Tag Archives: letter-dd-tech

Toward optical chips


September 19, 2014

Chips that use light, rather than electricity, to move data would consume much less power — and energy efficiency is a growing concern as chips’ transistor counts rise.

Of the three chief components of optical circuits — light emitters, modulators, and detectors — emitters are the toughest to build. One promising light source for optical chips is molybdenum disulfide (MoS2), which has excellent optical properties when deposited as a single, atom-thick layer. Other experimental on-chip light emitters have more-complex three-dimensional geometries and use rarer materials, which would make them more difficult and costly to manufacture.

In the next issue of the journal Nano Letters, researchers from MIT’s departments of Physics and of Electrical Engineering and Computer Science will describe a new technique for building MoS2 light emitters tuned to different frequencies, an essential requirement for optoelectronic chips. Since thin films of material can also be patterned onto sheets of plastic, the same work could point toward thin, flexible, bright, color displays.

The researchers also provide a theoretical characterization of the physical phenomena that explain the emitters’ tunability, which could aid in the search for even better candidate materials. Molybdenum is one of several elements, clustered together on the periodic table, known as transition metals. “There’s a whole family of transition metals,” says Institute Professor Emeritus Mildred Dresselhaus, the corresponding author on the new paper. “If you find it in one, then it gives you some incentive to look at it in the whole family.”

Joining Dresselhaus on the paper are joint first authors Shengxi Huang, a graduate student in electrical engineering and computer science, and Xi Ling, a postdoc in the Research Laboratory of Electronics; associate professor of electrical engineering and computer science Jing Kong; and Liangbo Liang, Humberto Terrones, and Vincent Meunier of Rensselaer Polytechnic Institute.

Monolayer — with a twist

Most optical communications systems — such as the fiber-optic networks that provide many people with Internet and TV service — maximize bandwidth by encoding different data at different optical frequencies. So tunability is crucial to realizing the full potential of optoelectronic chips.

The MIT researchers tuned their emitters by depositing two layers of MoS2 on a silicon substrate. The top layers were rotated relative to the lower layers, and the degree of rotation determined the wavelength of the emitted light.

Ordinarily, MoS2 is a good light emitter only in monolayers, or atom-thick sheets. As Huang explains, that’s because the two-dimensional structure of the sheet confines the electrons orbiting the MoS2 molecules to a limited number of energy states.

MoS2, like all light-emitting semiconductors, is what’s called a direct-band-gap material. When energy is added to the material, either by a laser “pump” or as an electrical current, it kicks some of the electrons orbiting the molecules into higher energy states. When the electrons fall back into their initial state, they emit their excess energy as light.

In a monolayer of MoS2, the excited electrons can’t escape the plane defined by the material’s crystal lattice: Because of the crystal’s geometry, the only energy states available to them to leap into cross the light-emitting threshold. But in multilayer MoS2, the adjacent layers offer lower-energy states, below the threshold, and an excited electron will always seek the lowest energy it can find.

Mind the gap

So while the researchers knew that rotating the layers of MoS2 should alter the wavelength of the emitted light, they were by no means certain that the light would be intense enough for use in optoelectronics. As it turns out, however, the rotation of the layers relative to each other alters the crystal geometry enough to preserve the band gap. The emitted light is not quite as intense as that produced by a monolayer of MoS2, but it’s certainly intense enough for practical use — and significantly more intense than that produced by most rival technologies.

The researchers were able to precisely characterize the relationship between the geometries of the rotated layers and the wavelength and intensity of the light emitted. “For different twisted angles, the actual separation between the two layers is different, so the coupling between the two layers is different,” Huang explains. “This interferes with the electron densities in the bilayer system, which gives you a different photoluminescence.” That theoretical characterization should make it much easier to predict whether other transition-metal compounds will display similar light emission.

“This thing is something really new,” says Fengnian Xia, an assistant professor of electrical engineering at Yale University. “It gives you a new model for tuning.”

“I expected that this kind of angle adjustment would work, but I didn’t expect that the effect would be so huge,” Xia adds. “They get quite significant tuning. That’s a little bit surprising.”

Xia believes that compounds made from other transition metals, such as tungsten disulfide or tungsten diselenide, could ultimately prove more practical than MoS2. But he agrees that the MIT and RPI researchers’ theoretical framework could help guide future work. “They use density-functional theory,” he says. “That’s a kind of general theory that can be applied to other materials also.”

Researchers from the University of Alabama in Huntsville and the University of Oklahoma have found a new way to control the properties of quantum dots, those tiny chunks of semiconductor material that glow different colors depending on their size. Quantum dots, which are so small they start to exhibit atom-like quantum properties, have a wide range of potential applications, from sensors, light-emitting diodes, and solar cells, to fluorescent tags for biomedical imaging and qubits in quantum computing.

This image shows the experimental set-up researchers used to analyze the behavior of quantum dots placed on metal oxides. A laser illuminated the quantum dots to make them glow and a spectrometer was used to analyze the light they emitted. Credit: Seyed Sadeghi/ University of Alabama, Huntsville

This image shows the experimental set-up researchers used to analyze the behavior of quantum dots placed on metal oxides. A laser illuminated the quantum dots to make them glow and a spectrometer was used to analyze the light they emitted. Credit: Seyed Sadeghi/ University of Alabama, Huntsville

A key property of quantum dots that makes them so useful is their fluorescence. Scientists can “tune” quantum dots to emit a specific color of light by adjusting their size — small dots glow blue and large dots glow red. However, the dots’ ability to glow can change over time with exposure to light and air.

Seyed Sadeghi, a physicist at the University of Alabama in Huntsville, wondered if it would be possible to better control how quantum dots react to their environment. His team had previously found that placing quantum dots of a certain type on nanometer-thin layers of chromium and aluminum oxides significantly altered the dots’ behavior: the aluminum oxide increased their emission efficiency, while the chromium oxide increased the dots’ degradation rate when exposed to air. The researchers decided to extend their investigations to quantum dots with different structures.

Quantum dots come in a variety of shapes, sizes, and materials. For Sadeghi and his colleagues’ most recent studies, published in the Journal of Applied Physics, from AIP Publishing, the researchers probed the behavior of four different types of commercially available quantum dots. Some of the quantum dots had protective shells, while others did not. Additionally, some of the dots had cores made of binary materials (two types of semiconductors), while others had ternary material cores (three types of semiconductors). All of the quantum dots had been manufactured by chemical synthesis.

The researchers found that ultrathin aluminum oxide could make quantum dots glow brighter and that the effect was much more significant for quantum dots without protective shells. They also found that while quantum dots with both binary and ternary cores shrink after reacting with the oxygen in air, ternary core dots placed on aluminum oxide glowed brighter despite the shrinkage. This observation surprised the researchers, Sadeghi said, and while they don’t yet have an explanation for the difference, they are continuing to study it.

“The results of these studies can serve to enhance emission efficiency of quantum dots, which is an important feature for many applications such as light emitting devices, sensors, detectors, photovoltaic devices, and the investigation of a wide range of quantum and nano-scale physical phenomena,” Sadeghi said. Quantum dots have already helped increase the efficiencies of many optical devices, he noted, and the further development and application of quantum dots’ unique properties, including in the fields of biological imaging and medicine, continues to be a prime focus of scientific study. As a next step in their own research, Sadeghi and his colleagues plan to investigate how metal oxides might affect the behavior of quantum dots when they are close to metallic nanoparticles.

You can’t fix what you can’t find. You can’t control what you can’t measure. 

BY DAVID W. PRICE and DOUGLAS G. SUTHERLAND

This is the first in a series of 10 installments which will discuss fundamental truths about process control—inspection and metrology—for the semiconductor industry. By fundamental, we imply the following:

  • Unassailable: They are self-evident, can be proven from first principles, or are supported by the dominant behavior at fabs worldwide
  • Unchanging: these concepts are equally true today for 28nm as they were 15 years ago for 0.25μm, and are expected to hold true in the future
  • Universal: They are not unique to a specific segment of process control; rather they apply to process control as a group, as well as to each individual component of process control within the fab

Each article in this series will introduce one of the 10 fundamental truths and discuss interesting applications of these truths to semiconductor IC fabs. Given the increasing complexity of advanced devices and process integration, process control is growing in importance. By understanding the fundamental nature of process control, fabs can better implement strategies to identify critical defects, find excursions, and reduce sources of variation.

