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Cadence Design Systems, Inc. (NASDAQ: CDNS) today announced several new capabilities resulting from its close collaboration with TSMC to further 7nm FinFET design innovation for mobile and high-performance computing (HPC) platforms. The Cadence digital, signoff and custom/analog tools have achieved certification for v1.0 Design Rule Manual (DRM) and SPICE certification for the TSMC 7nm process. Cadence has also delivered solutions for a new process design kit (PDK) enabling optimal power, performance and area (PPA) when designing with TSMC’s 7nm process. In addition, the Cadence 7nm Custom Design Reference Flow (CDRF) and the library characterization flow have been enhanced, and its 7nm DDR4 PHY IP is in deployment with customers.

7nm Tool Certification Cadence provides a fully integrated digital flow from implementation to final signoff that has been certified by TSMC for the 7nm process. The digital flow includes the Innovus Implementation System, Quantus QRC Extraction Solution, Tempus Timing Signoff Solution, Voltus IC Power Integrity Solution, Voltus-Fi Custom Power Integrity Solution, Physical Verification System (PVS) and Layout-Dependent Effect (LDE) Electrical Analyzer.

Support for TSMC’s 7nm HPC platform includes via-pillar modeling in the Genus Synthesis Solution and full via-pillar-capable implementation and signoff environments. Additionally, clock-mesh handling and bus-routing capabilities in the tools support the high-performance library to deliver better PPA and mitigated electromigration (EM). These capabilities enable customers to successfully design advanced-node systems while reducing iterations and achieving cost and performance objectives.

The certified custom/analog tools include the Spectre Accelerated Parallel Simulator (APS), Spectre eXtensive Partitioning Simulator (XPS), Spectre Classic Simulator, Virtuoso Layout Suite, Virtuoso Schematic Editor, and Virtuoso Analog Design Environment (ADE). Enhancements made for the 7nm process include advanced device snapping and an accelerated custom placement and routing flow that enables customers to improve productivity and meet power, multiple patterning, density and EM requirements.

7nm CDRF Delivery Cadence delivered an enhanced Custom Design Reference Flow (CDRF) to address 7nm custom and mixed-signal design challenges. The CDRF incorporates advanced methodologies and features that provide productivity improvements through a series of in-depth “how-to” circuit design, layout implementation, and signoff and verification modules. The circuit design module covers “how-to” topics, such as capturing schematics with device arrays using module generator (ModGen) constraints and the TSMC PDK, functional verification, yield estimation and optimization, and the latest reliability analyses. For signoff verification, the physical verification modules highlight design rule and layout-versus-schematic (LVS) checking, signoff parasitic extraction, and electromigration and IR drop (EM/IR) signoff checks.

The layout implementation module includes connectivity and constraint-driven layout for FinFET device placement, enabling designers to avoid design rule violations and address layout-dependent effects (LDEs). The routing module offers a color-aware flow and an innovative track-pattern system that reduces design time, mitigates parasitics and helps designers avoid EM issues.

7nm Library Characterization Tool Flow Delivery In addition to tool certification, the Cadence Virtuoso Liberate Characterization Solution and the Virtuoso Variety Statistical Characterization Solution have been validated to deliver Liberty libraries for the TSMC 7nm process including advanced timing, noise and power models. The solutions utilized innovative methods to characterize the Liberty Variation Format (LVF), enabling process variation signoff and the ability to create EM models enabling signal EM optimizations and signoff.

7nm IP Collaboration As a leader in DDR controller and PHY IP, Cadence has deployed its DDR4 PHY and LPDDR4 PHY in multiple generations of TSMC process technologies, ranging from 28HPM/28HPC/28HPC+ to 16FF+/16FFC nodes. Through close collaborations with TSMC and customers, Cadence began developing IP on the 7nm process last year. Cadence has taped out its flagship DDR4 PHY using the 7nm process node in Q4 2016, and key customers have integrated the 7nm DDR PHYs into their enterprise-class SoCs.

“TSMC’s latest process advancements combined with enhancements to Cadence tools and IP offer our mutual customers optimal solutions for advanced-node designs,” said Dr. Anirudh Devgan, executive vice president and general manager of the Digital & Signoff Group and the System & Verification Group at Cadence. “This certification and the v1.0 process maturity milestone represent our readiness to meet the production needs of our most innovative customers using the 7nm process.”

