Tag Archives: letter-wafer-tech

Genmark Automation, a developer of tool and factory automation solutions for the semiconductor and related industries, today announced the launch of its new CODEX Stocker. The CODEX Stocker integrates stocking, sorting and metrology functions in a single tool that stores and delivers various substrates on demand, of defined quality and in defined numbers. Consolidating the functions of these traditionally nonrevenue-generating tools frees up fab floor space for production equipment, enabling a facility to maximize its productivity and yield.

“There is a clear market opportunity for a high-quality, highly reliable tool that can enable the functions of sort, stocking and metrology simultaneously,” said Carl McMahon, President & EVP of Global Customer Operations at Genmark Automation. “Given the continual pressure to improve yield and productivity, the benefits of storing, measuring and tracking all media in one location, using less cleanroom floor space, quickly becomes evident.”

Key differentiators of the CODEX Stocker include:

  • Reduced overall tool footprint. Novel rotary “carousel” module, which increases the volume of substrates stored compared with existing rack systems, and allows the robot to access the wafers from a single side.
  • First library retrieval system for semiconductor manufacturing. Integrated stocker and metrology systems enable real-time measurement and data tracking. Storing all substrates in a single location allows for more effective tracking of the substrate life cycle.
  • Gantry robot to provide extended range and larger working envelope for wafer delivery.

“Beyond the traditional Si wafer market, the glass wafer for bond/debond, reticle and reticle box storage are important targets for this type of integrated system,” said McMahon. “Taking the glass wafers used in bond/debond as an example, concentricity, uniformity and thickness are very important. By stocking all media in one location with onboard metrology, you can easily make decisions on when the usable lifetime of a wafer is up and when to change it out, to consistently maximize productivity.”

The CODEX’s modular design is easily configurable to customers’ specific needs, whether integrated device manufacturers or original equipment manufacturers. A high-capacity system, it is performance-optimized for high throughput, has a configurable architecture and is readily expandable. For example, using 300mm wafers, each carousel can hold up to 1,700 wafers, depending on thickness. The tool supports 200mm, 300mm and 450mm wafers as well as reticles.

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Imec and Panasonic Corp. announced today that they have fabricated a 40nm TaOx-based RRAM (resistive RAM) technology with precise filament positioning and high thermal stability. This breakthrough result paves the way to realizing 28nm embedded applications. The results were presented at this year’s VLSI technology symposium (Kyoto, June 15-19 2015).

One of today’s most promising concepts for scaled memory is RRAM which is based on the electronic (current-or voltage-induced) switching of a resistor element material between two metals. Imec and Panasonic developed a method that overcomes filament instability in RRAM, one of the critical parameters that impacts the memory state during read operation in resistive memory.

The method was realized using a combination of process technologies such as low-damage etching, cell side oxidation, and an innovative encapsulated cell structure with an Ir/Ta2O5/TaOx/TaN stacked film structurefeaturing a filament at the cell center. With these methods, a 2-Mbit 40nm TaOx-based RRAM cell with precise filament positioning and high thermal stability was achieved. The memory array  showed excellent reliability of 100k cycles and 10 years’ retention at 85°C. Additionally, the filament control and thermal stability technologies offer the potential to realize 28nm cell sizes.

Gosia Jurczak, director of imec’s research program on RRAM devices stated: “With these breakthrough results, we have proven the potential of this promising memory concept as embedded nonvolatile memory in 28nm technology node where conventional NOR Flash shows scaling limitations. This result is a confirmation of our leadership position in research and development on resistive memory.”

Cross-sectional TEM of 40-nm Ir(TE)/Ta2O5/TaOx/TaN (BE) RRAM

Cross-sectional TEM of 40-nm Ir(TE)/Ta2O5/TaOx/TaN (BE) RRAM

Applied Materials, Inc. today unveiled the Applied Olympia ALD system, featuring a unique, modular architecture that delivers high-performance ALD technology to manufacturers of leading-edge 3D memory and logic chips. The 3D device inflection is driving growth in ALD with demand for new patterning films, new conformal materials and lower thermal budgets. The Olympia system is well positioned to fulfill these requirements with uncompromising ALD performance, addressing industry needs with the process flexibility to precisely engineer and efficiently deposit a variety of low-temperature, high-quality films for multiple applications.