The first fundamental truth of process control for the semiconductor IC industry is:

You can’t fix what you can’t find. You can’t control what you can’t measure.

While it’s true that inspection and metrology systems are not used to make IC devices—they do not add or remove materials or create patterns—they are critical for making high-yielding, reliable devices. By finding defects and measuring critical parameters, inspection and metrology systems monitor the hundreds of steps required to manufacture a device, ensuring the processes meet strict manufacturing specifications and helping fab engineers identify and troubleshoot process issues when there is an excursion. Without inspection and metrology, it would be near impossible for fabs to pinpoint process issues that affect yield. However, it’s not enough to simply “find” and “measure” — a fab’s process control strategy needs to be capable and cost-effective.

Capable inspection and metrology strategies find and measure the defects and parameters that affect device yield. Cost-effective inspection and metrology is performed at the lowest total cost to the factory, where total cost is the sum of the cost of lost yield plus the cost of process control.

First, make it capable

If you can’t find it, you can’t fix it. At the heart of this truth is the understanding that, above all else, a fab’s inspection and metrology strategy must be capable. It must highlight the problems that are limiting baseline yield. It must also provide actionable information that can enable fabs to quickly find and fix excursions (FIGURE 1).

We emphasize this need for capability first because we have observed that some fabs are too quick tosacrifice capability for cost reductions. No strategy is cost-effective if it doesn’t accomplish its fundamental objective.

Below are specific questions that can help fab management evaluate the capability of its process control strategy:

  • Are you finding all sources of your defect-limited yield? Are you finding these in-line or at end-of-line?
  • Does your defect Pareto have sufficient resolution of the top yield-limiters in each module to direct the most appropriate use of factory engineering resources?
  • Have you fully characterized all of the important measurements and defect types (size range, kill ratio, root cause, solution)?
  • Do you understand the most probable incursion scenarios? What is the smallest excursion that you absolutely must detect at this step? How many lots are you willing to have exposed to this excursion before it is detected?
  • Are you inspecting and measuring at all the right steps? Can you quickly isolate the point of formation for excursions? Can you quickly disposition potentially affected lots?
  • Does a particular defect signature become confused by defects added at subsequent process steps? Or do you need separate inspections at each step in order to partition the problem? 
  • Do you have overlapping inspections to guard against the high-frequency, high-impact excursions?
  • What is the alpha risk and beta risk for each inspection or measurement? How are these related to the capture rate, accuracy, precision, matching and more?

Process control Fig 1b Process control fig 1a

 

FIGURE 1. You can’t fix what you can’t find. And you can’t control what you can’t measure. Left: P-MOS SiGe critical dimension measurement. Right: Fin patterning particle leading to a Fin Spire defect at post dummy gate etch. Source: KLA-Tencor

Then, make it cost-effective

Once a capable strategy is in place, then a fab can start the process of making it cost-effective. The best known method for optimizing total cost is usually adjusting the overall lot sampling rate. This is generally preferred because the capability remains constant.

In some cases, it may be possible to migrate to a less sensitive inspection (lower cost of ownership tool or larger pixel size); however, this is a dangerous path because it re-introduces uncertainty (alpha/beta risk) that reduces a fab’s process control capability. This concept will be discussed in more detail in our next article on sampling strategies.

Finally, it is worth pointing out that it is not enough to implement a capable strategy. The fab must ensure that what was once a capable strategy, stays a capable strategy. A fab cannot measure with a broken inspection tool or trust a poorly maintained inspection tool. Therefore, most fabs have programs in place to maintain and monitor the ongoing performance of their inspection and metrology tools.