“The availability of new v1.0 design rules and PDK indicates that we’ve reached a new pinnacle with 7nm production designs,” said Suk Lee, TSMC senior director, Design Infrastructure Marketing Division. “We’ve collaborated closely with Cadence to certify its tools and deliver IP innovations for 7nm designs, which enable our customers to achieve their PPA objectives with mobile and HPC designs.”

“ARM has collaborated closely with Cadence and TSMC to enable a 7nm design flow for our joint customers,” said Monika Biddulph, general manager of the Systems and Software Group, ARM. “This flow is enabling the development of platforms for high-end mobile and high-performance computing applications.”

Cadence Design Systems, Inc. (NASDAQ:  CDNS) today announced new optimization capabilities within its holistic, integrated design flow for TSMC’s advanced wafer-level Integrated Fan-Out (InFO) packaging technology. The integrated flow provides design and analysis capabilities and modeling of cross-die interactions for mobile and IoT applications.

The Cadence tools in the enhanced flow include the OrbitIO interconnect designer, System-in-Package (SiP) Layout, Quantus QRC Extraction Solution, Sigrity XtractIM technology, Tempus Timing Signoff Solution, Physical Verification System (PVS), Voltus-Sigrity Package Analysis, Sigrity PowerDC technology and Sigrity PowerSI 3D-EM Extraction Option. With the new flow, system-on-chip (SoC) designers can:

  • Quickly generate netlists among the multiple dies and InFO package in the context of the full system within a single-canvas multi-fabric environment: The OrbitIO interconnect designer efficiently handles multi-die integrations with TSMC InFO technologies to generate top-level netlists that can be directly used for subsequent design steps such as detailed electrical and timing analysis.
  • Generate Standard Parasitic Exchange Format (SPEF) directly from the package design database, which greatly eases timing signoff: Rather than using a traditional methodology that requires converting the package design database of an InFO design to an IC design database to generate SPEF, Sigrity XtractIM technology automatically generates SPEF for heterogeneous InFO systems, which accelerates the timing signoff process and speeds time to market.

“We’ve continued to see strong demand from mobile and IoT customers who want to deploy systems based on TSMC’s InFO technology,” said Steve Durrill, senior product engineering group director at Cadence. “By working closely with TSMC, we are enabling our mutual customers to shorten design and verification cycle times so they can deliver reliable, innovative SoCs to market faster.”

“The Cadence flow developed specifically for our InFO technology is an enabler for customers who need to increase bandwidth within small form factors,” said Suk Lee, TSMC senior director, Design Infrastructure Marketing Division. “The integrated full-flow includes a comprehensive set of Cadence digital, signoff and custom IC technologies that address this market need, and our collaboration is helping customers to efficiently achieve their design goals.”

Quantum dots are very small particles that exhibit luminescence and electronic properties different from those of their bulk materials. As a result, they are attractive for use in solar cells, optoelectronics, and quantum computing. Quantum computing involves applying a small voltage to quantum dots to regulate their electron spin state, thus encoding information. While traditional computing is based on a binary information system, electron spin states in quantum dots can display further degrees of freedom because of the possibility of superposition of both states at the same time. This feature could increase the density of encoded information.

Readout of the electron spin of quantum dots is necessary to realize quantum computing. Single-shot spin readout has been used to detect spin-dependent single-electron tunneling events in real time. The performance of quantum computing could be improved considerably by single-shot readout of multiple spin states.

A Japanese research collaboration based at Osaka University has now achieved the first successful detection of multiple spin states through single-shot readout of three two-electron spin states of a single quantum dot. They reported their findings in Physical Review Letters.

To read out multiple spin states simultaneously, the researchers used a quantum point contact charge sensor positioned near a gallium arsenide quantum dot. The change in current of the charge sensor depended on the spin state of the quantum dot and was used to distinguish between singlet and two types of triplet spin states.

“We obtained single-shot ternary readout of two-electron spin states using edge-state spin filtering and the orbital effect,” study first author Haruki Kiyama says.

That is, the rate of tunneling between the quantum dot and electron reservoir depended on both the spin state of the electrons and the interaction between electron spin and the orbitals of the quantum dot. The team identified one ground state and two excited states in the quantum dot using their setup.

The researchers then used their ternary readout setup to investigate the spin relaxation behavior of the three detected spin states.

“To confirm the validity of our readout system, we measured the spin relaxation of two of the states,” Kiyama explains. “Measurement of the dynamics between the spin states in a quantum dot is an important application of the ternary spin readout setup.”

The spin relaxation times for the quantum dot measured using the ternary readout system agreed with those reported, providing evidence that the system yielded reliable measurements.

