A stacking structure including a first die, a second die stacked on the first die, and a filling material is provided. The first die has a first bonding structure, and the first bonding structure includes first bonding pads and a first heat dissipating element. The second die has a second bonding structure, and the second bonding structure includes second bonding pads and a second heat dissipating element. The first bonding pads are bonded with the second bonding pads. The first heat dissipating element is connected to one first bonding pad of the first bonding pads and the second heat dissipating element is connected to one second bonding pad of the second bonding pads. The filling material is disposed over the first die and laterally around the second die. The first and second dies are bonded through the first and second bonding structures.

An interconnect structure comprises a first dielectric layer, a first metal layer, a second dielectric layer, a metal via, and a second metal layer. The first dielectric layer is over a substrate. The first metal layer is over the first dielectric layer. The first metal layer comprises a first portion and a second portion spaced apart from the first portion. The second dielectric layer is over the first metal layer. The metal via has an upper portion in the second dielectric layer, a middle portion between the first and second portions of the first metal layer, and a lower portion in the first dielectric layer. The second metal layer is over the metal via. From a top view the second metal layer comprises a metal line having longitudinal sides respectively set back from opposite sides of the first portion of the first metal layer.

Representative techniques and devices including process steps may be employed to mitigate the potential for delamination of bonded microelectronic substrates due to metal expansion at a bonding interface. For example, a metal pad having a larger diameter or surface area (e.g., oversized for the application) may be used when a contact pad is positioned over a TSV in one or both substrates.

A nanowire bonding interconnect for fine-pitch microelectronics is provided. Vertical nanowires created on conductive pads provide a debris-tolerant bonding layer for making direct metal bonds between opposing pads or vias. Nanowires may be grown from a nanoporous medium with a height between 200-1000 nanometers and a height-to-diameter aspect ratio that enables the nanowires to partially collapse against the opposing conductive pads, creating contact pressure for nanowires to direct-bond to opposing pads. Nanowires may have diameters less than 200 nanometers and spacing less than 1 μm from each other to enable contact or direct-bonding between pads and vias with diameters under 5 μm at very fine pitch. The nanowire bonding interconnects may be used with or without tinning, solders, or adhesives. A nanowire forming technique creates a nanoporous layer on conductive pads, creates nanowires within pores of the nanoporous layer, and removes at least part of the nanoporous layer to reveal a layer of nanowires less than 1 μm in height for direct bonding.

In some embodiments, the present disclosure relates to a 3D integrated circuit (IC) stack that includes a first IC die bonded to a second IC die. The first IC die includes a first semiconductor substrate, a first interconnect structure arranged on a frontside of the first semiconductor substrate, and a first bonding structure arranged over the first interconnect structure. The second IC die includes a second semiconductor substrate, a second interconnect structure arranged on a frontside of the second semiconductor substrate, and a second bonding structure arranged on a backside of the second semiconductor substrate. The first bonding structure faces the second bonding structure. Further, the 3D IC stack includes a first backside contact that extends from the second bonding structure to the backside of the second semiconductor substrate and is thermally coupled to at least one of the first or second interconnect structures.

A semiconductor structure including a semiconductor substrate, an interconnect structure disposed over the semiconductor substrate, and a bonding structure disposed over the interconnect structure is provided. The bonding structure includes a dielectric layer covering the interconnect structure, signal transmission features penetrating through the dielectric layer, and a thermal conductive feature penetrating through the dielectric layer. The thermal conductive feature includes a thermal routing and thermal pads, and the thermal pads are disposed on and share the thermal routing.

A semiconductor structure including a semiconductor substrate, an interconnect structure disposed over the semiconductor substrate, and a bonding structure disposed over the interconnect structure is provided. The bonding structure includes a dielectric layer covering the interconnect structure, signal transmission features penetrating through the dielectric layer, and a thermal conductive feature penetrating through the dielectric layer. The thermal conductive feature includes a thermal routing and thermal pads, and the thermal pads are disposed on and share the thermal routing.

A method includes depositing a first dielectric layer over a substrate; forming a first dummy metal layer over the first dielectric layer, wherein the first dummy metal layer has first and second portions laterally separated from each other; depositing a second dielectric layer over the first dummy metal layer; etching an opening having an upper portion in the second dielectric layer, a middle portion between the first and second portions of the first dummy metal layer, and a lower portion in the first dielectric layer, wherein a width of the lower portion of the opening is greater than a width of the middle portion of the opening, and a bottom of the opening is higher than a bottom of the first dielectric layer; and forming a dummy via in the opening and a second dummy metal layer over the dummy via and the second dielectric layer.

In some embodiments, the present disclosure relates to a 3D integrated circuit (IC) stack that includes a first IC die bonded to a second IC die. The first IC die includes a first semiconductor substrate, a first interconnect structure arranged on a frontside of the first semiconductor substrate, and a first bonding structure arranged over the first interconnect structure. The second IC die includes a second semiconductor substrate, a second interconnect structure arranged on a frontside of the second semiconductor substrate, and a second bonding structure arranged on a backside of the second semiconductor substrate. The first bonding structure faces the second bonding structure. Further, the 3D IC stack includes a first backside contact that extends from the second bonding structure to the backside of the second semiconductor substrate and is thermally coupled to at least one of the first or second interconnect structures.

A semiconductor structure including a semiconductor substrate, an interconnect structure disposed over the semiconductor substrate, and a bonding structure disposed over the interconnect structure is provided. The bonding structure includes a dielectric layer covering the interconnect structure, signal transmission features penetrating through the dielectric layer, and a thermal conductive feature penetrating through the dielectric layer. The thermal conductive feature includes a thermal routing and thermal pads, and the thermal pads are disposed on and share the thermal routing.