Category Archives: Displays

By Christian G. Dieseldorff, Industry Research & Statistics Group at SEMI (September 6, 2016)

SEMI’s Industry Research and Statistics group has published its August update of the World Fab Forecast report. The report has served the industry for 24 years, observing and analyzing spending, capacity, and technology changes for all front-end facilities worldwide, from high-volume to R&D fabs.  SEMI’s latest data show increasing equipment spending, reaching 4.1 percent YOY in 2016 and 10.6 percent in 2017. Figure 1 (below) shows a forecast of  -2 percent decline from 2H2015 to 1H2016 and an 18 percent increase from 1H2016 to. 2H2016.

Figure 1: Fab Equipment Spending by Quarter

Figure 1: Fab Equipment Spending by Quarter

The largest growth drivers for the industry are mobile devices (including devices using SSDs), automotive, and soon anticipated to be IoT, with these applications, in many cases, requiring 3D NAND and Logic 10nm/7nm.

The SEMI report indicates that the two industry segments leading to the biggest increase in 2H16 are Foundry (29 percent) and Memory (21 percent).  Growth in Memory is driven by a significant increase in 3D NAND spending in 2016. Comparing 2016 to 2017, Foundry growth remains quite steady, with a 14 percent increase in 2016 and 13 percent in 2017.

Companies like Samsung, Micron, Flash Alliance, Intel, and SK Hynix drive Memory growth with 3D NAND to an astounding 152 percent increase in 2016 and 29 percent in 2017. However, utilization of all this equipment is still low in 2016 but is expected to increase in 2017.

Looking at other product segments, DRAM equipment spending is expected to decline by 31 percent in 2016 and then recover slightly with 2 percent growth in 2017. Power devices also show strong growth with 25 percent in 2016 and 16 percent in 2017. The Analog segment will slump by -15 percent in 2016 but increase by 20 percent in 2017. Similarly, MPU will drop -20 percent in 2016 and then is expected to increase by 48 percent in 2017.

Comparing spending by region in 2016, SE Asia shows the largest growth, with 157 percent in 2016, driven mainly by 3D NAND (see Figure 2).

China, in third place for overall spending, shows 64 percent growth for 2016 primarily due to 3D NAND by non-Chinese companies, closely followed by Foundry companies. Although the largest spenders in China currently are overseas device companies, China-based chipmakers are starting to pick up investment activity.

Figure 2: Fab Equipment Spending by Region

Figure 2: Fab Equipment Spending by Region

By contrast, the largest growth rate in 2017 is in Europe/Mideast with about 60 percent which is mainly due to ramping of 10nm facilities. Korea is in second place for total spending, mainly driven by Samsung’s investment in DRAM and Flash. Japan in third place driven by Flash Alliance (3D NAND).

The World Fab Forecast report provides more detailed information by company and fab for construction spending, equipment spending and capacities by region and product type.  Since the last publication in May 2016, the SEMI research team has made over 330 changes to 300 facilities/lines. This includes 27 new records and 18 records closed.

For information about semiconductor manufacturing for the remainder of 2016 and in 2017, and for details about capex for construction projects, fab equipping, technology levels, and products, order the SEMI World Fab Forecast Report. The report, in Excel format, tracks spending and capacities for over 1,100 facilities including over 82 future facilities, across industry segments from Analog, Power, Logic, MPU, Memory, and Foundry to MEMS and LEDs facilities.  Using a bottoms-up approach methodology, the SEMI Fab Forecast provides high-level summaries and graphs, and in-depth analyses of capital expenditures, capacities, technology and products by fab.

The SEMI Worldwide Semiconductor Equipment Market Subscription (WWSEMS) data tracks only new equipment for fabs and test and assembly and packaging houses.  The SEMI World Fab Forecast and its related Fab Database reports track any equipment needed to ramp fabs, upgrade technology nodes, and expand or change wafer size, including new equipment, used equipment, or in-house equipment. Also check out the Opto/LED Fab Forecast. Learn more about the SEMI fab databases at: www.semi.org/MarketInfo/FabDatabase and www.youtube.com/user/SEMImktstats

Super cement’s secret


August 30, 2016

Simple cements are everywhere in construction, but researchers want to create novel construction materials to build smarter infrastructure. The cement known as mayenite is one smart material — it can be turned from an insulator to a transparent conductor and back. Other unique properties of this material make it suitable for industrial production of chemicals such as ammonia and for use as semiconductors in flat panel displays.

The secret behind mayenite’s magic is a tiny change in its chemical composition, but researchers hadn’t been sure why the change had such a big effect on the material, also known as C12A7. In new work, researchers show how C12A7 components called electron anions help to transform crystalline C12A7 into semiconducting glass.

The study, published Aug. 24 in Proceedings of the National Academy of Sciences, uses computer modeling that zooms in at the electron level along with lab experiments. They showed how the small change in composition results in dramatic changes of the glass properties and, potentially, allows for greater control of the glass formation process.

“We want to get rid of the indium and gallium currently used in most flat panel displays,” said materials scientist Peter Sushko of the Department of Energy’s Pacific Northwest National Laboratory. “This research is leading us toward replacing them with abundant non-toxic elements such as calcium and aluminum.”