This ternary readout system can be extended to quantum dots composed of other materials, revealing a new approach to examine the spin dynamics of quantum dots and representing an advance in quantum information processing.

Metamaterials don’t exist in nature, but their ability to make ultra-thin lenses and ultra-efficient cell phone antennas, bend light to keep satellites cooler and let photovoltaics absorb more energy mean they offer a world of possibilities.

Formed by nanostructures that act as “atoms,” arranged on a substrate to alter light’s path in ways no ordinary material can achieve, these surrogate substances can manipulate an incoming light beam to enable the creation of more efficient versions of ubiquitous, valuable devices — optical filters, lasers, frequency converters and devices that steer beams, for example.

But extensive commercial use of metamaterials has been restrained by the limitations imposed by the materials comprising them. Metal-based metamaterials are “lossy” (lose energy) at shorter wavelengths and can operate effectively only at low frequencies, such as the radio frequencies used by radar, before being overwhelmed by their own absorption. Silicon doesn’t emit light and can transmit it only in a limited wavelength range because of its narrow working range (bandgap). So neither class of material can create a metamaterial that will operate in the infrared and optical ranges, where most military and commercial applications would take place.

This three-resonator-thick III-V metasurface of cylindrical resonators illustrates three possible uses: The left light beam changes color as it passes through the metasurfaces, signifying that nonlinear harmonic generation is taking place that converts the light beam to a shorter wavelength. The blue trace in the middle shows a train of pulses passing through the surface. As they pass, the pulse width decreases due to pulse compression, which requires that the phase of the transmitted optical wave vary with the wavelength. The multilayer metasurfaces are able to achieve the correct phase variation -- something not possible with single layer metasurfaces. The beam on the right signifies that these metasurfaces can act as efficient emitters of light. Click on the thumbnail for a high-resolution image. Credit: (Illustration courtesy of Sandia National Laboratories)

This three-resonator-thick III-V metasurface of cylindrical resonators illustrates three possible uses: The left light beam changes color as it passes through the metasurfaces, signifying that nonlinear harmonic generation is taking place that converts the light beam to a shorter wavelength. The blue trace in the middle shows a train of pulses passing through the surface. As they pass, the pulse width decreases due to pulse compression, which requires that the phase of the transmitted optical wave vary with the wavelength. The multilayer metasurfaces are able to achieve the correct phase variation — something not possible with single layer metasurfaces. The beam on the right signifies that these metasurfaces can act as efficient emitters of light. Click on the thumbnail for a high-resolution image. Credit: (Illustration courtesy of Sandia National Laboratories)

Optical metamaterials enter the arena

Sandia National Laboratories researchers are helping lead the way to the use of III-V semiconductors as the building blocks of metamaterials. (III-V refers to elements in those columns in the periodic table.) Sandia researchers have published technical papers, including three in the past year, on work featuring materials like gallium-arsenide and aluminum-arsenide, which are more efficient than metals for optical metamaterial applications, with wider bandgap ranges than silicon. The work is promising enough to have been featured on the covers of two technical journals.

“There is very little work worldwide on all-dielectric metamaterials using III-V semiconductors,” said Sandia researcher Igal Brener, who leads the Sandia work with researchers Mike Sinclair and Sheng Liu. “Our advantage is Sandia’s vast access to III-V technology, both in growth and processing, so we can move pretty fast.”

Shinier than gold

The new Sandia dielectric materials — a kind of electrical insulator — offer more than just efficiency. They lose little incoming energy and can even be fabricated in multiple layers to form complex, three-dimensional meta-atoms that reflect more light than shiny gold surfaces, usually considered the ultimate in infrared reflectivity. The III-V materials also emit photons when excited — something that silicon, which can reflect, transmit and absorb — can’t do.

Another advantage is their highly variable outputs, across the color spectrum so they might be used to extend the wavelength range of lasers or for generating “entangled photons” for quantum computing.

Sandia’s approach also is attractive for its relatively simple method of forming the artificial atoms, known as resonators, that are the guts of the metamaterial.

Created under the supervision of Liu, the meta-atoms are a few hundred nanometers in diameter and made of many actual atoms. One of Liu’s improvements was to oxidize these tiny groupings around their perimeters to create layered coatings with a low index of refraction, rather than use a more expensive, time-consuming “flip-chip” bonding process. The complexity of previous methods was an obstacle to cost- and time-efficiency. Other Sandia researchers had used a variant of his simplification previously to make lasers, but not metamaterials, he said.

