Tag Archives: Ju Li

IBM and its working 7nm test chip

I wrote abut IBM and its plans for a 7nm computer chip last year in a July 11, 2014 posting, which featured IBM and mention of HP Labs and other company’s plans for shrinking their computer chips. Almost one year later, IBM has announced, in a July 9, 2015 IBM news release on PRnewswire.com the accomplishment of a working 7nm test chip,

An alliance led by IBM Research (NYSE: IBM) today announced that it has produced the semiconductor industry’s first 7nm (nanometer) node test chips with functioning transistors.  The breakthrough, accomplished in partnership with GLOBALFOUNDRIES and Samsung at SUNY Polytechnic Institute’s Colleges of Nanoscale Science and Engineering (SUNY Poly CNSE), could result in the ability to place more than 20 billion tiny switches — transistors — on the fingernail-sized chips that power everything from smartphones to spacecraft.

To achieve the higher performance, lower power and scaling benefits promised by 7nm technology, researchers had to bypass conventional semiconductor manufacturing approaches. Among the novel processes and techniques pioneered by the IBM Research alliance were a number of industry-first innovations, most notably Silicon Germanium (SiGe) channel transistors and Extreme Ultraviolet (EUV) lithography integration at multiple levels.

Industry experts consider 7nm technology crucial to meeting the anticipated demands of future cloud computing and Big Data systems, cognitive computing, mobile products and other emerging technologies. Part of IBM’s $3 billion, five-year investment in chip R&D (announced in 2014), this accomplishment was made possible through a unique public-private partnership with New York State and joint development alliance with GLOBALFOUNDRIES, Samsung and equipment suppliers. The team is based at SUNY Poly’s NanoTech Complex in Albany [New York state].

“For business and society to get the most out of tomorrow’s computers and devices, scaling to 7nm and beyond is essential,” said Arvind Krishna, senior vice president and director of IBM Research. “That’s why IBM has remained committed to an aggressive basic research agenda that continually pushes the limits of semiconductor technology. Working with our partners, this milestone builds on decades of research that has set the pace for the microelectronics industry, and positions us to advance our leadership for years to come.”

Microprocessors utilizing 22nm and 14nm technology power today’s servers, cloud data centers and mobile devices, and 10nm technology is well on the way to becoming a mature technology. The IBM Research-led alliance achieved close to 50 percent area scaling improvements over today’s most advanced technology, introduced SiGe channel material for transistor performance enhancement at 7nm node geometries, process innovations to stack them below 30nm pitch and full integration of EUV lithography at multiple levels. These techniques and scaling could result in at least a 50 percent power/performance improvement for next generation mainframe and POWER systems that will power the Big Data, cloud and mobile era.

“Governor Andrew Cuomo’s trailblazing public-private partnership model is catalyzing historic innovation and advancement. Today’s [July 8, 2015] announcement is just one example of our collaboration with IBM, which furthers New York State’s global leadership in developing next generation technologies,” said Dr. Michael Liehr, SUNY Poly Executive Vice President of Innovation and Technology and Vice President of Research.  “Enabling the first 7nm node transistors is a significant milestone for the entire semiconductor industry as we continue to push beyond the limitations of our current capabilities.”

“Today’s announcement marks the latest achievement in our long history of collaboration to accelerate development of next-generation technology,” said Gary Patton, CTO and Head of Worldwide R&D at GLOBALFOUNDRIES. “Through this joint collaborative program based at the Albany NanoTech Complex, we are able to maintain our focus on technology leadership for our clients and partners by helping to address the development challenges central to producing a smaller, faster, more cost efficient generation of semiconductors.”

The 7nm node milestone continues IBM’s legacy of historic contributions to silicon and semiconductor innovation. They include the invention or first implementation of the single cell DRAM, the Dennard Scaling Laws, chemically amplified photoresists, copper interconnect wiring, Silicon on Insulator, strained engineering, multi core microprocessors, immersion lithography, high speed SiGe, High-k gate dielectrics, embedded DRAM, 3D chip stacking and Air gap insulators.

In 2014, they were talking about carbon nanotubes with regard to the 7nm chip, this shift to silicon germanium is interesting.

Sebastian Anthony in a July 9, 2015 article for Ars Technica offers some intriguing insight into the accomplishment and the technology (Note: A link has been removed),

… While it should be stressed that commercial 7nm chips remain at least two years away, this test chip from IBM and its partners is extremely significant for three reasons: it’s a working sub-10nm chip (this is pretty significant in itself); it’s the first commercially viable sub-10nm FinFET logic chip that uses silicon-germanium as the channel material; and it appears to be the first commercially viable design produced with extreme ultraviolet (EUV) lithography.