By optimizing process control strategy to be capable and cost-effective, fabs ultimately find what needs to be fixed and measure what should be controlled—driving higher yield and better profitability.

Bend them, stretch them, twist them, fold them: modern materials that are light, flexible and highly conductive have extraordinary technological potential, whether as artificial skin or electronic paper.

Making such concepts affordable enough for general use remains a challenge but a new way of working with copper nanowires and a PVA “nano glue” could be a game-changer.

Previous success in the field of ultra-lightweight “aerogel monoliths” has largely relied on the use of precious gold and silver nanowires.

By turning instead to copper, both abundant and cheap, researchers at Monash University and the Melbourne Centre for Nanofabrication have developed a way of making flexible conductors cost-effective enough for commercial application.

“Aerogel monoliths are like kitchen sponges but ours are made of ultra fine copper nanowires, using a fabrication process called freeze drying,” said lead researcher Associate Professor Wenlong Cheng, from Monash University’s Department of Chemical Engineering.

“The copper aerogel monoliths are conductive and could be further embedded into polymeric elastomers – extremely flexible, stretchable materials – to obtain conducting rubbers.”

Despite its conductivity, copper’s tendency to oxidation and the poor mechanical stability of copper nanowire aerogel monoliths mean its potential has been largely unexplored.

The researchers found that adding a trace amount of poly(vinyl alcohol) (PVA) to their aerogels substantially improved their mechanical strength and robustness without impairing their conductivity.

What’s more, once the PVA was included, the aerogels could be used to make electrically conductive rubber materials without the need for any prewiring. Reshaping was also easy.

“The conducting rubbers could be shaped in arbitrary 1D, 2D and 3D shapes simply by cutting, while maintaining the conductivities,” Associate Professor Cheng said.

The versatility extends to the degree of conductivity. “The conductivity can be tuned simply by adjusting the loading of copper nanowires,” he said. “A low loading of nano wires would be appropriate for a pressure sensor whereas a high loading is suitable for a stretchable conductor.”

Affordable versions of these materials open up the potential for use in a range of new-generation concepts: from prosthetic skin to electronic paper, for implantable medical devices, and for flexible displays and touch screens.

They can be used in rubber-like electronic devices that, unlike paper-like electronic devices, can stretch as well as bend. They can also be attached to topologically complex curved surfaces, serving as real skin-like sensing devices, Associate Professor Cheng said.

In their report, published recently in ACS Nano, the researchers noted that devices using their copper-based aerogels were not quite as sensitive as those using gold nanowires, but had many other advantages, most notably their low-cost materials, simpler and more affordable processing, and great versatility.

Scientists have developed what they believe is the thinnest-possible semiconductor, a new class of nanoscale materials made in sheets only three atoms thick.

As seen under an optical microscope, the heterostructures have a triangular shape. The two different monolayer semiconductors can be recognized through their different colors.

The University of Washington researchers have demonstrated that two of these single-layer semiconductor materials can be connected in an atomically seamless fashion known as a heterojunction. This result could be the basis for next-generation flexible and transparent computing, better light-emitting diodes, or LEDs, and solar technologies.

As seen under an optical microscope, the heterostructures have a triangular shape. The two different monolayer semiconductors can be recognized through their different colors. Photo credit: U of Washington

As seen under an optical microscope, the heterostructures have a triangular shape. The two different monolayer semiconductors can be recognized through their different colors. Photo credit: U of Washington

“Heterojunctions are fundamental elements of electronic and photonic devices,” said senior author Xiaodong Xu, a UW assistant professor of materials science and engineering and of physics. “Our experimental demonstration of such junctions between two-dimensional materials should enable new kinds of transistors, LEDs, nanolasers, and solar cells to be developed for highly integrated electronic and optical circuits within a single atomic plane.”

The research was published online this week in Nature Materials.

The researchers discovered that two flat semiconductor materials can be connected edge-to-edge with crystalline perfection. They worked with two single-layer, or monolayer, materials – molybdenum diselenide and tungsten diselenide – that have very similar structures, which was key to creating the composite two-dimensional semiconductor.

