High-resolution in-situ study of gold electromigration: test time reduction

The electromigration behaviour of a large set of gold interconnections is studied using the high-resolution in-situ measurement technique. First, initial resistance drifts (DeltaR/R-0=0.1%) have been recorded on only one sample for each stress level in a broad matrix of stress levels. Using these measurements, the activation energy and the current exponent have been determined accurately. Second, failure times (DeltaR/R-0=10%) and values for sigma have been obtained by applying higher stress levels on a population of test lines. A combination of this two-step procedure with our high-resolution equipment yields a full characterisation of gold electromigration and a lifetime prediction with a significant higher accuracy and far less measurement time than using low resolution test systems. (C) 2001 Elsevier Science Ltd. All rights reserved.