Low resistance replacement metal gate structure
First Claim
1. A method of forming a semiconductor structure, said method comprising:
- providing a structure comprising a first gate cavity of a first width and exposing a first portion of a semiconductor material portion and a second gate cavity of a second width that is greater than said first width and exposing a second portion of said semiconductor material portion, wherein a dielectric spacer surrounds said first and said second gate cavities;
forming a material stack comprising, from bottom to top, a high k dielectric material layer and a metal nitride hard mask layer on exposed surfaces of said structure located inside and outside of said first and said second gate cavities;
forming an amorphous-silicon cap over said material stack, wherein said amorphous-silicon cap has a first portion located on horizontal surfaces of said material stack having a first thickness and a second portion located on vertical surfaces of said material stack having a second thickness that is less than said first thickness;
exposing inner sidewall surfaces of said dielectric spacer surrounding said first and said second gate cavities using said first portion of said amorphous-silicon cap as a mask;
forming additional amorphous-silicon sealing said first gate cavity, but not said second gate cavity;
removing said additional amorphous-silicon, remaining portions of said amorphous-silicon cap, and remaining portions of said metal nitride hard mask to expose remaining portions of said high k dielectric material layer located within an upper and lower portion of said first and said second gate cavities; and
forming a gate structure comprises from bottom to top, a workfunction metal portion having a stair-like surface profile, a diffusion barrier portion, a metal structure and a dielectric cap on said remaining portions of said high k dielectric material layer located within said lower portion of said first and said second gate cavities, wherein during forming of said workfunction metal portion, said remaining portions of said high k dielectric material layer are removed from said upper portion of said first and said second gate cavities.
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Accused Products
Abstract
A first sacrificial gate structure of a first width and a second sacrificial gate structure of a second width greater than the first width are provided on a semiconductor material portion. A dielectric spacer and a planarizing dielectric material are provided surrounding each sacrificial gate structure. Each sacrificial gate structure is then removed forming gate cavities. A high k dielectric material, a metal nitride hard mask and a physical vapor deposited (PVD) amorphous-silicon cap are provided. Vertical portions of the metal nitride hard mask and the high k dielectric material are removed from a portion of each gate cavity. Additional PVD amorphous silicon is then deposited and then all amorphous silicon and remaining metal nitride hard mask portions are removed. A work function portion having a stair-like surface, a diffusion barrier portion, a conductive metal structure and a dielectric cap are then formed into to each of the gate cavities.
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Citations
11 Claims
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1. A method of forming a semiconductor structure, said method comprising:
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providing a structure comprising a first gate cavity of a first width and exposing a first portion of a semiconductor material portion and a second gate cavity of a second width that is greater than said first width and exposing a second portion of said semiconductor material portion, wherein a dielectric spacer surrounds said first and said second gate cavities; forming a material stack comprising, from bottom to top, a high k dielectric material layer and a metal nitride hard mask layer on exposed surfaces of said structure located inside and outside of said first and said second gate cavities; forming an amorphous-silicon cap over said material stack, wherein said amorphous-silicon cap has a first portion located on horizontal surfaces of said material stack having a first thickness and a second portion located on vertical surfaces of said material stack having a second thickness that is less than said first thickness; exposing inner sidewall surfaces of said dielectric spacer surrounding said first and said second gate cavities using said first portion of said amorphous-silicon cap as a mask; forming additional amorphous-silicon sealing said first gate cavity, but not said second gate cavity; removing said additional amorphous-silicon, remaining portions of said amorphous-silicon cap, and remaining portions of said metal nitride hard mask to expose remaining portions of said high k dielectric material layer located within an upper and lower portion of said first and said second gate cavities; and forming a gate structure comprises from bottom to top, a workfunction metal portion having a stair-like surface profile, a diffusion barrier portion, a metal structure and a dielectric cap on said remaining portions of said high k dielectric material layer located within said lower portion of said first and said second gate cavities, wherein during forming of said workfunction metal portion, said remaining portions of said high k dielectric material layer are removed from said upper portion of said first and said second gate cavities. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification