Topography directed patterning
A pattern having exceptionally small features is formed on a partially fabricated integrated circuit during integrated circuit fabrication. The pattern comprises features formed by self-organizing material, such as diblock copolymers. The organization of the copolymers is directed by spacers which have been formed by a pitch multiplication process in which spacers are formed at the sides of sacrificial mandrels, which are later removed to leave spaced-apart, free-standing spacers. Diblock copolymers, composed of two immiscible block species, are deposited over and in the space between the spacers. The copolymers are made to self-organize, with each block species aggregating with other block species of the same type.
1. A method for semiconductor fabrication, comprising:
providing a plurality of pitch multiplied lines having a pitch of about 200 nm or less, wherein providing the plurality of pitch multiplied lines comprises:
providing a plurality of mandrels;
depositing a layer of spacer material on the mandrels;
etching the spacer material to define spacers on sidewalls of the mandrels;
removing the mandrels to leave a pattern of freestanding spacers, the spacers forming the pitch multiplied lines; and
forming a pattern comprising block copolymers between the plurality of lines, wherein the block copolymers form a plurality of spaced-apart features between the plurality of lines.
2. The method of claim 1 , wherein the pitch is about 100 nm or less.
3. The method of claim 1 , further comprising selectively removing at least one block forming the block copolymers.
4. The method of claim 1 , wherein forming the pattern comprises annealing a film comprising the block copolymers.
5. The method of claim 4 , wherein the film has a thickness less than about a length scale of the block polymers.
6. The method of claim 1 , wherein the block copolymers are formed of immiscible blocks.
7. The method of claim 1 , wherein the lines comprise silicon.
8. The method of claim 7 , wherein the lines comprise silicon oxide.
9. A method for mask formation, comprising:
providing a pattern of spacers over a semiconductor substrate;
providing a homogeneous film of mask material extending between pairs of the spacers;
converting the homogeneous film into a patterned film comprising a pattern defined by mask material moieties, the patterned film extending continuously from a first spacer to a second spacer of each pair of spacers, wherein the mask material moieties define a plurality of mask features between each pair of spacers; and
exposing the mask material to an etchant to form a pattern of voids in the exposed mask material.
10. The method of claim 9 , wherein providing the pattern of spacers comprises performing pitch multiplication.
11. The method of claim 9 , wherein providing the pattern of spacers comprises providing a plurality of free standing spacers.
12. The method of claim 9 , wherein providing the pattern of spacers comprises providing spacers on sidewalls of mandrels.
13. The method of claim 12 , further comprising removing the mandrels after exposing the mask material.
14. The method of claim 13 , further comprising depositing a second layer of mask material after removing the mandrels.
15. The method of claim 14 , further comprising self-segregating mask material moieties of the second layer of mask material to form a pattern defined by the mask material moieties of the second layer of mask material, wherein self-segregating occurs in a volume formerly occupied by the mandrels.
16. The method of claim 9 , wherein converting the homogeneous film comprises promoting a self-segregation of chemical species forming the mask before exposing the mask material, wherein promoting the self-segregation organizes the mask material into domains, the domains each predominantly formed of a different moiety forming the chemical species.
17. The method of claim 16 , wherein chemical species are block copolymers, wherein the moieties are blocks forming the copolymer and wherein exposing the mask material to etchant selectively removes a block species forming the block copolymers.
18. The method of claim 17 , wherein the homogeneous mask material has a thickness sufficient to allow the formation of vertical lamellae within the mask material.
19. The method of claim 17 , wherein the homogeneous mask material has a thickness sufficient to cause the formation of vertical cylinders within the mask material.
20. The method of claim 9 , wherein exposing the mask material to the etchant comprises performing a dry etch.
21. The method of claim 9 , wherein exposing the mask material to the etchant comprises performing a wet etch.
22. The method of claim 21 , wherein the etchant comprises acetic acid.
23. The method of claim 9 , wherein the remaining mask material comprises lines having a critical dimension of about 50 nm or less.
24. The method of claim 23 , wherein the critical dimension is about 30 nm or less.
25. The method of claim 24 , wherein the critical dimension is about 20 nm or less.