Future EUV/FEL Strategy – The Beam Line Approaches

As many of you know, I've been following the progress of EUV lithography over the years, observing and commenting on the program's many engineering successes as well as the delays in the convergence of EUV lithography and the anticipated HVM time line (High Volume Manufacturing). In spite of improvements in laser technology and the availability of low dose photoresists, the development of high power LPP (Laser Produced Plasma) EUV source technology >100 watts remains problematic. EUV HVM insertion remains elusive and unpredictable. The source power limitations and MTBF (Mean Time Between Failure) of LPP technology have gated the program. A few years ago many in the SPIE community sought to explore the potential of a FEL source for high power EUV applications. At the time, Free Electron Laser [1] Technology was not yet a topic for dinner table discussion so in September, 2014 I published Future FEL/EUV Strategy – The Light at the End of the Beam Line. [2] On-going FEL developments at SLAC and recent related commentary from companies like GLOBALFOUNDRIES have generated new interest in FEL technology. As many new engineers and investors have joined our ranks, I thought a more comprehensive review was in order, so I've excerpted portions of my 1994 primer on FEL/EUV strategy to point out the enabling feature/benefits of a high power, high reliability light source for EUV lithography.

What are the current obstacles to high power EUV?

In ASML's current LPP source designs, a solid state "pre-pulse" laser and a second, high energy CO2 laser are fired at micron sized tin (Sn) pellets, evaporating them and releasing EUV light as a byproduct. Knowledgeable sources have informed me that the currently employed CO2 lasers are at or near the maximum of their pulse rate capabilities, effectively limiting further power output. As more CO2 laser power becomes available, there may still be practical limitations on the scaling and feed rate of Sn (tin) target material. As determined by physics, the inherent energy conversion factor for tin approximates 4%, and further incremental improvements in efficiency are obtained with diminishing returns. Assuming additional laser power becomes available for ASML, further complications can result from higher LPP source power levels as the rate of residual particulate contamination from evaporated tin increases in approximate proportion with increased laser power. Critical beam line mirror surfaces and other source components rapidly lose their efficiencies as tin contamination accumulates, reducing the available up time of the stepper (MTBF). It was originally anticipated that an optimal LPP EUV source design would provide 13.5nm light at power levels >200 watts, providing current and future lithography requirements. However, more recent demands for even higher EUV power levels have been identified. ASML and Carl Zeiss acknowledged in an invited paper at SPIE Advanced Lithography 2015, that higher resolutions will require 60mJ/cm2 for half pitch nodes <8nm. [3] ASML's recent (2015) collaboration with Carl Zeiss has produced an optical system with a numeric aperture (NA) of 0.55 vs. ASML's current EUV NA of 0.33. The higher NA system will require 500 watts of EUV power to achieve the estimated 60 mJ/cm2 dosimetry required for throughput of 150 wafers/hour. While this concept extends the viability of 13.5nm lithography, the delivery of a reliable 500 watt EUV source remains a critical item on the agenda, meaning the availability of free electron laser technology will probably gate related programs. A recent article appearing in the SPIE News Room, Extending extreme-UV lithography technology, [4] suggests that power levels of 500 – 1000 watts may be required for a single stepper necessitating a large scale central source EUV FEL.

A Primer on Free Electron Lasers

What is a free electron laser and how is it different from conventional lasers and LPP systems? To answer this question we must entertain the convergence of the US DOE's high energy physics community with the semiconductor industry and discuss recent innovations in technology. In previous and current generation stepper and scanner systems, it's been common to utilize laser light sources producing the desired wavelengths required for semiconductor photolithography. In current 193nm lithography systems, an argon fluoride (ArF) laser produces the light. The laser light produced is monochromatic, of sufficient brilliance and provides many hours of trouble free uptime. It would seem this simplistic approach might be applied to EUV lithography. Why not build an EUV laser with a wavelength of 13.5 nanometers? This has not been possible due to limitations in physics. The highly reflective optics required for laser efficiencies have yet to be created for EUV spectra. Current Bragg cell mirrors reflect EUV with a closely approximated 90% efficiency. However, FEL is a game changer. Some history and an analogy:


The term LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. The first solid state, 694nm synthetic ruby laser produced at Hughes Research in 1960, [5] utilized xenon flash lamps to inject high energy photons throughout the core of a ruby rod, stimulating the emission of photons from its lattice structures. Lasers operate at specific wavelengths which are determined by the seed (or lazing) material's inherent spectral signature. The 694nm wavelength is derived from the band gap emissions of the ruby's crystalline composition. We might compare the ruby crystal in this laser with a quartz crystal in a radio which determines its operational frequency. Accordingly, we might otherwise assign “channel I” as an identifier of I-line photolithography operating at 365nm.

The Foundation Physics of FEL

 A Radio Logical Analogy

A radio transmitter's frequency has historically been controlled by quartz crystal elements. Y-cut quartz crystals oscillate (vibrate) at specific frequencies which are dependent upon their thickness. The thinner the crystal, the higher the frequency obtained. Inversely, the thicker the crystal, the lower the frequency obtained. Passing an electric current through a quartz crystal induces it to oscillate at its inherent resonant frequency, so determined by its thickness. The frequency produced is extremely stable and the resulting wave form is of high purity, providing an excellent medium for control of radio frequencies and instrumentation. Crystals also produce harmonic frequencies. A harmonic is a multiple of the crystal's fundamental resonant frequency. As such, a crystal oscillating at 3 MHz will also produce a weaker signal at 6MHz (its second harmonic frequency), and a still weaker third harmonic at 9MHz and so on. When impractical to manufacture crystals at their desired fundamental frequencies, "third overtone" crystals are often utilized to provide a harmonic frequency which can be sufficiently amplified and utilized as an effective fundamental frequency, thus extending the upper limits (and our usage) of the radio spectrum. Even with clever engineering, over the years radio frequency control became problematic as multi-channel communication systems evolved, requiring large banks of crystals to span a given range of frequencies; one crystal required for each channel frequency. Rather than utilize thousands of crystals to span the radio spectrum, communications equipment evolved to employ a frequency control device called a VFO: a Variable Frequency Oscillator. In this scenario, several fundamental frequency crystals and specially designed varactor diode/phased locked loop circuits comprise a heterodyne oscillator, sometimes known as an IF (Intermediate Frequency) mixer. Such an oscillator can generate a wide range of possible frequency combinations by mixing (heterodyning) the output obtained from the crystals to produce the desired sum/difference of their frequencies by way of constructive or destructive interference. As a VFO radio tuning dial is manipulated, it changes one of the mixing frequencies to produce the desired sum/difference operational frequency for both transmitter and receiver. The advantage to such a design is the elimination of separate transmitter/receiver controls, and thousands of individual crystals normally assigned for each desired radio channel. The conceptual use of both harmonic and sum/difference frequency synthesis has found its way into many applications in physics and electronics.

Free Electron Laser Fundamentals

Imagine that we might adjust and control a laser's wavelength using a concept similar to a radio's Variable Frequency Oscillator but with a different set of physics. By electronically tuning a laser's wavelength, we can eliminate the need for specialized crystalline, gaseous or other lazing materials and operate outside the spectral wavelength segments they are physically limited to. FEL technology can produce tunable wavelengths of light throughout the microwave, visible spectrum and x-ray regime. A free electron laser is comprised of a large beamline/electron source which accelerates electrons to near the speed of light. On opposite sides of the electron beam line are interposed field coils of opposing polarity called undulators or "wigglers", which when energized establish a transverse sinusoidal field across the beam path. Electrons accelerated into the transverse field produce incoherent photons in a mixed assortment of sinusoidal wavelengths sometimes referred to as “bunches”, emitting photons at wavelengths determined by their acceleration and the transverse field strength (synchrotron radiation). By adjusting the electron beam energy or the magnetic field strength of the undulators, the wavelength of the emitted photons can be tuned selectively to produce coherent light. Variations on this concept have evolved as follows:

A Tunable SASE FEL

A SASE FEL is able to produce laser light over a broad range of spectrum without the requirement for conventional lazing materials such as ruby crystal or argon fluoride etc. In a tunable SASE (Self Amplified Spontaneous Emission) FEL, high energy source electrons passing through an undulator can produce an assortment of incoherent photons (initially at randomly different wavelengths) which become bunched in the transverse sine wave and interact via constructive or destructive interference, producing incidental derivative wavelengths (spontaneous emission). That is to say the bunched photons add and subtract their wavelength values from one another producing new sum/difference valued photons at the mathematically resulting wavelengths. When tuned to a specific wavelength of interest by adjusting the electron beam energy or the magnetic field strength of the undulators, such subsequently produced photons arrive in phase (at the same wavelength) and cumulatively intensify to release high energy coherent laser light (self amplification). While a very useful concept for a variety of applications, the spontaneous emission in a SASE FEL can propagate statistical artifacts resulting from the inherent mathematical sum/difference phenomenon, and consequently can produce a beam exhibiting limited shot to shot reproducibility. As such, the utility of a SASE FEL might be limited in applications which require extremely accurate dosimetry. The limited shot to shot reproducibility might also contribute to the dosimetry phenomenon known as “shot noise”.

A Tunable HGHG FEL

FEL performance can be modified and improved by utilizing an external seed laser as a source wavelength. The seed laser is a conventional laser utilizing a material such as ruby crystal (one example) to produce a monochromatic feed source of photons. In an HGHG (High Gain Harmonic Generation) FEL, the seed laser interacts with the electron beam as it propagates through the first undulator (called a modulator), tuned to the seed laser's wavelength. The resulting interaction with the seed laser induces coherent modulation of the electron beam energy, creating photon bunching as well as consequential harmonic propagation (photons which are the mathematical multiples of the seed laser's wavelength). The micro-bunched beam of photons are then injected into a long undulator tuned to the desired harmonic wavelength. The desired wavelength comprised of harmonically produced photons arrive in phase and cumulatively intensify to release high energy coherent light at the newer, shorter wavelength of interest. A recent FERMI paper illustrates 500 shot reproducibility of 8th harmonic spectra at 32.5nm (obtained from a 260nm seed laser) exhibiting normalized photon/energy stability in the order of 7x10^-5 (root mean square), a marked improvement over previous SASE FEL data obtained over the same photon energy range. The high purity monochromatic spectra of an HGHG seed laser improves the system's shot to shot repeatability as its mode of operation does not incur the statistical deviation phenomena found in spontaneous emission spectra typically observed in a SASE FEL. As such, an HGHG FEL might be more advantageous for use in EUV applications requiring highly precise dosimetry, possibly reducing shot noise phenomenon. 

The EUV Source Challenge Ahead

Large scale projects are underway to build FEL systems to accommodate a wide range of wavelengths and scientific applications. FEL is next generation laser technology which is perhaps the best candidate to replace the LPP/EUV source designs currently offered by ASML.

Known for its work in actinic inspection at the 13.5 nm EUV wavelength, Lawrence Berkeley CXRO Lab [6] is also part of a DOE consortium currently working on LCLS-II (Linac Coherent Light Source-II) [7] at Lawrence Livermore and SLAC. Last June at the 2015 International Workshop on EUV Lithography in Maui, Aaron Tremaine of SLAC presented a comprehensive review of possible FEL designs that might be considered for EUV lithography and identified the consortium of DOE laboratories participating in the EUV FEL program. The Who's Who list of DOE participants includes SLAC, Lawrence Berkeley National Labs, Fermilab, Argonne National Lab, Cornell, UCLA, RadiaBeam, AES and Radiasoft. In order to appreciate the scale and capital intensity of this project it becomes necessary to review Aaron Tremaine's 2015 EUV Litho, Inc. Workshop presentation, LCLS-II and Free electron laser drivers for EUV Lithography [8]. The report describes FEL design considerations and recommends a “Straight Shooter” beamline configuration for semiconductor EUV lithography applications. The report addresses Erik R. Hosler's (GLOBALFOUNDRIES) 2015 SPIE publication, “Considerations for a free-electron laser based extreme-ultraviolet lithography program”, (Proc. of SPIE Vol. 9422, 94220D, 2015). The good news is that many new FEL programs are in progress [9] and the LCLS-II at SLAC might provide a viable, solution for HVM/EUV lithography. More recently, visible collaboration between GLOBALFOUNDRIES and SLAC has established the ground work for possible in-fab FEL source designs. The subsequent challenge for any future FEL/EUV initiative, is that once again the convergence of the semiconductor industry and our national laboratory community will be required to deliver future lithography source technology for EUV and beyond.

