Analysis of tungsten and titanium migration during ESD contact burnout

• Published in: IEEE transactions on electron devices Vol. 50; no. 7; pp. 1617 - 1622
• Main Authors: Walker, A.J., Le, K.Y., Shearer, J., Mahajani, M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2003; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Contact; Electromigration; Electron microscopy; Electrostatic discharges; Failure; Failure analysis; Fuel consumption; Metallization; Pellets; Scanning electron microscopy; Silicon; Titanium; Tungsten
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2003.814972

A physical and chemical analysis of a machine model (MM) electrostatic discharge (ESD) failure in a silicon circuit was carried out. Focused ion beam (FIB) was used to make cross sections through the region of contact burnout. The resulting samples were analyzed using scanning electron microscopy (SEM) and two-dimensional (2-D) auger electron spectroscopic (AES) mapping. It is shown for the first time that both titanium (Ti) and tungsten (W) migrated throughout the melted silicon filament. Large pellets of the W plug were embedded in the bulk silicon but only on the cathode side of the junction. Mechanisms are discussed to explain these phenomena. These involve the melting of titanium disilicide (TiSi/sub 2/), dissolution of Ti and W in the molten silicon and the formation of W pellets through electromigration at temperatures below /spl sim/1800 K.