MIT engineers build advanced microprocessor out of carbon nanotubes
New approach harnesses the same fabrication processes used for silicon chips, offers key advance toward next-generation computers.
Rob Matheson | MIT News Office
August 28, 2019
After years of tackling numerous design and manufacturing challenges, MIT researchers have built a modern microprocessor from carbon nanotube transistors, which are widely seen as a faster, greener alternative to their traditional silicon counterparts.
The microprocessor, described today in the journal Nature, can be built using traditional silicon-chip fabrication processes, representing a major step toward making carbon nanotube microprocessors more practical.
Silicon transistors — critical microprocessor components that switch between 1 and 0 bits to carry out computations — have carried the computer industry for decades. As predicted by Moore’s Law, industry has been able to shrink down and cram more transistors onto chips every couple of years to help carry out increasingly complex computations. But experts now foresee a time when silicon transistors will stop shrinking, and become increasingly inefficient.
Making carbon nanotube field-effect transistors (CNFET) has become a major goal for building next-generation computers. Research indicates CNFETs have properties that promise around 10 times the energy efficiency and far greater speeds compared to silicon. But when fabricated at scale, the transistors often come with many defects that affect performance, so they remain impractical.
The MIT researchers have invented new techniques to dramatically limit defects and enable full functional control in fabricating CNFETs, using processes in traditional silicon chip foundries. They demonstrated a 16-bit microprocessor with more than 14,000 CNFETs that performs the same tasks as commercial microprocessors. The Nature paper describes the microprocessor design and includes more than 70 pages detailing the manufacturing methodology.
The microprocessor is based on the RISC-V open-source chip architecture that has a set of instructions that a microprocessor can execute. The researchers’ microprocessor was able to execute the full set of instructions accurately. It also executed a modified version of the classic “Hello, World!” program, printing out, “Hello, World! I am RV16XNano, made from CNTs.”
“This is by far the most advanced chip made from any emerging nanotechnology that is promising for high-performance and energy-efficient computing,” says co-author Max M. Shulaker, the Emanuel E Landsman Career Development Assistant Professor of Electrical Engineering and Computer Science (EECS) and a member of the Microsystems Technology Laboratories. “There are limits to silicon. If we want to continue to have gains in computing, carbon nanotubes represent one of the most promising ways to overcome those limits. [The paper] completely re-invents how we build chips with carbon nanotubes.”
Joining Shulaker on the paper are: first author and postdoc Gage Hills, graduate students Christian Lau, Andrew Wright, Mindy D. Bishop, Tathagata Srimani, Pritpal Kanhaiya, Rebecca Ho, and Aya Amer, all of EECS; Arvind, the Johnson Professor of Computer Science and Engineering and a researcher in the Computer Science and Artificial Intelligence Laboratory; Anantha Chandrakasan, the dean of the School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science; and Samuel Fuller, Yosi Stein, and Denis Murphy, all of Analog Devices.
Fighting the “bane” of CNFETs
The microprocessor builds on a previous iteration designed by Shulaker and other researchers six years ago that had only 178 CNFETs and ran on a single bit of data. Since then, Shulaker and his MIT colleagues have tackled three specific challenges in producing the devices: material defects, manufacturing defects, and functional issues. Hills did the bulk of the microprocessor design, while Lau handled most of the manufacturing.
For years, the defects intrinsic to carbon nanotubes have been a “bane of the field,” Shulaker says. Ideally, CNFETs need semiconducting properties to switch their conductivity on an off, corresponding to the bits 1 and 0. But unavoidably, a small portion of carbon nanotubes will be metallic, and will slow or stop the transistor from switching. To be robust to those failures, advanced circuits will need carbon nanotubes at around 99.999999 percent purity, which is virtually impossible to produce today.
The researchers came up with a technique called DREAM (an acronym for “designing resiliency against metallic CNTs”), which positions metallic CNFETs in a way that they won’t disrupt computing. In doing so, they relaxed that stringent purity requirement by around four orders of magnitude — or 10,000 times — meaning they only need carbon nanotubes at about 99.99 percent purity, which is currently possible.
Designing circuits basically requires a library of different logic gates attached to transistors that can be combined to, say, create adders and multipliers — like combining letters in the alphabet to create words. The researchers realized that the metallic carbon nanotubes impacted different pairings of these gates differently. A single metallic carbon nanotube in gate A, for instance, may break the connection between A and B. But several metallic carbon nanotubes in gates B may not impact any of its connections.
In chip design, there are many ways to implement code onto a circuit. The researchers ran simulations to find all the different gate combinations that would be robust and wouldn’t be robust to any metallic carbon nanotubes. They then customized a chip-design program to automatically learn the combinations least likely to be affected by metallic carbon nanotubes. When designing a new chip, the program will only utilize the robust combinations and ignore the vulnerable combinations.
