Method for fin formation with a self-aligned directed self-assembly process and cut-last scheme
A method of making a semiconductor device includes disposing a first hard mask (HM), amorphous silicon, and second HM on a substrate; disposing oxide and neutral layers on the second HM; removing a portion of the oxide and neutral layers to expose a portion of the second HM; forming a guiding pattern by selectively backfilling with a polymer; forming a self-assembled block copolymer (BCP) on the guiding pattern; removing a portion of the BCP to form an etch template; transferring the pattern from said template into the substrate and forming uniform silicon fin arrays with two types of HM stacks with different materials and heights; gap-filling with oxide followed by planarization; selectively removing and replacing the taller HM stack with a third HM material; planarizing the surface and exposing both HM stacks; and selectively removing the shorter HM stack and the silicon fins underneath.
1. A method of making a semiconductor device, the method comprising:
disposing a hard mask on a substrate;
disposing an oxide layer and a neutral layer on the hard mask;
removing a portion of the oxide layer and the neutral layer to expose a portion of the hard mask;
forming a guiding pattern by selectively backfilling a polymeric material in the exposed portion of the hard mask;
forming a self-assembled block copolymer layer on the guiding pattern, the guiding pattern comprising the neutral layer and the polymeric material that is backfilled;
removing a portion of the block copolymer layer to form an etch template with the polymeric material that is remaining;
etching the neutral layer, the oxide layer, and the hard mask to transfer a pattern from the etch template into the neutral layer, the oxide layer, and the hard mask;
etching the substrate to transfer the pattern from the hard mask into the substrate and form a first fin and a second fin.
2. The method of claim 1 , wherein the hard mask is a stack comprising a first hard mask layer in contact with the substrate, an amorphous silicon layer on the first hard mask layer, and a second hard mask layer on the amorphous silicon layer.
3. The method of claim 1 , further comprising removing the first fin.
4. The method of claim 2 , wherein the first hard mask layer comprises silicon nitride.
5. The method of claim 2 , wherein the second hard mask layer comprises silicon nitride.
6. The method of claim 1 , further comprising replacing a portion of the hard mask on second fin with another hard mask material by a selective etch process.
7. The method of claim 6 , wherein the hard mask on the second fin that is replaced is different than the another hard mask material.
8. The method of claim 1 , wherein the neutral layer is disposed by spin-coating.
9. The method of claim 1 , wherein the block copolymer comprises polystyrene.
10. The method of claim 1 , wherein the neutral layer comprises random copolymers of styrene and methylmethacrylate.
11. The method of claim 1 , wherein the neutral layer facilitates perpendicular morphology and directs orientation of BCPs disposed above self-assembled block copolymer.
12. The method of claim 1 , wherein the polymeric material is backfilled by spin-coated.
13. The method of claim 1 , wherein the polymeric material is annealed after being backfilled.
14. The method of claim 1 , wherein the hard mask comprises an amorphous silicon layer between two hard mask layers.
15. The method of claim 14 , wherein the two hard mask layers comprise silicon nitride.
16. The method of claim 1 , wherein the polymeric material does not react with the neutral layer.
17. The method of claim 1 , wherein the polymeric material only form a monolayer of polymer on the exposed hard mask.
18. The method of claim 17 , wherein the block copolymer comprises a first polymer domain and a second polymer domain, and the second polymer domain self-aligns with the monolayer of the polymeric material.
19. The method of claim 1 , wherein the substrate comprises silicon, germanium, silicon carbide, gallium arsenide, indium arsenide, indium phosphide, or any combination thereof.
20. The method of claim 1 , wherein the block copolymer comprises poly(methyl methacrylate).