Collaborators from the electron microscopy center at the University of Warwick in England found that all the atoms in both materials formed a single honeycomb lattice structure, without any distortions or discontinuities. This provides the strongest possible link between two single-layer materials, necessary for flexible devices. Within the same family of materials it is feasible that researchers could bond other pairs together in the same way.

A high-resolution scanning transmission electron microscopy (STEM) image shows the lattice structure of the heterojunctions in atomic precision. Photo credit: U of Warwick

A high-resolution scanning transmission electron microscopy (STEM) image shows the lattice structure of the heterojunctions in atomic precision. Photo credit: U of Warwick

The researchers created the junctions in a small furnace at the UW. First, they inserted a powder mixture of the two materials into a chamber heated to 900 degrees Celsius (1,652 F). Hydrogen gas was then passed through the chamber and the evaporated atoms from one of the materials were carried toward a cooler region of the tube and deposited as single-layer crystals in the shape of triangles.

After a while, evaporated atoms from the second material then attached to the edges of the triangle to create a seamless semiconducting heterojunction.

“This is a scalable technique,” said Sanfeng Wu, a UW doctoral student in physics and one of the lead authors. “Because the materials have different properties, they evaporate and separate at different times automatically. The second material forms around the first triangle that just previously formed. That’s why these lattices are so beautifully connected.”

With a larger furnace, it would be possible to mass-produce sheets of these semiconductor heterostructures, the researchers said. On a small scale, it takes about five minutes to grow the crystals, with up to two hours of heating and cooling time.

“We are very excited about the new science and engineering opportunities provided by these novel structures,” said senior author David Cobden, a UW professor of physics. “In the future, combinations of two-dimensional materials may be integrated together in this way to form all kinds of interesting electronic structures such as in-plane quantum wells and quantum wires, superlattices, fully functioning transistors, and even complete electronic circuits.”

This photoluminescence intensity map shows a typical piece of the lateral heterostructures. The junction region produces an enhanced light emission, indicating its application potential in optoelectronics. Photo credit: U of Washington

This photoluminescence intensity map shows a typical piece of the lateral heterostructures. The junction region produces an enhanced light emission, indicating its application potential in optoelectronics. Photo credit: U of Washington

The researchers have already demonstrated that the junction interacts with light much more strongly than the rest of the monolayer, which is encouraging for optoelectric and photonic applications like solar cells.

Other co-authors are Chunming Huang and Pasqual Rivera of UW physics; Ana Sanchez, Richard Beanland and Jonathan Peters at the University of Warwick; Jason Ross of UW materials science and engineering; and Wang Yao, a theoretical physicist of the University of Hong Kong.

This research was funded by the U.S. Department of Energy, the UW’s Clean Energy Institute, the Research Grant Council of Hong Kong, the University Grants Committee of Hong Kong, the Croucher Foundation, the Science City Research Alliance and the Higher Education Funding Council for England’s Strategic Development Fund.

Intersil Corporation, a provider of power management and precision analog solutions, today announced the ISL98611 display power and LED driver for smartphones. The ISL98611 is the first power management IC that integrates the display power and backlight LED driver functions in a single chip. It significantly improves efficiency of both functions to increase smartphone battery life by an hour or more.

In addition to extending battery life, the ISL98611 also improves display brightness uniformity and color consistency. The highly integrated ISL98611 has a boost regulator, LDO and inverting charge pump for generating two output rails at +5V and -5V in a single device. It also includes a boost regulator with 3-channel current sinks for the LED backlight driver. This single-chip solution offers designers four key benefits:

  • Extended battery life: When used for web browsing and emails, a smartphone’s backlight LEDs and display power consume the majority of its battery power. The ISL98611 backlight LED driver delivers seven percent higher efficiency (up to 93 percent) than competitive multi-chip solutions and generates +/-5V display power supplies with greater than 88 percent efficiency at 15mA load using a 2.5x2mm2 size inductor, compared to 85 percent efficiency of the nearest competitor.
  • Improved display uniformity: The ISL98611 provides excellent LED current matching at very low LED current: it achieves +/- 2.2 percent matching down to 1mA and +/- 2.8 percent at 50μA.
  • Improved display color consistency: The ISL98611 includes hybrid dimming to eliminate white LED color shift issues at low LED current, which occur with DC dimming.
  • Smallest footprint: The ISL98611’s total display power plus backlight solution uses 24 percent less PCB area compared to the competition, while requiring only eight external components. This provides additional space to house the phone’s battery.

