Detection of resistive shorts in deep sub-micron technologies

Abstract

Current-based tests are the most effective methods available to detect resistive shorts. Delta IDDQ testing is the most sensitive variant and can handle off-state currents of 10-100 mA of a single core. Nevertheless this is not sufficient to handle the next generations of very deep sub-micron technologies. Moreover delay-fault testing and very-low voltage testing are not a real alternative for the detection of resistive shorts. The main limitation of ∆IDDQ testing is the intra-die variation of the threshold voltage which results in variations in the off-state current. Two methods are investigated that improve the detection capabilities of ∆IDDQ testing. The first method reduces the impact of intra-die variation by reducing the amount of logic that switches states. This method can handle very large off-state currents although at the cost of a substantial increase in test time. The second method investigates the correct scaling of the intra-die variations as a function of temperature. We show that both methods improve the detection capabilities of ∆IDDQ testing.