Charge-induced threshold voltage tuning in III-N transistors
Disclosed herein are IC structures, packages, and devices that include III-N transistors implementing various means by which their threshold voltage it tuned. In some embodiments, a III-N transistor may include a doped semiconductor material or a fixed charge material included in a gate stack of the transistor. In other embodiments, a III-N transistor may include a doped semiconductor material or a fixed charge material included between a gate stack and a III-N channel stack of the transistor. Including doped semiconductor or fixed charge materials either in the gate stack or between the gate stack and the III-N channel stack of III-N transistors adds charges, which affects the amount of 2DEG and, therefore, affects the threshold voltages of these transistors.
1. An integrated circuit (IC) structure, comprising:
a transistor that includes:
a III-N semiconductor material,
a gate electrode material, and
a further material between the gate electrode material and the III-N semiconductor material, the further material including a semiconductor material with dopant atoms in concentration of at least 1×10 18 dopant atoms per cubic centimeter, wherein the further material includes doped silicon.
2. The IC structure according to claim 1 , wherein the further material has a thickness between 1 nanometer and 50 nanometers.
3. The IC structure according to claim 1 , wherein:
the transistor further includes a gate dielectric material, and
the further material is between the gate electrode material and the gate dielectric material.
4. The IC structure according to claim 1 , wherein:
the transistor further includes a polarization material, where a lattice constant of the polarization material is smaller than a lattice constant of the III-N semiconductor material, and
the further material is in contact with the polarization material.
5. The IC structure according to claim 1 , wherein:
the transistor further includes a polarization material, and
the III-N semiconductor material is between the polarization material and the gate electrode material.
6. The IC structure according to claim 5 , wherein:
the transistor further includes a gate dielectric material, and
the further material is between the gate electrode material and the gate dielectric material.
7. The IC structure according to claim 5 , wherein a lattice constant of the polarization material is smaller than a lattice constant of the III-N semiconductor material.
8. The IC structure according to claim 1 , wherein the further material has a U-shaped cross-section.
9. An integrated circuit (IC) structure, comprising:
a substrate; and
a transistor, comprising:
a III-N semiconductor material,
a polarization material, where a lattice constant of the polarization material is smaller than a lattice constant of the III-N semiconductor material,
a gate electrode material, and
a further material between the gate electrode material and the III-N semiconductor material, wherein the further material includes fixed charges in concentration of at least 1×10 18 fixed charges per cubic centimeter, and wherein the further material includes oxygen.
10. The IC structure according to claim 9 , wherein the further material further includes lanthanum.
11. The IC structure according to claim 9 , wherein:
the transistor further includes a gate dielectric material, and
the further material is between the gate electrode material and the gate dielectric material.
12. The IC structure according to claim 9 , wherein the further material interfaces the polarization material.
13. The IC structure according to claim 9 , wherein:
the III-N semiconductor material is between the polarization material and the gate electrode material;
the transistor further includes a gate dielectric material, and
the further material is between the gate electrode material and the gate dielectric material.
14. The IC structure according to claim 9 , wherein, in a cross-section along a plane perpendicular to the substrate, the further material has a U-shape.
15. An integrated circuit (IC) structure, comprising:
a transistor that includes:
a gate electrode material;
a polarization material;
a III-N semiconductor material between the polarization material and the gate electrode material, wherein a lattice constant of the polarization material is smaller than a lattice constant of the III-N semiconductor material; and
a further material between the gate electrode material and the III-N semiconductor material, the further material including a semiconductor material with dopant atoms in concentration of at least 1×10 18 dopant atoms per cubic centimeter.
16. The IC structure according to claim 15 , wherein the further material includes gallium and nitrogen.
17. The IC structure according to claim 15 , wherein:
the transistor further includes a gate dielectric material, and
the further material is between the gate electrode material and the gate dielectric material.
18. The IC structure according to claim 15 , wherein the further material includes silicon.
19. The IC structure according to claim 15 , wherein the further material includes magnesium.