“With each new product generation, smartphone designers are challenged to add more features, reduce size and extend battery life,” said Andrew Cowell, senior vice president of Intersil’s Mobile Power Products. “The ISL98611 delivers the integration, extended battery life and display image quality improvement our customers want in their next-generation smartphone designs.”

A “valley of death” is well-known to entrepreneurs–the lull between government funding for research and industry support for prototypes and products. To confront this problem, in 2013 the National Science Foundation (NSF) created a new program called InTrans to extend the life of the most high-impact NSF-funded research and help great ideas transition from lab to practice.

Today, in partnership with Intel Corporation, NSF announced the first InTrans award of $3 million to a team of researchers who are designing customizable, domain-specific computing technologies for use in healthcare.

The work could lead to less exposure to dangerous radiation during x-rays by speeding up the computing side of medicine. It also could result in patient-specific cancer treatments.

Led by the University of California, Los Angeles, the research team includes experts in computer science and engineering, electrical engineering and medicine from Rice University and Oregon Health and Science University. The team comes mainly from the Center of Domain-Specific Computing (CDSC), which was supported by an NSF Expeditions in Computing Award in 2009.

Expeditions, consisting of five-year, $10 million awards, represent some of the largest investments currently made by NSF’s Computer, Information Science and Engineering (CISE) directorate.

Today’s InTrans grant extends research efforts funded by the Expedition program with the aim of bringing the new technology to the point where it can be produced at a microchip fabrication plant (or fab) for a mass market.

“We see the InTrans program as an innovative approach to public-private partnership and a way of enhancing research sustainability,” said Farnam Jahanian, head of NSF’s CISE Directorate. “We’re thrilled that Intel and NSF can partner to continue to support the development of domain-specific hardware and to transition this excellent fundamental research into real applications.”

In the project, the researchers looked beyond parallelization (the process of working on a problem with more than one processor at the same time) and instead focused on domain-specific customization, a disruptive technology with the potential to bring orders-of-magnitude improvements to important applications. Domain-specific computing systems work efficiently on specific problems–in this case, medical imaging and DNA sequencing of tumors–or a set of problems with similar features, reducing the time to solution and bringing down costs.

“We tried to create energy-efficient computers that are more like brains,” explained Jason Cong, the director of CDSC, a Chancellor’s Professor of computer science and electrical engineering at UCLA, and the lead on the project.

“We don’t really have a centralized central processing unit in there. If you look at the brain you have one region responsible for speech, another region for motor control, another region for vision. Those are specialized ‘accelerators.’ We want to develop a system architecture of that kind, where each accelerator can deliver a hundred to a thousand times better efficiency than the standard processors.”

The team plans to identify classes of applications that share similar computation kernels, thereby creating hardware that solves a range of common related problems with high efficiency and flexibility. This differs from specialized circuits that are designed to solve a single problem (such as those used in cell phones) or general-purpose processors designed to solve all problems.

“The group laid out a different way of presenting the problem of domain-specific computing, which is: How to determine the common features and support them efficiently?” said Sankar Basu, program officer at NSF. “They developed a framework for domain-specific hardware design that they believe can be applied in many other domains as well.”

The group selected medical imaging and patient specific cancer treatments–two important problems in healthcare–as the test applications upon which to create their design because of healthcare’s significant impact on the national economy and quality of life.

Medical imaging is now used diagnose a multitude of medical problems. However, diagnostic methods like x-ray CT (computed tomography) scanners can expose the body to cumulative radiation, which increases risk to the patient in the long term.

Scientists have developed new medical imaging algorithms that lead to less radiation exposure, but these have been constrained due to a lack of computing power.

