Three-dimensional memory device with embedded dynamic random-access memory

1. A three-dimensional (3D) memory device, comprising:

a first semiconductor structure comprising a peripheral circuit, a first bonding layer comprising at least one first bonding contact electronically connected to the peripheral circuit, and a first interconnect layer vertically between the first bonding layer and the peripheral circuit;

a second semiconductor structure comprising an array of 3D NAND memory strings, a second bonding layer comprising at least one second bonding contact electronically connected to the array of 3D NAND memory strings, and a second interconnect layer vertically between the second bonding layer and the array of 3D NAND memory strings; and

a bonding interface between the first semiconductor structure and the second semiconductor structure.

2. The 3D memory device of claim 1 , wherein the first semiconductor structure comprises:

a substrate;

the peripheral circuit on the substrate; and

the first bonding layer above the peripheral circuit.

3. The 3D memory device of claim 2 , wherein the second semiconductor structure comprises:

the second bonding layer above the first bonding layer;

a memory stack above the second bonding layer;

the array of 3D NAND memory strings extending vertically through the memory stack; and

a semiconductor layer above and in contact with the array of 3D NAND memory strings.

4. The 3D memory device of claim 3 , further comprising a pad-out interconnect layer above the semiconductor layer.

5. The 3D memory device of claim 3 , wherein the semiconductor layer comprises polysilicon.

6. The 3D memory device of claim 3 , wherein the semiconductor layer comprises single-crystal silicon.

7. The 3D memory device of claim 1 , wherein the second semiconductor structure comprises:

a substrate;

a memory stack above the substrate;

the array of 3D NAND memory strings extending vertically through the memory stack; and

the second bonding layer above the memory stack and the array of 3D NAND memory strings.

8. The 3D memory device of claim 7 , wherein the first semiconductor structure comprises:

the first bonding layer above the second bonding layer;

the peripheral circuit above the first bonding layer; and

a semiconductor layer above and in contact with the peripheral circuit.

9. The 3D memory device of claim 8 , further comprising a pad-out interconnect layer above the semiconductor layer.

10. The 3D memory device of claim 1 , wherein the peripheral circuit is electrically connected to the array of 3D NAND memory strings through the first and second interconnect layers and the at least one first bonding contact and the at least one second bonding contact.

11. The 3D memory device of claim 1 , wherein each of the first interconnect layer and the second interconnect layer comprises at least one lateral interconnect line and at least one vertical interconnect access contact.

12. The 3D memory device of claim 11 , wherein each of the first interconnect layer and the second interconnect layer comprises one or more interlayer dielectric layers in which the at least one lateral interconnect line and the at least one vertical interconnect access contact are formed.

13. The 3D memory device of claim 1 , wherein:

the peripheral circuit comprises peripheral transistors; and

the first semiconductor structure comprises dynamic random-access memory (DRAM) selection transistors in a same device layer with the peripheral transistors.

14. A method for forming a three-dimensional (3D) memory device, comprising:

forming a first semiconductor structure comprising a peripheral circuit, a first bonding layer comprising at least one first bonding contact electronically connected to the peripheral circuit, and a first interconnect layer vertically between the first bonding layer and the peripheral circuit;

forming a second semiconductor structure comprising an array of 3D NAND memory strings, a second bonding layer comprising at least one second bonding contact electronically connected to the array of 3D NAND memory strings, and a second interconnect layer vertically between the second bonding layer and the array of 3D NAND memory strings; and

bonding the first semiconductor structure and the second semiconductor structure in a face-to-face manner, such that the first semiconductor structure and the second semiconductor structure are in contact at a bonding interface.

15. The method of claim 14 , wherein forming the first semiconductor structure comprises:

forming the peripheral circuit on a first substrate;

forming the first interconnect layer above the peripheral circuit; and

forming the first bonding layer above the first interconnect layer.

16. The method of claim 14 , wherein forming the second semiconductor structure comprises:

forming a memory stack above a second substrate;

forming the array of 3D NAND memory strings extending vertically through the memory stack;

forming the second interconnect layer above the array of 3D NAND memory strings; and

forming the second bonding layer above the second interconnect layer.

17. The method of claim 16 , further comprising:

thinning the second substrate to form a semiconductor layer after the bonding; and

forming a pad-out interconnect layer above the semiconductor layer.

18. The method of claim 17 , wherein the first semiconductor structure is above the second semiconductor structure after the bonding.

19. The method of claim 14 , wherein forming the second interconnect layer comprises:

forming at least one lateral interconnect line and at least one vertical interconnect access contact in one or more interlayer dielectric layers to make electrical connections with the array of 3D NAND memory strings.

20. The method of claim 14 , wherein the second semiconductor structure is above the first semiconductor structure after the bonding.