The oxidized, low-index surface surrounds the high-index core “like in wintertime, you have a coat surrounding you,” Liu said. “To confine light, you need a high refractive-index contrast.” Put another way, interior light bumping into the low-indexed oxide surface is herded back by the refractive difference so it travels along the high-index core.

Liu’s Sandia colleague Gordon Keeler achieved controlled oxidation simply by putting III-V materials in a hot oven and flowing water vapor over the sample. “It will oxidize at a certain rate,” Liu says. “The more material, the longer it takes.”

The man-made meta-atoms are sculpted in place during a lithographic process that permits researchers to make any pattern they chose for the placement of the metamaterial components. “We use simulations to direct us,” Liu said. Spacing is determined to some extent by the size of the manmade atoms.

Fractured cubic nanostructures store unusually large amounts of energy

The researchers experimented with cylindrical and cubic nanostructures, reducing the symmetry of the latter to achieve even better properties.

“Cylinders are much easier to fabricate and typically can be used for conventional metasurfaces,” said Brener. “But broken-symmetry cubes are crucial to obtain very sharp resonances. That’s the key issue of the paper.”

The idea of intentionally reducing the symmetry of a cubic resonator nanostructure originated five or six years ago, said Sinclair, with a serendipitous design that happened to break the intentionally symmetrical shape of the meta-atoms when the team tried to mimic a particular manufacturing flaw.

“During a Laboratory Directed Research and Development [LDRD] Metamaterials Grand Challenge, when we were first fabricating cubic resonators in our effort to see if we could get beyond microwaves into infrared and optical metamaterials, we were playing with the shape of resonators to try to simulate the effect of lithography errors. In one simulation, we happened to cut a corner of the cube and all of a sudden very sharp reflection bands appeared,” Sinclair said.

Prior to that discovery, dielectric resonator metamaterials only showed broad bands that didn’t trap much energy. The researchers found the new sharp resonances allowed greater energy storage — beneficial for efficient frequency conversion, and perhaps even for light emission and lasing.

Exploration of the crimped resonator had to wait for a later project, sponsored by the Department of Energy’s Office of Science. Salvatore Campione, building on previous work by Lorena Basilio, Larry Warne and William Langston — all of Sandia — used electromagnetic simulations to unravel precisely how the cubes trap light. Sandia’s Willie Luk measured the cubes’ reflective properties. Another LDRD grant currently supports research into metamaterial lasing.

“We feel we’ve created a pretty flexible platform for a lot of different kinds of devices,” Sinclair said.

The ongoing work is aided by Sandia’s John Reno, nationally known for growing extremely precise crystalline structures, who contributed the III-V wafers.

Three patents on aspects of the work have been submitted.

The field of metamaterials, an intersection of materials science, physics, nanotechnology and electrical engineering, aims to produce structures with unusual electromagnetic properties. Through the careful combination of multiple materials in a precise periodic arrangement, the resulting metamaterials exhibit properties that otherwise couldn’t exist, such as a negative index of refraction. Some metamaterials can even channel electromagnetic waves around their surfaces, rendering them invisible for certain wavelengths of light.

The precision needed for arranging a metamaterial’s constitutive parts, also known as inclusions, has been a challenging step in their development and application.

Now, University of Pennsylvania engineers have shown a way to make metamaterials with a single inclusion, providing easier fabrication, among other useful features.

Physical experiments showed that the location of the dielectric rod and the shape of the ENZ material did not effect the properties of the resulting metamaterial. Credit: University of Pennsylvania

Physical experiments showed that the location of the dielectric rod and the shape of the ENZ material did not effect the properties of the resulting metamaterial. Credit: University of Pennsylvania

Analogous to electronic “doping,” where adding a small amount of atomic impurities to a “pure” material gives it electronic properties necessary for many computational and sensing devices, this “photonic doping” would allow for new ways of sculpting and tailoring light-matter interactions, with future impact on optical technology, such as flexible photonics.

The study, published in the journal Science, was led by Nader Engheta, H. Nedwill Ramsey Professor of Electrical and Systems Engineering, together with members of his group, Iñigo Liberal, Ahmed M. Mahmoud, Yue Li and Brian Edwards.

“Just as in electronic doping, when adding a set of foreign atoms in an otherwise pure material can significantly alter the electronic and optical properties of the host,” Engheta said, “‘photonic doping’ means adding a foreign photonic object in a specialized photonic host structure can change the optical scattering of the original structure in a major way.”

