A problem addressed by an embodiment of the present invention lies in providing a UBM structure which includes thin layers and can prevent diffusion of solder into an electrode. The UBM structure according to an embodiment of the present invention includes: a first UBM layer on an electrode, a second UBM layer on the first UBM layer, and a passivated metal layer between the first UBM layer and the second UBM layer. The passivated metal layer functions as a barrier layer with respect to solder diffusion.

According to one embodiment, a semiconductor device includes a semiconductor substrate having a first surface and a second surface opposite to the first surface, a first electrode extending in a first direction through the semiconductor substrate between the first surface and the second surface, a first wiring layer on the first surface and electrically connected to the first electrode, and a second wiring layer on the first wiring layer, the first wiring layer being between the semiconductor substrate and the second wiring layer in the first direction. The second wiring layer includes a connection region at which a second electrode is connected and a first air gap between the connection region and an outer edge of the second wiring layer in a second direction crossing the first direction.

According to one embodiment, a semiconductor device includes a semiconductor substrate having a first surface and a second surface opposite to the first surface, a first electrode extending in a first direction through the semiconductor substrate between the first surface and the second surface, a first wiring layer on the first surface and electrically connected to the first electrode, and a second wiring layer on the first wiring layer, the first wiring layer being between the semiconductor substrate and the second wiring layer in the first direction. The second wiring layer includes a connection region at which a second electrode is connected and a first air gap between the connection region and an outer edge of the second wiring layer in a second direction crossing the first direction.

A method of ultrasonically bonding semiconductor elements includes the steps of: (a) aligning surfaces of a plurality of first conductive structures of a first semiconductor element to respective surfaces of a plurality of second conductive structures of a second semiconductor element; and (b) ultrasonically bonding ones of the first conductive structures to respective ones of the second conductive structures. A bonding surface of at least one of the first conductive structures and the second conductive structures includes a frangible coating.

A method of ultrasonically bonding semiconductor elements includes the steps of: (a) aligning surfaces of a plurality of first conductive structures of a first semiconductor element to respective surfaces of a plurality of second conductive structures of a second semiconductor element; and (b) ultrasonically bonding ones of the first conductive structures to respective ones of the second conductive structures. A bonding surface of at least one of the first conductive structures and the second conductive structures includes a frangible coating.

A method of ultrasonically bonding semiconductor elements includes the steps of: (a) aligning surfaces of a plurality of first conductive structures of a first semiconductor element to respective surfaces of a plurality of second conductive structures of a second semiconductor element; and (b) ultrasonically bonding ones of the first conductive structures to respective ones of the second conductive structures. A bonding surface of at least one of the first conductive structures and the second conductive structures includes a frangible coating.

A method of ultrasonically bonding semiconductor elements includes the steps of: (a) aligning surfaces of a plurality of first conductive structures of a first semiconductor element to respective surfaces of a plurality of second conductive structures of a second semiconductor element; and (b) ultrasonically bonding ones of the first conductive structures to respective ones of the second conductive structures. A bonding surface of at least one of the first conductive structures and the second conductive structures includes a frangible coating.