People/Web Search Calendar Emergency Info A-Z Index UVA Email University of Virginia

Computer Science Colloquia

Jens Lienig, Dresden University of Technology, Dresden, Germany

Friday, August 15, 2014

11:00 AM, Rice Hall, Rm. 242 (Light refreshments will be served)

HOST: Worthy Martin

Electromigration and its Impact on Physical Design in Future Technologies


Excessive current density within interconnects is a major concern for IC designers, which if not effectively mitigated leads to electromigration and electrical overstress. This is increasingly a problem in modern ICs due to smaller feature sizes and higher currents associated with lower supply voltages. While analog designers have been aware of this problem for some time, increasingly digital designs are also affected. The latest edition of the ITRS roadmap predicts that all minimum-sized interconnect will be EM-affected by 2018, limiting any further downscaling of wire sizes.

Current density verification and thus the detection of electromigration problems is already an integral part of the sign-off verification of circuit layouts. Current density violations detected in that process are corrected by layout modifications, e. g., widening of wires. However, complex circuits permit only a small number of such late corrections. Therefore, the amount of corrections needed must not increase in the future. Consequently, the current density limits have to be maximized by exploiting electromigration inhibiting effects, such as Blech length, reservoir effects and via doubling, and applying them during physical IC design. Specifically, an effective dependence of the applied current density limits on the specific layout geometry must be established. This enables to define electromigration-robust layout configurations to which future IC design will be increasingly limited.

The talk will give a comprehensive overview of electromigration and its affects in physical design of current and future ICs. We first introduce the physical process of electromigration and present in detail its specific characteristics that can be affected during physical design. It is then shown how these effects can be exploited in current and future technologies in order to reduce the negative impact of EM on the circuit's reliability.

Bio: Jens Lienig received the Ph.D. (Dr.-Ing.) degree in Electrical Engineering from Dresden University of Technology, Dresden, Germany, in 1991. From 1991 to 1994, he was as a Postdoctoral Fellow at Concordia University in Montréal, PQ, Canada. From 1994 to 1996, he stayed as a Visiting Assistant Professor at the Department of Computer Science, University of Virginia, Charlottesville, VA. From 1996 to 1999, he was with Tanner Research Inc., in Pasadena, CA, and from 1999 to 2002, he worked as Tool Manager at Robert Bosch GmbH in Reutlingen, Germany. In 2002, he was appointed a Full Professor of Electrical Engineering at Dresden University of Technology where he became also Director of the Institute of Electromechanical and Electronic Design.

Prof. Lienig's current research interests are in the physical design automation of VLSI circuits, MCMs, and PCBs, with a special emphasis on (i) electromigration avoidance in physical design, (ii) 3D design, and (iii) constraint- driven design methodologies. He has (co-)authored around 60 publications and 5 textbook chapters. He is author of the only German language textbook on physical design automation currently in print. Prof. Lienig has served on the Technical Program Committees of the DATE, SLIP and ISPD conferences. He is a Senior Member of IEEE.