiplication. Spacer material is blanket deposited over the blocks. The spacer material is subjected to a spacer etch to form spacers on sidewalls of the mandrels. The mandrels are selectively removed to leave free-standing spacers. The spacers may be used as pitch-multiplied mask features to define a pattern in an underlying substrate.
1. A method for patterning a semiconductor substrate, comprising:
providing a layer comprising block copolymers;
selectively removing one block of the block copolymers to leave laterally-separated mandrels comprising an other block of the block copolymers;
blanket depositing spacer material on the mandrels;
etching the spacer material to form spacers on sidewalls of the mandrels; and
transferring a pattern defined by the spacers to the substrate.
2. The method of claim 1 , wherein providing the layer formed of block copolymers comprises:
depositing a block copolymer solution over the substrate; and
segregating blocks constituting the block copolymers to form a repeating pattern defined by blocks of the copolymers over the substrate.
3. The method of claim 2 , wherein providing the layer formed of block copolymers further comprises providing laterally spaced apart copolymer self-assembly guides over the substrate, wherein depositing the block copolymer solution comprises depositing the block copolymer solution between the copolymer segregation guides.
4. The method of claim 3 , wherein depositing the block copolymer solution between the copolymer segregation guides comprises forming a block copolymer reservoir directly over the guides.
5. The method of claim 3 , wherein the guides are formed of a material which attracts or repels a block forming the block copolymers.
6. The method of claim 3 , wherein the guides are formed of a material selected from the group consisting of silicon oxide, silicon and a dielectric anti-reflective coating.
7. The method of claim 1 , further comprising removing the mandrels before transferring the pattern defined by the spacers to the substrate.
8. The method of claim 7 , further comprising transferring the pattern defined by the spacers to an underlying hard mask layer before transferring the pattern defined by the spacers to the substrate.
9. The method of claim 8 , wherein the hard mask layer comprises amorphous carbon.
10. The method of claim 1 , further comprising:
depositing a selectively-definable material over the spacers; and
defining an other pattern in the selectively-definable material,
wherein transferring the pattern defined by the spacers to the substrate comprises transferring a combined pattern formed from the pattern and the other pattern to the substrate.
11. The method of claim 10 , wherein the selectively-definable layer is deposited on and between the spacers.
12. The method of claim 11 , wherein the selectively-definable layer is photoresist.
13. The method of claim 12 , wherein the photoresist is negative photoresist.
14. The method of claim 10 , further comprising transferring the combined pattern formed from the pattern and the other pattern to an underlying hard mask layer before transferring the combine pattern to the substrate.
15. The method of claim 10 , wherein transferring the combined pattern to the substrate transfers the pattern defined by the spacers to an array region of a partially-fabricated integrated circuit and transfers the other pattern to a periphery region of the partially-fabricated integrated circuit.
16. The method of claim 1 , wherein transferring the pattern defined by the spacers to the substrate defines interconnects in the substrate.
17. A method for forming a mask for patterning a substrate, comprising:
providing a layer of a self-organizing material;
aggregating like chemical species of the self-organizing material to form a repeating pattern having domains defined by the chemical species;
preferentially removing one of the chemical species to form spaced apart mandrels; and
forming spacers on sidewalls of the mandrels.
18. The method of claim 17 , wherein the self-organizing material comprises a block copolymer.
19. The method of claim 18 wherein the block copolymer is a diblock copolymer.
20. The method of claim 19 , wherein the diblock copolymer comprises polystyrene.
21. The method of claim 20 , wherein the diblock copolymer further comprises polymethylmethacrylate.
22. The method of claim 17 , further comprising extending a height of the repeating pattern defined by the chemical species.
23. The method of claim 22 , wherein extending the height of the repeating pattern defined by the chemical species comprises:
depositing additional self-organizing material over the repeating pattern defined by the chemical species; and
aligning like chemical moieties of the additional self-organizing material with the domains defined by the chemical species.
24. The method of claim 23 , wherein the self-organizing material and the additional self-organizing material are block copolymers.
25. The method of claim 24 , wherein the self-organizing material and the additional self-organizing material are a same block copolymers.
26. The method of claim 23 , wherein preferentially removing one of the chemical species comprises etching like chemical moieties of the additional self-organizing material and etching one of the chemical species.
27. A method for integrated circuit fabrication, comprising:
exposing a block copolymer layer to a wet etch to define free-standing, regularly-spaced, spaced-apart placeholders in the block copolymer layer;
forming spacers on sidewalls of the placeholders; and
transferring a pattern derived from the spacers to an underlying substrate.
28. The method of claim 27 , wherein the wet etch comprises acetic acid.
29. The method of claim 28 , wherein the block copolymer comprises blocks of polystyrene and polymethylmethacrylate.
30. The method of claim 27 , wherein the placeholders have a pitch of about 100 nm or less.
31. The method of claim 30 , wherein the placeholders have a pitch of about 50 nm or less.
32. The method of claim 27 , wherein the free-standing, spaced-apart placeholders comprise vertical lamellae.
33. The method of claim 27 , wherein the free-standing, spaced-apart placeholders comprise vertically extending isolated pillars.
34. The method of claim 27 , wherein the transferring the pattern comprises defining regularly spaced features in an array region of a partially fabricated intergrated circuit.
35. The method of claim 27 , wherein forming spacers comprises:
blanket depositing a layer of spacer material over the placeholders; and
anisotropically etching the layer of spacer material.
36. The method of claim 27 , further comprising, before exposing the block copolymer layer to the wet etch:
depositing a solution of block copolymers over the substrate; and
annealing the block copolymer solution to cause self-assembly of the block copolymers into regularly-spaced block domains.