Efficient FET Body and Substrate Contacts
Integrated circuit structures that significantly reduce the resistance associated with the body contact region and substrate region contact of a field-effect transistor (FET) compared to conventional designs. Embodiments include a FET having a body contact region, and optionally a substrate region contact, that includes germanium (Ge) alone or as an alloy with silicon (SiGe) and/or as a layered combination with silicon (e.g., a layer of Ge on a layer of Si). A first method includes fabricating a body contact region of a field-effect transistor by fabricating the field-effect transistor with an Si body contact region, and diffusing or implanting Ge within the Si. A second method includes fabricating a body contact region of a field-effect transistor by fabricating the field-effect transistor with an Si body contact region, etching away at least part of the Si body contact region to form a well, and depositing Ge within the well.
1 . A field-effect transistor including a body contact region that includes germanium.
2 . The field-effect transistor of claim 1 , wherein the body contact region includes a mixture of germanium and silicon.
3 . The field-effect transistor of claim 1 , wherein the body contact region includes a mixture of germanium and silicon having a gradient of mostly silicon in a first region, a mixture of silicon and germanium in a second region adjacent to the first region, and mostly germanium in a third region adjacent to the second region.
4 . The field-effect transistor of claim 1 , wherein the body contact region is created by implantation or diffusion of germanium into silicon.
5 . The field-effect transistor of claim 1 , wherein the body contact region is created by deposition of germanium into an etched well.
6 . The field-effect transistor of claim 1 , wherein the body contact region includes a mixture of between about 1% germanium and about 100% germanium.
7 . The field-effect transistor of claim 1 , wherein the body contact region includes an overall concentration of germanium between about 15% and about 45% of the total material in the body contact region.
8 . The field-effect transistor of claim 1 , wherein the body contact region is in electrical contact with a body region of the field-effect transistor.
9 . The field-effect transistor of claim 1 , wherein the body contact region is in electrical contact with a body region and a substrate of the field-effect transistor.
10 . The field-effect transistor of claim 1 , wherein the body contact region is doped with P+ material.
11 . The field-effect transistor of claim 1 , wherein the body contact region is capped with a salicide layer.
12 . A field-effect transistor including a body contact region that includes germanium or a silicon-germanium alloy.
13 . The field-effect transistor of claim 12 , wherein the body contact region includes an alloy of germanium and silicon having a gradient of mostly silicon in a first region, a mixture of silicon and germanium in a second region adjacent to the first region, and mostly germanium in a third region adjacent to the second region.
14 . The field-effect transistor of claim 12 , wherein the body contact region is created by implantation or diffusion of germanium into silicon.
15 . The field-effect transistor of claim 12 , wherein the body contact region is created by deposition of germanium into an etched well.
16 . The field-effect transistor of claim 12 , wherein the body contact region includes a mixture of between about 1% germanium and about 100% germanium.
17 . The field-effect transistor of claim 12 , wherein the body contact region includes an overall concentration of germanium between about 15% and about 45% of the total material in the body contact region.
18 . The field-effect transistor of claim 12 , wherein the body contact region is in electrical contact with a body region of the field-effect transistor.
19 . The field-effect transistor of claim 12 , wherein the body contact region is in electrical contact with a body region and a substrate of the field-effect transistor.
20 . The field-effect transistor of claim 12 , wherein the body contact region is doped with P+ material.
21 .- 72 . (canceled)