Complementary field effect transistor (CFET) with balanced N and P drive current
Disclosed are complementary field effect transistors (CFETs) with balanced n and p drive current, and methods for making the same. In an aspect, a CFET structure comprises an nFET with horizontal p-doped nanosheet channels arranged in a first vertical stack, each horizontal p-doped nanosheet channel having a width W 1 , and connecting a first source contact to a first drain contact through a first gate-all-around (GAA) region having a length L 1 . The CFET structure further comprises a pFET with horizontal n-doped nanosheet channels arranged in a second vertical stack disposed on the first vertical stack, each horizontal n-doped nanosheet channel having a width W 2 , and connecting a second source contact to a second drain contact through a second GAA region having a length L 2 , wherein W 2 /L 2 is not equal to W 1 /L 1.
1. A complementary field effect transistor (CFET) structure, comprising:
an n-channel field effect transistor (nFET) having a plurality of horizontal p-doped nanosheet channels arranged in parallel in a first vertical stack and separated from each other by a first vertical distance (D 1 ), each horizontal p-doped nanosheet channel having a first width (W 1 ), and connecting a first source contact to a first drain contact through a first gate-all-around (GAA) region having a first length (L 1 ) and being connected to a first gate contact; and
a p-channel field effect transistor (pFET) having a plurality of horizontal n-doped nanosheet channels arranged in parallel in a second vertical stack and separated from each other by a second vertical distance (D 2 ), each horizontal n-doped nanosheet channel having a second width (W 2 ), and connecting a second source contact to a second drain contact through a second GAA region having a second length (L 2 ) and being connected to a second gate contact,
wherein the first vertical stack is disposed on the second vertical stack, and wherein W 2 /L 2 is not equal to W 1 /L 1 , and
wherein the first source contact, the first gate contact, and the first drain contact are disposed on a first surface of the CFET structure and the second source contact, the second gate contact, and the second drain contact are disposed on a second surface of the CFET structure opposite the first surface of the CFET structure.
2. The CFET structure of claim 1 , wherein a magnitude of a saturation current of the nFET is equal to a magnitude of a saturation current of the pFET.
3. The CFET structure of claim 1 , wherein:
the first vertical stack is horizontally centered around a first vertical axis and the second vertical stack is horizontally centered around a second vertical axis different from the first vertical axis; or
the first vertical stack and the second vertical stack are horizontally centered around a common shared vertical axis.
4. The CFET structure of claim 1 , wherein one or more of the group of the plurality of horizontal p-doped nanosheet channels and the plurality of horizontal n-doped nanosheet channels comprises Si, Ge, or SiGe.
5. The CFET structure of claim 1 , wherein each of the plurality of horizontal p-doped nanosheet channels are separated from the first GAA region by an insulating layer disposed between the plurality of horizontal p-doped nanosheet channels and the first GAA region.
6. The CFET structure of claim 1 , wherein each of the plurality of horizontal n-doped nanosheet channels are separated from the second GAA region by an insulating layer disposed between the plurality of horizontal n-doped nanosheet channels and the second GAA region.
7. The CFET structure of claim 1 , wherein the first GAA region is in direct contact with the second GAA region.
8. A complementary field effect transistor (CFET) structure, comprising:
an n-channel field effect transistor (nFET) having a plurality of horizontal p-doped nanosheet channels arranged in parallel in a first vertical stack and separated from each other by a first vertical distance (D 1 ), each horizontal p-doped nanosheet channel having a first width (W 1 ), and connecting a first source contact to a first drain contact through a first gate-all-around (GAA) region having a first length (L 1 ) and being connected to a first gate contact; and
a p-channel field effect transistor (pFET) having a plurality of horizontal n-doped nanosheet channels arranged in parallel in a second vertical stack and separated from each other by a second vertical distance (D 2 ), each horizontal n-doped nanosheet channel having a second width (W 2 ), and connecting a second source contact to a second drain contact through a second GAA region having a second length (L 2 ) and being connected to a second gate contact,
wherein the first vertical stack is disposed on the second vertical stack, and wherein W 2 /L 2 is not equal to W 1 /L 1 , and
wherein a ratio of (W 2 /L 2 ) to (W 1 /L 1 ) is less than or equal to 4.4.