ASML has taken the lead in providing viable interim EUV technology permitting the characterization of materials, resists, masks and process precision required for future generation lithography. Double patterning techniques utilizing 193i lithography will continue to enable CDs =<10nm. We can also speculate how 13.5nm multiple patterning might enable future nodes and continued process development. In the interim, the current ASML LPP/EUV initiative has enabled the ground work our industry requires for future precision nanometer scale lithography.

Let's continue working together to secure next generation EUV and the preservation of Moore's Law.

During the course of researching this article I digested many components of the SLAC Conceptual Design Report for the LCLS-II (Linear Coherent Light Source).  Among many, two components of the LCLS-II are the SXR (Soft X-Ray) and HXR (Hard X-Ray) undulators and their respective beam lines.  It is with some amusement that my FCC designated amateur radio call sign is WA2HXR which I acquired in 1970. It should be noted that my amateur radio operations are restricted to applicable licensed amateur radio frequency spectra which excludes X-Ray wavelengths.  
CQ SLAC CQ SLAC CQ SLAC DE WA2HXR K.     73   

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Thomas D. Jay
Semiconductor Industry Consultant
Thomas.Dale.Jay@gmail.com
https://ThomasDaleJay.blogspot.com

Thomas D. Jay YouTube Channel

Visit my new Amateur Radio blog at:
www.WA2HXR.blogspot.com


















Corporate, private entities or publications referenced or linked in this article are the respective owners of their logos, trademarks, service marks, media content and intellectual property. Unless otherwise disclosed, Thomas D. Jay has no financial interest in companies referenced in blog articles or other published media communications. Thomas D. Jay is not a registered financial advisor. No representation is made to either buy or sell securities. Opinions expressed by Thomas D. Jay are his own. Thomas D. Jay does not employ or otherwise utilize/authorize third party agents to express his opinions, represent his interests or conduct business on his behalf except where formally contractually designated. Thomas D. Jay does not agree to indemnify or hold harmless vendors, clients or third parties to related contractual agreements and reserves the right to applicable legal remedies in lieu of arbitration. These terms are subject to change. Concerned parties should check this blog site for periodic updates.

Acknowledgments and Reference Links

[1] Free Electron Laser
Wikipedia

[2] Future FEL/EUV Strategy – The Light at the End of the Beam Line
Thomas D. Jay, Blog Publication, September 20, 2014

[3] ASML and Carl Zeiss acknowledged in an invited paper at SPIE Advanced Lithography 2015, that higher resolutions will require 60mJ/cm2 for half pitch nodes <8nm
SPIE Proceedings

[4] Extending extreme-UV lithography technology
SPIE News Room, Erik R. Hosler, Obert R. Wood II, Moshe E Preil

[5] The first solid state, 694nm synthetic ruby laser produced at Hughes Research in 1960
Wikipedia

[6] Lawrence Berkeley CXRO Lab
Lawrence Berkeley National Labs CXRO Web Site

[7] Linac Coherent Light Source-II
Stanford Linear Accelerator Web Site

[8] LCLS-II and Free electron laser drivers for EUV Lithography
Aaron Tremaine Presentation, SLAC
EUV Litho, Inc. Web Site, 2015 Program, Maui

[9] many new FEL programs are in progress
University of California, Santa Barbara FEL Web Site
Site Maintained by G. Ramian

