Gate structure of vertical FET and method of manufacturing the same
A vertical field-effect transistor (VFET) device and a method of manufacturing the same are provided. The VFET device includes: a fin structure formed on a substrate; a gate structure including a gate dielectric layer formed on an upper portion of a sidewall of the fin structure, and a conductor layer formed on a lower portion of the gate dielectric layer; a top source/drain (S/D) region formed above the fin structure and the gate structure; a bottom S/D region formed below the fin structure and the gate structure; a top spacer formed on an upper portion of the gate dielectric layer, and between the top S/D region and a top surface of the conductor layer; and a bottom spacer formed between the gate structure and the bottom S/D region. A top surface of the gate dielectric layer is positioned at the same or substantially same height as or positioned lower than a top surface of the top spacer, and higher than the top surface of the conductor layer.
1. A vertical field-effect transistor (VFET) device comprising:
a fin structure formed on a substrate;
a gate structure comprising:
a gate dielectric layer formed on an upper portion of a sidewall of the fin structure; and
a conductor layer formed on a lower portion of the gate dielectric layer;
a top source/drain (S/D) region formed above the fin structure and the gate structure;
a bottom S/D region formed below the fin structure and the gate structure;
a top spacer formed on an upper portion of the gate dielectric layer, and between the top S/D region and a top surface of the conductor layer; and
a bottom spacer formed between the gate structure and the bottom S/D region;
wherein a top surface of the gate dielectric layer is positioned at the same or substantially same height as or positioned lower than a top surface of the top spacer, and higher than the top surface of the conductor layer, and
wherein the upper portion of the gate dielectric layer, on which the top spacer is formed, is laterally thicker than the lower portion of the gate dielectric layer having a uniform or substantially uniform lateral thickness along a lower portion of the sidewall of the fin structure.
2. The VFET of claim 1 , wherein the top surface of the gate dielectric layer is positioned at the same or substantially same height as the top surface of the top spacer.
3. The VFET of claim 1 , wherein the top surface of the gate dielectric layer is positioned lower than the top surface of the top spacer, and
wherein the top spacer is formed on the top surface of gate dielectric layer.
4. The VFET of claim 1 , wherein the top surface of the conductor layer is positioned below a top end of the lower portion of the gate dielectric layer.
5. The VFET of claim 1 , wherein the conductor layer is not laterally formed on the upper portion of the gate dielectric layer.
6. The VFET device of claim 1 , wherein the gate dielectric layer comprises:
an interfacial layer conformally formed on the sidewall of the fin structure; and
a high-κ dielectric layer conformally formed on the interfacial layer except at a position where the high-κ dielectric layer is extendedly formed on a top surface of the bottom spacer.
7. The VFET device of claim 6 , wherein the interfacial layer comprises at least one of silicon oxide (SiO), silicon dioxide (SiO 2 ), and silicon nitride (SiON), and
wherein the high-κ dielectric layer has a dielectric constant value greater than 7 and comprises a metal oxide of or a metal silicate of Hf, Al, Zr, La, Mg, Ba, Ti, Pb, or a combination thereof.
8. The VFET device of claim 7 , wherein the high-κ dielectric layer has the dielectric constant value greater than 15, and comprises at least one of HfO 2 and HfSiON.
9. The VFET device of claim 1 , further comprising an interlayer formed on a side wall of the conductor layer, the top spacer and the top S/D region to insulate the VFET from an outside conduction source, the interlayer comprising nitride, oxide, or a combination thereof.
10. The VFET device of claim 1 , wherein a vertical thickness of the top spacer is greater than or equal to a vertical length of the upper portion of the gate dielectric layer.
11. A vertical field-effect transistor (VFET) device comprising:
a fin structure formed on a substrate;
a gate structure comprising:
a gate dielectric layer formed on an upper portion of a sidewall of the fin structure; and
a conductor layer formed on a lower portion of the gate dielectric layer;
a top source/drain (S/D) region formed above the fin structure to cover the gate structure;
a bottom S/D region formed below the fin structure and the gate structure;
an interlayer formed outside the gate structure and the top S/D region;
an air gap formed between the top S/D region and a top surface of the conductor layer of the gate structure, and between the gate structure and the interlayer; and
a bottom spacer formed between the gate structure and the bottom S/D region.
12. The VFET device of claim 11 , wherein the gate dielectric layer comprises:
an interfacial layer conformally formed on the sidewall of the fin structure; and
a high-κ dielectric layer conformally formed on the interfacial layer except at a position where the high-κ dielectric layer is extendedly formed on a top surface of the bottom spacer.
13. The VFET device of claim 12 , wherein the gate dielectric layer has a uniform thickness along the sidewall of the fin structure except at the position where the high-κ dielectric layer is extendedly formed on the top surface of the bottom spacer.