Stanford University, Calif., and the Massachusetts Institute of Technology, Cambridge, announce that researchers have developed a new semiconductor chip made of carbon nanotubes and resistive random-access memory (RRAM) cells. The two are built vertically over one another, making a new, dense 3-D computer architecture with interleaving layers of logic and memory.
The researchers integrated over one million RRAM cells and two million carbon nanotube field-effect transistors, making the most complex nanoelectronic system ever made with emerging nanotechnologies.
The RRAM and carbon nanotubes are built vertically over one another, making a new, dense 3D computer architecture with interleaving layers of logic and memory. By inserting ultradense wires between these layers, this 3-D architecture promises to address the communication bottleneck.
The key in this work is that carbon nanotube circuits and RRAM memory can be fabricated at much lower temperatures, below 200°C. “This means they can be built up in layers without harming the circuits beneath,” Prof. Max Shulaker says.
This provides several simultaneous benefits for future computing systems. “The devices are better: Logic made from carbon nanotubes can be an order of magnitude more energy-efficient compared to today’s logic made from silicon, and similarly, RRAM can be denser, faster, and more energy-efficient compared to DRAM,” Prof. H.-S. Philip Wong says, referring to a conventional memory known as dynamic random-access memory.
“In addition to improved devices, 3-D integration can address another key consideration in systems: the interconnects within and between chips,” Prof. Krishna Saraswat adds.
“The new 3-D computer architecture provides dense and fine-grained integration of computing and data storage, drastically overcoming the bottleneck from moving data between chips,” Mitra says. “As a result, the chip is able to store massive amounts of data and perform on-chip processing to transform a data deluge into useful information.”
To demonstrate the potential of the technology, the researchers took advantage of the ability of carbon nanotubes to also act as sensors. On the top layer of the chip they placed over one million carbon nanotube-based sensors, which they used to detect and classify ambient gases.
Due to the layering of sensing, data storage, and computing, the chip was able to measure each of the sensors in parallel, and then write directly into its memory, generating huge bandwidth, Prof. Shulaker says.