Breaking the glass ceiling

More than a decade ago, materials scientist Hideo Hosono at the Tokyo Institute of Technology and colleagues plucked an oxygen atom from a crystal of C12A7 oxide, which turned the transparent insulating material into a transparent conductor. This switch is rare because the conducting material is transparent: Most conductors are not transparent (think metals) and most transparent materials are not conductive (think window glass).

Back in the crystal, C12A7 oxide’s departing oxygen leaves behind a couple electrons and creates a material known as an electride. This electride is remarkably stable in air, water, and ambient temperatures. Most electrides fall apart in these conditions. Because of this stability, materials scientists want to harness the structure and properties of C12A7 electride. Unfortunately, its crystalline nature is not suitable for large-scale industrial processes, so they needed to make a glass equivalent of C12A7 electride.

And several years ago, they did. Hosono and colleagues converted crystalline C12A7 electride into glass. The glass shares many properties of the crystalline electride, including the remarkable stability.

Crystals are neat and tidy, like apples and oranges arranged orderly in a box, but glasses are unordered and messy, like that same fruit in a plastic grocery bag. Researchers make glass by melting a crystal and cooling the liquid in such a way that the ordered crystal doesn’t reform. With C12A7, the electride forms a glass at a temperature about 200 degrees lower than the oxide does.

This temperature — when the atoms stop flowing as a liquid and freeze in place — is known as the glass transition temperature. Controlling the glass transition temperature allows researchers to control certain properties of the material. For example, how car tires wear down and perform in bad weather depends on the glass transition temperature of the rubber they’re made from.

Sushko, his PNNL colleague Lewis Johnson, Hosono and others at Tokyo Tech wanted to determine why the electride’s glass transition temperature was so much lower than the oxide’s. They suspected components of the electride known as electron anions were responsible. Electron anions are essentially freely moving electrons in place of the much-larger negatively charged oxygen atoms that urge the oxide to form a tidy crystal.

Moveable feat

The team simulated Hosono’s lab experiments using molecular dynamics software that could capture the movement of both the atoms and the electron anions in both the melted material and glass. The team found that that the negatively-charged electron anions paired up between positively charged aluminum or calcium atoms, replacing the negatively charged oxygen atoms that would typically be found between the metals.

The bonds that the electron anions formed between the metal atoms were weaker than bonds between metal and oxygen atoms. These weak links could also move rapidly through the material. This movement allowed a small number of electron anions to have a greater effect on the glass transition temperature than much larger quantities of minerals typically used as additives in glasses.

To rule out other factors as the impetus for the lower transition temperature — such as the electrical charge or change in oxygen atoms — the researchers simulated a material with the same composition as the C12A7 electride but with the electrons spread evenly through the material instead of packed in as electron anions. In this simulation, the glass transition temperature was no different than C12A7 oxide’s. This result confirmed that the network of weak links formed by the electron anions was responsible for changes to the glass transition temperature.

According to the scientists, electron anions form a new type of weak link that can affect the conditions under which a material can form a glass. They join the ranks of typical additives that disrupt the ability of the material to form long chains of atoms, such as fluoride, or form weak, randomly oriented bonds between atoms of opposite charge, such as sodium. The work suggests researchers might be able to control the transition temperature by changing the amount of electron anions they use.

“This work shows us not just how a glass forms,” said PNNL’s Johnson, “but also gives us a new tool for how to control it.”

A research team led by Professor Keon Jae Lee from the Korea Advanced Institute of Science and Technology (KAIST) and by Dr. Jae-Hyun Kim from the Korea Institute of Machinery and Materials (KIMM) has jointly developed a continuous roll-processing technology that transfers and packages flexible large-scale integrated circuits (LSI), the key element in constructing the computer’s brain such as CPU, on plastics to realize flexible electronics (Advanced Materials, “Simultaneous Roll Transfer and Interconnection of Flexible Silicon NAND Flash Memory”).

This schematic image shows the flexible silicon NAND flash memory produced by the simultaneous roll-transfer and interconnection process. (Image: KAIST)

This schematic image shows the flexible silicon NAND flash memory produced by the simultaneous roll-transfer and interconnection process. (Image: KAIST)

Professor Lee previously demonstrated the silicon-based flexible LSIs using 0.18 CMOS (complementary metal-oxide semiconductor) process in 2013 (ACS Nano, “In Vivo Silicon-based Flexible Radio Frequency Integrated Circuits Monolithically Encapsulated with Biocompatible Liquid Crystal Polymers”) and presented the work in an invited talk of 2015 International Electron Device Meeting (IEDM), the world’s premier semiconductor forum.

Highly productive roll-processing is considered a core technology for accelerating the commercialization of wearable computers using flexible LSI. However, realizing it has been a difficult challenge not only from the roll-based manufacturing perspective but also for creating roll-based packaging for the interconnection of flexible LSI with flexible displays, batteries, and other peripheral devices.