Using their customizable heterogeneous platform, Cong and his team were able to make one of the leading CT image reconstruction algorithms a hundred times faster, thereby reducing a subject’s exposure to radiation significantly. They presented their results in May 2014 at the IEEE International Symposium on Field-Programmable Custom Computing Machines.

“The low-dose CT scan allows you to get a similar resolution to the standard CT, but the patient can get several times lower radiation,” said Alex Bui, a professor in the UCLA Radiological Sciences department and a co-lead of the project. “Anything we can do to lower that exposure will have a significant health impact.”

In theory, the technology also exists to determine the specific strain of cancer a patient has through DNA sequencing and to use that information to design a patient-specific treatment. However, it currently takes so long to sequence the DNA that once one determines a tumor’s strain, the cancer has already mutated. With domain-specific hardware, Cong believes rapid diagnoses and targeted treatments will be possible.

“Power- and cost-efficient high-performance computation in these domains will have a significant impact on healthcare in terms of preventive medicine, diagnostic procedures and therapeutic procedures,” said Cong.

“Cancer genomics, in particular, has been hobbled by the lack of open, scalable and efficient approaches to rapidly and accurately align and interpret genome sequence data,” said Paul Spellman, a professor at OHSU, who works on personalized cancer treatment and served as another co-lead on the project.

“The ability to use hardware approaches to dramatically improve these speeds will facilitate the rapid turnarounds in enormous datasets that will be necessary to deliver on precision medicine.”

Down the road, the team will work with Spellman and other physicians at OHSU to test the application of the hardware in a real-world environment.

“Intel excels in creating customizable computing platforms optimized for data-intensive computation,” said Michael C. Mayberry, corporate vice president of Intel’s Technology and Manufacturing Group and chair of Corporate Research Council. “These researchers are some of the leading lights in the field of domain-specific computing.

“This new effort enables us to maximize the benefits of Intel architecture. For example, we can ensure that Intel Xeon processor features are optimized, in connection with various accelerators, for a specific application domain and across all architectural layers,” Mayberry said. “Life science and healthcare research will undoubtedly benefit from the performance, flexibility, energy efficiency and affordability of this application.”

The InTrans program not only advances important fundamental research and integrates it into industry, it also benefits society by improving medical imaging technologies and cancer treatments, helping to extend lives.

“Not every research project will get to the stage where they’re ready to make a direct impact on industry and on society, but in our case, we’re quite close,” Cong said. “We’re thankful for NSF’s support and are excited about continuing our research under this unique private-public funding model.”

Renesas Electronics America Inc., a supplier of advanced semiconductor solutions, today announced development of innovative new intellectual property (IP) that implements capacitive-touch sensing technology ideal for home appliances and healthcare equipment. The IP achieves high-touch sensitivity five times superior compared to that of Renesas’ R8C/3xT microcontrollers (MCUs), as well as high-noise immunity allowing the technology to pass strict noise tests. Furthermore, for the first time, Renesas IP supports the mutual-capacitance method which is more reliable and versatile than the conventional self-capacitance method.

In the human machine interface (HMI) field for electric and electronic equipment, touch-key manipulation interfaces are the subject of increasing attention. Capacitive-touch panels are being rapidly adopted because touch-key operation can easily improve reliability in product design and enhance the end-user experience. In fact, system manufacturers are now developing new touch panels with a curved surface, instead of the traditional planar surfaces that have been mainstream until now. Looking ahead, touch-panel technologies with even better sensitivity and noise resistance will become highly demanded for a wide range of applications.

Renesas helped to drive adoption of touch-key manipulation systems in October 2009 when it launched its R8C/3xT series of MCUs supporting capacitive-touch interfaces. Renesas expects strong growth in the market for touch-key systems and, by leveraging innovative technologies like its newest IP, the company intends to be a key player with technology and products supporting HMI applications.

A nanoparticle ink that can be used for printing electronics without high-temperature annealing presents a possible profitable approach for manufacturing flexible electronics.