The phenomenon works with a specific class of materials that have permittivity, a parameter that has to do with the electric response of the material, mathematically represented by the Greek letter epsilon, that is nearly zero.

The key quality of these epsilon-near-zero, or ENZ, materials is that the wave’s magnetic field is distributed uniformly throughout the two-dimensional ENZ hosts, regardless of their cross-sectional shape. Such ENZ materials occur either naturally or can be made by traditional metamaterial means.

Rather than engineer complicated periodic structures that significantly alter the optical and magnetic properties of such materials, Engheta and his group devised a way for a single inclusion in a 2-D ENZ structure to accomplish the same task: changing which wavelengths of light that will reflect or pass through, or altering the magnetic response of the structure

“If I want to change the way a piece of material interacts with light, I normally have to change all of it,” Engheta said, “Not here. If I place a single dielectric rod anywhere within this ENZ material, the entire structure will look different from the perspective of an external wave.”

The dielectric rod is a cylindrical structure made out of an insulating material that can be polarized. When inserted in a 2-D ENZ host, it can affect the magnetic field within this host and consequently can notably change the optical properties of the host ENZ material.

Because the wave’s magnetic field in the 2-D ENZ host has a uniform spatial distribution, the dielectric rod can be placed anywhere within the material. Incoming waves thus behave as if the host material has a significantly different set of optical properties. Since the rod does not need to be placed at a precise location, construction of such photonically doped structures may be achieved with relative ease.

Applying these metamaterial concepts via “photonic doping” has implications for information processing systems and applications within telecommunications.

“When we’re working with a wave, this photonic doping can be a new way for us to determine the path this wave takes from A to B within a device,” Engheta said. “With a relatively small change in the dielectric rod, we can make waves ‘go this way’ and ‘don’t go that way.’ That we only need to make a change to the rod, which is a tiny part of the host material, should help with the speed of the device, and, because the effect is the same for the ENZ host with arbitrary shape while keeping its cross-sectional area fixed, this property may be very useful for flexible photonics.”

Further research demonstrates more complicated ways of applying photonic doping to ENZ materials, such as adding multiple rods with different diameters.

“The dielectric property of the rod can be responsive to thermal, optical or electrical changes,” Engheta said. “That means we could use the host ENZ material as the read-out of a sensor, as it would transmit or reflect light due to changes in that rod. Adding more rods would allow for even finer tuning of the material’s response.”

NXP Semiconductors N.V. (NASDAQ:NXPI) today announced the world’s smallest single-chip SoC solution – the MC9S08SUx microcontroller (MCU) family – with an integrated 18V-to-5V LDO and MOSFET pre-driver that delivers ultra-high-voltage solution for drones, robots, power tools, DC fan, healthcare and other low-end brushless DC electric motor control (BLDC) applications. Extending the company’s S08 family of MCUs, the robust 8-bit MC9S08SUx microcontroller family offers 4.5V~18V supply voltage range with lower bill of materials (BOM) cost and tighter integration for higher performance and reliability. The new SoC units address the growing demand to replace multiple device solutions with a single MCU to reduce cost and system size, while simplifying integration and layout for space-constrained use cases.

“The market trend is pointing towards integrated solutions that save system size and cost, and NXP is leading the industry as the only provider to offer a single-chip offering with integrated microcontroller and MOSFET pre-driver in a 4x4x0.65mm form factor, which also makes it possible to cut the printed circuit board size in half,” said Geoff Lees, senior vice president and general manager of the microcontroller business line at NXP. “Historically, several devices were needed to address the needs of BLDC motor control applications, which can be expensive and large in size; our latest addition to the S08 MCU family underscores our dedication to solving unique challenges by introducing new microcontrollers for the broad market.”

Based on the HCS08 core, the MC9S08SUx leverages the enhanced S08L central processor unit with three-phase MOSFET pre-drivers to deliver all-in-one unit for 4.5V-18V motor control applications. The single-chip MC9S08SUx MCU removes the need for Low Drop Out (LDO) voltage regulator(s), operational amplifiers, and pre-drivers for a streamlined, cost-effective solution. Additionally, NXP has integrated virtually all of the necessary features in BLDC motor control, including zero crossing point detection, pulse width measurement, over voltage protection and over current protection, enabling developers to simply configure registers and easily use the functions in applications. The MC9S08SUx family also includes amplifiers for current measurement and supports three high-side PMOSes as well as three low-side NMOSes.

