Best paper award for Sapatnekar research group

Researchers led by professor Sachin Sapatnekar have received the best paper award at the 2021 IEEE/ACM International Conference on Computer-Aided Design. The paper is titled “Analytical Modeling of Transient Electromigration Stress based on Boundary Reflections,” and addresses the problem of electromigration that adversely affects circuits, and leads to their decline. 

Wires in modern integrated circuits carry large currents through extremely thin filaments. This results in large current densities within wires, where the "electron wind" associated with the current causes a phenomenon called electromigration, whereby metal atoms physically migrate along the wire. Over several years, this migration can induce stress that creates breaks in a wire leading to circuit failure. Designers have long recognized this problem and have a toolbox of methods for overcoming them, but methods for identifying electromigration-susceptible wires have been empirical and inexact. More exact physics-based models have been proposed in the past, but they have involved prohibitive computation and have been impractical. In the award winning paper, researchers use a physics-based framework, and develop a new analogy between electromigration and a "stress wave," which is used to efficiently compute the distribution of electromigration-induced stress in an on-chip wire. The method enables, for the first time, electromigration checks of interconnect systems with hundreds of thousands of wires in about a minute of computation.

The work was conducted by graduate students Mohammad Shohel and Vidya Chhabria, and is the result of a collaboration with professor Nestor Evmorfopoulos of the University of Thessaly, who was a Fulbright Scholar at the University in spring 2020. Although Prof. Evmorfopoulos's visit to Minnesota was cut short by the pandemic, the collaboration continued online and has resulted in this new line of work.

Doctoral candidate Vidya Chhabria’s research lies in the field of electronic design automation (EDA) that designs complex circuits systematically and efficiently through software. Her doctoral work addresses three key challenges within the EDA industry: prohibitive cost of EDA software tools; heuristic nature of EDA tools that often deliver suboptimal solutions; long computation times that increase time to market for ICs. Chhabria’s work involves building new EDA tools that are open-source and machine learning (ML)-based. The open-source aspect makes software freely available to the public, encourages collaborative efforts, and drives research-to-product transition. Chhabria is the recipient of the Doctoral Dissertation Fellowship, and the Louise T. Dosdall Fellowship, both awarded by the University of Minnesota Graduate School, and the Cadence Women in Technology Scholarship awarded by Cadence. 

Doctoral student Mohammad Abdullah Al Shohel joined ECE as a doctoral student in 2019. He joins us from Bangladesh, where he earned his bachelor’s degree in electrical engineering from Bangladesh University of Engineering and Technology. His current research interests include electronic design automation and reliability analysis of VLSI circuits. He is currently working on a project titled “Enhancing the Reliability of Mixed-Signal Integrated Circuits.” It is funded by the National Science Foundation, with professor Sachin Sapatnekar as the Principal Investigator. Shohel is a recipient of the Lowell E. Norton Fellowship.