The present disclosure is directed to a compact vertical oven for reflow of solder bumps for backend processes in semiconductor wafer assembly and packaging. This disclosure describes a vertical oven which uses a plurality of wafers (e.g., an example value is 50-100 wafers) in a batch with controlled injection of the reducing agent (e.g. formic acid), resulting in a process largely free of contamination. This disclosure describes controlled formic acid flow through a vertical system using laminar flow technology in a sub-atmospheric pressure environment, which is not currently available in the industry. The efficacy of the process depends on effective formic acid vapor delivery, integrated temperature control during heating and cooling, and careful design of the vapor flow path with exhaust. Zone-dependent reaction dynamics managed by vapor delivery process, two-steps temperature ramp control, and controlled cooling process and formic acid content ensures the effective reaction without any flux.

A bonding system for bonding a semiconductor element to a substrate is provided. The bonding system includes a substrate oxide reduction chamber configured to receive a substrate. The substrate includes a plurality of first electrically conductive structures. The substrate oxide reduction chamber is configured to receive a reducing gas to contact each of the plurality of first electrically conductive structures. The bonding system also includes a substrate oxide prevention chamber for receiving the substrate after the reducing gas contacts the plurality of first electrically conductive structures. The substrate oxide prevention chamber has an inert environment when receiving the substrate. The bonding system also includes a reducing gas delivery system for providing a reducing gas environment during bonding of a semiconductor element to the substrate.

Process for producing an electronic subassembly by low-temperature pressure sintering, comprising the following steps: arranging an electronic component on a circuit carrier having a conductor track, connecting the electronic component to the circuit carrier by the low-temperature pressure sintering of a joining material which connects the electronic component to the circuit carrier, characterized in that, to avoid the oxidation of the electronic component or of the conductor track, the low-temperature pressure sintering is carried out in a low-oxygen atmosphere having a relative oxygen content of 0.005 to 0.3%.

A bonding system for bonding a semiconductor element to a substrate is provided. The bonding system includes a substrate oxide reduction chamber configured to receive a substrate. The substrate includes a plurality of first electrically conductive structures. The substrate oxide reduction chamber is configured to receive a reducing gas to contact each of the plurality of first electrically conductive structures. The bonding system also includes a substrate oxide prevention chamber for receiving the substrate after the reducing gas contacts the plurality of first electrically conductive structures. The substrate oxide prevention chamber has an inert environment when receiving the substrate. The bonding system also includes a reducing gas delivery system for providing a reducing gas environment during bonding of a semiconductor element to the substrate.

A bonding system for bonding a semiconductor element to a substrate is provided. The bonding system includes a substrate oxide reduction chamber configured to receive a substrate. The substrate includes a plurality of first electrically conductive structures. The substrate oxide reduction chamber is configured to receive a reducing gas to contact each of the plurality of first electrically conductive structures. The bonding system also includes a substrate oxide prevention chamber for receiving the substrate after the reducing gas contacts the plurality of first electrically conductive structures. The substrate oxide prevention chamber has an inert environment when receiving the substrate. The bonding system also includes a reducing gas delivery system for providing a reducing gas environment during bonding of a semiconductor element to the substrate.

A method of forming an interconnection includes: providing an electronic component having a first main face and a first metallic layer disposed on the first main face; providing an electric component having a second main face and a second metallic layer disposed on the second main face, at least one of the first or second metallic layers including an oxide layer provided on a main face thereof; disposing a reducing agent on one or both of the electronic component and the electric component such that the reducing agent is enabled to remove the oxide layer; and connecting the electronic component to the electric component by directly connecting the first metallic layer of the electronic component with the second metallic layer of the electric component by applying pressure and heat.

A method of forming an interconnection includes: providing an electronic component having a first main face and a first metallic layer disposed on the first main face; providing an electric component having a second main face and a second metallic layer disposed on the second main face, at least one of the first or second metallic layers including an oxide layer provided on a main face thereof; disposing a reducing agent on one or both of the electronic component and the electric component such that the reducing agent is enabled to remove the oxide layer; and connecting the electronic component to the electric component by directly connecting the first metallic layer of the electronic component with the second metallic layer of the electric component by applying pressure and heat.

A method of liquid assisted bonding includes: forming a structure with a liquid layer between an electrode of a device and a contact pad of a substrate, and two opposite surfaces of the liquid layer being respectively in contact with the electrode and the contact pad in which hydrogen bonds are formed between the liquid layer and at least one of the electrode and the contact pad; and evaporating the liquid layer to break said hydrogen bonds such that at least one of a surface of the electrode facing the contact pad and a surface of the contact pad facing the electrode is activated so as to assist a formation of a diffusion bonding between the electrode of the device and the contact pad in which a contact area between the electrode and the contact pad is smaller than or equal to about 1 square millimeter.

A method of liquid assisted bonding includes: forming a structure with a liquid layer between an electrode of a device and a contact pad of a substrate, and two opposite surfaces of the liquid layer being respectively in contact with the electrode and the contact pad in which hydrogen bonds are formed between the liquid layer and at least one of the electrode and the contact pad; and evaporating the liquid layer to break said hydrogen bonds such that at least one of a surface of the electrode facing the contact pad and a surface of the contact pad facing the electrode is activated so as to assist a formation of a diffusion bonding between the electrode of the device and the contact pad in which a contact area between the electrode and the contact pad is smaller than or equal to about 1 square millimeter.

A semiconductor device includes a first substrate and a second substrate that is stacked on a first surface of the first substrate in a stacking direction and includes a second surface facing the first surface. A plurality of first terminals is provided on the first surface of the first substrate. A plurality of second terminals is provided on the second surface of the second substrate. A plurality of metallic portions is respectively provided between the plurality of first terminals and the plurality of second terminals. In a cross-section substantially perpendicular to the stacking direction, at least one of (i) each of the plurality of first terminals or (ii) each of the plurality of second terminals (a) includes a recessed portion in a first direction toward an adjacent first terminal or second terminal or (b) includes a projecting portion in a second direction intersecting with the first direction.