Pulse-Vanishing Test for Interposers Wires in 2.5-D IC

In this paper, we present a general at-speed test method for die-to-die interconnects and demonstrate its particular application to the interposer wires in a 2.5-D IC. At the heart of this method is a pulse-vanishing test technique (called PV-test), in which a short-duration pulse signal is applied to an interposer wire under test at the driver end. If this pulse vanishes at the receiver's output, then it indicates the presence of a delay fault. This PV-test technique is effective for detecting not only resistive open faults, but also resistive bridging faults between interposer wires. This method has several other advantages. For example, the implementation is especially easy as it incorporates only logic cells and can be merged with boundary scan cells. Also, it can support on-the-spot diagnosis which is desirable in applications where subsequent built-in self-repair is needed.