Scanning SQUID microscopy for current imaging

• Published in: Microelectronics and reliability 2001-08, Vol.41 (8), p.1211-1229
• Main Authors: Knauss, L.A., Cawthorne, A.B., Lettsome, N., Kelly, S., Chatraphorn, S., Fleet, E.F., Wellstood, F.C., Vanderlinde, W.E.
• Format: Article
• Language: English
• ISSN: 0026-2714; 1872-941X
• DOI: 10.1016/S0026-2714(01)00108-1

As process technologies of integrated circuits become more complex and the industry moves toward flip-chip packaging, present tools and techniques are having increasing difficulty meeting failure analysis needs [The Industrial Physicist, 1998. p.11]. In particular, flip-chip packaging requires that nondestructive measurements be made through the silicon substrate. The package substrates for these new integrated circuits are also becoming more complex with finer pitch dimensions and many layers of metallization often with several ground and power planes that complicate nondestructive analysis. To meet the needs of failure analysis for some present and most future applications, new techniques are needed. Recent developments in magnetic field imaging provide failure analysts with a tool to help overcome some of the hurdles involved in fault isolation of present and next generation semiconductor devices. Through the use of a superconducting quantum interference device, which is a very sensitive magnetic sensor, currents in integrated circuits can be imaged via the magnetic fields they produce. These images can reveal the locations of shorts and other current anomalies at both the die and package levels. This instrument has applications in fault isolation, design verification, and defective component isolation in full assemblies. A description of this technology and a summary of the various applications of this tool at the die, package, and assembly levels are presented in this paper.