Silicon Photonics in the Year of Light

As we celebrate UNESCO's International Year of Light 2015, it is with some irony that earlier this month on May 12, 2015 IBM announced [1] it had fully fabricated and tested an integrated wavelength, multiplexed 100 Gb/sec silicon CMOS nano-photonic optical tranceiver chip whose design concept was first announced in December 2010 [2]. IBM's effort is echoed by consortiums of major players in the semiconductor industry, all in hot pursuit of silicon photonics [3] technology, and for good reason. The silicon photonics market is estimated to be worth $975 Million by the year 2020 [4]. Key players in this market include IBM, Intel Corporation and the CLR4 Innovators, PETRA (Japan's Photonics Electronics Technology Research Association), Hamamatsu Photonics, Finisar Corporation, Luxtera, Inc., ST Microelectronics, 3S Photonics, Oclaro Inc., Mellanox technologies, and Infinera Inc. The Optical Fiber Communication Conference and Exposition (OFC) [5] took place in Tokyo in March this year where many of these companies presented reports on their silicon photonic technologies.

IBM's recent announcement places emphasis on its compact device package and process proven fabrication techniques which will enable larger scale manufacturing of the devices for use in cloud computing and data centers in anticipation of “Big Data” network scaling. While IBM's most recent announcement is coincident with the International Year of Light, silicon photonics have been a glimmer in the eyes of semiconductor engineers for the past thirty years. In a recent SPIETV video presentation on silicon photonics, Yurii A. Vlasov of IBM [6] stated that during the past ten years over $1.5 B has been spent in the global quest for light based chip technology.  A portion of this investment resulted in an IBM silicon nano-photonic device design in which interconnected beams of wave guided light replace traditional electrical signals carried on copper circuit paths. Data carried by electrical signals on copper circuits propagate at only 66-70% of the speed of light as determined by dielectric properties near conductors and other physical factors. Device design engineers anticipated the day when this speed limitation would slow network server systems, as well as chip to chip intra-device data flow, and eventually singular on chip communications. To most smart phone owners, it's difficult to imagine a scenario in which electrical signals traveling at 66 to 70% of the speed of light becomes a limiting factor in computer chip design and performance, but in a world where global communications servers are linked by fiber optics, satellites and GPS navigation systems, cumulative device delay times have already created bottle necks in our global networks.

Interestingly, many original glass fiber optic cables transported light at about 70% of light's velocity in a vacuum.  New research and development in fiber optics and materials have resulted in the fabrication of optical fibers which can transport light at better than 99% of its vacuum velocity (186,282 miles/sec).  New silicon photonic devices are being optimized to provide maximum light velocity [7] while simultaneously implementing WDM (Wave Division Multiplexing) to maximize data speeds and throughput.  As such, silicon photonic devices might vary in performance as per the designs of their manufacturers.  

Why are silicon photonics important? I'll review some important observations I've made in my November 2013 blog article, “The Cloud of Nations” [8].

On a global scale we observe that in a vacuum, light travels approximately 186,282 miles per second and can circle the earth in 134 milliseconds (about one tenth of a second). If we consider the earth as a large computer, the continents might be compared to microprocessors interconnected by our global Internet, milliseconds apart. If we observe our immediate, personal photometric sphere of existence, we find that in one nanosecond light travels one foot. How precise must our world be?

Chip Level Clock Skew

In the metrics of semiconductors nanosecond measurements are woefully imprecise and we must calibrate metrology in picoseconds in order to measure the speed of data traversing millimeter sized computer chips. In the semiconductor industry we refer to differences in data arrival time on a computer chip as clock skew. On a real semiconductor device, electrical signals on copper conductors travel at approximately 66-70% of light speed. An acceptable clock skew range approximating 20 to 200 picoseconds (pico = 10^-12) usually provides acceptable device performance but this specification can vary across device types and circuit designs. For each tick of the chip's master system clock, billions of transistor gates must be switched on and off in precise unison. A microprocessor operating at a 2 gigahertz clock speed must have sufficient temporal uniformity across the device so that the arrival time of gate switching signals are all within an acceptable time window. If the switching signal's arrival time falls outside this window, the microprocessor and the program it's running will crash. Careful design considerations go into device fabrication technique and wafer processing to ensure product and performance quality. More information on computer chip clock skew can be found in the paper “Skew Variability in 3-D ICs with Multiple Clock Domains” [9] Hu Xu, Vasilis F. Pavlidis, and Giovanni De Micheli, LSI - EPFL, CH-1015, Switzerland Email: {hu.xu, vasileios.pavlidis, giovanni.demicheli}@epfl.ch

