Temporary extrusion failures in accelerated lifetime tests of copper interconnects

• Published in: IEEE electron device letters Vol. 26; no. 9; pp. 622 - 624
• Main Authors: Zhang, Y., Choy, J.H., Chapman, G.H., Kavanagh, K.L.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.09.2005; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Accelerated tests; Acceleration; Applied sciences; Capillary force; Circuit testing; Condition monitoring; Copper; copper damascene technology; Design. Technologies. Operation analysis. Testing; Devices; Electric fields; Electromigration; electron wind force; Electronics; Exact sciences and technology; Extrusion; Extrusions; Failure; Integrated circuit interconnections; Integrated circuits; Leakage current; Life estimation; Lifetime estimation; Microelectronic fabrication (materials and surfaces technology); Sampling methods; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; soft failure; temporary extrusion; soft failure; Modeling; Microelectronic fabrication; Capillary force; Electrodiffusion; Sampling; Chemical mechanical polishing; Electric fault; Metallic bond; Rupture; Durability; electromigration; Failures; Damascene process; temporary extrusion; Accelerated test; Contact line; Short circuit; Electric field; Interconnection; Integrated circuit; Extrusion; Leakage current; Reliability; copper damascene technology; electron wind force
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2005.854356

A novel electromigration failure mode was detected in 0.13-μm technology, copper dual damascene interconnects. Extrusions formed between the test lead and neighboring monitor lines, resulting in short-circuit failure. However, many of these extrusions were short lived, shrinking within a period of a minute to an hour. These phenomena indicated that a temporary "soft failure" existed in accelerated copper electromigration tests in addition to the traditional permanent failure or "hard failure." These soft failures would be missed unless short sampling intervals (less than a minute) and continuous monitoring of the leakage current between test metal lines and neighboring circuits were carried out. Consistent with our experimental results, physical modeling suggested that capillary forces were able to rupture a long and narrow extrusion and the electric field across the extrusion could accelerate this process.