A semiconductor device has a first build-up interconnect structure formed over a substrate. The first build-up interconnect structure includes an insulating layer and conductive layer formed over the insulating layer. A vertical interconnect structure and semiconductor die are disposed over the first build-up interconnect structure. The semiconductor die, first build-up interconnect structure, and substrate are disposed over a carrier. An encapsulant is deposited over the semiconductor die, first build-up interconnect structure, and substrate. A second build-up interconnect structure is formed over the encapsulant. The second build-up interconnect structure electrically connects to the first build-up interconnect structure through the vertical interconnect structure. The substrate provides structural support and prevents warpage during formation of the first and second build-up interconnect structures. The substrate is removed after forming the second build-up interconnect structure. A portion of the insulating layer is removed exposing the conductive layer for electrical interconnect with subsequently stacked semiconductor devices.

A method of forming semiconductor devices includes providing a wafer having a first side and second side, electrically conductive pads at the second side, and an electrically insulative layer at the second side with openings to the pads. The first side of the wafer is background to a desired thickness and an electrically conductive layer is deposited thereon. Nickel layers are simultaneously electrolessly deposited over the electrically conductive layer and over the pads, and diffusion barrier layers are then simultaneously deposited over the nickel layers. Another method of forming semiconductor devices includes depositing backmetal (BM) layers on the electrically conductive layer including a titanium layer, a nickel layer, and/or a silver layer. The BM layers are covered with a protective coating and a nickel layer is electrolessly deposited over the pads. A diffusion barrier layer is deposited over the nickel layer over the pads, and the protective coating is removed.

A method of forming semiconductor devices includes providing a wafer having a first side and second side, electrically conductive pads at the second side, and an electrically insulative layer at the second side with openings to the pads. The first side of the wafer is background to a desired thickness and an electrically conductive layer is deposited thereon. Nickel layers are simultaneously electrolessly deposited over the electrically conductive layer and over the pads, and diffusion barrier layers are then simultaneously deposited over the nickel layers. Another method of forming semiconductor devices includes depositing backmetal (BM) layers on the electrically conductive layer including a titanium layer, a nickel layer, and/or a silver layer. The BM layers are covered with a protective coating and a nickel layer is electrolessly deposited over the pads. A diffusion barrier layer is deposited over the nickel layer over the pads, and the protective coating is removed.

A semiconductor device has a first semiconductor die and second semiconductor die with a conductive layer formed over the first semiconductor die and second semiconductor die. The second semiconductor die is disposed adjacent to the first semiconductor die with a side surface and the conductive layer of the first semiconductor die contacting a side surface and the conductive layer of the second semiconductor die. An interconnect, such as a conductive material, is formed across a junction between the conductive layers of the first and second semiconductor die. The conductive layer may extend down the side surface of the first semiconductor die and further down the side surface of the second semiconductor die. An extension of the side surface of the first semiconductor die can interlock with a recess of the side surface of the second semiconductor die. The conductive layer extends over the extension and into the recess.

A semiconductor device has a first semiconductor die and second semiconductor die with a conductive layer formed over the first semiconductor die and second semiconductor die. The second semiconductor die is disposed adjacent to the first semiconductor die with a side surface and the conductive layer of the first semiconductor die contacting a side surface and the conductive layer of the second semiconductor die. An interconnect, such as a conductive material, is formed across a junction between the conductive layers of the first and second semiconductor die. The conductive layer may extend down the side surface of the first semiconductor die and further down the side surface of the second semiconductor die. An extension of the side surface of the first semiconductor die can interlock with a recess of the side surface of the second semiconductor die. The conductive layer extends over the extension and into the recess.

A PoP semiconductor device has a top semiconductor package disposed over a bottom semiconductor package. The top semiconductor package has a substrate and a first semiconductor die disposed over the substrate. First and second encapsulants are deposited over the first semiconductor die and substrate. A first build-up interconnect structure is formed over the substrate after depositing the second encapsulant. The top package is disposed over the bottom package. The bottom package has a second semiconductor die and modular interconnect units disposed around the second semiconductor die. A second build-up interconnect structure is formed over the second semiconductor die and modular interconnect unit. The modular interconnect units include a plurality of conductive vias and a plurality of contact pads electrically connected to the conductive vias. The I/O pattern of the build-up interconnect structure on the top semiconductor package is designed to coincide with the I/O pattern of the modular interconnect units.

A PoP semiconductor device has a top semiconductor package disposed over a bottom semiconductor package. The top semiconductor package has a substrate and a first semiconductor die disposed over the substrate. First and second encapsulants are deposited over the first semiconductor die and substrate. A first build-up interconnect structure is formed over the substrate after depositing the second encapsulant. The top package is disposed over the bottom package. The bottom package has a second semiconductor die and modular interconnect units disposed around the second semiconductor die. A second build-up interconnect structure is formed over the second semiconductor die and modular interconnect unit. The modular interconnect units include a plurality of conductive vias and a plurality of contact pads electrically connected to the conductive vias. The I/O pattern of the build-up interconnect structure on the top semiconductor package is designed to coincide with the I/O pattern of the modular interconnect units.

A method of making an assembly can include juxtaposing a top surface of a first electrically conductive element at a first surface of a first substrate with a top surface of a second electrically conductive element at a major surface of a second substrate. One of: the top surface of the first conductive element can be recessed below the first surface, or the top surface of the second conductive element can be recessed below the major surface. Electrically conductive nanoparticles can be disposed between the top surfaces of the first and second conductive elements. The conductive nanoparticles can have long dimensions smaller than 100 nanometers. The method can also include elevating a temperature at least at interfaces of the juxtaposed first and second conductive elements to a joining temperature at which the conductive nanoparticles can cause metallurgical joints to form between the juxtaposed first and second conductive elements.

A method of making an assembly can include juxtaposing a top surface of a first electrically conductive element at a first surface of a first substrate with a top surface of a second electrically conductive element at a major surface of a second substrate. One of: the top surface of the first conductive element can be recessed below the first surface, or the top surface of the second conductive element can be recessed below the major surface. Electrically conductive nanoparticles can be disposed between the top surfaces of the first and second conductive elements. The conductive nanoparticles can have long dimensions smaller than 100 nanometers. The method can also include elevating a temperature at least at interfaces of the juxtaposed first and second conductive elements to a joining temperature at which the conductive nanoparticles can cause metallurgical joints to form between the juxtaposed first and second conductive elements.

An object of the present invention is to provide an electrically conductive paste and a sintered body thereof having a low electric resistance value and excellent electrical conductivity when made into a sintered body. An electrically conductive paste comprising: a flake-like silver powder having a median diameter D50 of 15 μm or less; a silver powder having a median diameter D50 of 25 μm or more; and a solvent, wherein the content of the flake-like silver powder is 15 to 70 parts by mass and the content of the silver powder having a median diameter D50 of 25 μm or more is 30 to 85 parts by mass based on 100 parts by mass in total of the flake-like silver powder and the silver powder having a median diameter D50 of 25 μm or more.