Open defects in vias are a dominant failure mechanism in nanometer technologies. Their defect probability has increased with the introduction of the copper process, smaller geometries, and via counts on the order of billions for modern integrated circuits. In this work, the aggravated via reliability due to a manufacturing narrowing defect is analyzed.We quantify the reliability risk by estimating the Mean Time to Failure (MTF) as a function of the void size due to narrowing by applying Blacks Law to three possible geometric models for a defective via. Bidirectional current condition in signal paths was considered to estimate electromigration (EM) and self-heating effects. For redundant via structures, the MTF of the good vias was estimated when there is one defective via. Our results show that despite resistive vias showing little disturbance to the signal transmission until severe voiding occurs, the electromigration and self-heating threat are significant even for relatively small initial via voiding. The MTF degradation is significant despite of the bidirectional current condition of signal paths. Hence, our results indicates that new electromigration design rules for signal paths considering the presence of resistive vias are required.
Resistive Opens, Small Delay Defect, Via Reliability, Electromigration, Blacks Law, Via Duplication
J. Segura, V. Champac, C. Hawkins, R. Gomez and H. VILLACORTA, "Reliability Analysis of Small Delay Defects Due to Via Narrowing in Signal Paths," in IEEE Design & Test of Computers.