NXP’s S08 microcontrollers, including the new MC9S08SUx family, are supported by CodeWarrior IDE. FreeMASTER support is offered as run-time debugging tool. In addition, IAR Embedded Workbench supports the NXP S08 MCU portfolio, offering a single toolbox complete with configuration files, code examples and project templates. IAR Embedded Workbench support for the MC9S08SUx MCU family will be available March 2017.

“The leading optimization technology in IAR Embedded Workbench helps developers to maximize performance and minimize power consumption for applications based on the new MC9S08SUx MCU family from NXP,” said Jan Nyrén, Product Manager, IAR Systems.

Imec and Holst Centre (initiated by imec and TNO) have developed a novel phase-tracking receiver bringing further power and cost reduction for the next generations of Bluetooth and IEEE802.15.4 radio chips. The ultra-low power digital-style receiver is 3x smaller than the current state-of-the-art. It supports supply voltages as low as 0.85V and consumes less than 1.6mW peak. An innovative low power antenna impedance detection technique enhances radio performance, especially for wearables or implantable applications.

The ongoing evolution towards an intuitive IoT has created unprecedented opportunities in various application domains. However, the deployment of massive numbers of interconnected sensors requires ultra-low power solutions enabling multi-year battery life. To increase the autonomy of sensors, imec develops ultra-low power wireless technology for IoT applications, such as next-generation Bluetooth Low Energy and IEEE 802.15.4.

Imec’s novel receiver concept features sub-1nJ/bit energy efficiency and low supply voltage operation at 0.85V while maintaining similar RX sensitivity as best-in-class products. The receiver employs digital phase-tracking to directly translate the RF input to demodulated digital data. A digitally-controlled oscillator (DCO) is used instead of a power hungry phase locked loop (PLL). The receiver, implemented in 40nm CMOS, is only 0.3mm2, which is at least 3x smaller compared to the state-of-the-art. Due to this small size it can be manufactured at strongly reduced cost.

Especially in wearable or implantable devices, the antenna impedance can dynamically change due to variations in a device’s position or surroundings. This can deteriorate the radio’s performance and degrade battery lifetime. Imec demonstrated a fully integrated, sub-mW impedance detection technique for ultra-low power radios, enabling tunable matching between the antenna and the radio front-end. This technique can be implemented in an adaptive radio front-end to further improve receiver sensitivity and transmitter efficiency in the presence of antenna impedance variations.

“This innovative receiver concept will not only serve the new Bluetooth 5 devices, but provides our industrial partners a long term competitive advantage for multiple new generations of Bluetooth and 802.15.4 radios, still to come,” says Kathleen Philips, Program Director Perceptive Systems at imec/Holst Centre. “This great achievement is a confirmation of our continuous efforts to push the technology limits toward ever higher performance, lower power consumption and smaller form factor, which are essential features for internet-of-things radio solutions.”

imec and holst

Russian physicists, with their colleagues from Europe through changing the light parameters, learned to generate quasiparticles – excitons, which were fully controllable and also helped to record information at room temperature. These particles act as a transitional form between photons and electrons so the researchers believe that with excitons, they will be able to create compact optoelectronic devices for rapid recording and processing an optical signal. The proposed method is based on use of a special class of materials called metal-organic frameworks. The study appeared in Advanced Materials.

The way of how the light with different wavelengths influences on a MOF crystal: different types of excitons are showed in red and blue (left). Image of crystals (right). Credit: ITMO University

The way of how the light with different wavelengths influences on a MOF crystal: different types of excitons are showed in red and blue (left). Image of crystals (right). Credit: ITMO University

To simplify the description of complex effects in quantum mechanics, scientists have introduced a concept of quasiparticles. One of them which is called exciton is an “electron – hole” pair, which provides energy transfer between photons and electrons. According to the scientific community, this mediation of quasiparticles will help to combine optics with electronics to create a fundamentally new class of equipment – more compact and energy efficient. However, all exciton demo devices either operate only at low temperature, or are difficult to manufacture which inhibits their mass adoption.

In the new study, the scientists from ITMO University in Saint Petersburg, Leipzig University in Germany and Eindhoven University of Technology in the Netherlands could generate excitons at room temperature by changing the light parameters. The authors also managed to control the quasiparticles with ultra-high sensitivity of about hundreds of femtoseconds (10-13 s). Finally, they developed an easy method for data recording with excitons. This all became possible through the use of an individual class of materials called metal-organic frameworks.