As clock speeds increase and device geometries decrease, the <10nm design node will pose additional technical challenges in device timing and data throughput. The evolution of light speed photonic interconnects for on and off chip communication will minimize concerns with clock skew across chips and networks as device structures shrink to critical dimensions (CD) <10nm and become stacked in dense arrays. As the integration of CMOS silicon nano-photonics matures, we may eventually see microprocessors, memory chips and 3D devices structured on photonics instead of conventional copper conductors. In the interim, IBM anticipates that the more immediate advantages afforded by silicon nano-photonic inter-chip speeds could dramatically improve cloud server/network performance, and advance its Exascale super computer initiative which could potentially perform over a thousand times the speed of currently available systems. While the initial focus of silicon nano-photonics targets network centers and cloud servers, the wider proliferation of the technology can profoundly effect our evolving Internet.

IBM's silicon photonic chip will address concerns across networks as four 25 Gb/sec optical tranceivers operating on as many different wavelengths will combine to provide a throughput of 100Gb/sec. Installed in server systems, these optical chips could dramatically improve data throughput, reducing network latency and clock skew by eliminating delays inherent in copper conductors found in servers and data center network interfacing. Using sub 100nm design rules (typically 90nm), electrical and optical device structures are formed on the same substrate to maximize efficiency. IBM estimates the device's bandwidth can accommodate the transfer of a high definition movie (approximately 1.5 to 2 Gigabytes) in two seconds.

To achieve maximum bandwidth over distance, most of today's data centers employ Vertical Cavity Surface Emitting Lasers (VCSEL) distributed on multi-mode optical fiber. Remotely located cloud servers have placed new demands on network resources as even larger bandwidths over greater distances are required. To illustrate the importance of IBM's initial 2010 achievement, note that IBM's on-chip silicon photonic wavelength multiplexing emulates the initial success of dense wave multiplexing utilized in early generation fiber optic networks, the major difference being that IBM has achieved this capability at the chip level.  Previous dense wave fiber optic implementations utilized bulky hardware to enhance long haul fiber optic bandwidth. In 1998, AT&T researchers transmitted 100 simultaneous optical signals, each at a data rate of 10 gigabits per second over a distance of 400 km utilizing dense wavelength-division multiplexing (DWDM) technology [10], allowing multiple wavelengths to be combined into one optical signal. This technique increased the total data rate on one fiber to one terabit per second. Although IBM's current silicon photonic chip design utilizes 4 discreet channel wavelengths providing 100Gbit/sec, data throughput is scalable and could be configured to accommodate many demanding applications. While IBM's silicon nano-photonic initiative is impressive, significant global competition is not far behind.

Intel's CLR4 Silicon Photonic Initiative

The silicon photonic initiative is also being pursued by Intel [11] who has helped form a consortium of companies to agree upon product designs and industry standards. The CLR4 Innovators [12] are an alliance of 27 companies inclusive of Intel, HP, Dell, MACOM and SEMATECH (see the above CLR4 link for a complete list).  In April 2014, Intel outlined its silicon photonic initiative in a presentation [13] which addresses the common requirements of the CLR4. The 100 Gb/sec silicon photonics under development utilizes 4X25 Gb/sec tranceivers which can span 1000 meters to link server centers.

Unfortunately, Intel's initiative was set back in February this year as a key component in its silicon photonic module did not meet specifications and quality control standards. [14] The new modules will not ship till the end of 2015 which means they won't be installed till early 2016. Intel's customers (and possibly CLR4 Innovator members) intending to integrate its silicon photonic technology are in a holding pattern till next year.

