Self-aligned quadruple patterning process
View Patent ↗Methods for modifying a spacer and/or spaces between spacers to enable a fin cut mask to be dropped between the spacers are provided. A first set of second mandrel structures having a first width is formed on facing sidewall surfaces of a neighboring pair of first mandrel structures and a second set of second mandrel structures having a second width less than the first width are formed on non-facing sidewall surfaces of the neighboring pair of first mandrel structures. Each first mandrel structure is removed and a spacer is formed on a sidewall surface of the first and second sets of second mandrel structures. In the region between the neighboring pair of first mandrel structure, a merged spacer is formed. The first and second sets of second mandrel structures are removed. A portion of an underlying substrate can be patterned utilizing each spacer and the merged spacer as etch masks.
1. A method of forming a mandrel structure comprising:
forming a plurality of first mandrel structures comprising a neighboring pair of first mandrel structures on a surface of a substrate;
forming an additive mask on facing sidewall surfaces of said neighboring pair of first mandrel structures and on said surface of said substrate that is located between said neighboring pair of first mandrel structures;
forming a first spacer on said additive mask and exposed surfaces of each first mandrel structure and said exposed surfaces of said substrate;
removing portions of each first spacer and said additive mask to provide a first set of second mandrel structures having a first width on said facing sidewall surfaces of said neighboring pair of first mandrel structures and a second set of second mandrel structures having a second width that is less than said first width on non-facing sidewall surfaces of said neighboring pair of first mandrel structures;
removing each first mandrel structure;
forming a second spacer on a sidewall surface of said first and second sets of second mandrel structures, wherein in a region between said neighboring pair of first mandrel structures a merged spacer is formed;
removing said first and second sets of second mandrel structures; and
patterning a portion of said substrate utilizing said second spacer and said merged spacer as etch masks.
2. The method of claim 1 , wherein said first set of second mandrel structures comprises a remaining portion of an additive mask and a remaining portion of said first spacer.
3. The method of claim 2 , wherein a sidewall surface of said remaining portion of said additive mask is in direct physical contact with said facing sidewall surfaces of said neighboring pair of first mandrel structures.
4. The method of claim 2 , wherein said second set of second mandrel structures comprises another remaining portion of said first spacer and is in direct physical contact with said non-facing sidewalls of said neighboring pair of first mandrel structures.
5. The method of claim 1 , wherein said forming said plurality of first mandrel structures comprises:
depositing a mandrel material; and
patterning said mandrel material by lithography and etching.
6. The method of claim 1 , wherein said forming said additive mask comprises:
depositing an additive mask material; and
patterning said additive mask material by lithography and etching.
7. The method of claim 1 , wherein said first set of second mandrel structures and said second set of second mandrel structures each have a topmost surface that is coplanar with a topmost surface of said neighboring pair of first mandrel structures.
8. The method of claim 1 , wherein said neighboring pair of first mandrel structures comprises a different material than said first set of second mandrel structures and a second set of second mandrel structures.
9. The method of claim 1 , wherein said removing each of said first mandrel structures comprises anisotropic or isotropic etching.
10. The method of claim 1 , wherein said forming said second spacer comprises depositing a dielectric material and etching.
11. The method of claim 1 , wherein said second spacer has a topmost surface that is coplanar with said first set of second mandrel structures and said second set of second mandrel structures.
12. The method of claim 1 , wherein said removing said first and second sets of second mandrel structures comprises an anisotropic or isotropic etch.
13. The method of claim 1 , wherein said patterning of said substrate comprises anisotropic etching.
14. The method of claim 1 , further comprising removing said second spacer and said merged spacer by etching or chemical mechanical planarization.
15. The method of claim 1 , wherein said substrate comprises a semiconductor material, and wherein a first semiconductor fin having a first width and at least one second semiconductor fin having a second width that is greater than said first width is provided by said patterning.
16. The method of claim 15 , wherein said at least one second semiconductor fin is located between a first set of said first semiconductor fins and a second set of said first semiconductor fins.
17. The method of claim 16 , further comprising cutting said at least one second semiconductor fin, wherein said cutting occurs prior to, or after removal of second spacer or prior to or after forming a functional gate structure.
18. The method of claim 1 , wherein said neighboring pair of first mandrel structures have a constant width.
19. The method of claim 1 , wherein one of said first mandrel structures of said neighboring pair of first mandrel structures has a first width and another of said first mandrel structures of said neighboring pair of first mandrel structures has a second width that differs from said first width.