To overcome these challenges, the research team started fabricating NAND flash memories on a silicon wafer using conventional semiconductor processes, and then removed a sacrificial wafer leaving a top hundreds-nanometer-thick circuit layer. Next, they simultaneously transferred and interconnected the ultrathin device on a flexible substrate through the continuous roll-packaging technology using anisotropic conductive film (ACF). The final silicon-based flexible NAND memory successfully demonstrated stable memory operations and interconnections even under severe bending conditions. This roll-based flexible LSI technology can be potentially utilized to produce flexible application processors (AP), high-density memories, and high-speed communication devices for mass manufacture.

Professor Lee said, “Highly productive roll-process was successfully applied to flexible LSIs to continuously transfer and interconnect them onto plastics. For example, we have confirmed the reliable operation of our flexible NAND memory at the circuit level by programming and reading letters in ASCII codes. Out results may open up new opportunities to integrate silicon-based flexible LSIs on plastics with the ACF packing for roll-based manufacturing.”

Dr. Kim added, “We employed the roll-to-plate ACF packaging, which showed outstanding bonding capability for continuous roll-based transfer and excellent flexibility of interconnecting core and peripheral devices. This can be a key process to the new era of flexible computers combining the already developed flexible displays and batteries.”

North America-based manufacturers of semiconductor equipment posted $1.79 billion in orders worldwide in July 2016 (three-month average basis) and a book-to-bill ratio of 1.05, according to the July Equipment Market Data Subscription (EMDS) Book-to-Bill Report published today by SEMI.  A book-to-bill of 1.05 means that $105 worth of orders were received for every $100 of product billed for the month.

SEMI reports that the three-month average of worldwide bookings in July 2016 was $1.79 billion. The bookings figure is 4.7 percent higher than the final June 2016 level of $1.71 billion, and is 13.1 percent higher than the July 2015 order level of $1.59 billion.

The three-month average of worldwide billings in July 2016 was $1.71 billion. The billings figure is 0.6 percent lower than the final June 2016 level of $1.72 billion, and is 9.6 percent higher than the July 2015 billings level of $1.56 billion.

“Monthly bookings have exceeded $1.7 billion for the past three months with monthly billings trending in a similar manner,” said Denny McGuirk, president and CEO of SEMI. “Recent earnings announcements have indicated that strong purchasing activity by China and 3D NAND producers will continue in the near-term.”

The SEMI book-to-bill is a ratio of three-month moving averages of worldwide bookings and billings for North American-based semiconductor equipment manufacturers. Billings and bookings figures are in millions of U.S. dollars.

Billings
(3-mo. avg)

Bookings
(3-mo. avg)

Book-to-Bill
February 2016

$1,204.4

$1,262.0

1.05
March 2016

$1,197.6

$1,379.2

1.15
April 2016

$1,460.2

$1,595.4

1.09
May 2016

$1,601.5

$1,750.5

1.09
June 2016 (final)

$1,715.2

$1,714.3

1.00
July 2016 (prelim)

$1,705.1

$1,794.7

1.05

Source: SEMI (www.semi.org), August 2016

Imagine an electronic newspaper that you could roll up and spill your coffee on, even as it updated itself before your eyes.

It’s an example of the technological revolution that has been waiting to happen, except for one major problem that, until now, scientists have not been able to resolve.

Researchers at McMaster University have cleared that obstacle by developing a new way to purify carbon nanotubes – the smaller, nimbler semiconductors that are expected to replace silicon within computer chips and a wide array of electronics.

Artistic rendition of a metallic carbon nanotube being pulled into solution, in analogy to the work described by the Adronov group. Credit: Alex Adronov, McMaster University

Artistic rendition of a metallic carbon nanotube being pulled into solution, in analogy to the work described by the Adronov group. Credit: Alex Adronov, McMaster University

“Once we have a reliable source of pure nanotubes that are not very expensive, a lot can happen very quickly,” says Alex Adronov, a professor of Chemistry at McMaster whose research team has developed a new and potentially cost-efficient way to purify carbon nanotubes.

Carbon nanotubes – hair-like structures that are one billionth of a metre in diameter but thousands of times longer – are tiny, flexible conductive nano-scale materials, expected to revolutionize computers and electronics by replacing much larger silicon-based chips.

A major problem standing in the way of the new technology, however, has been untangling metallic and semiconducting carbon nanotubes, since both are created simultaneously in the process of producing the microscopic structures, which typically involves heating carbon-based gases to a point where mixed clusters of nanotubes form spontaneously as black soot.

Only pure semiconducting or metallic carbon nanotubes are effective in device applications, but efficiently isolating them has proven to be a challenging problem to overcome. Even when the nanotube soot is ground down, semiconducting and metallic nanotubes are knotted together within each grain of powder. Both components are valuable, but only when separated.

Researchers around the world have spent years trying to find effective and efficient ways to isolate carbon nanotubes and unleash their value.

While previous researchers had created polymers that could allow semiconducting carbon nanotubes to be dissolved and washed away, leaving metallic nanotubes behind, there was no such process for doing the opposite: dispersing the metallic nanotubes and leaving behind the semiconducting structures.

Now, Adronov’s research group has managed to reverse the electronic characteristics of a polymer known to disperse semiconducting nanotubes – while leaving the rest of the polymer’s structure intact. By so doing, they have reversed the process, leaving the semiconducting nanotubes behind while making it possible to disperse the metallic nanotubes.

