Measurement and Interpretation of stress in aluminum-based metallization as a function of thermal history

Mechanical stress in interconnections is a problem of growing importance in VLSI devices. The origins of this stress are discussed, and a measurement technique based on the determination of wafer curvature with a laser scanning device is described. The changes in stress observed during thermal cycles are interpreted quantitatively in terms of a simple model of elastic and plastic strain in the metal. The effects of changes in deposition conditions, film composition, and film structure are discussed.