“Our Olympia system is a major technology innovation for the 3D device inflection,” said Dr. Mukund Srinivasan, vice president and general manager of Applied’s Dielectric Systems and Modules group. “The Olympia system overcomes fundamental limitations chipmakers are experiencing with conventional ALD technologies, such as reduced chemistry control of single-wafer solutions and long cycle times of furnaces. Because of this, we’re seeing strong market response with Olympia systems installed at multiple customers to support their move to 10nm and beyond.” 

The Olympia system’s adaptable modular architecture enables a uniquely flexible and rapid process sequence vital for controlling the more complex chemistries needed to develop the next generation of ALD films. Further, the modular designcreates complete separation of chemistries, eliminating the pump/purge steps of conventional ALD technologies for improved productivity. The combined advantages of the Olympia system offer a superior solution to conventional ALD systems and position the tool for widespread adoption.  

Applied Materials, Inc. develops solutions for the semiconductor, flat panel display and solar photovoltaic industries. 

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Applied Materials and Tokyo Electron terminate merger

Graphene, the only one atom thick carbon network, achieved overnight fame with the 2010 Nobel Prize. But now comes competition: Such layers can also be formed by black phosphorous. Chemists at the Technische Universität München (TUM) have now developed a semiconducting material in which individual phosphorus atoms are replaced by arsenic. In a collaborative international effort, American colleagues have built the first field-effect transistors from the new material.

For many decades silicon has formed the basis of modern electronics. To date silicon technology could provide ever tinier transistors for smaller and smaller devices. But the size of silicon transistors is reaching its physical limit. Also, consumers would like to have flexible devices, devices that can be incorporated into clothing and the likes. However, silicon is hard and brittle. All this has triggered a race for new materials that might one day replace silicon.

Black arsenic phosphorus might be such a material. Like graphene, which consists of a single layer of carbon atoms, it forms extremely thin layers. The array of possible applications ranges from transistors and sensors to mechanically flexible semiconductor devices. Unlike graphene, whose electronic properties are similar to those of metals, black arsenic phosphorus behaves like a semiconductor.

Phosphorene vs. graphene

A cooperation between the Technical University of Munich and the University of Regensburg on the German side and the University of Southern California (USC) and Yale University in the United States has now, for the first time, produced a field effect transistor made of black arsenic phosphorus. The compounds were synthesized by Marianne Koepf at the laboratory of the research group for Synthesis and Characterization of Innovative Materials at the TUM. The field effect transistors were built and characterized by a group headed by Professor Zhou and Dr. Liu at the Department of Electrical Engineering at USC.

The new technology developed at TUM allows the synthesis of black arsenic phosphorus without high pressure. This requires less energy and is cheaper. The gap between valence and conduction bands can be precisely controlled by adjusting the arsenic concentration. “This allows us to produce materials with previously unattainable electronic and optical properties in an energy window that was hitherto inaccessible,” says Professor Tom Nilges, head of the research group for Synthesis and Characterization of Innovative Materials.

Detectors for infrared

With an arsenic concentration of 83 percent the material exhibits an extremely small band gap of only 0.15 electron volts, making it predestined for sensors which can detect long wavelength infrared radiation. LiDAR (Light Detection and Ranging) sensors operate in this wavelength range, for example. They are used, among other things, as distance sensors in automobiles. Another application is the measurement of dust particles and trace gases in environmental monitoring.

A further interesting aspect of these new, two-dimensional semiconductors is their anisotropic electronic and optical behavior. The material exhibits different characteristics along the x- and y-axes in the same plane. To produce graphene like films the material can be peeled off in ultra thin layers. The thinnest films obtained so far are only two atomic layers thick.

As scientists continue to hunt for a material that will make it possible to pack more transistors on a chip, new research from McGill University and Université de Montréal adds to evidence that black phosphorus could emerge as a strong candidate.

In a study published today in Nature Communications, the researchers report that when electrons move in a phosphorus transistor, they do so only in two dimensions. The finding suggests that black phosphorus could help engineers surmount one of the big challenges for future electronics: designing energy-efficient transistors.

