US Patent 9070674 Through-silicon coaxial via structure and method

A silicon interconnect structure includes a peripheral outer via in a silicon substrate, a solid core inner via in the silicon substrate, the solid core inner via coaxial with the peripheral outer via to form a coaxial via structure, a metal interconnect stack formed over a first surface of the peripheral outer via and the solid core inner via, at least portions of the metal interconnect stack forming an electrical connection with the peripheral outer via and the solid core inner via, first contact pads on a surface of the metal interconnect stack, and second contact pads on an exposed surface of the peripheral outer via and the solid core inner via.