The researchers worked closely with experts and equipment from McMaster’s Faculty of Engineering and the Canada Centre for Electron Microscopy, located on the university’s campus.

“There aren’t many places in the world where you can to this type of interdisciplinary work,” Adronov says.

The next step, he explains, is for his team or other researchers to exploit the discovery by finding a way to develop even more efficient polymers and scale up the process for commercial production.

Problems frequently arise as a result of an incomplete or absent formal risk assessment when processes are modified or new materials introduced.

BY ALAN IFOULD and ANDREW CHAMBERS, Edwards, North Somerset, UK

The sub-fab is home to the many pumps and abatement systems that not only help to create the pristine environments required in the process chambers of the numerous tools in the cleanroom, but also handle the exhaust gases and by-products generated by the manufacturing process. In this respect, the efficiency and efficacy of sub-fab operations directly affect the availability, productivity, total operating cost and yield of the manufacturing fab above. Perhaps more importantly, in addition to supporting the process vacuum, equipment in the sub-fab is designed to render cleanroom process wastes harmless and ready for safe disposal or, if appropriate, release into the environment. As such, they are vital to protecting the safety of the people working in the fab as well as those living and working in the surrounding community, and ultimately, all of us who share that environment. The very nature of the process materials and reaction byproducts handled in the sub fab, which may be variously corrosive, toxic, pyrophoric, flammable or environmentally damaging, creates significant risks, especially for those who must operate and maintain the equipment located there. Moreover, as device manufacturing becomes more complex, with the introduction of new materials, new precursors and new processes, the risk of mistakes with potentially catastrophic consequences in both human and financial terms will only increase.

While ultimate responsibility for personnel safety in the sub-fab lies with the fab operator, equipment manufac- turers have a part to play by optimizing their products not only for efficient, effective and reliable operation, but also by ensuring any risks associated with operation, maintenance and repair are assessed and minimised to the greatest extent possible.

There is often a strong focus on technical performance and cost attributes when selecting sub-fab equipment. However, processes and procedures to ensure optimum operation and continuous mitigation of risks to service personnel are equally critical; these demand the devel- opment of clear and effective operating procedures and guidelines – in industry jargon “best known methods” or BKMs – to ensure the equipment achieves its full performance potential and safety integrity maintained. The manufacturers of sub-fab equipment are perhaps in the best position to define these guidelines since they will typically have acquired an understanding of the risks posed by hazardous materials on a case-by-case basis during the course of system optimization. Frequent development of BKMs is undertaken in collaboration with the process tool manufacturer or early adopters of the process. However, defining operating and maintenance methods and procedures that are truly the best known requires a commitment to doing so at the highest levels of corporate management, and a formal process of reporting, analysis, synthesis and dissemination throughout the equipment support community.

A key component of any BKM program is the active participation of the equipment manufacturer’s service personnel who are responsible for installing, commissioning and maintaining the equipment and are also likely to have first- hand knowledge and experience of the potential hazards. Since service personnel are invariably in the front-line when safety incidents occur, they are well motivated to contribute since they themselves are often at greatest risk, and it is essential that their contribution is incorporated into product development programs to complement the technical performance with assured safety and reliability.

Even a cursory search of the internet will quickly reveal numerous examples of fab and sub-fab incidents. Amongst the lessons that can be taken from these events is that the risk management process and the resulting controls have to cover every foreseeable circumstance across the equipment lifecycle: installation, commissioning, operation, servicing and maintenance. Notable recent serious accidents include:

– March 2014 – A fab worker dies after a carbon dioxide leak

– January 2013 – One worker dies and four others are hospitalized after a hydrofluoric acid leak at a manufacturing facility

– September 2013 – A fire at major memory fab results in the closure of the facility with losses estimated in the range of $1 billion and a measurable impact on global DRAM pricing

– August 2012 – A security guard and 3 firefighters are hospitalized when a fire occurs in the exhaust ducts of a photovoltaic manufacturing laboratory in Singapore. The entire facility is shut down for weeks and 35 workers are laid off

These were events with consequences visible and far-reaching enough to make the national and international news. However, experience indicates that smaller events, often with narrowly-averted disastrous consequences, occur on a much more frequent basis with adverse impacts on fab productivity. These events are typically not widely broadcast, thereby limiting the community learning that might otherwise take place.

In respect of process exhausts, three types of hazard recur repeatedly as manufacturing processes evolve and new process materials are introduced: condensation of reactive chemical precursors or reaction products, corrosion due to condensation of acidic materials, and pipe blockage due to accumulation of condensate in significant volume. The images in FIGURES 1-3 show a few examples.

FIGURE 1. (left) Condensed explosive polysiloxane material in an epitaxial deposition system process foreline, (middle and right) CVD exhaust pipe destroyed by explosion of condensed process by-product.

FIGURE 1. (left) Condensed explosive polysiloxane material in an epitaxial deposition system process foreline, (middle and right) CVD exhaust pipe destroyed by explosion of condensed process by-product.

FIGURE 2. (left) Acidic TEOS-based polymer with a pH of approximately 1, (middle) Condensed corrosive Br2-based liquid, (right) Exhaust pipe damaged by exposure to condensed acidic material.

