Graphene nanoribbons and carbon nanotubes fabricated from SiC fins or nanowire templates
Semiconductor structures including parallel graphene nanoribbons or carbon nanotubes oriented along crystallographic directions are provided from a template of silicon carbide (SiC) fins or nanowires. The SiC fins or nanowires are first provided and then graphene nanoribbons or carbon nanotubes are formed on the exposed surfaces of the fin or the nanowires by annealing. In embodiments in which closed carbon nanotubes are formed, the nanowires are suspended prior to annealing. The location, orientation and chirality of the graphene nanoribbons and the carbon nanotubes that are provided are determined by the corresponding silicon carbide fins and nanowires from which they are formed.
1. A semiconductor structure comprising:
at least one silicon fin located on a surface of a substrate;
a silicon carbide fin located on each bare sidewall of said at least one silicon fin;
a graphene nanoribbon located on a sidewall of each silicon carbide fin; and
a gate structure oriented perpendicular to each silicon carbide fin and said at least one silicon fin, said gate structure overlapping a portion of each graphene nanoribbon and located atop a portion of each of said silicon carbide fins and said at least one silicon fin, wherein the portion of each graphene nanoribbon overlapped by said gate structure defines a channel region of the semiconductor structure.
2. The semiconductor structure of claim 1 wherein said substrate comprises, from bottom to top, a handle substrate and a buried insulating layer.
3. The semiconductor structure of claim 1 further comprising a patterned hard mask located on an upper surface of said at least one silicon fin.
4. The semiconductor structure of claim 1 wherein said gate structure comprises a gate dielectric and a gate conductor.
5. The semiconductor structure of claim 4 wherein said gate dielectric is located on sidewalls and an upper surface of each of said graphene nanoribbons, on an upper surface of each of said silicon carbide fins and atop an upper surface of said silicon fin.
6. The semiconductor structure of claim 5 wherein a patterned hard mask is located on said upper surface of the silicon fin, and said patterned hard mask separates a portion of said gate dielectric from said upper surface of the silicon fin.
7. The semiconductor structure of claim 1 wherein each silicon carbide fin and said silicon fin have a same crystal orientation.
8. The semiconductor structure of claim 1 wherein a height of each graphene nanoribbon is the same as a height of each silicon carbide fin.
9. The semiconductor structure of claim 1 wherein an upper surface of said silicon fin, an upper surface of each silicon carbide fin and an upper surface of each graphene nanoribbon are coplanar to each other.
10. The semiconductor structure of claim 4 wherein said gate dielectric is selected from HfO 2 , ZrO 2 , La 2 O 3 , Al 2 O 3 , TiO 2 , SrTiO 3 , LaAlO 3 , Y 2 O 3 , HfO x N y , ZrO x N y , La 2 O x N y , Al 2 O x N y , TiO x N y , SrTiO x N y , LaAO x N y , Y 2 O x N y , SiON, SiN X , a silicate thereof, and an alloy thereof, wherein each value of x is independently from 0.5 to 3 and each value of y is independently from 0 to 2.
11. The semiconductor structure of claim 4 wherein said gate conductor is selected from polycrystalline silicon, polycrystalline silicon germanium, an elemental metal, an alloy of at least two metals, a metal nitride, a metal silicide and multilayered combinations thereof.
12. A semiconductor structure comprising:
at least one pair of spaced apart graphene nanoribbons located on a surface of a substrate;
a first gate structure located on one sidewall of each spaced apart graphene nanoribbon, said sidewalls of each graphene nanoribbon containing said first gate structure are not facing each other;
a planarizing dielectric material located adjacent said first gate structure; and
at least a gate conductor of a second gate structure located between the at least one pair of spaced apart graphene nanoribbons.
13. The semiconductor structure of claim 12 further comprising a silicon carbide fin located on another sidewall of each of graphene nanoribbons, and wherein a lower portion of said gate conductor of said second gate structure directly contacts a sidewall of said silicon carbide fin.
14. The semiconductor structure of claim 12 further comprising a silicon carbide fin located on another sidewall of each of graphene nanoribbons, and a gate dielectric located between the gate conductor of said second gate structure and each of said silicon carbide fins.
15. The semiconductor structure of claim 14 wherein a bottom surface of said gate conductor of said second gate structure is in direct contact with an upper surface of said substrate.
16. The semiconductor structure of claim 14 wherein a bottom surface of said gate conductor of said second gate structure is separated from an upper surface of said substrate by a portion of the gate dielectric of the second gate structure that lies beneath the bottom surface of the gate conductor of the second gate structure.
17. The semiconductor structure of claim 12 wherein an upper portion of said gate conductor of said second gate structure contacts an upper surface of the first gate structure.
18. The semiconductor structure of claim 12 wherein said first gate structure is electrically separated from said second gate structure.
19. The semiconductor structure of claim 12 wherein said substrate comprises, from bottom to top, a handle substrate and a buried insulating layer.
20. The semiconductor structure of claim 12 wherein said first gate structure includes a gate conductor that differs from the gate conductor of the second gate structure.