Technologically, SiGe and EUV are both very significant. SiGe has higher electron mobility than pure silicon, which makes it better suited for smaller transistors. The gap between two silicon nuclei is about 0.5nm; as the gate width gets ever smaller (about 7nm in this case), the channel becomes so small that the handful of silicon atoms can’t carry enough current. By mixing some germanium into the channel, electron mobility increases, and adequate current can flow. Silicon generally runs into problems at sub-10nm nodes, and we can expect Intel and TSMC to follow a similar path to IBM, GlobalFoundries, and Samsung (aka the Common Platform alliance).

EUV lithography is an more interesting innovation. Basically, as chip features get smaller, you need a narrower beam of light to etch those features accurately, or you need to use multiple patterning (which we won’t go into here). The current state of the art for lithography is a 193nm ArF (argon fluoride) laser; that is, the wavelength is 193nm wide. Complex optics and multiple painstaking steps are required to etch 14nm features using a 193nm light source. EUV has a wavelength of just 13.5nm, which will handily take us down into the sub-10nm realm, but so far it has proven very difficult and expensive to deploy commercially (it has been just around the corner for quite a few years now).

If you’re interested in the nuances, I recommend reading Anthony’s article in its entirety.

One final comment, there was no discussion of electrodes or other metallic components associated with computer chips. The metallic components are a topic of some interest to me (anyway), given some research published by scientists at the Massachusetts Institute of Technology (MIT) last year. From my Oct. 14, 2014 posting,

Research from the Massachusetts Institute of Technology (MIT) has revealed a new property of metal nanoparticles, in this case, silver. From an Oct. 12, 2014 news item on ScienceDaily,

A surprising phenomenon has been found in metal nanoparticles: They appear, from the outside, to be liquid droplets, wobbling and readily changing shape, while their interiors retain a perfectly stable crystal configuration.

The research team behind the finding, led by MIT professor Ju Li, says the work could have important implications for the design of components in nanotechnology, such as metal contacts for molecular electronic circuits. [my emphasis added]

This discovery and others regarding materials and phase changes at ever diminishing sizes hint that a computer with a functioning 7nm chip might be a bit further off than IBM is suggesting.

Silver nanoparticles: liquid on the outside, crystal on the inside

Research from the Massachusetts Institute of Technology (MIT) has revealed a new property of metal nanoparticles, in this case, silver. From an Oct. 12, 2014 news item on ScienceDaily,

A surprising phenomenon has been found in metal nanoparticles: They appear, from the outside, to be liquid droplets, wobbling and readily changing shape, while their interiors retain a perfectly stable crystal configuration.

The research team behind the finding, led by MIT professor Ju Li, says the work could have important implications for the design of components in nanotechnology, such as metal contacts for molecular electronic circuits.

The results, published in the journal Nature Materials, come from a combination of laboratory analysis and computer modeling, by an international team that included researchers in China, Japan, and Pittsburgh, as well as at MIT.

An Oct. 12, 2014 MIT news release (also on EurekAlert), which originated the news item, offers both more information about the research and a surprising comparison of nanometers to the width of a human hair,

The experiments were conducted at room temperature, with particles of pure silver less than 10 nanometers across — less than one-thousandth of the width of a human hair. [emphasis mine] But the results should apply to many different metals, says Li, senior author of the paper and the BEA Professor of Nuclear Science and Engineering.

Silver has a relatively high melting point — 962 degrees Celsius, or 1763 degrees Fahrenheit — so observation of any liquidlike behavior in its nanoparticles was “quite unexpected,” Li says. Hints of the new phenomenon had been seen in earlier work with tin, which has a much lower melting point, he says.

The use of nanoparticles in applications ranging from electronics to pharmaceuticals is a lively area of research; generally, Li says, these researchers “want to form shapes, and they want these shapes to be stable, in many cases over a period of years.” So the discovery of these deformations reveals a potentially serious barrier to many such applications: For example, if gold or silver nanoligaments are used in electronic circuits, these deformations could quickly cause electrical connections to fail.

It was a bit surprising to see the reference to 10 nanometers as being less than 1/1,000th (one/one thousandth) of the width of a human hair in a news release from MIT. Generally, a nanometer has been described as being anywhere from less than 1/50,000th to 1/120,000th of the width of a human hair with less than 1/100,000th being one of the most common descriptions. While it’s true that 10 nanometers is less than 1/1,000th of the width of a human hair, it seems a bit misleading when it could be described, in keeping with the more common description, as less than 1/10,000th.

Getting back to the research, the news release offers more details as to how it was conducted,

The researchers’ detailed imaging with a transmission electron microscope and atomistic modeling revealed that while the exterior of the metal nanoparticles appears to move like a liquid, only the outermost layers — one or two atoms thick — actually move at any given time. As these outer layers of atoms move across the surface and redeposit elsewhere, they give the impression of much greater movement — but inside each particle, the atoms stay perfectly lined up, like bricks in a wall.