“Transistors work more efficiently when they are thin, with electrons moving in only two dimensions,” says Thomas Szkopek, an associate professor in McGill’s Department of Electrical and Computer Engineering and senior author of the new study. “Nothing gets thinner than a single layer of atoms.”

In 2004, physicists at the University of Manchester in the U.K. first isolated and explored the remarkable properties of graphene — a one-atom-thick layer of carbon. Since then scientists have rushed to to investigate a range of other two-dimensional materials. One of those is black phosphorus, a form of phosphorus that is similar to graphite and can be separated easily into single atomic layers, known as phosphorene.

Phosphorene has sparked growing interest because it overcomes many of the challenges of using graphene in electronics. Unlike graphene, which acts like a metal, black phosphorus is a natural semiconductor: it can be readily switched on and off.

“To lower the operating voltage of transistors, and thereby reduce the heat they generate, we have to get closer and closer to designing the transistor at the atomic level,” Szkopek says. “The toolbox of the future for transistor designers will require a variety of atomic-layered materials: an ideal semiconductor, an ideal metal, and an ideal dielectric. All three components must be optimized for a well designed transistor. Black phosphorus fills the semiconducting-material role.”

The work resulted from a multidisciplinary collaboration among Szkopek’s nanoelectronics research group, the nanoscience lab of McGill Physics Prof. Guillaume Gervais, and the nanostructures research group of Prof. Richard Martel in Université de Montréal’s Department of Chemistry.

To examine how the electrons move in a phosphorus transistor, the researchers observed them under the influence of a magnetic field in experiments performed at the National High Magnetic Field Laboratory in Tallahassee, FL, the largest and highest-powered magnet laboratory in the world. This research “provides important insights into the fundamental physics that dictate the behavior of black phosphorus,” says Tim Murphy, DC Field Facility Director at the Florida facility.

“What’s surprising in these results is that the electrons are able to be pulled into a sheet of charge which is two-dimensional, even though they occupy a volume that is several atomic layers in thickness,” Szkopek says. That finding is significant because it could potentially facilitate manufacturing the material — though at this point “no one knows how to manufacture this material on a large scale.”

“There is a great emerging interest around the world in black phosphorus,” Szkopek says. “We are still a long way from seeing atomic layer transistors in a commercial product, but we have now moved one step closer.”

EV Group (EVG), a supplier of wafer bonding and lithography equipment for the MEMS, nanotechnology and semiconductor markets, today unveiled the HERCULES NIL—a fully integrated track system that combines cleaning, resist coating and baking pre-processing steps with EVG’s SmartNIL large-area nanoimprint lithography (NIL) process in a single platform. Offering industry-leading productivity and throughput, the HERCULES NIL provides a complete, dedicated UV-NIL solution that is ideally suited for high-volume manufacturing (HVM) of emerging photonic devices. It does so by imprinting structures in sizes ranging from tens of nanometers up to several micrometers that alter or improve the optical response of surfaces and devices, such as anti-reflective layers, color and polarizer filters, light guiding plates, patterned sapphire substrates used in manufacturing light emitting diodes (LEDs), and many others. Other rapidly emerging applications for NIL include MEMS, NEMS, biological and nano-electronic applications.

“The HERCULES NIL demonstrates EVG’s ‘Triple i’ philosophy of ‘invent-innovate-implement’ at work,” stated Paul Lindner, executive technology director at EV Group. “EVG has been an early pioneer in the development of NIL equipment. After more than a decade of research and continuous improvements, EVG has now propelled NIL technology to a level of maturity that enables significant advantages for certain applications compared to traditional optical lithography. In addition, the Hercules NIL allows a wider array of applications, particularly in the fields of photonics and biotechnology, to finally leverage the cost-of-ownership and resolution benefits of NIL in volume production.”

The HERCULES NIL combines EVG’s expertise in NIL, resist processing and HVM solutions into a single integrated system that offers unmatched throughput (40 wph for 200-mm wafers). The system is built on a highly configurable and modular platform that accommodates a variety of imprint materials and structure sizes—giving customers greater flexibility in addressing their manufacturing needs. The fully integrated approach also minimizes the risk of particle contamination.

