Sub-lithographic gate length transistor using self-assembling polymers
View Patent ↗A semiconductor structure including at least one transistor located on a surface of a semiconductor substrate, wherein the at least one transistor has a sub-lithographic channel length, is provided. Also provided is a method to form such a semiconductor structure using self-assembling block copolymer that can be placed at a specific location using a pre-fabricated hard mask pattern.
1. A method of fabricating a semiconductor structure having a sub-lithographic channel length comprising:
providing a structure including a patterned hard mask located above a sacrificial layer and a semiconductor substrate, wherein said patterned hard mask includes at least one lithographically defined opening exposing a surface of said sacrificial layer;
providing a block copolymer having a single unit polymer block with a sub-lithographic width inside the at least one lithographically defined opening, wherein the single unit polymer block comprises a second polymeric block component which is embedded in a polymeric matrix that comprises a first polymeric block component of said block copolymer;
selectively removing the second polymeric block component relative to the first polymeric block component to form a sub-lithographic opening in the polymeric matrix inside the at least one lithographically defined opening;
transferring said sub-lithographic opening to said sacrificial layer;
removing the block copolymer and the patterned hard mask;
forming a gate dielectric and a gate conductor within said at least one lithographical defined opening; and
removing the sacrificial layer.
2. The method of claim 1 wherein said block copolymer is selected from the group consisting of polystyrene-block-polymethylmethacrylate (PS-b-PMMA), polystyrene-block-polyisoprene (PS-b-PI), polystyrene-block-polybutadiene (PS-b-PBD), polystyrene-block-polyvinylpyridine (PS-b-PVP), polystyrene-block-polyethyleneoxide (PS-b-PEO), polystyrene-block-polyethylene (PS-b-PE), polystyrene-b-polyorganosilicate (PS-b-POS), polystyrene-block-polyferrocenyldimethylsilane (PS-b-PFS), polyethyleneoxide-block-polyisoprene (PEO-b-PI), polyethyleneoxide-block-polybutadiene (PEO-b-PBD), polyethyleneoxide-block-polymethylmethacrylate (PEO-b-PMMA), polyethyleneoxide-block-polyethylethylene (PEO-b-PEE), polybutadiene-block-polyvinylpyridine (PBD-b-PVP), and polyisoprene-block-polymethylmethacrylate (PI-b-PMMA).
3. The method of claim 2 wherein the block copolymer comprises PS-b-PMMA having a PS:PMMA weight ratio ranging from about 20:80 to about 80:20.
4. The method of claim 1 wherein said second polymeric copolymer component of the block copolymer comprises an ordered array of cylinders that is aligned vertical to a surface of said semiconductor substrate.
5. The method of claim 1 wherein said providing said block copolymer includes deposition and annealing.
6. The method of claim 5 wherein said annealing includes at least one of thermal annealing, ultra-violet annealing, laser annealing, solvent vapor-assisted annealing and supercritical fluid-assisted annealing.
7. The method of claim 1 wherein said sub-lithographic opening has a width of less than 60 nm.
8. The method of claim 1 wherein said gate dielectric and said gate conductor have a feature size of less than 60 nm and a line edge roughness in terms of 3-sigma of less than 6 nm.