Long term noise measurements and median time to failure test for the characterization of electromigration in metal lines

The high sensitivity, which can be obtained by means of noise measurements, is especially useful for the characterization of the early stages of the electromigration phenomenon. In addition, with the noise being strictly dependent on the sample microstructure, it is obvious to expect that it can be used for monitoring the different stages of the degradation process. In this paper, the results obtained by performing noise measurements during lifetime tests are presented, with the aim of investigating the evolution of the electromigration noise during the entire life of the sample. Conventional Median Time to Failure (MTF) tests have been performed on samples belonging to the same set. One of the aims of this work is to investigate the possibility of establishing a new failure criterion based on noise measurement capable of providing, in a shorter time, the same type of information normally obtained from MTF tests.