Scanning SQUID microscopy for current imaging

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 Industria l Physicist, 1998. p.11]. In particular, flip-chip packaging requires that nondestructive measurements be made through the silicon substrate. The pack age substrates for these new integrated circuits are also becoming more com plex with finer pitch dimensions and many layers of metallization often wit h several ground and power planes that complicate nondestructive analysis. To meet the needs of failure analysis for some present and most future appl ications, 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 su perconducting quantum interference device, which is a very sensitive magnet ic sensor, currents in integrated circuits can be imaged via the magnetic f ields they produce. These images can reveal the locations of shorts and oth er current anomalies at both the die and package levels. This instrument ha s applications in fault isolation, design verification, and defective compo nent isolation in full assemblies. A description of this technology and a s ummary of the various applications of this tool at the die, package, and as sembly levels are presented in this paper. (C) 2001 Elsevier Science Ltd. A ll rights reserved.