Stable multiple threshold voltage devices on replacement metal gate CMOS devices
View Patent ↗A technique for a multiple voltage threshold transistor structure is provided. A narrow channel and long channel are formed on a fin. An epitaxial layer is formed on the fin, and an interlayer dielectric layer is formed on the epitaxial layer. Spacers on the fin define the narrow channel and the long channel. A high-k dielectric material is deposited in the narrow and long channels. A metal layer is deposited on the high-k dielectric material in the narrow and long channels. A height of the high-k dielectric material in the narrow channel is recessed. The metal layer is removed from the narrow and long channels. A work function metal is deposited in the narrow and long channels. A gate conduction metal is deposited to fill the narrow channel and long channel. A capping layer is deposited on the top surface of the structure.
1. A multiple threshold voltage transistor structure, the structure comprising:
at least one first transistor having a high-k dielectric material with a first height on sidewalls of a first trench, the high-k dielectric material having the first height being formed directly on a fin; and
at least one second transistor having the high-k dielectric material with a second height on sidewalls of a second trench, the high-k dielectric material having the second height being formed directly on the fin, wherein the first height of the high-k dielectric material in the at least one first transistor is less than the second height of the high-k dielectric material in the at least one second transistor, wherein the first height and the second height are defined from the fin, wherein the at least one first transistor and the at least one second transistor have a voltage threshold difference of about 80 millivolts such that the at least one first transistor has a lower voltage threshold than the at least one second transistor.
2. The structure of claim 1 , wherein the first height is about 20 nanometers or less shorter than the second height.
3. The structure of claim 1 , wherein the first height is about 20 nanometers shorter than the second height.
4. The structure of claim 1 , wherein the first height is about 30 nanometers shorter than the second height.
5. The structure of claim 1 , wherein the first height is about 20-40 nanometers shorter than the second height.
6. The structure of claim 1 , wherein the first height is about half the second height.
7. The structure of claim 1 , wherein the high-k dielectric material includes hafnium oxide.
8. The structure of claim 1 , wherein the at least one first transistor and the at least one second transistor are separated by a dielectric layer disposed on top of an epitaxial layer, where the epitaxial layer is disposed on top of the fin.
9. The structure of claim 1 , wherein the fin is disposed on a substrate.