Non-invasive pre-bond TSV test using ring oscillators and multiple voltage levels

摘要

A design for test (DfT) architecture is provided that enables pre-bond parametric testing of through-silicon vias (TSVs). A grouping of N number of input/output (I/O) segments are configured to receive a test signal in a feedback loop, where each I/O segment includes one or more buffers (or inverters) and a TSV connected at one end to the one or more buffers. The TSV acts as a shunt-connected capacitor—when defect free—and includes a load resistance when the TSV contains a defect. Each I/O segment can also include one or two multiplexers to control whether the I/O segment receives a test or functional signal and, optionally, whether the I/O segment is bypassed or included in the ring oscillator. The varying loads caused by the defects cause variations in the delay across the buffers (or inverters) of an I/O segment that can be detected in the output signal.

主权项

1. A method of pre-bond testing through-silicon vias (TSVs), the method comprising:
generating a reference value from known fault-free TSVs by connecting at least one reference TSV as a reference load in a reference ring oscillator and measuring a reference oscillation period for the at least one reference TSV; performing a parametric test of TSVs using a ring oscillator in which each TSV is configured at one end for connection as a load in the ring oscillator, wherein performing the parametric test of the TSVs comprises connecting at least one of the TSVs as the load in the ring oscillator and measuring an oscillation period while the at least one of the TSVs is connected as the load; detecting defects in the TSVs based on deviations in the oscillation period compared to the reference value from the known fault-free TSVs; and performing the parametric test of TSVs a first time using a first supply voltage and a second time using a second supply voltage level different than the first supply voltage level, wherein a higher of the two supply voltage levels is applied to detect a resistive open fault defect and a lower of the two supply voltage levels is applied to detect a leakage fault defect.