Methods and structures for die-to-die bonding

1. A method for bonding, comprising:

dicing one or more device wafers to obtain a plurality of dies;

placing at least one first die of the plurality of dies onto a first carrier wafer and at least one second die of the plurality of dies onto a second carrier wafer, the at least one first die and the at least one second die each being functional, wherein:

each first die comprises:

a 3D NAND memory array including an array of 3D NAND memory strings on a first side of a first semiconductor layer,

a first interconnect layer including a plurality of first interconnects coupled with the array of 3D NAND memory strings,

a first bonding layer including a plurality of first bonding contacts coupled with the plurality of first interconnects,

a pad-out interconnect layer on a second side of the first semiconductor layer opposite to the first side, and

at least one contact pad in the pad-out interconnect layer configured to transfer electrical signals to outside circuits;

each second die comprises:

an embedded DRAM array including an array of embedded DRAM cells on a second semiconductor layer,

a periphery circuit including a plurality of peripheral transistors on the second semiconductor layer and configured to control operations of the 3D NAND memory array and the embedded DRAM array,

a second interconnect layer including a plurality of second interconnects coupled with the array of embedded DRAM cells and the plurality of peripheral transistors, and

a second bonding layer including a plurality of second bonding contacts coupled with the plurality of second interconnects;

bonding the at least one first die each with a respective second die; and

completely removing, respectively, the first carrier wafer and the second carrier wafer to form a plurality of bonded semiconductor devices each comprising one first die and the respective second die.

2. The method of claim 1 , further comprising:

forming a respective protection layer over the one or more device wafers before the dicing; and

dicing, with the respective protection layer, the one or more device wafers to form the plurality of dies each under a respective protection layer portion.

3. The method of claim 2 , wherein:

the first carrier wafer and the second carrier wafer each comprises a respective adhesive layer on a surface that is in contact with the respective dies; and

placing the at least one first die and the at least one second die onto the respective carrier wafer comprises attaching the at least one first die and the at least one second die to the respective adhesive layer, the portion of the respective protection layer facing away from the adhesive layer.

4. The method of claim 3 , wherein:

forming the adhesive layer comprises forming a plurality of adhesion portions on the surface in contact with the respective dies, the plurality of adhesion portions being in contact with one another; and

placing the at least one first die and the at least one second die onto the respective carrier wafer comprises attaching the at least one first die and the at least one second die to the respective adhesive portion of the respective adhesive layer.

5. The method of claim 3 , further comprising forming a plurality of respective openings in the first carrier wafer and the second carrier wafer, wherein:

forming the adhesive layer comprises forming an adhesive portion on the bottom of each of the openings; and

attaching the at least one first die and the at least one second die to the respective adhesive layer comprises placing the at least one first die and the at least one second die each into a respective opening of the respective carrier wafer.

6. The method of claim 3 , further comprising removing the respective protection layer portion from each of the at least one first die and the at least one second die.

7. The method of claim 6 , further comprising performing a respective surface treatment on each of the at least one first die and the at least one second die after the respective protection layer portion is removed.

8. The method of claim 1 , wherein the bonding comprises hybrid bonding.

9. The method of claim 1 , wherein placing the at least one first die comprises placing a plurality of first dies in a uniform distribution on the first carrier wafer.

10. The method of claim 9 , further comprising placing the plurality of first dies in full coverage over the first carrier wafer.

11. The method of claim 1 , wherein bonding the at least one first die each with the respective second die comprises:

hybrid bonding the first bonding layer with the second bonding layer, such that the plurality of first bonding contacts are joined with the plurality of second bonding contacts respectively at a bonding interface.

12. A method for bonding, comprising:

dicing a first device wafer to obtain a plurality of first dies each including:

a 3D NAND memory array including an array of 3D NAND memory strings on a first side of a first semiconductor layer,

a first interconnect layer including a plurality of first interconnects coupled with the array of 3D NAND memory strings,

a first bonding layer including a plurality of first bonding contacts coupled with the plurality of first interconnects,

a pad-out interconnect layer on a second side of the first semiconductor layer opposite to the first side, and

at least one contact pad in the pad-out interconnect layer configured to transfer electrical signals to outside circuits;

dicing a second device wafer to obtain a plurality of second dies each including;

an embedded DRAM array including an array of embedded DRAM cells on a second semiconductor layer,

a periphery circuit including a plurality of peripheral transistors on the second semiconductor layer and configured to control operations of the 3D NAND memory array and the embedded DRAM array,

a second interconnect layer including a plurality of second interconnects coupled with the array of embedded DRAM cells and the plurality of peripheral transistors, and

a second bonding layer including a plurality of second bonding contacts coupled with the plurality of second interconnects;

placing the plurality of first dies onto a first carrier wafer and the plurality of second dies onto a second carrier wafer;

bonding the plurality of first dies and the plurality of second dies, such that each first die is joined with a corresponding second die; and

completely removing the first carrier wafer and the second carrier wafer to form a plurality of bonded semiconductor devices each comprising one first die and the corresponding second die.

13. The method of claim 12 , further comprising: forming a respective protection layer over the first and second device wafers before the dicing; and after dicing the first and second device wafers, each of the plurality of first and second dies is under a respective protection layer portion.

14. The method of claim 13 , wherein:

the first carrier wafer and the second carrier wafer each comprises a respective adhesive layer on a surface that is in contact with the respective first and second dies; and

placing the at least one first die and the at least one second die onto the respective carrier wafer comprises attaching the at least one first die and the at least one second die to the respective adhesive layer, the portion of the respective protection layer facing away from the adhesive layer.

15. The method of claim 14 , wherein:

forming the adhesive layer comprises forming a plurality of adhesion portions on the surface in contact with the respective first and second dies, the plurality of adhesion portions being in contact with one another; and

placing the at least one first die and the at least one second die onto the respective carrier wafer comprises attaching the at least one first die and the at least one second die to the respective adhesive portion of the respective adhesive layer.

16. The method of claim 15 , further comprising forming a plurality of respective openings in the first carrier wafer and the second carrier wafer, wherein:

forming the adhesive layer comprises forming an adhesive portion on the bottom of each of the openings; and

attaching the at least one first die and the at least one second die to the respective adhesive layer comprises placing the at least one first die and the at least one second die each into a respective opening of the respective carrier wafer.

17. The method of claim 15 , further comprising:

removing the respective protection layer portion from each of the at least one first die and the at least one second die; and

performing a respective surface treatment on each of the at least one first die and the at least one second die after the respective protection layer portion is removed.

18. The method of claim 12 , wherein placing the at least one first die comprises placing a plurality of first dies in a uniform distribution on the first carrier wafer.

19. The method of claim 18 , further comprising placing the plurality of first dies in full coverage over the first carrier wafer.

20. The method of claim 12 , wherein bonding the plurality of first dies and the plurality of second dies comprises:

hybrid bonding the first bonding layer with the second bonding layer, such that the plurality of first bonding contacts are joined with the plurality of second bonding contacts respectively at a bonding interface.