FIGURE 2. (left) Acidic TEOS-based polymer with a pH of approximately 1, (middle) Condensed corrosive Br2-based liquid, (right) Exhaust pipe damaged by exposure to condensed acidic material.

FIGURE 3. Exhaust blockage caused by various materials (left) AlCl3 from a metal etch process, (middle) NH4Cl from an LPCVD process, (right) Unknown material deposited in the exhaust of a metal carbide CVD process.

FIGURE 3. Exhaust blockage caused by various materials (left) AlCl3 from a metal etch process, (middle) NH4Cl from an LPCVD process, (right) Unknown material deposited in the exhaust of a metal carbide CVD process.

In many cases, the cause of the risk is understood and solutions exist, but problems frequently arise as a result of an incomplete or absent formal risk assessment when processes are modified or new materials introduced. For example, condensation of potentially dangerous or explosive materials can usually be prevented by carefully controlling the temperature of the exhaust gas through the pipework and pumps. Pipe heating systems are widely available for forelines and exhaust pipes, and pumps can be designed with internal thermal management, but if the risk is not properly assessed, the appropriate controls will not be put in place. Furthermore, while a risk analysis may conclude that exhaust pipe heating is required in a specific case, it should also recognize that key to its effective implementation is the avoidance of cool spots, particularly at bends and junctions. Even a small local drop in temperature can create a hazardous situation despite the application of what is widely perceived as an effective protective measure – a subtle effect, but one with which field service personnel have become familiar through hard-won experience. At a practical level, if each process exhaust is designed in isolation, such considerations make their design and implementation a time-consuming and labor-intensive process. However, as noted in a previous publication [1] the ability to maintain effective thermal control throughout the exhaust stream can be enhanced by integrating the vacuum pumping and point- of-use abatement functions together with the interconnecting exhaust pipes into a single unified system. In this way the pipe routing can be standardized to permit optimization of the exhaust pipe heating installation for each specific process and to avoid the need for customization in the field. Integration and standardization also permits careful optimization of pump capacities and pipe diameters and routing to minimize power consumption and maximize destruction or removal efficiency (DRE). Finally, whether consid- ering an integrated system or not, secondary enclosures for pumps, abatement and exhaust pipes provide an additional layer of protection by permitting hazardous materials to be routed away from personnel in the event of an unintended release.

In some cases, it is not possible to prevent the accumu- lation of hazardous materials. It then becomes essential to monitor the deposition and remove it through periodic maintenance procedures. For example, blockage can be monitored by measuring the pressure drop over the length of the exhaust pipe – as material accumulates in the pipe the pressure drop increases. By monitoring for blockage, operators can ensure that the system is cleaned before its performance impacts production and at the same time avoid cleaning more frequently than required. Integrated vacuum and abatement systems often combine monitoring capabilities with automated software to alert operators of the need for maintenance.

While problems associated with accumulation of materials in process exhausts is arguably the most frequently encountered hazard faced by sub-fab maintenance personnel, another widely applied risk mitigation strategy, particularly for flammable process materials, is dilution below their lower flammability limit (LFL) with an inert gas such as nitrogen. However, it is important to understand the nature of the chemical processes occurring in the deposition chamber and to base the dilution calculation on the composition and volume of the effluent gas rather than the precursor. For example, TEOS is a precursor gas widely used in the chemical vapor deposition of silicon oxide films. The lower temperature needed for the CVD process and the absence of aggressive reaction products are the main advan- tages of using TEOS compared with traditional precursors such as silane and the mechanical and electrical properties of Si02 films deposited from TEOS are also very good. The decomposition products of TEOS in the gas phase in the absence of oxygen include organic fragments (ethanol, ethanal, ethene, methane, carbon monoxide), and in the presence of oxygen include water vapour, carbon dioxide, ethanal and methanol [2], many of which are flammable. A dilution calculation based on the amount of TEOS entering the chamber rather than the volume of decompo- sition products exiting the chamber could easily lead to an underestimate of the required volume of diluent and the presence of a flammable mixture in the exhaust pipe in some circumstances. Once again, a rigorous risk assessment is required to identify such potential hazards and put corrective measures in place where needed.

Risk assessment and communication

It should be clear from the preceding discussion that a detailed technical understanding of semiconductor manufacturing processes and materials and their impact on sub-fab equipment is a prerequisite for safe and efficient pumping and abatement of process exhaust. In particular, ensuring the safety of sub fab operations requires a formal process for risk assessment. Once determined, safe operating proce- dures must be codified and effectively communicated to field personnel, and a mechanism must exist to update procedures based on feed-back from the field. FIGURE 4 is taken from the Risk Assessment Procedure [3] used at Edwards (adapted from Semi S10) and illustrates the Risk Rating Table, a matrix by which risks are evaluated and appropriate responses determined.

Once risks are assessed the information must be effec- tively communicated to users and field service personnel. To ensure appropriate dissemination of required information, Edwards publishes Application Notes for equipment users and Safety Application Procedures (SAP) for service engineers.