Metal-organic frameworks (MOF) synthesized at ITMO University, have a layered structure. Between the layers, there is a physical attraction called van der Waals force. To prevent the plates from uncontrollably coming together, the interlayer space is filled with an organic liquid, which fixes the framework to be three-dimensional.

In such crystals, the researchers learned to bring two types of excitons individually: intralayer and interlayer. The first arise when a photon absorbed by the crystal turns into an electron-hole pair inside a layer, but the second appear when an electron and a hole belong to neighboring layers. In some time, both kinds of quasiparticles disintegrate, re-radiating the energy as a photon. But excitons can move around the crystal while they exist.

The life time of intralayer excitons is relatively short, but their high density and agility allow one to use these quasiparticles to generate light in LEDs and lasers, for instance. Interlayer excitons are more stable, but slow-moving, so the researchers propose them to be used for the data recording. Both types of excitons fit processing of an optical signal, according to the physicists.

The innovative approach for information recording concerns the changing a distance between crystal layers to switch “on” and “off” the interlayer excitons. Valentin Milichko, the first author of the paper, associate professor of Department of Nanophotonics and Metamaterials at ITMO University, comments: “We locally heated the crystal with a laser. In the place of exposure, the layers stuck together and the luminescence of excitons disappeared while the rest of the crystal continued shining. This could mean that we recorded 1 bit of information, and the record, in the form of a dark spot, was kept for many days. To delete the data, it was enough to put the MOF into the same organic liquid that supports layers. In this case, the crystal itself is not affected, but the recorded information (the dark spot) disappears.”

The authors believe that in the future the new material will help to bring processing of an optical signal to the usual pattern of zeros and ones: “In fact, we can influence the exciton behavior in the crystal, changing the light intensity. At weak irradiation, excitons are accumulated (in ‘1’ state), but if the laser power increases, the concentration of quasiparticles grows so much that they can instantly disintegrate (in ‘0’ state),” says Valentin Milichko.

Typically, excitons occur in dielectric and semiconductor crystals, but the scientists could create these quasiparticles and get control over them in a completely different class of materials, which never was used for this. The MOF crystal combines organic components with inorganic that gives it additional properties not available for materials of a single nature. Thus, the organic term allows one to generate excitons at room temperature, but inorganic provides their efficient transfer around the crystal.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Similar to carbon, silicon forms two dimensional networks that are only one atomic layer thick. Like graphene, for whose discovery Andre Geim and Konstantin Novoselov received the Nobel Prize in 2010, these layers possess extraordinary optoelectrical properties. Silicon nanosheets might thus find application in nanoelectronics, for example in flexible displays, field-effect transistors and photodetectors. With its ability to store lithium ions, it is also under consideration as an anode material in rechargeable lithium batteries.

“Silicon nanosheets are particularly interesting because today’s information technology builds on silicon and, unlike with graphene, the basic material does not need to be exchanged,” explains Tobias Helbich from the WACKER Chair for Macromolecular Chemistry at TUM. “However, the nanosheets themselves are very delicate and quickly disintegrate when exposed to UV light, which has significantly limited their application thus far.”

Polymer and nanosheets – the best of both worlds in one

Now Helbich, in collaboration with Professor Bernhard Rieger, Chair of Macromolecular Chemistry, has for the first time successfully embedded the silicon nanosheets into a polymer, protecting them from decay. At the same time, the nanosheets are protected against oxidation. This is the first nanocomposite based on silicon nanosheets.

“What makes our nanocomposite special is that it combines the positive properties of both of its components,” explains Tobias Helbich. “The polymer matrix absorbs light in the UV domain, stabilizes the nanosheets and gives the material the properties of the polymer, while at the same time maintaining the remarkable optoelectronic properties of the nanosheets.”

Long-term goal of nanoelectronics – In leaps and bounds to industrial application

Its flexibility and durability against external influences also makes the newly developed material amenable to standard polymer technology for industrial processing. This puts actual applications within an arm’s reach.

The composites are particularly well suited for application in the up and coming field of nanoelectronics. Here, “classical” electronic components like circuits and transistors are implemented on scales of less than 100 nanometers. This allows whole new technologies to be realized – for faster computer processors, for example.

Nanoelectronic photodetector

The first successful application of the nanocomposite constructed by Helbich was only recently presented in the context of the ATUMS Graduate Program (Alberta / TUM International Graduate School for Functional Hybrid Materials): Alina Lyuleeva and Prof. Paolo Lugli from the Institute of Nanoelectronics at TU Munich, in collaboration with Helbich and Rieger, succeeded in building a photodetector based on these silicon nanosheets.