“The interior is crystalline, so the only mobile atoms are the first one or two monolayers,” Li says. “Everywhere except the first two layers is crystalline.”

By contrast, if the droplets were to melt to a liquid state, the orderliness of the crystal structure would be eliminated entirely — like a wall tumbling into a heap of bricks.

Technically, the particles’ deformation is pseudoelastic, meaning that the material returns to its original shape after the stresses are removed — like a squeezed rubber ball — as opposed to plasticity, as in a deformable lump of clay that retains a new shape.

The phenomenon of plasticity by interfacial diffusion was first proposed by Robert L. Coble, a professor of ceramic engineering at MIT, and is known as “Coble creep.” “What we saw is aptly called Coble pseudoelasticity,” Li says.

Now that the phenomenon has been understood, researchers working on nanocircuits or other nanodevices can quite easily compensate for it, Li says. If the nanoparticles are protected by even a vanishingly thin layer of oxide, the liquidlike behavior is almost completely eliminated, making stable circuits possible.

There are some benefits to this insight (from the news release),

On the other hand, for some applications this phenomenon might be useful: For example, in circuits where electrical contacts need to withstand rotational reconfiguration, particles designed to maximize this effect might prove useful, using noble metals or a reducing atmosphere, where the formation of an oxide layer is destabilized, Li says.

The new finding flies in the face of expectations — in part, because of a well-understood relationship, in most materials, in which mechanical strength increases as size is reduced.

“In general, the smaller the size, the higher the strength,” Li says, but “at very small sizes, a material component can get very much weaker. The transition from ‘smaller is stronger’ to ‘smaller is much weaker’ can be very sharp.”

That crossover, he says, takes place at about 10 nanometers at room temperature — a size that microchip manufacturers are approaching as circuits shrink. When this threshold is reached, Li says, it causes “a very precipitous drop” in a nanocomponent’s strength.

The findings could also help explain a number of anomalous results seen in other research on small particles, Li says.

For more details about the various attempts to create smaller computer chips, you can read my July 11, 2014 posting about IBM and its proposed 7 nanometer chip where you will also find links to announcements and posts about Intel’s smaller chips and HP Labs’ attempt to recreate computers.

As for the research into liquid-like metallic (silver) nanoparticles, here’s a link to and a citation for the paper,

Liquid-like pseudoelasticity of sub-10-nm crystalline ​silver particle by Jun Sun, Longbing He, Yu-Chieh Lo, Tao Xu, Hengchang Bi, Litao Sun, Ze Zhang, Scott X. Mao, & Ju Li. Nature Materials (2014) doi:10.1038/nmat4105 Published online 12 October 2014

This paper is behind a paywall. There is a free preview via ReadCube Access.

The relationship between Valyrian steel (from Game of Thrones), Damascus steel, and nuclear nanotechnology

There’s a very interesting June 20, 2014 posting by Charles Day on his Dayside blog (located on the Physics Today website). Day manages to relate the Game of Thrones tv series to nuclear power and nanotechnology,

The military technology of A Song of Ice and Fire, George R. R. Martin’s series of fantasy novels, is medieval with an admixture of the supernatural. Dragons aside, among the most prized weapons are swords made from Valyrian steel, which are lighter, stronger, and sharper than ordinary steel swords.

Like many of the features in the rich world of the novels and their TV adaptation, Game of Thrones, Valyrian steel has a historical inspiration. Sometime before 300 BC, metalworkers in Southern India discovered a way to make small cakes of high-carbon steel known as wootz. Thanks to black wavy bands of Fe3C particles that pervade the metal, wootz steel was already strong. …

Perhaps because the properties of wootz and Damascus steels depended, in part, on a particular kind of iron ore, the ability of metallurgists to make the alloys was lost sometime in the 18th century. In A Song of Ice and Fire, the plot plays out during an era in which making Valyrian steel is a long-lost art.

Martin’s knowledge of metallurgy is perhaps shaky. …

Interestingly, the comments on the blog posting largely concern themselves with whether George RR Martin knows anything about metallurgy. The consensus being that he does and that the problems in the Game of Thrones version of metallurgy lie with the series writers.

I first came across the Damascus steel, wootz, and carbon nanotube story in 2008 and provided a concise description on my Nanotech Mysteries wiki Middle Ages page,

Damascus steel blades were first made in the 8th century CE when they acquired a legendary status as unlike other blades they were able to cut through bone and stone while remaining sharp enough to cut a piece of silk. They were also flexible which meant they didn’t break off easily in a sword fight. The secret for making the blades died (history does not record how) about 1700 CE and there hasn’t been a new blade since.