Conclusion

The hazardous nature of many of the materials present in the semiconductor manufacturing process creates significant safety risks for fab personnel and others living or working near the fab, and financial risks for manufacturers and investors. Managing those risks takes more than good intentions and common sense precautions. It requires a detailed and continuously updated technical understanding of the processes and materials based on broad experience across many different types of applications, and ideally, partnership with process tool manufacturers during development and optimization of new processes. As in other high risk industries – nuclear, aviation, automotive, healthcare, oil, rail and military – best practice safety and risk management is heavily influ- enced by equipment manufacturers, who are in the best position to understand the capabil-
ities of their products across a wide range of applications.

Ultimately the fab management team own the responsibility for managing risk and safety with the highest levels of corporate respon- sibility. Semiconductor equipment manufacturers, and in particular, manufacturers of pumping and abatement systems that handle and safely dispose of hazardous materials, have an invaluable supporting role to play with their continuous accumulation of know-how and formal processes for risk assessment, including a mechanism for distributing safety information to, and incorporating feedback from, the field.

References

1. Andrew Chambers, Managing hazardous process exhausts in high volume manufacturing, Solid State Technology, 2016 Issue 2
2. Van der Vis, M.G.M., et al, The thermodynamic properties of tetrae- thoxysilane (TEOS) and an infrared study of its thermal decomposition, Colloque C3, supplement au Journal de Physique 11, Volume 3, aofit 1993, http://dx.doi.org/10.1051/jp4:1993309
3. Adapted from Semiconductor Equipment and Materials International (SEMI) standard S-10, http://www. semi.org

Pixelligent Technologies, a developer of high-index advanced materials for solid state lighting and display applications and producer of PixClear products, announced today that it closed $10.4 million in new funding. The round was led by The Abell Foundation, The Bunting Family Office, and David Testa, the former Chief Investment Officer of T. Rowe Price. Funds will be used to complete the installation of additional manufacturing capacity, open new offices in Asia, and continue to drive innovation in lighting, display and optical applications.

To date Pixelligent has raised over $36.0M in equity funding and has been awarded more than $12M in U.S. government grant programs to support the development of its proprietary PixClear products and PixClearProcess. The Pixelligent nanotechnology platform includes proprietary nanocrystal synthesis, capping technology, high volume manufacturing and application engineering that supports ink jet, slot die, UV curing, spray coating, and numerous other manufacturing processes.

“We have clearly established Pixelligent as the leading high-index materials manufacturer for demanding solid state lighting and OLED display applications throughout the world. Pixelligent is partnering with leading advanced materials suppliers to deliver breakthrough performance that currently spans applications in 12 discrete markets including: lighting, displays, printed and flexible electronics, AR/VR, optically clear adhesives, MEMS, gradient index lenses, and others with a combined total over $9B in market opportunities. We have numerous commercial applications currently in the market and expect additional product introductions before the end of 2016,” said Craig Bandes, President & CEO of Pixelligent Technologies.

“We started our partnership with Pixelligent in 2011 when the company relocated to Baltimore City and have seen the company achieve all of their critical technology and manufacturing milestones, while establishing a global brand and presence. Our investment objective is to support leading edge companies that deliver breakthrough technology and products and create jobs in our local community. Pixelligent is at the forefront in delivering on the promise of the nanotechnology revolution. We are proud of what the team at Pixelligent has accomplished to date and we look forward to their continued growth and success,” said Eileen O’Rourke, CFO of The Abell Foundation.

Unique optical features of quantum dots make them an attractive tool for many applications, from cutting-edge displays to medical imaging. Physical, chemical or biological properties of quantum dots must, however, be adapted to the desired needs. Unfortunately, up to now quantum dots prepared by chemical methods could be functionalized using copper-based click reactions with retention of their luminescence. This obstacle can be ascribed to the fact that copper ions destroy the ability of quantum dots to emit light. Scientists from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw and the Faculty of Chemistry of the Warsaw University of Technology (FC WUT) have shown, however, that zinc oxide (ZnO) quantum dots prepared by an original method developed by them, after modification by the click reaction with the participation of copper ions, fully retain their ability to emit light.

“Click reactions catalyzed by copper cations have long attracted the attention of chemists dealing with quantum dots. The experimental results, however, were disappointing: after modification, the luminescence was so poor that they were just not fit for use. We were the first to demonstrate that it is possible to produce quantum dots from organometallic precursors in a way they do not lose their valuable optical properties after being subjected to copper-catalysed click reactions,” says Prof. Janusz Lewinski (IPC PAS, FC WUT).

Quantum dots are crystalline structures with size of a few nanometers (billionth parts of a meter). As semiconductor materials, they exhibit a variety of interesting features typical of quantum objects, including absorbing and emitting radiation of only a strictly defined energy. Since atoms interact with light in a similar way, quantum dots are often called artificial atoms. In some respects, however, quantum dots offer more possibilities than atoms. Optical properties of each dot actually depend on its size and the type of material from which it is formed. This means that quantum dots may be precisely designed for specific applications.

To meet the need of specific applications, quantum dots have to be tailored in terms of physico-chemical properties. For this purpose, chemical molecules with suitable characteristics are attached to their surface. Due to the simplicity, efficacy, and speed of the process, an exceptionally convenient method is the click reaction. Unfortunately, one of the most widely used click reactions takes place with the participation of copper ions, which was reported to result in the almost complete quenching of the luminescence of the quantum dots.

