STRESS IN AL, ALSICU, AND ALVPD FILMS ON OXIDIZED SI SUBSTRATES

Electromigration and stress migration in Al metallization are major re liability issues for advanced IC's. Recently it has been shown that, c ompared to AlSiCu alloy films, alloys containing Si, V and Pd combine excellent plasma etchability with good corrosion resistance, while a h igh resistance against electromigration is maintained [1]. It is commo nly accepted that the resistance against stress migration, i.e. the cr eep strength, of Al can be improved by addition of alloying elements i n combination with appropriate heat treatments (e.g. precipitation har dening). We present data on the influence of alloying elements on the behaviour of stress as a function of temperature for a number of Al-al loy films. Pure mono- and polycrystalline Al, AlSi(1.0 at%)Cu(1.0 at%) and AlV(0.1 at%)Pd(0.1 at%) films were studied. The sputter condition s, the film thickness and the annealing conditions were similar to rel iability tests described in the literature. These films are subjected to thermal cycles from 50 to 425 degrees C in a vacuum furnace, while the stress behaviour was measured by means of wafer curvature measurem ents.