Printing semiconductor devices are considered to provide low-cost high performance flexible electronics that outperform amorphous silicon thin film transistors currently limiting developments in display technology. However the nanoparticle inks developed so far have required annealing, which limits them to substrates that can withstand high temperatures, ruling out a lot of the flexible plastics that could otherwise be used. Researchers at the National Institute of Materials Science and Okayama University in Japan have now developed a nanoparticle ink that can be used with room-temperature printing procedures.

Developments in thin film transistors made from amorphous silicon have provided wider, thinner displays with higher resolution and lower energy consumption. However further progress in this field is now limited by the low response to applied electric fields, that is, the low field-effect mobility. Oxide semiconductors such as InGaZnO (IGZO) offer better performance characteristics but require complicated fabrication procedures.

Nanoparticle inks should allow simple low-cost manufacture but the nanoparticles usually used are surrounded in non-conductive ligands – molecules that are introduced during synthesis for stabilizing the particles. These ligands must be removed by annealing to make the ink conducting. Takeo Minari, Masayuki Kanehara and colleagues found a way around this difficulty by developing nanoparticles surrounded by planar aromatic molecules that allow charge transfer.

The gold nanoparticles had a resistivity of around 9 x 10-6 Ω cm – similar to pure gold. The researchers used the nanoparticle ink to print organic thin film transistors on a flexible polymer and a paper substrate at room temperature, producing devices with mobilities of 7.9 and 2.5 cm2 V-1 s-1 for polymer and paper respectively – figures comparable to IGZO devices.

As the researchers conclude in their report of the work, “This room temperature printing process is a promising method as a core technology for future semiconductor devices.”

On Monday, Applied Materials announced two new systems, a Reflexion LK Prime CMP system and a Producer XP Precision CVD system, both aimed at complex devices with 3D architectures. The company has introduced six new products over the last three months, with a new VIISta ion implanter introduced in June, and an Endura Ventura PVD system, Endura Volta CVD Cobalt system and Vericell solar wafer inspection system introduced in May.

The transition from planar to 3D devices, such as finFETs and 3D NAND, creates a variety of new challenges for equipment and materials. CMP, for example, now directly determines gate dimensions. “In planar, it was basically about depth of focus, basically providing ability to build metal layers one on top of another,” explained Sid Huey. “Now, with 3D, CMP is at the gate. It’s really at the heart of the transistor and this controls the device performance. What this means is that the performance required now is really an order of magnitude more stringent than what it was in the past.” Huey, director, CMP product manager, CMP Division, Silicon Systems Group, Applied Materials.

In the past, advances in CMP were largely centered around new polishing pads and slurries (which provide the “mechanical” part of chemical-mechanical polishing) and low downforce polishing heads. Today, the focus is on multiple process steps which enables better process control. New device architectures can require additional polishing steps. Logic 3D FinFETs involve up to 10 more planarization steps; 3D NAND require up to 5 more.  The latter are especially long processes, making it harder to maintain a steady removal rate and achieve an ultra-uniform surface. Dividing them into several shorter steps yields superior results. The system controls FinFET gate height with nanometer-level uniformity for every die.

The new Reflexion features 14 processing stations for polishing and cleaning: six polishing stations and eight integrated cleaning stations. Some processes are done with the wafer held vertically. The system includes a pre-cleaning module to reduce defectivity, and real-time process control designed for the influx of new on-wafer materials. The increase in processing modules doubles wafer throughput for many applications, providing up to a 100 percent boost in productivity.

The 3D NAND industry inflection also requires enabling deposition technology for vertical gate formation and complex patterning applications. The Producer XP Precision CVD system supports the 3D NAND transition by delivering essential nanometer-level layer-to-layer film thickness control for excellent CD uniformity across the wafer. Key to this performance is the system’s capability to tune crucial parameters that include temperature, plasma, and gas flow. This engineering flexibility supports the alternate deposition of different high-quality, low-defect films.

The Producer CP Precision CVD system.

The Producer CP Precision CVD system.

Reflexion LK Prime CMP system

Reflexion LK Prime CMP system