Thermographic analysis of electromigration phenomena in aluminum metallization

Electromigration-induced void growth in Al metallization was investigated by comparing it with the electrical resistance change and the thermographically measured change in temperature distribution. Constant current flowing through two different-width interconnects in series consistently induced void growth at their junction so that it could be observed with high resolution in the fixed fields of an infrared microscope and an optical microscope. The electrical resistance change occurring as a result of an electromigration test was found to directly reflect a local temperature change resulting from the void growth: a pulse phenomenon in the electrical resistance corresponds to a temperature increase of more than 200 degrees C around the void-growing area. This phenomenon can be attributed to a local melting induced by the void growth and to a void healing process after recrystallization of the adjacent Al grains. (C) 1996 American Institute of Physics.