“Failure is usually a result of the inadequate quality of quantum dots, which is determined by the synthesis method. Currently, ZnO dots are mainly produced by the sol-gel method from inorganic precursors. Quantum dots generated in this manner are coated with a heterogeneous and probably leaky protective shell, made of various sorts of chemical molecules. During a click reaction, the copper ions are in direct contact with the surface of quantum dots and quench the luminescence of the dot, which becomes completely useless,” explains Dr. Agnieszka Grala (IPC PAS), the first author of the article in the Chemical Communications journal.

For several years, Prof. Lewinski’s team has been developing alternative methods for the preparation of high quality ZnO quantum dots. The method presented in this paper affords the quantum dots derived from organozinc precursors. Composition of the nanoparticles can be programmed at the stage of precursors preparation, which makes it possible to precisely control the character of their organic-inorganic interface.

“Nanoparticles produced by our method are crystalline and all have almost the same size. They are spherical and have characteristics of typical quantum dots. Every nanoparticle is stabilized by an impermeable protective jacket, built of organic compounds, strongly anchored on the surface of the semiconductor core. As a result, our quantum dots remain stable for a long time and do not aggregate, that is clump together, in solutions,” describes Malgorzata Wolska-Pietkiewicz, a PhD student at FC WUT.

“The key to success is producing a uniform stabilizing shell. Such coatings are characteristic of the ZnO quantum dots obtained by our method. The organic layer behaves as a tight protective umbrella protecting dots from direct influence of the copper ions,” says Dr. Grala and clarifies: “We carried out click reaction known as alkyne-azide cycloaddition, in which we used a copper(l) compound as catalysts. After functionalization, our quantum dots shone as brightly as at the beginning.”

Quantum dots keep finding more and more applications in various industrial processes and as nanomarkers in, among others, biology and medicine, where they are combined with biologically active molecules. Nanoobjects functionalized in this manner are used to label both individual cells as well as whole tissues. The unique properties of quantum dots also enable long-term monitoring of the labelled item. Commonly used quantum dots, however, contain toxic heavy metals, including cadmium. In addition, they clump together in solutions, which supports the thesis of the lack of tightness of their shells. Meanwhile, the ZnO dots produced by Prof. Lewinski’s group are non-toxic, they do not aggregate, and can be bound to many chemical compounds – so they are much more suitable for medical diagnosis and for imaging cells and tissues.

Research on the methods of production of functionalized ZnO quantum dots was carried out under an OPUS grant from the Poland’s National Science Centre.

Towards a better screen


August 9, 2016

Harvard University researchers have designed more than 1,000 new blue-light emitting molecules for organic light-emitting diodes (OLEDs) that could dramatically improve displays for televisions, phones, tablets and more.

OLED screens use organic molecules that emit light when an electric current is applied. Unlike ubiquitous liquid crystal displays (LCDs), OLED screens don’t require a backlight, meaning the display can be as thin and flexible as a sheet of plastic. Individual pixels can be switched on or entirely off, dramatically improving the screen’s color contrast and energy consumption. OLEDs are already replacing LCDs in high-end consumer devices but a lack of stable and efficient blue materials has made them less competitive in large displays such as televisions.

The interdisciplinary team of Harvard researchers, in collaboration with MIT and Samsung, developed a large-scale, computer-driven screening process, called the Molecular Space Shuttle, that incorporates theoretical and experimental chemistry, machine learning and cheminformatics to quickly identify new OLED molecules that perform as well as, or better than, industry standards.

“People once believed that this family of organic light-emitting molecules was restricted to a small region of molecular space,” said Alán Aspuru-Guzik, Professor of Chemistry and Chemical Biology, who led the research. “But by developing a sophisticated molecular builder, using state-of-the art machine learning, and drawing on the expertise of experimentalists, we discovered a large set of high-performing blue OLED materials.”

The research is described in the current issue of Nature Materials.

The biggest challenge in manufacturing affordable OLEDs is emission of the color blue.

Like LCDs, OLEDs rely on green, red and blue subpixels to produce every color on screen.  But it has been difficult to find organic molecules that efficiently emit blue light. To improve efficiency, OLED producers have created organometallic molecules with expensive transition metals like iridium to enhance the molecule through phosphorescence. This solution is expensive and it has yet to achieve a stable blue color.

Aspuru-Guzik and his team sought to replace these organometallic systems with entirely organic molecules.

The team began by building libraries of more than 1.6 million candidate molecules. Then, to narrow the field, a team of researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), led by Ryan Adams, Assistant Professor of Computer Science, developed new machine learning algorithms to predict which molecules were likely to have good outcomes, and prioritize those to be virtually tested. This effectively reduced the computational cost of the search by at least a factor of ten.

“This was a natural collaboration between chemistry and machine learning,” said David Duvenaud, a postdoctoral fellow in the Adams lab and coauthor of the paper. “Since the early stages of our chemical design process starts with millions of possible candidates, there’s no way for a human to evaluate and prioritize all of them. So, we used neural networks to quickly prioritize the candidates based on all the molecules already evaluated.”