To this end, they mounted the polymer embedded silicon nanosheets onto a silicon dioxide surface coated with gold contacts. Because of its Lilliputian dimensions, this kind of nanoelectronic detector saves a lot of both space and energy.

The research is part of the ATUMS Graduate Program (Alberta / TUM International Graduate School for Functional Hybrid Materials (ATUMS; IRTG 2022)) in which German and Canadian scientists in the fields of chemistry, electrical engineering and physics collaborate closely. Their goal is not only to create novel functions based on nanoparticles and polymer materials, but, at the same time, to develop first applications. The work is funded by the German Research Council (DFG) and the Natural Science and Engineering Research Council of Canada (NSERC).

EV Group (EVG), a supplier of wafer bonding and lithography equipment for the MEMS, nanotechnology and semiconductor markets, today unveiled the IQ Aligner NT–its latest and most advanced automated mask alignment system for high-volume advanced packaging applications. Featuring high-intensity and high-uniformity exposure optics, new wafer handling hardware, full 200-mm and 300-mm wafer coverage that enables global multi-point alignment, and optimized tool software, the new IQ Aligner NT provides a 2X increase in throughput and 2X improvement in alignment accuracy over EVG’s previous-generation IQ Aligner. The system surpasses the most demanding requirements for wafer bump and other back-end lithography applications while providing up to 30 percent lower cost of ownership compared to competing systems.

The IQ Aligner NT from EV Group is the industry's most advanced automated mask alignment system for advanced packaging applications. It provides a 2X increase in throughput and 2X improvement in alignment accuracy over the previous-generation system, as well as up to 30 percent lower cost of ownership compared to competing systems.

The IQ Aligner NT from EV Group is the industry’s most advanced automated mask alignment system for advanced packaging applications. It provides a 2X increase in throughput and 2X improvement in alignment accuracy over the previous-generation system, as well as up to 30 percent lower cost of ownership compared to competing systems.

The IQ Aligner NT is ideally suited for a variety of advanced packaging types, including Wafer-level Chip Scale Packaging (WLCSP), Fan-out Wafer Level Packaging (FOWLP), 3D-IC/Through-silicon Via (TSV), 2.5D Interposers, and Flip Chip.

New lithography capabilities needed

Semiconductor advanced packaging is continually evolving to enable new types of devices with increasing functionality at a lower cost per function. As a result, new developments in lithography are now required to address the unique needs of the advanced packaging market. These needs include:
Extremely tight alignment accuracy
Managing wafer warpage and addressing dimensional mismatch of wafer and mask layout to achieve optimized overlay

Sufficient exposure of the thicker resists and dielectric layers found in back-end processing
Higher resolution to address shrinking bumps and interconnects due to device scaling
At the same time, all of these needs must be met in a highly cost-effective and high-productivity lithography tool platform.

“Leveraging more than three decades of experience in lithography, EVG has pushed the envelope of mask alignment technology to new boundaries with our new IQ Aligner NT,” stated Paul Lindner, executive technology director at EV Group. “This latest addition to our suite of lithography solutions provides unprecedented levels of throughput, accuracy and cost-of-ownership performance, which in turn has opened up a variety of new market opportunities for EVG. We look forward to working closely with customers to meet their critical advanced packaging lithography needs.”

The IQ Aligner NT incorporates a variety of improvements to achieve industry-leading mask alignment performance for advanced packaging lithography:

High-power optics provides a 3X increase in illumination intensity compared to EVG’s previous-generation IQ Aligner, making it ideal for exposing thick resists and other films associated with processing bumps, pillars and other high-topography features:

  • Full clearfield mask movement over 300-mm substrates, which offers the highest process compatibility and flexibility in dark field mask alignment and pattern positioning
  • Dual substrate size concept eliminates the need for any retooling effort, providing a quick and easy on-the-fly bridge tool for two different wafer sizes
  • Fully automated as well as semi-automated/manual wafer loading operation is supported for maximum flexibility
  • Latest EVG CIMFramework system software based on the latest fab software standards and protocols
  • Unsurpassed accuracy and productivity performance

Combining optical and mechanical engineering with optimized tool software, the IQ Aligner NT provides a two-fold increase in throughput (>200 wph for first print, >160 wph for top side alignment) as well as a two-fold improvement in alignment accuracy (250nm 3-sigma). As a result of the tighter alignment specification, customers can also realize improved yields for high-end and high-bandwidth packaging products.