Ferroelectric thin-film structure and electronic device including the same
Provided is a ferroelectric thin-film structure including a semiconductor substrate, a first ferroelectric layer on the semiconductor substrate, and a second ferroelectric layer on the semiconductor substrate. The second ferroelectric layer is spaced apart from the first ferroelectric layer and has a different dielectric constant from the first ferroelectric layer. The first ferroelectric layer and the second ferroelectric layer may be different from each other in terms of the amount of a dopant contained therein, and may exhibit different threshold voltages when applied to transistors.
1. A ferroelectric thin-film structure comprising:
a semiconductor substrate;
a first ferroelectric layer on a first transistor region of the semiconductor substrate; and
a second ferroelectric layer on a second transistor region of the semiconductor substrate, the second ferroelectric layer spaced apart from the first ferroelectric layer, a dielectric constant of the second ferroelectric layer being different than a dielectric constant of the first ferroelectric layer, wherein
the first transistor region of the semiconductor substrate and the second transistor region of the semiconductor substrate are spaced apart from each other.
2. The ferroelectric thin-film structure of claim 1 , wherein the first ferroelectric layer and the second ferroelectric layer comprise a HfO 2 -based dielectric material.
3. The ferroelectric thin-film structure of claim 2 , wherein
the first ferroelectric layer comprises Hf x Zr (1-x) O, wherein 0<x<1, and
the second ferroelectric layer comprises Hf x Zr (1-x) O doped with a dopant, wherein 0<x<1.
4. The ferroelectric thin-film structure of claim 3 , wherein the dopant comprises one of Si, Hf, Zr, Al, La, Y, Sr, and Gd.
5. The ferroelectric thin-film structure of claim 3 , wherein the first ferroelectric layer comprises:
at least one first atomic layer including HfO 2 ; and
at least one second atomic layer including ZrO 2 .
6. The ferroelectric thin-film structure of claim 3 , wherein the second ferroelectric layer comprises:
at least one first atomic layer including HfO 2 ;
at least one second atomic layer including ZrO 2 ; and
at least one third atomic layer including HfO 2 doped with the dopant or ZrO 2 doped with the dopant.
7. The ferroelectric thin-film structure of claim 6 , wherein the at least one third atomic layer has a thickness of about 10 nm or less.
8. The ferroelectric thin-film structure of claim 3 , wherein an amount of the dopant is in a range of about 1% to about 10%.
9. A The ferroelectric thin-film structure of claim 1 , wherein
the first ferroelectric layer and the second ferroelectric layer each include a plurality of first atomic layers and a plurality of second atomic layers stacked on each other,
a material of the plurality of first atomic layers is different than a material of the plurality of second atomic layers, and
the second ferroelectric layer further includes one or more third atomic layers having a dopant.
10. The ferroelectric thin-film structure of claim 9 , wherein
the plurality of first atomic layers include HfO 2 ,
the plurality of second atomic layers include ZrO 2 , and
the one or more third atomic layers include HfO 2 or ZrO 2 .
11. The ferroelectric thin-film structure of claim 9 , wherein
the dopant includes one of Si, Hf, Zr, Al, La, Y, Sr, and Gd.
12. The ferroelectric thin-film structure of claim 2 , wherein
the one or more third atomic layers each have a thickness of about 10 nm or less.
13. An electronic device, comprising:
the ferroelectric thin-film structure of claim 9 ;
a first transistor including the first ferroelectric layer; and
a second transistor including the second ferroelectric layer, wherein
a threshold voltage of the first transistor is different than a threshold voltage of the second transistor.
14. An electronic device comprising:
a semiconductor substrate including a first channel region, a first source and a first drain each connected to the first channel region, a second channel region, and a second source and a second drain each connected to the second channel region;
a first transistor including the first channel region, the first source, the first drain, a first ferroelectric layer on the first channel region, and a first gate electrode on the first ferroelectric layer; and
a second transistor including the second channel region, the second source, the second drain, a second ferroelectric layer on the second channel region, and a second gate electrode on the second ferroelectric layer, a dielectric constant of the second ferroelectric layer being different than a dielectric constant of the first ferroelectric layer.
15. The electronic device of claim 14 , wherein the first ferroelectric layer and the second ferroelectric layer comprise a HfO 2 -based dielectric material.
16. The electronic device of claim 15 , wherein
the first ferroelectric layer comprises Hf x Zr (1-x) O, wherein 0<x<1, and
the second ferroelectric layer comprises Hf x Zr (1-x) O doped with a dopant, wherein 0<x<1.
17. The electronic device of claim 16 , wherein the dopant comprises one of Si, Al, La, Y, Sr, and Gd.
18. The electronic device of claim 16 , wherein the first ferroelectric layer comprises:
at least one first atomic layer including HfO 2 ; and
at least one second atomic layer including ZrO 2 .
19. The electronic device of claim 16 , wherein the second ferroelectric layer comprises:
at least one first atomic layer including HfO 2 ;
at least one second atomic layer including ZrO 2 ; and
at least one third atomic layer including HfO 2 doped with the dopant or ZrO 2 doped with the dopant.
20. The electronic device of claim 19 , wherein the at least one third atomic layer is located at a position closest to the second channel region among the at least one first atomic layer, the at least one second atomic layer, and the at least one third atomic layer.
21. The electronic device of claim 19 , wherein the at least one third atomic layer has a thickness of about 10 nm or less.
22. The electronic device of claim 16 , wherein an amount of the dopant is in a range of about 1% to about 10%.
23. The electronic device of claim 14 , wherein the first channel region and the second channel region each comprise at least one of Si, Ge, SiGe, a Group III-V semiconductor, an oxide semiconductor, a nitride semiconductor, an oxynitride semiconductor, a two-dimensional (2D) material, quantum dots, and an organic semiconductor.
24. The electronic device of claim 14 , wherein at least one of the first transistor and the second transistor further comprises an insulating layer between the first channel region and the first ferroelectric layer or between the second channel region and the second ferroelectric layer.
25. The electronic device of claim 14 , wherein at least one of the first transistor and the second transistor further comprises:
an insulating layer between the first ferroelectric layer and the first gate electrode or between the second ferroelectric layer and the second gate electrode; and
a metal layer between the insulating layer and the first ferroelectric layer or between the insulating layer and the second ferroelectric layer.
26. The electronic device of claim 14 , wherein one of the first transistor and the second transistor is a transistor for a logic device and an other of the first transistor and the second transistor is a transistor for a memory device.