Transistor with coupled gate and ground plane
An integrated circuit includes a silicon substrate, a ground plane above the substrate, a buried insulator layer above the ground plane, a silicon layer above the buried insulator layer and separated from the ground plane by the buried insulator layer, and an FDSOI transistor. The transistor has a channel adapted for being formed in the silicon layer, a source and drain in and/or on the silicon layer, and a gate covering an upper face of the channel and having a lateral portion covering a lateral face of the channel and above the ground plane. A distance between the lateral portion and the ground plane is not more than three nanometers and at least five times less than a thickness of the buried insulator layer between the ground plane and the silicon layer. The ground plane is separated from the gate by the buried insulator layer.
1. A manufacture comprising an integrated circuit, said integrated circuit comprising a silicon substrate, a ground plane disposed above said silicon substrate, a buried insulator layer disposed above said ground plane, a silicon layer disposed above said buried insulator layer and separated from said ground plane by said buried insulator layer, and an FDSOI transistor having a channel adapted for being formed in said silicon layer, a source and drain disposed in and/or on said silicon layer, and a gate that covers an upper face of said channel and that comprises a lateral portion covering a lateral face of said channel and disposed above said ground plane, wherein a distance between said lateral portion and said ground plane is greater than zero but less than or equal to three nanometers and is at least five times less than a thickness of said buried insulator layer between said ground plane and said silicon layer, and wherein said ground plane is separated from said gate by said buried insulator layer.
2. The manufacture of claim 1 , wherein said ground plane is adapted for being in electrical contact with said gate.
3. The manufacture of claim 1 , wherein said lateral portion of said gate extends in said thickness of said buried insulator layer.
4. The manufacture of claim 1 , wherein said ground plane extends in said thickness of said buried insulator layer below said lateral portion of said gate.
5. The manufacture of claim 1 , wherein a ratio of a width of said channel to a thickness of said channel lies between 0.75 and 2.5.
6. The manufacture of claim 1 , wherein said transistor is adapted for comprising an other channel extending between said source and said drain, said gate covering an upper face of said other channel and comprising an other lateral portion covering a lateral face of said other channel and disposed above said ground plane, a distance between said other lateral portion and said ground plane being less than a thickness of said buried insulator layer between said ground plane and said silicon layer.
7. A method of fabricating an integrated circuit, said method comprising providing an element comprising a silicon substrate, a ground plane disposed above said substrate, a buried insulator layer disposed above said ground plane, and a silicon layer disposed above said buried insulator layer and separated from said ground plane by said buried insulator layer, forming a channel of an FDSOI transistor in said silicon layer, forming a source and a drain of said FDSOI transistor in and/or on said silicon layer, and forming a gate of said FDSOI transistor covering an upper face of said channel and comprising a lateral portion covering a lateral face of said channel and disposed above said ground plane, said ground plane being separated from said gate by said buried insulator layer, wherein a distance between said lateral portion and said ground plane is greater than zero but less than or equal to three nanometers and at least five times less than a thickness of said buried insulator layer between said ground plane and said silicon layer.
8. The method of claim 7 , wherein formation of said gate comprises formation of an electrical contact between said gate and said ground plane.
9. The method of claim 7 , further comprising separating said gate from said ground plane by said buried insulator layer.
10. The method of claim 7 , further comprising extending the lateral portion of said gate into said thickness of said buried insulator layer.
11. The method of claim 7 , further comprising a step of epitaxy so as to form a part of said ground plane extending in said thickness of said buried insulator layer below said lateral portion of said gate.