“Machine learning tools are really coming of age and starting to see applications in a lot of scientific domains,” said Adams.  “This collaboration was a wonderful opportunity to push the state of the art in computer science, while also developing completely new materials with many practical applications. It was incredibly rewarding to see these designs go from machine learning predictions to devices that you can hold in your hand.”

“We were able to model these molecules in a way that was really predictive,” said Rafael Gómez-Bombarelli, a postdoctoral fellow in the Aspuru-Guzik lab and first author of the paper.  “We could predict the color and the brightness of the molecules from a simple quantum chemical calculation and about 12 hours of computing per molecule. We were charting chemical space and finding the frontier of what a molecule can do by running virtual experiments.”

“Molecules are like athletes,” Aspuru-Guzik said. “It’s easy to find a runner, it’s easy to find a swimmer, it’s easy to find a cyclist but it’s hard to find all three. Our molecules have to be triathletes. They have to be blue, stable and bright.”

But finding these super molecules takes more than computing power — it takes human intuition, said Tim Hirzel, a senior software engineer in the Department of Chemistry and Chemical Biology and coauthor of the paper.

To help bridge the gap between theoretical modeling and experimental practice, Hirzel and the team built a web application for collaborators to explore the results of more than half a million quantum chemistry simulations.

Every month, Gómez-Bombarelli and coauthor Jorge Aguilera-Iparraguirre, also a postdoctoral fellow in the Aspuru-Guzik lab, selected the most promising molecules and used their software to create “baseball cards,” profiles containing important information about each molecule. This process identified 2500 molecules worth a closer look.  The team’s experimental collaborators at Samsung and MIT then voted on which molecules were most promising for application. The team nicknamed the voting tool “molecular Tinder” after the popular online dating app.

“We facilitated the social aspect of the science in a very deliberate way,” said Hirzel.

“The computer models do a lot but the spark of genius is still coming from people,” said Gómez-Bombarelli.

“The success of this effort stems from its multidisciplinary nature,” said Aspuru-Guzik. “Our collaborators at MIT and Samsung provided critical feedback regarding the requirements for the molecular structures.”

“The high throughput screening technique pioneered by the Harvard team significantly reduced the need for synthesis, experimental characterization, and optimization,” said Marc Baldo, Professor of Electrical Engineering and Computer Science at MIT and coauthor of the paper. “It shows the industry how to advance OLED technology faster and more efficiently.”

After this accelerated design cycle, the team was left with hundreds of molecules that perform as well as, if not better than, state-of-the-art metal-free OLEDs.

Applications of this type of molecular screening also extend far beyond OLEDs.

“This research is an intermediate stop in a trajectory towards more and more advanced organic molecules that could be used in flow batteries, solar cells, organic lasers, and more,” said Aspuru-Guzik. “The future of accelerated molecular design is really, really exciting.”

In addition to the authors mentioned, the manuscript was coauthored by Dougal Maclaurin, Martin A. Blood-Forsythe, Hyun Sik Chae, Markus Einzinger, Dong-Gwang Ha, Tony Wu, Georgios Markopoulos, Soonok Jeon, Hosuk Kang, Hiroshi Miyazaki, Masaki Numata, Sunghan Kim, Wenliang Huang and Seong Ik Hong.

The research was supported by the Samsung Advanced Institute of Technology.

Because of seasonally very weak demand and the ramping of new capacity in China, flat-panel display (FPD) supply exceeded demand by 20 percent in the first quarter of 2016, the largest glut since early 2012. The market began to rapidly correct itself in the second quarter and is now trending toward surprising tightness in the second half of 2016. Supply is expected to tighten still further in 2017, according to IHS Markit (Nasdaq: INFO).

flat panel display correction

Rapidly falling panel prices late last year and early this year have encouraged consumers to buy larger TVs. At the same time, notebook and monitor demand has started to stabilize. Finally, capacity growth is restricted, as manufacturers adopt new and more complicated processes in some factories, and more importantly close less productive facilities.

“South Korean panel makers are being particularly aggressive in shutting down older LCD fabs, including Gen 5 and even Gen 7 facilities,” said Charles Annis, senior director at IHS Markit. “The South Korean Gen 7 facility expected to be taken off-line late this year accounts for approximately nearly 4 percent of capacity dedicated to large-area production. It would be the largest factory shutdown in the history of FPD manufacturing.”

Based on the latest IHS Markit Display Supply Demand & Equipment Tracker, demand for large-area FPD applications is expected to grow 5 percent to 6 percent per year from 2016 through 2018; however, capacity dedicated to large-area production is only expected to expand 1 percent in 2017 and 5 percent in 2018. By the second half of 2018, the market is again expected to start trending towards looseness, as even more Chinese capacity is brought on-line, including the world’s first Gen 10.5 factory.

“Historically, the FPD market has corrected itself by reducing factory utilization and delaying capacity expansion plans,” Annis said. “With the rise of Chinese FPD manufacturing, neither of these strategies seemed likely in 2016. This situation has pushed makers in other regions to rationalize their current production assets at unprecedented and unexpected rates ”