Correcting errors in integrated circuits caused by radiation

Dr. Li Chen, Department of Electrical Engineering, University of Saskatchewan

Dr. Li Chen works on ways to detect and repair the havoc that radiation can wreak on microelectronics, not only in space but also here on Earth.

The Associate Professor at the University of Saskatchewan returned to Canada from the United States in 2006, in part because of the research support he can get from CMC Microsystems. “In terms of microelectronics, we have better community assistance here than in the United States. Most of my research is aided by CMC-supported infrastructure, fabrication services, tools and testing.”

One of his projects involves using a space simulation chamber to develop electronic devices and systems that can tolerate radiation and the harsh temperatures found in outer space and other extreme environments. The latest crucial component of the project is a chip that will be designed in conjunction with collaborators from Cisco Canada. Other partners are involved, including the Texas-based Johnson Space Center and researchers at Vanderbilt University in Tennessee, a world leader in the study of radiation affecting electronics.

Electronic systems used in space are usually built with triple redundancies to protect them from radiation. But that approach can be too expensive for consumer products. Yet radiation particles like neutrons can travel through the atmosphere and reach the ground, says Chen. The sun is one source of such particles. Cosmic rays are another source. These particles can damage microelectronics, causing what are known as single-event effects. 

“With the ever-decreasing geometries on an integrated circuit (IC), single events are a major reliability issue, affecting an IC’s memory cells, for example. The soft error rate expresses how often a system may encounter damaging radiation hits on combinational and sequential logic circuits. This rate is predicted to increase significantly with technology scaling trends," he says. He is working on a sensor that will detect when these types of errors occur. Chen is also investigating systems that are “self-healing” to repair soft error damage using correcting codes and other circuit techniques.

A patent application for the proposed sensor has been filed. Transferring this technology to industry can effectively improve the reliability of microelectronic devices and systems and allow FPGA vendors to reduce the soft error rates in their products.

Dr. Chen received a Bachelor of Engineering degree from Tianjin University, China, in 1991 and then worked in industry for six years as a design engineer on embedded systems. He received a PhD from the University of Alberta in 2004 then moved to the United States, taking a position at the South Dakota School of Mines and Technology. However, he found that his research there was hampered by the difficulty of getting the chips he needed in a timely manner.

His return to Canada means he can leverage affordable resources through CMC to accelerate his research. “I have access to highly advanced technology and can study the single-event effects in these technologies. For example, I have access to 28-nanometre CMOS technology, when my collaborators at Vanderbilt University in the United States or Hanyang University in South Korea do not. They always admire the assistance available from CMC.” The supportive research environment in Canada contributes to his ability to attract funding, develop critical collaborations, and achieve research results.

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