“The ‘DREAM’ pun is very much intended, because it’s the dream solution,” Shulaker says. “This allows us to buy carbon nanotubes off the shelf, drop them onto a wafer, and just build our circuit like normal, without doing anything else special.”
Exfoliating and tuning
CNFET fabrication starts with depositing carbon nanotubes in a solution onto a wafer with predesigned transistor architectures. However, some carbon nanotubes inevitably stick randomly together to form big bundles — like strands of spaghetti formed into little balls — that form big particle contamination on the chip.
To cleanse that contamination, the researchers created RINSE (for “removal of incubated nanotubes through selective exfoliation”). The wafer gets pretreated with an agent that promotes carbon nanotube adhesion. Then, the wafer is coated with a certain polymer and dipped in a special solvent. That washes away the polymer, which only carries away the big bundles, while the single carbon nanotubes remain stuck to the wafer. The technique leads to about a 250-times reduction in particle density on the chip compared to similar methods.
Lastly, the researchers tackled common functional issues with CNFETs. Binary computing requires two types of transistors: “N” types, which turn on with a 1 bit and off with a 0 bit, and “P” types, which do the opposite. Traditionally, making the two types out of carbon nanotubes has been challenging, often yielding transistors that vary in performance. For this solution, the researchers developed a technique called MIXED (for “metal interface engineering crossed with electrostatic doping”), which precisely tunes transistors for function and optimization.
In this technique, they attach certain metals to each transistor — platinum or titanium — which allows them to fix that transistor as P or N. Then, they coat the CNFETs in an oxide compound through atomic-layer deposition, which allows them to tune the transistors’ characteristics for specific applications. Servers, for instance, often require transistors that act very fast but use up energy and power. Wearables and medical implants, on the other hand, may use slower, low-power transistors.
The main goal is to get the chips out into the real world. To that end, the researchers have now started implementing their manufacturing techniques into a silicon chip foundry through a program by Defense Advanced Research Projects Agency, which supported the research. Although no one can say when chips made entirely from carbon nanotubes will hit the shelves, Shulaker says it could be fewer than five years. “We think it’s no longer a question of if, but when,” he says.
The work was also supported by Analog Devices, the National Science Foundation, and the Air Force Research Laborato
— Read on news.mit.edu/2019/carbon-nanotubes-microprocessor-0828
- GANG-STALKING defined & explained: January 26, 2022
- Nanoparticles can turn off genes in bone marrow cells October 8, 2020
- Functional Near-Infrared Spectroscopy (fNIRS) Cognitive Brain MonitorNew signal-processing techniques excludes motion artifacts to yield more accurate data February 29, 2020
- The Origin of Consciousness in the Breakdown of the Bicameral Mind, February 16, 2020
- Experimentally Observed Cherenkov Light Generation in the Eye During Radiation Therapy- the flashes you see have been proven. January 10, 2020
- Using nanoparticals to stimulate the brain remotely. January 10, 2020
- Biotechnology and nanotechnology September 27, 2019
- Thousands in China Exposed to ‘Mind Control’ Technology Seek Answers September 24, 2019
- Detecting patients’ pain levels via their brain signals | MIT News September 18, 2019
- Living sensors at your fingertips | MIT News September 3, 2019
- Stretchy optical fibers for implanting in the body | MIT News September 3, 2019
- Engineers 3-D print a “living tattoo” | MIT News September 3, 2019
- Robotic thread is designed to slip through the brain’s blood vessels | MIT News September 3, 2019
- Synthetic biological organisms designed and created for industrial process using genetic engineering August 29, 2019
- MIT engineers build advanced microprocessor out of carbon nanotubes | MIT News August 29, 2019
- Information about through the wall radar, and active radio wave effects on the human body, various surveillance technologies used against unsuspecting humans August 23, 2019
- Human hair as a nanoreactor in the synthesis of gold (and other) nanoparticles August 23, 2019
- Colour-changing artificial ‘chameleon skin’ powered by light-triggered nanoparticles August 22, 2019
- Detection of neuronal activity using microwave energy August 17, 2019
- A poem. June 2, 2019
- History of Morgellons disease: from delusion to definition May 24, 2019
- (no title) May 19, 2019
- Limits of Human Perception July 24, 2017
- evidence for the apparent existence of Invisible Terrestrial Entities of the first kind (ITE-1) & Invisible Terrestrial Entities of the second kind (ITE-2) or bright ITE July 24, 2016