Key product attributes include:

  • Fully automated UV-NIL imprinting and low-force detachment
  • Processing substrates up to 200mm in diameter
  • Full-area imprint coverage, which avoids pattern stitching errors associated with step-and-repeat lithography systems due to limited field size
  • Volume manufacturing of structures down to 40nm and smaller
  • Highest coating uniformity of +/- 1 percent, which results in minimal residual layer thickness and variation for processed structures over the entire wafer
  • Supports a wide range of structure sizes and shapes, including 3-D
  • Can be used on high-topography (rough) surfaces
  • Ability to fabricate multiple-use soft stamps to extend the lifetime of master imprint templates

EVG’s new HERCULES NIL system is available now. Systems have already been installed and are being used for high-volume manufacturing at production sites of leading photonic device manufacturers.

Flexing graphene may be the most basic way to control its electrical properties, according to calculations by theoretical physicists at Rice University and in Russia.

The Rice lab of Boris Yakobson in collaboration with researchers in Moscow found the effect is pronounced and predictable in nanocones and should apply equally to other forms of graphene.

The researchers discovered it may be possible to access what they call an electronic flexoelectric effect in which the electronic properties of a sheet of graphene can be manipulated simply by twisting it a certain way.

The work will be of interest to those considering graphene elements in flexible touchscreens or memories that store bits by controlling electric dipole moments of carbon atoms, the researchers said.

Perfect graphene – an atom-thick sheet of carbon – is a conductor, as its atoms’ electrical charges balance each other out across the plane. But curvature in graphene compresses the electron clouds of the bonds on the concave side and stretches them on the convex side, thus altering their electric dipole moments, the characteristic that controls how polarized atoms interact with external electric fields.

The researchers who published their results this month in the American Chemical Society’s Journal of Physical Chemistry Letters discovered they could calculate the flexoelectric effect of graphene rolled into a cone of any size and length.

The researchers used density functional theory to compute dipole moments for individual atoms in a graphene lattice and then figure out their cumulative effect. They suggested their technique could be used to calculate the effect for graphene in other more complex shapes, like wrinkled sheets or distorted fullerenes, several of which they also analyzed.

“While the dipole moment is zero for flat graphene or cylindrical nanotubes, in between there is a family of cones, actually produced in laboratories, whose dipole moments are significant and scale linearly with cone length,” Yakobson said.

Carbon nanotubes, seamless cylinders of graphene, do not display a total dipole moment, he said. While not zero, the vector-induced moments cancel each other out.

That’s not so with a cone, in which the balance of positive and negative charges differ from one atom to the next, due to slightly different stresses on the bonds as the diameter changes. The researchers noted atoms along the edge also contribute electrically, but analyzing two cones docked edge-to-edge allowed them to cancel out, simplifying the calculations.

Yakobson sees potential uses for the newly found characteristic. “One possibly far-reaching characteristic is in the voltage drop across a curved sheet,” he said. “It can permit one to locally vary the work function and to engineer the band-structure stacking in bilayers or multiple layers by their bending. It may also allow the creation of partitions and cavities with varying electrochemical potential, more ‘acidic’ or ‘basic,’ depending on the curvature in the 3-D carbon architecture.”

Storing solar energy as hydrogen is a promising way for developing comprehensive renewable energy systems. To accomplish this, traditional solar panels can be used to generate an electrical current that splits water molecules into oxygen and hydrogen, the latter being considered a form of solar fuel. However, the cost of producing efficient solar panels makes water-splitting technologies too expensive to commercialize. EPFL scientists have now developed a simple, unconventional method to fabricate high-quality, efficient solar panels for direct solar hydrogen production with low cost. The work is published in Nature Communications.

This is a photograph of a single-flake-layer WSe2 thin film deposited on flexible Sn:In2O3 (ITO)-coated PET plastic. Credit: Kevin Sivula (EPFL)

This is a photograph of a single-flake-layer WSe2 thin film deposited on flexible Sn:In2O3 (ITO)-coated PET plastic. Credit: Kevin Sivula (EPFL)

Many different materials have been considered for use in direct solar-to-hydrogen conversion technologies but “2-D materials” have recently been identified as promising candidates. In general these materials–which famously include graphene–have extraordinary electronic properties. However, harvesting usable amounts of solar energy requires large areas of solar panels, and it is notoriously difficult and expensive to fabricate thin films of 2-D materials at such a scale and maintain good performance.