PETRA's Silicon Photonic Demonstration

Japan's Photonics Electronics Technology Research Association (PETRA), recently demonstrated [15] 100 Gb/sec transmissions over 300 meters using its silicon photonics device technology. The device's 5mm x 5mm package containing 4x25 Gbp/sec transceivers, can be expanded to 12 or more channels to obtain throughputs greater than 300 Gbp/sec.  This scalability enables accommodation of future demands and upgrades of installed network infrastructure.  

Silicon Photonic Research at IMEC

IMEC is also active in silicon photonic research. In February 2015 this year at the International Solid State Circuits Conference, IMEC and its collaborators released results of recent developments in their laboratories [16] demonstrating a 4x20 Ghz/sec wavelength division multiplexing hybrid CMOS silicon photonics tranceiver.  The larger global effort to standardize silicon photonic performance specifications sets the stage for future implementation over many platforms.

Silicon Photonics and The "Internet of Things"

Silicon photonics can assist us in resolving a potential net neutrality dilemma. Much has been debated regarding the FCC's recent adaption of a net neutrality policy which precludes Internet service providers from charging premiums for high speed commercial traffic on the web while intentionally throttling speeds on their networks. Conspicuous consumption of bandwidth by consumers is now the norm given HD and 4K video programming available on the web. If you travel frequently and patronize fast food establishments or coffee shops and use their complementary Wi-Fi systems, you become acutely aware of the limitations on available bandwidth. Many fast food restaurants preface their Wi-Fi login screens with disclaimers of suitability for a particular use, proclaiming “intended for text and email only” and “not intended for video streaming”. All too often, email and other essential services are slow when compared with Asian and European networks. The intentional throttling of Wi-Fi bandwidth often lowers video resolutions to “wax paper” quality. It's disheartening to see 1080P video rendered at resolutions below that of 1960s era analog broadcast quality. Will the FCC's net neutrality policy effectively address these concerns? Should the concept of net neutrality also accommodate the anticipated “Internet of Things” (IoT)? The IoT envisions the interconnection of “things” on the web to include household utility monitors, appliances, cars, watches, and any imaginable “thing” assigned an IP address. A few months ago I read a story describing hackers launching malware they had placed on someone's refrigerator sporting an on board computer. The fridge's door featured an HD flat screen providing an interactive family kiosk in the kitchen, but connected to the web it also kept malware in cold storage. Should ISP's be required to provide equal bandwidth and network routing for email, video conferencing, refrigerators and toasters? A humorous question, but if you're video conferencing from the fridge while snacking in the kitchen, net neutrality/equality for appliances becomes a pertinent IoT policy discussion. That said, the new IPv6 Internet protocol will provide an exponential increase in available URL's required for new email addresses, web sites and “things” attached to the web. Accordingly, the projected increase in Internet traffic can only be accommodated by enhancing routing systems and cloud services, ensuring network speeds are optimized and remain viable as global connectivity escalates.

In this regard we might agree that from both consumer and enterprise perspectives, silicon photonic solutions are long overdue and will enjoy rapid acceptance when available for shipment and implementation.

Closing Thoughts

- It will be interesting to track the evolution of silicon photonics as market demands are met with the delivery of Intel's technology to the CLR4 group of companies.

- IBM will seek to optimize its positioning in the enterprise markets, leveraging its silicon nano-photonics, cloud server infrastructure and possible ramp of MRAM technology for strategic product applications. IBM's advances could also provide “warp speed” for networks if additionally optimized with its fasp (TM) Aspera [17] file transfer platform.

- IMEC could leverage its own silicon photonic designs as its partnered R&D effort yields finished products ready for deployment.

- PETRA and its member companies have demonstrated competitive silicon photonic technology with the ability to scale for future throughput demands. 

- Possible additions to the silicon photonic market equation are prospects for more efficiently deployed Software Defined Networking (SDN) [18] which could reduce traditional hardware and infrastructure costs while enhancing network speed, efficiency and reliability.

- Lucent Bell Labs has introduced an ultra-dense network architecture designed for silicon photonics at the optical network unit. [19] A proof of principal experiment demonstrated an FDMA architecture providing up to eight 300-MBd 16QAM (Quadrature Amplitude Modulation) subbands providing a bidirectional data rate of 9.6 Gb/sec.

