Negative capacitance transistor with a diffusion blocking layer

1. A semiconductor device, comprising:

a substrate;

a dielectric layer disposed over a portion of the substrate;

a diffusion blocking layer disposed over the dielectric layer, wherein the diffusion blocking layer and the dielectric layer have different material compositions, and wherein the diffusion blocking layer includes lanthanum oxide or praseodymium oxide; and

a ferroelectric layer disposed over the diffusion blocking layer.

2. The semiconductor device of claim 1 , wherein the dielectric layer and the diffusion blocking layer each have a dielectric constant greater than a dielectric constant of silicon dioxide, wherein the dielectric layer is a gate dielectric layer of a transistor, and wherein the dielectric layer and the diffusion blocking layer have different material compositions.

3. The semiconductor device of claim 1 , wherein:

the ferroelectric layer is doped with dopants.

4. The semiconductor device of claim 3 , wherein:

the ferroelectric layer includes: hafnium zirconium oxide, hafnium silicon oxide, hafnium aluminum oxide, lead zirconium titanium oxide, or barium titanium oxide; and

the dopants in the ferroelectric layer include zirconium, silicon, aluminum, lead, barium, or titanium.

5. The semiconductor device of claim 1 , wherein the diffusion blocking layer includes a plurality of sub-layers that each have a different diffusion-blocking material.

6. The semiconductor device of claim 1 , further comprising: an interfacial layer configured to tune a capacitance of the semiconductor device, the interfacial layer having a different material composition than the dielectric layer, the diffusion blocking layer, and the ferroelectric layer.

7. The semiconductor device of claim 1 , wherein:

the semiconductor device includes a negative capacitance transistor;

the dielectric layer, the diffusion blocking layer, and the ferroelectric layer are portions of a gate dielectric of the negative capacitance transistor; and

the negative capacitance transistor further comprises: a metal gate electrode disposed over the ferroelectric layer.

8. The semiconductor device of claim 7 , wherein the negative capacitance transistor exhibits hysteresis in a graph of remanent polarization versus coercivity.

9. The semiconductor device of claim 1 , wherein:

a thickness of the dielectric layer is in a range from about 1 nanometer and about 3 nanometers;

a thickness of the diffusion blocking layer is in a range from about 1 nanometer and about 3 nanometers; and

a thickness of the ferroelectric layer is in a range from about 1 nanometer and about 10 nanometers.

10. A semiconductor device, comprising:

a channel region formed in a substrate;

a gate dielectric layer located over the channel region, wherein the gate dielectric layer has a dielectric constant greater than a dielectric constant of silicon dioxide;

an interfacial oxide layer disposed between the channel region and the gate dielectric layer;

a diffusion blocking layer located over the gate dielectric layer, wherein the diffusion blocking layer and the gate dielectric layer contain different types of high-k dielectric materials, and wherein the diffusion blocking layer includes lanthanum oxide or praseodymium oxide;

a ferroelectric layer located over the diffusion blocking layer, wherein the ferroelectric layer contains dopants, and wherein a material composition of the diffusion blocking layer is configured to be non-reactive with the dopants and to reduce dopant diffusion from the ferroelectric layer into the gate dielectric layer; and

a metal gate electrode located over the ferroelectric layer;

wherein the semiconductor device is a negative capacitance device.

11. The semiconductor device of claim 10 , wherein:

the gate dielectric layer includes hafnium oxide;

the ferroelectric layer includes: hafnium zirconium oxide, hafnium silicon oxide, hafnium aluminum oxide, lead zirconium titanium oxide, or barium titanium oxide; and

the dopants in the ferroelectric layer include zirconium, silicon, aluminum, lead, barium, or titanium.

12. The semiconductor device of claim 10 , wherein the negative capacitance device exhibits an S-curved hysteresis in a graph of remanent polarization versus coercivity.

13. The semiconductor device of claim 10 , wherein the diffusion blocking layer includes a plurality of sub-layers that each have a different diffusion-blocking material.

14. The semiconductor device of claim 10 , wherein:

a thickness of the gate dielectric layer is in a range from about 1 nanometer and about 3 nanometers;

a thickness of the diffusion blocking layer is in a range from about 1 nanometer and about 3 nanometers; and

a thickness of the ferroelectric layer is in a range from about 1 nanometer and about 10 nanometers.

15. A method of fabricating a semiconductor device, comprising:

forming a dielectric layer over a channel region of a transistor;

depositing a diffusion blocking layer over the dielectric layer;

forming a ferroelectric layer over the diffusion blocking layer, wherein the ferroelectric layer contains dopants; and

forming a gate electrode over the ferroelectric layer;

wherein:

a first annealing process is performed after the ferroelectric layer is formed but before the gate electrode is formed;

one or more second annealing processes are performed during the formation of the gate electrode; and

the diffusion blocking layer reduces dopant diffusion from the ferroelectric layer into the dielectric layer during the first annealing process and the one or more second annealing processes.

16. The method of claim 15 , further comprising, before the forming the dielectric layer: forming an interfacial oxide layer over the channel region, wherein the dielectric layer is formed over the interfacial oxide layer.

17. The method of claim 15 , wherein the forming of the diffusion blocking layer comprises performing an atomic layer deposition (ALD) process.

18. The method of claim 15 , wherein the dielectric layer, the diffusion blocking layer, and the ferroelectric layer are formed to have different material compositions.

19. The method of claim 15 , wherein the forming of the diffusion blocking layer comprises forming aluminum oxide, tantalum oxide, titanium oxide, lanthanum oxide, or praseodymium oxide as the diffusion blocking layer.

20. The method of claim 15 , wherein the forming of the ferroelectric layer comprises:

depositing a material that contains hafnium zirconium oxide, hafnium silicon oxide, hafnium aluminum oxide, lead zirconium titanium oxide, or barium titanium oxide; and

doping the deposited material with zirconium, silicon, aluminum, lead, barium, or titanium.