 The blades were generally made from metal ingots prepared in India using special recipes which probably put just the right amount of carbon and other impurities into the iron. By following these recipes and following specific forging techniques craftsmen ended up making nanotubes … When these blades were nearly finished, blacksmiths would etch them with acid. This brought out the wavy light and dark lines that make Damascus swords easy to recognize.3

 It turns out part of the secret to the blade is nanotechnology. Scientists discovered this by looking at a Damascus steel blade from 1700 under an electron microscope. It seems those unknown smiths were somehow encasing cementite nanowires in carbon nanotubes then forging them into the steel blades giving them their legendary strength and flexibility.

The reference information I used then seems to be no longer available online but there is this more than acceptable alternative, a Sept. 27, 2008 postiing by Ed Yong from his Not Exactly Rocket Science blog (on ScienceBlogs.com; Note: A link has been removed),

In medieval times, crusading Christian knights cut a swathe through the Middle East in an attempt to reclaim Jerusalem from the Muslims. The Muslims in turn cut through the invaders using a very special type of sword, which quickly gained a mythical reputation among the Europeans. These ‘Damascus blades‘ were extraordinarily strong, but still flexible enough to bend from hilt to tip. And they were reputedly so sharp that they could cleave a silk scarf floating to the ground, just as readily as a knight’s body.

They were superlative weapons that gave the Muslims a great advantage, and their blacksmiths carefully guarded the secret to their manufacture. The secret eventually died out in the eighteenth century and no European smith was able to fully reproduce their method.

Two years ago, Marianne Reibold and colleagues from the University of Dresden uncovered the extraordinary secret of Damascus steel – carbon nanotubes. The smiths of old were inadvertently using nanotechnology.

Getting back to Day, he goes on to explain the Damascus/Valyrian steel connection to nuclear power (Note: Links have been removed),

Valyrian and Damascus steels were on my mind earlier this week when I attended a session at TechConnect World on the use of nanotechnology in the nuclear power industry.

Scott Anderson of Lockheed Martin gave the introductory talk. Before the Fukushima disaster, Anderson pointed out, the principal materials science challenge in the nuclear industry lay in extending the lifetime of fuel rods. Now the focus has shifted to accident-tolerant fuels and safer, more durable equipment.

Among the other speakers was MIT’s Ju Li, who described his group’s experiments with incorporating carbon nanotubes (CNTs) in aluminum to boost the metal’s resistance to radiation damage. In a reactor core, neutrons and other ionizing particles penetrate vessels, walls, and other structures, where they knock atoms off lattice sites. The cumulative effect of those displacements is to create voids and other defects that weaken the structures.

Li isn’t sure yet how the CNTs resist irradiation and toughen the aluminum, but at the end of his talk he recalled their appearance in another metal, steel.

In 2006 Peter Paufler of Dresden University of Technology and his collaborators used high-resolution transmission electron microscopy (TEM) to examine the physical and chemical microstructure of a sample of Damascus steel from the 17th century.

The saber from which the sample was taken was forged in Isfahan, Persia, by the famed blacksmith Assad Ullah. As part of their experiment, Paufler and his colleagues washed the sample in hydrochloric acid to remove Fe3C particles. A second look with TEM revealed the presence of CNTs.

There’s still active interest in researching Damascus steel blades as not all the secrets behind the blade’s extraordinary qualities have been revealed yet. There is a March 13, 2014 posting here which describes a research project where Chinese researchers are attempting (using computational software) to uncover the reason for the blade’s unique patterns,

It seems that while researchers were able to answer some questions about the blade’s qualities, researchers in China believe they may have answered the question about the blade’s unique patterns, from a March 12, 2014 news release on EurekAlert,

Blacksmiths and metallurgists in the West have been puzzled for centuries as to how the unique patterns on the famous Damascus steel blades were formed. Different mechanisms for the formation of the patterns and many methods for making the swords have been suggested and attempted, but none has produced blades with patterns matching those of the Damascus swords in the museums. The debate over the mechanism of formation of the Damascus patterns is still ongoing today. Using modern metallurgical computational software (Thermo-Calc, Stockholm, Sweden), Professor Haiwen Luo of the Central Iron and Steel Research Institute in Beijing, together with his collaborator, have analyzed the relevant published data relevant to the Damascus blades, and present a new explanation that is different from other proposed mechanisms.

At the time the researchers were hoping to have someone donate a piece of genuine Damascus steel blade. From my March 13, 2014 posting,

Note from the authors: It would be much appreciated if anyone would like to donate a piece of genuine Damascus blade for our research.

Corresponding Author:

LUO Haiwen
Email: haiwenluo@126.com

Perhaps researchers will manage to solve the puzzle of how medieval craftsman were once able to create extraordinary steel blades.