Kevin Sivula and colleagues at EPFL addressed this problem with an innovative and cheap method that uses the boundary between two non-mixing liquids. The researchers focused on one of the best 2-D materials for solar water splitting, called “tungsten diselenide“. Past studies have shown that this material has a great efficiency for converting solar energy directly into hydrogen fuel while also being highly stable.

Before making a thin film of it, the scientists first had to achieve an even dispersion of the material. To do this, they mixed the tungsten diselenide powder with a liquid solvent using sonic vibrations to “exfoliate” it into thin, 2-D flakes, and then added special chemicals to stabilize the mix. Developed by Sivula’s lab (2014), this technique produces an even dispersion of the flakes that is similar to an ink or a paint.

The researchers then used an out-of-the-box innovation to produce high-quality thin films: they injected the tungsten diselenide ink at the boundary between two liquids that do not mix. Exploiting this oil-and-water effect, they used the interface of the two liquids as a “rolling pin” that forced the 2-D flakes to form an even and high-quality thin film with minimal clumping and restacking. The liquids were then carefully removed and the thin film was transferred to a flexible plastic support, which is much less expensive than a traditional solar panel.

The thin film produced like this was tested and found to be superior in efficiency to films made with the same material but using other comparable methods. At this proof-of-concept stage, the solar-to-hydrogen conversion efficiency was around 1%–already a vast improvement over thin films prepared by other methods, and with considerable potential for higher efficiencies in the future.

More importantly, this liquid-liquid method can be scaled up on a commercial level. “It is suitable for rapid and large-area roll-to-roll processing,” says Kevin Sivula. “Considering the stability of these materials and the comparative ease of our deposition method, this represents an important advance towards economical solar-to-fuel energy conversion.”

Portable electronics users tend to upgrade their devices frequently as new technologies offering more functionality and more convenience become available. A report published by the U.S. Environmental Protection Agency in 2012 showed that about 152 million mobile devices are discarded every year, of which only 10 percent is recycled — a legacy of waste that consumes a tremendous amount of natural resources and produces a lot of trash made from expensive and non-biodegradable materials like highly purified silicon.

Now researchers from the University of Wisconsin-Madison have come up with a new solution to alleviate the environmental burden of discarded electronics. They have demonstrated the feasibility of making microwave biodegradable thin-film transistors from a transparent, flexible biodegradable substrate made from inexpensive wood, called cellulose nanofibrillated fiber (CNF). This work opens the door for green, low-cost, portable electronic devices in future.

In a paper published this week in the Applied Physics Letters from AIP Publishing, the researchers describe the biodegradable device.

“We found that cellulose nanofibrillated fiber based transistors exhibit superior performance as that of conventional silicon-based transistors,” said Zhenqiang Ma, the team leader and a professor of electrical and computer engineering at the UW-Madison. “And the bio-based transistors are so safe that you can put them in the forest, and fungus will quickly degrade them. They become as safe as fertilizer.”

Nowadays, the majority of portable electronics are built on non-renewable, non-biodegradable materials such as silicon wafers, which are highly purified, expensive and rigid substrates, but cellulose nanofibrillated fiber films have the potential to replace silicon wafers as electronic substrates in environmental friendly, low-cost, portable gadgets or devices of the future.

Cellulose nanofibrillated fiber is a sustainable, strong, transparent nanomaterial made from wood. Compared to other polymers like plastics, the wood nanomaterial is biocompatible and has relatively low thermal expansion coefficient, which means the material won’t change shape as the temperature changes. All these superior properties make cellulose nanofibril an outstanding candidate for making portable green electronics.

To create high-performance devices, Ma’s team employed silicon nanomembranes as the active material in the transistor — pieces of ultra-thin films (thinner than a human hair) peeled from the bulk crystal and then transferred and glued onto the cellulose nanofibrill substrate to create a flexible, biodegradable and transparent silicon transistor.

But to make portable electronics, the biodegradable transistor needed to be able to operate at microwave frequencies, which is the working range of most wireless devices. The researchers thus conducted a series of experiments such as measuring the current-voltage characteristics to study the device’s functional performance, which finally showed the biodegradable transistor has superior microwave-frequency operation capabilities comparable to existing semiconductor transistors.

