Microprocessors and microcontrollers are important components in everything from everyday appliances like washing machines and coffeemakers to high-tech machines like supercomputers and smart phones. Smaller microprocessors can ultimately help improve performance and energy efficiency in electronic devices. Emre Salman, an assistant professor of electrical and computer engineering at Stony Brook University, New York, US, and his team at the Nanoscale Circuits and Systems (NanoCAS) Lab are looking at ways to design the next generation of processors to make them smaller, faster, and less power hungry.
Today's circuit boards typically consist of multiple chips connected with wires at the millimeter or centimeter scale. They are bulky, slow, and not always reliable. Salman and his team are working with 3D integration technology, in which chips are stacked on top of each other in a single package, to reduce the length of wires to a micrometer scale. This saves space, uses less power, and provides more performance. Furthermore, chips with different functions are packaged together, producing a heterogeneous chip that is smarter than a single 2D chip that fits in the same area.
Scientists have been working on 3D integration for more than a decade, mostly with homogeneous chips. Homogeneous chips contain similar functions; while heterogeneous chips are much more complex, and most have diverse functionalities with their own specialized instruction sets. Salman and his team are using 3D technology for heterogeneous integration, where sensing and communication planes are stacked with data processing and memory planes.
"We are developing design methodologies to reliably distribute power to each tier of a 3D chip," Salman says. "We are also exploring novel circuit topologies for 3D power management, thereby increasing energy efficiency," Salman says. "We are investigating various noise coupling paths within a 3D system and finding ways to protect sensitive transistors from noise. All of these activities serve the common goal of improving power, signal, and sensing integrity of a heterogeneous 3D chip."
Salman received a National Science Foundation Faculty Early Career Development (CAREER) award to pursue this research. The award has enabled the NanoCAS Lab to use the latest electronic design automation software to verify their algorithms, models, and design methods in addition to fabricating a heterogeneous 3D chip. Salman plans to integrate his research activities at the secondary, undergraduate, and graduate levels.
- Amanda Aubuchon