A method includes forming a conductive pad over an interconnect structure of a wafer, forming a capping layer over the conductive pad, forming a dielectric layer covering the capping layer, and etching the dielectric layer to form an opening in the dielectric layer. The capping layer is exposed to the opening. A wet-cleaning process is then performed on the wafer. During the wet-cleaning process, a top surface of the capping layer is exposed to a chemical solution used for performing the wet-cleaning process. The method further includes depositing a conductive diffusion barrier extending into the opening, and depositing a conductive material over the conductive diffusion barrier.

An adhesive with self-connecting interconnects is provided. The adhesive layer provides automatic 3D joining of microelectronic components with a conductively self-adjusting anisotropic matrix. In an implementation, the adhesive matrix automatically makes electrical connections between two surfaces that have opposing electrical contacts, and bonds the two surfaces together. Conductive members in the adhesive matrix are aligned to automatically establish electrical connections between at least partially aligned contacts on each of the two surfaces while providing nonconductive adhesion between parts of the two surfaces lacking aligned contacts. An example method includes forming an adhesive matrix between two surfaces to be joined, including conductive members anisotropically aligned in an adhesive medium, then pressing the two surfaces together to automatically connect corresponding electrical contacts that are at least partially aligned on the two surfaces. The adhesive medium in the matrix secures the two surfaces together.

A method includes forming a conductive pad over an interconnect structure of a wafer, forming a capping layer over the conductive pad, forming a dielectric layer covering the capping layer, and etching the dielectric layer to form an opening in the dielectric layer. The capping layer is exposed to the opening. A wet-cleaning process is then performed on the wafer. During the wet-cleaning process, a top surface of the capping layer is exposed to a chemical solution used for performing the wet-cleaning process. The method further includes depositing a conductive diffusion barrier extending into the opening, and depositing a conductive material over the conductive diffusion barrier.

3D joining of microelectronic components and a conductively self-adjusting anisotropic matrix are provided. In an implementation, an adhesive matrix automatically makes electrical connections between two surfaces that have electrical contacts, and bonds the two surfaces together. Conductive members in the adhesive matrix are aligned to automatically establish electrical connections between at least partially aligned contacts on each of the two surfaces while providing nonconductive adhesion between parts of the two surfaces lacking aligned contacts. An example method includes forming an adhesive matrix between two surfaces to be joined, including conductive members anisotropically aligned in an adhesive medium, then pressing the two surfaces together to automatically connect corresponding electrical contacts that are at least partially aligned on the two surfaces. The adhesive medium in the matrix secures the two surfaces together.

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 m from each other to enable contact or direct-bonding between pads and vias with diameters under 5 m 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 m in height for direct bonding.

3D joining of microelectronic components and a conductively self-adjusting anisotropic matrix are provided. In an implementation, an adhesive matrix automatically makes electrical connections between two surfaces that have electrical contacts, and bonds the two surfaces together. Conductive members in the adhesive matrix are aligned to automatically establish electrical connections between at least partially aligned contacts on each of the two surfaces while providing nonconductive adhesion between parts of the two surfaces lacking aligned contacts. An example method includes forming an adhesive matrix between two surfaces to be joined, including conductive members anisotropically aligned in an adhesive medium, then pressing the two surfaces together to automatically connect corresponding electrical contacts that are at least partially aligned on the two surfaces. The adhesive medium in the matrix secures the two surfaces together.

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 m from each other to enable contact or direct-bonding between pads and vias with diameters under 5 m 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 m in height for direct bonding.

A method of feeding underfill material to fill a space between a semiconductor die and a substrate onto which the semiconductor die has been bonded, the method comprises positioning a stencil over the semiconductor die. The stencil has an elongated slot extending adjacent to an edge of the semiconductor die. Underfill material is printed through the slot such that the underfill material falls through the slot onto the substrate next to the edge of the semiconductor die. Thereafter, the underfill material is heated such that the underfill material flows across the space between the semiconductor die and the substrate from the edge of the semiconductor die to an opposite edge thereof through capillary action.