Semiconductor devices with embedded ferroelectric field effect transistors

1. A method, comprising:

providing a structure having a substrate, gate stacks and source/drain (S/D) features over the substrate, S/D contacts over the S/D features, one or more dielectric layers over the gate stacks and the S/D contacts, and a via penetrating the one or more dielectric layers and electrically connecting to one of the gate stacks and the S/D contacts, wherein the via is above the one of the gate stacks and S/D contacts;

forming a ferroelectric (FE) stack directly above the structure, wherein the FE stack includes an FE layer and a top electrode layer over the FE layer, wherein the FE stack directly contacts the via; and

patterning the FE stack, resulting in a patterned FE stack including a patterned FE feature and a patterned top electrode over the patterned FE feature.

2. The method of claim 1 , wherein the FE layer includes one of PZT (Pb(Zr x Ti 1-x )O 3 ), SBT (SrBi 2 Ta 2 O 9 ), BLT ((Bi,La) 4 Ti 3 O 12 ), BIT (Bi 4 Ti 3 O 12 ), HfZrO 2 , HfO 2 , and BFO (BiFeO 3 ).

3. The method of claim 1 , wherein the top electrode layer includes one of Ru, Pt, Ta, TaN, Ti, TiO 2 , TiN, W, Ir, IrO 2 , SrRuO 3 , and LaNiO 3 .

4. The method of claim 1 , further comprising:

forming a first dielectric layer on sidewalls of the patterned FE stack.

5. The method of claim 4 , wherein the first dielectric layer includes one of La 2 O 3 , Al 2 O 3 , SiOCN, SiOC, SiCN, SiO 2 , SiC, ZnO, ZrN, ZrAlO, Ta 2 O 5 , ZrO 2 , HfO 2 , Si 3 N 4 , Y 2 O 3 , AlON, TaCN, and SiON.

6. The method of claim 1 , further comprising:

depositing a first dielectric layer over the patterned FE stack; and

forming a conductive structure that penetrates the first dielectric layer and directly contacts the patterned top electrode.

7. The method of claim 1 , wherein the FE stack further includes a bottom electrode layer under the FE layer and wherein the patterned FE stack further includes a patterned bottom electrode under the patterned FE feature.

8. The method of claim 1 , wherein the via includes one of Co, W, Ru, Al, Mo, Ti, TiN, TiSi, CoSi, NiSi, TaN, Ni, and TiSiN.

9. A method, comprising:

providing a structure having a substrate, gate stacks and source/drain (S/D) features over the substrate, S/D contacts over the S/D features, one or more dielectric layers over the gate stacks and the S/D contacts, and a via penetrating the one or more dielectric layers and electrically connecting to one of the gate stacks and the S/D contacts, wherein the via is above the one of the gate stacks and S/D contacts;

forming a ferroelectric (FE) stack directly above the structure, wherein the FE stack includes a bottom electrode layer, an FE layer over the bottom electrode layer, and a top electrode layer over the FE layer, wherein the FE stack directly contacts the via;

patterning the FE stack, resulting in a patterned FE stack including a patterned bottom electrode, a patterned FE feature over the patterned bottom electrode, and a patterned top electrode over the patterned FE feature; and

forming a dielectric liner surrounding sidewalls of the patterned FE stack.

10. The method of claim 9 , wherein the FE layer includes one of PZT (Pb(Zr x Ti 1-x )O 3 ), SBT (SrBi 2 Ta 2 O 9 ), BLT ((Bi,La) 4 Ti 3 O 12 ), BIT (Bi 4 Ti 3 O 12 ), HfZrO 2 , HfO 2 , and BFO (BiFeO 3 ).

11. The method of claim 9 , further comprising:

forming a first dielectric layer embedding the patterned FE stack; and

forming a conductive structure that penetrates the first dielectric layer and directly contacts the patterned top electrode.

12. The method of claim 9 , wherein the one or more dielectric layers include a dielectric cap that is directly on the one of the gate stacks and the S/D contacts.

13. The method of claim 9 , wherein the one or more dielectric layers include a contact etch stop layer and an inter-level dielectric layer over the contact etch stop layer.

14. The method of claim 9 , wherein the one or more dielectric layers include a dielectric cap that is directly on the one of the gate stacks and the S/D contacts, a contact etch stop layer over the dielectric cap, and an inter-level dielectric layer over the contact etch stop layer.

15. The method of claim 9 , wherein the patterning of the FE stack includes:

forming an etch mask using photolithography; and

etching the top electrode layer, the FE layer, and the bottom electrode layer through openings in the etch mask.

16. A method, comprising:

providing a structure having a substrate, gate stacks and source/drain (S/D) structures over the substrate, S/D contacts over the S/D structures, one or more dielectric layers over the gate stacks and the S/D contacts, and a via penetrating the one or more dielectric layers and electrically connecting to one of the gate stacks and the S/D contacts, wherein the via is above the one of the gate stacks and S/D contacts;

forming a ferroelectric (FE) stack directly above the via, wherein the FE stack includes an FE layer and a first electrode layer over the FE layer, wherein the FE layer directly contacts the via;

patterning the FE stack, resulting in a patterned FE stack including a patterned FE structure and a patterned first electrode over the patterned FE structure;

forming a dielectric liner over sidewalls of the patterned FE stack;

forming a first dielectric layer covering the patterned FE stack and the dielectric liner; and

forming a conductive structure that penetrates the first dielectric layer and directly contacts the patterned first electrode.

17. The method of claim 16 , wherein the dielectric liner is formed with rounded top corners.

18. The method of claim 17 , wherein the patterned first electrode is formed with rounded top corners.

19. The method of claim 18 , wherein the FE layer includes one of PZT (Pb(Zr x Ti 1-x )O 3 ), SBT (SrBi 2 Ta 2 O 9 ), BLT ((Bi,La) 4 Ti 3 O 12 ), BIT (Bi 4 Ti 3 O 12 ), HfZrO 2 , HfO 2 , and BFO (BiFeO 3 ).

20. The method of claim 19 , wherein the first electrode layer includes one of Ru, Pt, Ta, TaN, Ti, TiO 2 , TiN, W, Ir, IrO 2 , SrRuO 3 , and LaNiO 3 .