Fin-based RF diodes
Methods for forming a fin-based RF diode with improved performance characteristics and the resulting devices are disclosed. Embodiments include forming fins over a substrate, separated from each other, each fin having a lower portion and an upper portion; forming STI regions over the substrate, between the lower portions of adjacent fins; implanting the lower portion of each fin with a first-type dopant; implanting the upper portion of each fin, above the STI region, with the first-type dopant; forming a junction region around a depletion region and along exposed sidewalls and a top surface of the upper portion of each fin; and forming a contact on exposed sidewalls and a top surface of each junction region.
1. A method comprising:
forming fins over a substrate, separated from each other, each fin having a lower portion and an upper portion;
forming shallow trench isolation (STI) regions over the substrate, between the lower portions of adjacent fins;
implanting the lower portion of each fin with a first-type dopant;
implanting the upper portion of each fin, above the STI region, with the first-type dopant;
forming a junction region around a depletion region and along exposed sidewalls and a top surface of the upper portion of each fin; and
forming a contact on exposed sidewalls and a top surface of each junction region,
wherein the lower portion of each fin is implanted to a higher concentration level of the first-type dopant than the upper portion of each fin.
2. The method according to claim 1 , wherein the first-type dopant comprises a p-type dopant.
3. The method according to claim 1 , comprising:
forming the junction region by plasma doping or with an energy of 0.1 to 0.5 KeV.
4. The method according to claim 1 , comprising:
forming the upper portion of each fin with a top surface narrower than a bottom surface.
5. The method according to claim 4 , comprising:
forming an active depletion region between the depletion region and the lower portion of each fin.
6. The method according to claim 1 , comprising:
increasing a forward current capacity by increasing a concentration level of dopant in the junction region.
7. The method according to claim 1 , comprising:
increasing a forward current capacity by increasing an area of the junction region.
8. The method according to claim 1 , comprising:
forming the junction region by implanting the exposed sidewalls and the top surface of each fin with a diode cathode dopant.
9. The method according to claim 1 , comprising:
forming a layer of silicide material on the exposed sidewalls and the top surface of each fin for forming the junction region.
10. The method according to claim 1 , comprising:
reducing a charge capacitance in the depletion region by reducing a size of the depletion region.
11. A method comprising:
forming fins over a substrate, separated from each other, each fin having a lower portion and an upper portion, wherein a top surface of the upper portion is narrower than a bottom surface;
forming shallow trench isolation (STI) regions over the substrate, between the lower portions of adjacent fins;
implanting the upper portion of each fin, above the STI region, with a p-type dopant;
implanting the lower portion of each fin with the p-type dopant to a higher concentration level than the upper portion of each fin;
forming a junction region around a depletion region and along exposed sidewalls and a top surface of the upper portion of each fin by implanting the exposed sidewalls and the top surface of each fin with an n-type dopant or by forming a layer of silicide material on the exposed sidewalls and the top surface of each fin;
forming an active depletion region between the depletion region and the lower portion of each fin; and
forming a contact on a top surface of each junction region.
12. The method according to claim 11 , comprising:
increasing a forward current capacity by increasing a concentration level of the n-type dopant or by increasing an area of the junction region.