Detectability of Resistive Open Defects with Analog Relaxation Oscillators Under Unit-to-Unit Variations of Dies

We designed a built-in test circuit to detect resistive open defects at interconnects between dies in 3D stacked ICs using relaxation oscillators made of only analog circuit elements. We also designed a test circuit by which process variations of the oscillators could be eliminated in tests. We examined the detectability of such resistive open defects by the test method based on the test circuit in a 3D stacked IC made of dies whose process variations were not identical by circuit simulations. The results show that resistive open defects of 7.0 and above can be detected by the test circuit.