Embodiments of 3D memory devices and methods for forming the same are disclosed. In an example, a method for forming a 3D memory device is disclosed. A sacrificial layer above a second semiconductor layer at a first side of a substrate and a dielectric stack on the sacrificial layer are subsequently formed. A channel structure extending vertically through the dielectric stack and the sacrificial layer into the second semiconductor layer is formed. The sacrificial layer is replaced with a first semiconductor layer in contact with the second semiconductor layer. The dielectric stack is replaced with a memory stack, such that the channel structure extends vertically through the memory stack and the first semiconductor layer into the second semiconductor layer. A source contact is formed at a second side opposite to the first side of the substrate to be in contact with the second semiconductor layer.

A device comprises a first chip comprising a first connection pad embedded in a first dielectric layer and a first bonding pad embedded in the first dielectric layer, wherein the first bonding pad comprises a first portion and a second portion, the second portion being in contact with the first connection pad and a second chip comprising a second bonding pad embedded in a second dielectric layer of the second chip, wherein the first chip and the second chip are face-to-face bonded together through the first bonding pad the second bonding pad.

In one embodiment, a semiconductor device includes a lower interconnect layer including a plurality of lower interconnects, and a plurality of lower pads provided on the lower interconnects. The device further includes a plurality of upper pads provided on the lower pads and being in contact with the lower pads, and an upper interconnect layer including a plurality of upper interconnects provided on the upper pads. The lower pads include a plurality of first pads and a plurality of second pads. The upper pads include a plurality of third pads provided on the second pads and a plurality of fourth pads provided on the first pads, a lower face of each third pad is larger in area than a upper face of each second pad, and a lower face of each fourth pad is smaller in area than a upper face of each first pad.

A wafer-to-wafer bonding structure includes a first wafer including a first conductive pad in a first insulating layer and a first barrier layer surrounding a lower surface and side surfaces of the first conductive pad, a second wafer including a second conductive pad in a second insulating layer and a second barrier layer surrounding a lower surface and side surfaces of the second conductive pad, the second insulating layer being bonded to the first insulating layer, and at least a portion of an upper surface of the second conductive pad being partially or entirely bonded to at least a portion of an upper surface of the first conductive pad, and a third barrier layer between portions of the first and second wafers where the first and second conductive pads are not bonded to each other.

A 3D semiconductor device comprising: a first level; and a second level, wherein said first level comprises single crystal silicon and a plurality of logic circuits, wherein said plurality of logic circuits each comprise first transistors, wherein said second level is disposed above said first level and comprises a plurality of arrays of memory cells, said second level comprises a plurality of second transistors, wherein each of said memory cells comprises at least one of said second transistors, wherein said first level is bonded to said second level, wherein said bonded comprises regions of oxide to oxide bonds, wherein said bonded comprises regions of metal to metal bonds; and a thermal isolation layer disposed between said first level and said second level, wherein said thermal isolation layer provides a greater than 20° C. differential temperature between said first level and said second level during nominal operation of said device.

A method of manufacturing a bonded substrate stack includes: providing a first substrate having a first hybrid interface layer, the first hybrid interface layer including a first insulator and a first metal; and providing a second substrate having a second hybrid interface layer, the second hybrid interface layer including a second insulator and a second metal. The hybrid interface layers are surface-activated to generate dangling bonds on the hybrid interface layers. The surface-activated hybrid interface layers are brought into contact, such that the dangling bonds of the first hybrid interface layer and the dangling bonds of the second hybrid interface layer bond together to form first insulator to second insulator bonds and first metal to second metal bonds.

According to one embodiment, a semiconductor device includes a first semiconductor chip including a first metal pad and a second metal pad; and a second semiconductor chip including a third metal pad and a fourth metal pad, the third metal pad joined to the first metal pad, the fourth metal pad coupled to the second metal pad via a dielectric layer, wherein the second semiconductor chip is coupled to the first semiconductor chip via the first metal pad and the third metal pad.

A semiconductor device includes a first die, a second die on the first die, and a third die on the second die, the second die being interposed between the first die and the third die. The first die includes a first substrate and a first interconnect structure on an active side of the first substrate. The second die includes a second substrate, a second interconnect structure on a backside of the second substrate, and a power distribution network (PDN) structure on the second interconnect structure such that the second interconnect structure is interposed between the PDN structure and the second substrate.

A package includes a first die that includes a first metallization layer, one or more first bond pad vias on the first metallization layer, wherein a first barrier layer extends across the first metallization layer between each first bond pad via and the first metallization layer, and one or more first bond pads on the one or more first bond pad vias, wherein a second barrier layer extends across each first bond pad via between a first bond pad and the first bond pad via, and a second die including one or more second bond pads, wherein a second bond pad is bonded to a first bond pad of the first die.

Embodiments of semiconductor devices and fabrication methods thereof are disclosed. In an example, a semiconductor device includes a first semiconductor structure and a second semiconductor structure. The first semiconductor structure includes a first bonding layer having a plurality of first bonding contacts, and a first via structure extending vertically through the first bonding layer and into the first semiconductor structure. The second semiconductor structure includes a second bonding layer having a plurality of second bonding contacts, and a second via structure extending vertically through the second bonding layer and into the second semiconductor structure. The first bonding contacts are in contact with the second bonding contacts at the bonding interface, the first via structure is in contact with the second via structure, and sidewalls of the first via structure and the second via structures have a staggered profile at the bonding interface.