9. The CFET structure of claim 3 , wherein the first source contact, the first gate contact, the first drain contact, the second source contact, the second gate contact, and the second drain contact are disposed on a first surface of the CFET structure.
10. A method of fabricating a complementary field effect transistor (CFET) structure, the method comprising:
forming an n-channel field effect transistor (nFET) having a plurality of horizontal p-doped nanosheet channels arranged in parallel in a first vertical stack and separated from each other by a first vertical distance (D 1 ), each horizontal p-doped nanosheet channel having a first width (W 1 ), and connecting a first source contact to a first drain contact through a first gate-all-around (GAA) region having a first length (L 1 ) and being connected to a first gate contact; and
forming a p-channel field effect transistor (pFET) having a plurality of horizontal n-doped nanosheet channels arranged in parallel in a second vertical stack and separated from each other by a second vertical distance (D 2 ), each horizontal n-doped nanosheet channel having a second width (W 2 ), and connecting a second source contact to a second drain contact through a second GAA region having a second length (L 2 ) and being connected to a second gate contact,
wherein the first vertical stack is disposed on the second vertical stack, and wherein W 2 /L 2 is not equal to W 1 /L 1 , and
wherein the first source contact, the first gate contact, and the first drain contact are formed on a first surface of the CFET structure and the second source contact, the second gate contact, and the second drain contact are formed on a second surface of the CFET structure opposite the first surface of the CFET structure.
11. The method of claim 10 , wherein a magnitude of a saturation current of the nFET is equal to a magnitude of a saturation current of the pFET.
12. The method of claim 11 , wherein:
the first vertical stack is formed horizontally centered around a first vertical axis and the second vertical stack is formed horizontally centered around a second vertical axis different from the first vertical axis; or
the first vertical stack and the second vertical stack are formed horizontally centered around a common shared vertical axis.
13. The method of claim 10 , wherein one or more of the group of the plurality of horizontal p-doped nanosheet channels and the plurality of horizontal n-doped nanosheet channels comprises Si, Ge, or SiGe.
14. The method of claim 10 , wherein each of the plurality of horizontal p-doped nanosheet channels are separated from the first GAA region by an insulating layer formed between the plurality of horizontal p-doped nanosheet channels and the first GAA region.
15. The method of claim 10 , wherein each of the plurality of horizontal n-doped nanosheet channels are separated from the second GAA region by an insulating layer formed between the plurality of horizontal n-doped nanosheet channels and the second GAA region.
16. The method of claim 10 , wherein the first GAA region is formed in direct contact with the second GAA region.
17. A method of fabricating a complementary field effect transistor (CFET) structure, the method comprising;
forming an n-channel field effect transistor (nFET) having a plurality of horizontal p-doped nanosheet channels arranged in parallel in a first vertical stack and separated from each other by a first vertical distance (D 1 ), each horizontal p-doped nanosheet channel having a first width (W 1 ), and connecting a first source contact to a first drain contact through a first gate-all-around (GAA) region having a first length (L 1 ) and being connected to a first gate contact; and
forming a p-channel field effect transistor (pFET) having a plurality of horizontal n-doped nanosheet channels arranged in parallel in a second vertical stack and separated from each other by a second vertical distance (D 2 ), each horizontal n-doped nanosheet channel having a second width (W 2 ), and connecting a second source contact to a second drain contact through a second GAA region having a second length (L 2 ) and being connected to a second gate contact,
wherein the first vertical stack is disposed on the second vertical stack, and wherein W 2 /L 2 is not equal to W 1 /L 1 , and
wherein a ratio of (W 2 /L 2 ) to (W 1 /L 1 ) is less than or equal to 4.4.
18. The method of claim 13 , wherein the first source contact, the first gate contact, the first drain contact, and the second source contact, the second gate contact, and the second drain contact are formed on a first surface of the CFET structure.