Effects of low k film properties on electromigration performance

This paper will compare the reliability results of first-generation Carbon-doped low k dielectric film with a second-generation Carbon-doped film, developed to have a high mechanical strength (HMS) and improved toughness. The first-generation low k film possessed acceptable unit process results, but was found to have marginal electromigration (EM) performance due to cohesive failures that resulted in Cu extrusion at the anode end of lines. By replacing the first-generation film with the HMS film, EM test median time to fail was increased by a factor of more than two. This improvement was found to be due to increased film fracture toughness.