A Cu.sub.3Sn electrical interconnect and method of making same in an electrical device, such as for hybrid bond 3D-integration of the electrical device with one or more other electrical devices. The method of forming the Cu.sub.3Sn electrical interconnect includes: depositing a Sn layer in the via hole; depositing a Cu layer atop and in contact with the Sn layer; and heating the Sn layer and the Cu layer such that the Sn and Cu layers diffuse together to form a Cu.sub.3Sn interconnect in the via hole. During the heating, a diffusion front between the Sn and Cu layers moves in a direction toward the Cu layer as initially deposited, such that any remaining Cu layer or any voids formed during the diffusion are at an upper region of the formed Cu.sub.3Sn interconnect in the via hole, thereby allowing such voids or remaining material to be easily removed.

A Cu.sub.3Sn electrical interconnect and method of making same in an electrical device, such as for hybrid bond 3D-integration of the electrical device with one or more other electrical devices. The method of forming the Cu.sub.3Sn electrical interconnect includes: depositing a Sn layer in the via hole; depositing a Cu layer atop and in contact with the Sn layer; and heating the Sn layer and the Cu layer such that the Sn and Cu layers diffuse together to form a Cu.sub.3Sn interconnect in the via hole. During the heating, a diffusion front between the Sn and Cu layers moves in a direction toward the Cu layer as initially deposited, such that any remaining Cu layer or any voids formed during the diffusion are at an upper region of the formed Cu.sub.3Sn interconnect in the via hole, thereby allowing such voids or remaining material to be easily removed.

A microelectronic device includes a first microelectronic device and a second microelectronic device structure overlying the first microelectronic device structure. The first microelectronic device structure includes a first base structure, and a first dielectric oxycarbide material overlying the first base structure. The second microelectronic device structure includes a second dielectric oxycarbide material bonded to the first dielectric oxycarbide material of the first microelectronic device structure, and a second base structure overlying the second dielectric oxycarbide material. Related methods and memory devices are also described.

An integrated circuit (IC) die structure comprises a substrate material comprising silicon. Integrated circuitry is over a first side of the substrate material. A composite layer is in direct contact with a second side of the substrate material. The second side is opposite the first side. The composite layer comprises a first constituent material associated with a first linear coefficient of thermal expansion (CTE), and a first thermal conductivity exceeding that of the substrate. The composite layer also comprises a second constituent material associated with a second CTE that is lower than the first, and a second thermal conductivity exceeding that of the substrate.

A package structure includes the following: a logic die; and a plurality of core dies sequentially stacked on the logic die along a vertical direction, in which the plurality of core dies include a first core die and a second core die interconnected through a hybrid bonding member; the hybrid bonding member includes: a first contact pad located on a surface of the first core die; and a second contact pad located on a surface of the second core die; the first contact pad is in contact bonding with the second contact pad.