Test structures for stacking dies having through-silicon vias

摘要

A semiconductor die including a test structure is provided. The semiconductor die includes a loop-back formed on a surface of the semiconductor die. The loop-back structure includes a first bonding pad on a first surface; and a second bonding pad on the first surface, wherein the first and the second bonding pads are electrically disconnected from integrated circuit devices in the semiconductor die. A conductive feature electrically shorts the first and the second bonding pads. An additional die including an interconnect structure is bonded onto the semiconductor die. The interconnect structure includes a third and a fourth bonding pad bonded to the first and the second bonding pads, respectively. Through-wafer vias in the additional die are further connected to the third and fourth bonding pads.