“Biodegradable electronics provide a new solution for environmental problems brought by consumers’ pursuit of quickly upgraded portable devices,” said Ma. “It can be anticipated that future electronic chips and portable devices will be much greener and cheaper than that of today.”

Next, Ma and colleagues plan to develop more complicated circuit system based on the biodegradable transistors.

A new route to ultrahigh density, ultracompact integrated photonic circuitry has been discovered by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley. The team has developed a technique for effectively controlling pulses of light in closely packed nanoscale waveguides, an essential requirement for high-performance optical communications and chip-scale quantum computing.

Xiang Zhang, director of Berkeley Lab’s Materials Sciences Division, led a study in which a mathematical concept called “adiabatic elimination” is applied to optical nanowaveguides, the photonic versions of electronic circuits. Through the combination of coupled systems — a standard technique for controlling the movement of light through a pair of waveguides — and adiabatic elimination, Zhang and his research team are able to eliminate an inherent and vexing “crosstalk” problem for nanowaveguides that are too densely packed.

Integrated electronic circuitry is approaching its limits because of heat dissipation and power consumption issues. Photonics, in which electrical signals moving through copper wires and cables are replaced by pulses of light carrying data over optical fibers, is a highly touted alternative, able to carry greater volumes of data at faster speeds, while giving off much less heat and using far less power. However, the crosstalk problem in coupled optical nanowaveguides has been a major technological roadblock.

“When nanowaveguides in close proximity are coupled, the light in one waveguide impacts the other. This coupling becomes particularly severe when the separation is below the diffraction limit, placing a restriction on how close together the waveguides can be placed,” Zhang says. “We have experimentally demonstrated an adiabatic elimination scheme that effectively cuts off the cross-talk between them, enabling on-demand dynamical control of the coupling between two closely packed waveguides. Our approach offers an attractive route for the control of optical information in integrated nanophotonics, and provides a new way to design densely packed, power-efficient nanoscale photonic components, such as compact modulators, ultrafast optical signal routers and interconnects.”

Zhang, who also holds an appointment with the Kavli Energy NanoSciences Institute (ENSI) at Berkeley, is the corresponding author of a paper describing this research in Nature Communications. The paper is titled “Adiabatic elimination based coupling control in densely packed subwavelength waveguides.” Michael Mrejen, Haim Suchowski and Taiki Hatakeyama are the lead authors. Other authors are Chih-hui Wu, Liang Feng, Kevin O’Brien and Yuan Wang.

“A general approach to achieving active control in coupled waveguide systems is to exploit optical nonlinearities enabled by a strong control pulse,” Zhang says. “However this approach suffers from the nonlinear absorption induced by the intense control pulse as the signal and its control propagate in the same waveguide.”

Zhang and his group turned to the adiabatic elimination concept, which has a proven track record in atomic physics and other research fields. The idea behind adiabatic elimination is to decompose large dynamical systems into smaller ones by using slow versus fast dynamics.

“Picture three buckets side-by-side with the first being filled with water from a tap, the middle being fed from the first bucket though a hole while feeding the third bucket through another hole,” says co-lead author Mrejen. “If the flow rate into the middle bucket is equal to the flow rate out of it, the second bucket will not accumulate water. This, in a basic manner, is adiabatic elimination. The middle bucket allows for some indirect control on the dynamics compared to the case in which water goes directly from the first bucket to the third bucket.”

Zhang and his research group apply this concept to a coupled system of optical nanowaveguides by inserting a third waveguide in the middle of the coupled pair. Only about 200 nanometers separate each of the three waveguides, a proximity that would normally generate too much cross-talk to allow for any control over the coupled system. However, the middle waveguide operates in a “dark” mode, in the sense that it doesn’t seem to participate in the exchange of light between the two outer waveguides since it does not accumulate any light.

“Even though the dark waveguide in the middle doesn’t seem to be involved, it nonetheless influences the dynamics of the coupled system,” says co-lead author Suchowski, who is now with the Tel Aviv University. “By judiciously selecting the relative geometries of the outer and intermediate waveguides, we achieve adiabatic elimination, which in turn enables us to control the movement of light through densely packed nanowaveguides. Until now, this has been almost impossible to do.”

This research was supported by the Office of Naval Research.