- Parallel universes are no longer a figment of our imagination July 23, 2016
- toxoplasmosis changes behavior of host July 17, 2016
- Optogenetics Resource Center July 17, 2016
- Magic mushrooms’ psychedelic ingredient could help treat people with severe depression July 17, 2016
- Researchers identify gatekeeper neurons that control pain and itch | Science | The Guardian July 17, 2016
- Bumblebee’s electric field sensor identified | Science | The Guardian July 17, 2016
- Presidential Commission: Directed Energy Weapons Used On American Citizens in Tests July 17, 2016
- A Note on Timothy Trespas, Gang Stalking and the Gospel, by Bridget Howe. From:FaithWriters.com-Christian Encouragement – July 17, 2016
- SURVIVAL, EVASION, RESISTANCE AND ESCAPE MULTI-SERVICE TACTICS, TECHNIQUES AND PROCEDURES July 1, 2016
- TARGETING, GANGSTALKING, MORGELLONS, REMOTE-NEURAL-MONITORING,VOICE-2-SKULL, COVERT DRUGGING, ENERGY BASED WEAPONS, ATTACKS WITH FLEAS, MITES, VIRUS, BACTERIA, NEMATODE, NANOBOTS, SYNTHETIC BIOLOGY, NANOTECHNOLOGY, MICROWAVE WEAPONS, TRASHING THE VICTIM,COVERT DRUGGING, FUNGUS, MOLD, ERGOT, LSD,DMT, MIND-FUKING THE VICTIM, ETC, ETC , June 2, 2016
- In sickness and in… Timothy Trespas suffers from targeting and torture. May 30, 2016
- NOAA SPACE GEOMAGNETIC WEATHER Weather Scales 04-11-11 May 11, 2016
- Practical Real Time Spectrum Analyzer Applications Part 1 — Basics Of Interference Hunting And Spectrum Monitoring | Signal Hound May 10, 2016
- EPIC Sensor – Plessey Semiconductors May 5, 2016
- Some peculiarities of auditory sensations evoked by pulsed microwave fields – Tyazhelov – 1979 – Radio Science – Wiley Online Library May 4, 2016
- SHIELDING? Get SHUNGITE mineral -STONE OF HEALTH! Neutralize high-frequency electromagnetic radiation & they reflect all possible magnetic fields January 5, 2016
- Everyday benefits of Shield January 4, 2016
- The Herxheimer Reaction December 20, 2015
- MAX, our FRIEND & CAT has DIED…. R.I.P. MAX – YouTube October 26, 2015
- Mycoplasma incognitus – MicrobeWiki October 18, 2015
- Nanotechnology and forensics: nano-powders that have been engineered to be used in conjunction with SALDI-TOF2-MS.(Surface-assisted laser desorption/ionization time-of-flight (TOF)/reflectron (RTOF) mass spectrometry) August 1, 2015
- One paradigm is worth a thousand rules: How can we teach computers compassion (and stop humans from using them to hurt and kill!) ? Artificial Intelligence, Psychology, and theories of mind. August 1, 2015
- DSM-IV-TR: Diagnostic criteria for schizophrenia:- what the professional psychiatrists use to diagnose you as schizophrenic July 9, 2015
- amazing Nanotechnology – Images -materials science. Images can often convey information in a way that tables of data or equations cannot match May 26, 2015
- The 3D-architecture of individual free silver nanoparticles captured by X-ray scattering : Nature Communications : Nature Publishing Group May 26, 2015
- METALS IN MEDICINE AND THE ENVIRONMENT-Aluminum and Alzheimer’s Disease May 26, 2015
- about electromagnetic torture, mind control, and remote neural monitoring by/in The U.S.A. – by TIMOTHYTRESPAS
- I an a victim of Covert Drugging with Millitary LSD like drugs… by TIMOTHY TRESPAS
- microbiology from inside my body, provided by slow-kill nanotechnology, weaponized biological attacks, synthetic biology, parasitology, human experimentation, microscopic investigation
- Trauma based Neuro-linquistic programming-How it works: a real life example from Timothy Trespas in New York City
- victim of extrajudicial covert human experimentation, torture, repeated drugging with military LSD like compounds, exposure to nanotechnology, foreign DNA implantation, remote neural monitoring, mind control, gang-stalking, gas-lighting, electrocution, poisoning, surveillance, and other human rights abuses by operatives and informants of the NEW SECRET POLICE. by Timothy Trespas
- Welcome to the 21st century- the NEW HOLOCAUST- how Mind Control, remote neural connectivity, artificial intelligence, the Military? & Government of the USA? o.k. the cooking of humans with Microwave directed energy weapons, and worse!
- What if? A theory on STRESS & ‘Targeting’
- 330 west 51st street nyc
- artificial intelligence
- brain mapping
- brain wave
- covert drugging
- genetic manipulation
- human experimentation
- microwave weapons
- mind control
- Mind Control is HERE NOW and being used on entire population in the USA and abroad. embedded microchip marking of all human assets via bio-nanotechnology is real, possible, and being done to us as we
- mk ultra
- new word order
- new world order
- no-touch torture
- petra schiller.
- quantum dots
- remote neural
- remote neural monitoring
- smart dust
- synthetic biology
- SYNTHETIC TELEPATHY
- targeted individual
- targeted individuals
- timothy trespas
- top secret