Graphene-based transistor
View Patent ↗A graphene layer is formed on a surface of a silicon carbide substrate. A dummy gate structure is formed over the fin, in the trench, or on a portion of the planar graphene layer to implant dopants into source and drain regions. The dummy gate structure is thereafter removed to provide an opening over the channel of the transistor. Threshold voltage adjustment implantation may be performed to form a threshold voltage implant region directly beneath the channel, which comprises the graphene layer. A gate dielectric is deposited over a channel portion of the graphene layer. After an optional spacer formation, a gate conductor is formed by deposition and planarization. The resulting graphene-based field effect transistor has a high carrier mobility due to the graphene layer in the channel, low contact resistance to the source and drain region, and optimized threshold voltage and leakage due to the threshold voltage implant region.
1. A field effect transistor comprising:
a silicon carbide fin located directly on a silicon carbide substrate;
a pair of graphene layers located on a pair of sidewalls of said silicon carbide fin;
doped source and drain regions located between said pair of graphene layers and within said silicon carbide fin, said doped source and drain regions comprising a doped silicon carbide material;
a channel comprising a channel portion of said pair of graphene layers and contacting said doped source and drain regions;
a gate dielectric directly contacting said channel portion within said pair of graphene layers; and
a gate electrode directly contacting said gate dielectric.
2. The field effect transistor of claim 1 , further comprising a threshold voltage adjustment implant region located within said silicon carbide fin and abutting said pair of graphene layers and said doped source and drain regions.
3. The field effect transistor of claim 1 , further comprising:
a first planar graphene layer located on a top surface of said silicon carbide substrate;
a second planar graphene layer located on a top surface of said silicon carbide fin;
a first insulator layer directly contacting said first planar graphene layer; and
a second insulator layer directly contacting said second planar graphene layer, wherein said first insulator layer and said second insulator layer comprise the same material.
4. The field effect transistor of claim 3 , wherein said gate dielectric comprises a different material than said first insulator layer and said second insulator layer.
5. The field effect transistor of claim 4 , wherein said gate dielectric comprises a high-k dielectric material.
6. The field effect transistor of claim 5 , wherein said high-k dielectric material is selected from HfO 2 , ZrO 2 , Al 2 O 3 , TiO 2 , La 2 O 3 , SrTiO 3 , LaAlO 3 , hafnium silicates, barium-strontium-titanates (BSTs) and lead-zirconate-titanates (PZTs).
7. The field effect transistor of claim 3 , further comprising a gate level dielectric overlying said first insulator layer and said second insulator layer.
8. The field effect transistor of claim 7 , wherein a topmost surface of said gate level dielectric is coplanar with said topmost surface of said gate electrode.
9. The field effect transistor of claim 3 , wherein said second planar graphene layer is vertically spaced from said gate electrode by said second insulator layer.
10. The field effect transistor of claim 3 , wherein said first insulator layer is not in direct contact with said second insulator layer.
11. The field effect transistor of claim 1 , further comprising a gate level dielectric having a top surface which is substantially coplanar with a topmost surface of said gate electrode.
12. The field effect transistor of claim 11 , wherein said gate level dielectric has at least one sidewall which abuts said gate dielectric.
13. The field effect transistor of claim 1 , wherein said gate dielectric comprises a high-k dielectric material.
14. The field effect transistor of claim 13 , wherein said high-k dielectric material is selected from HfO 2 , ZrO 2 , Al 2 O 3 , TiO 2 , La 2 O 3 , SrTiO 3 , LaAlO 3 , hafnium silicates, barium-strontium-titanates (BSTs) and lead-zirconate-titanates (PZTs).