As silicon photonic infrastructure expands to enhance our global networks, we may eventually see the migration of this technology to microprocessor and memory devices for use in super computing and consumer products.  Congratulations to IBM, Intel and the global technology alliance members who are working to enlighten our future with photonics.

Please join me in supporting SPIE and the International Year of Light 2015 [20] (click on the icons below for additional site links).

Thomas D. Jay
Semiconductor Industry Consultant
Thomas.Dale.Jay@gmail.com 
www.ThomasDaleJay.blogspot.com
Thomas D. Jay YouTube Channel

Visit my new Amateur Radio blog at:
www.WA2HXR.blogspot.com

Corporate, private entities or publications referenced or linked in this article are the respective owners of their logos, trademarks, service marks, media content and intellectual property.  Unless otherwise disclosed, Thomas D. Jay has no financial interest in companies referenced in blog articles or other published media communications. No representation is made to either buy or sell securities. Opinions expressed by Thomas D. Jay are his own. Thomas D. Jay does not employ or otherwise utilize/authorize third party agents to express his opinions, represent his interests or conduct business on his behalf except where formally contractually designated.  Thomas D. Jay does not agree to indemnify or hold harmless vendors, clients or third parties to related contractual agreements and reserves the right to applicable legal remedies in lieu of arbitration.  These terms are subject to change. Concerned parties should check this blog site for periodic updates.

Acknowledgements and Reference Links

[1] https://www-03.ibm.com/press/us/en/pressrelease/46839.wss
IBM Press release, IBM web site May 12, 2015

[2] https://www-03.ibm.com/press/us/en/pressrelease/33115.wss
IBM Press Release, IBM web site, December 1, 2010

[3] http://en.wikipedia.org/wiki/Silicon_photonics
Wikipedia

[4] http://electronics.wesrch.com/paper-details/press-paper-EL1GP94JCLEHH-silicon-photonics-market-worth-497-53-million-by-2020
WeSRCH web site, MarketsandMarkets press release uploaded May 27, 2015

[5] http://www.ofcconference.org/en-us/home/about/
OFC web site

[6] https://www.youtube.com/watch?v=KRY53sEXyNI
Yurii A. Vlasov, SPIETV, YouTube

[7] http://www.nature.com/nphoton/journal/v7/n4/full/nphoton.2013.45.html
Nature Photonics

[8] http://www.thomasdalejay.blogspot.com/2013/11/the-cloud-of-nations.html
ThomasDaleJay.blogspot.com

[9]http://infoscience.epfl.ch/record/173534/files/ISCAS_11_1.pdf?version=1
InfoScience web site, Hu Xu, Vasilis F. Pavlidis, and Giovanni De Micheli, LSI - EPFL, CH-1015, Switzerland Email: {hu.xu, vasileios.pavlidis, giovanni.demicheli}@epfl.ch

[10] http://www.fiber-optics.info/history/P3/
Fiber Optics History web site

[11] http://www.intel.com/content/www/us/en/research/intel-labs-silicon-photonics-research.html
Intel web site

[12] http://www.intel.com/content/www/us/en/research/intel-labs-clr4-adopter-listing.html
Intel web site

[13] http://www.intel.com/content/www/us/en/research/intel-labs-clr4-presentation.html
Intel web site

[14] http://www.pcworld.com/article/2879152/intel-delays-part-for-highspeed-silicon-photonic-networking.html
PC World web site, Agam Shah, IDG News Service
February 2, 2015

[15] http://www.ofcconference.org/en-us/home/news-and-press/exhibitor-press-releases/petra-demonstrates-low-power-silicon-photonics-i-o/
OFC website

[16] http://www2.imec.be/be_en/press/imec-news/imec-ugent-tyndall-silicon-photonics-transceiver.html
IMEC web site

[17] http://asperasoft.com/resources/white-papers/ultra-high-speed-transport-technology/?gclid=Cj0KEQjw1pWrBRDuv-rhstiX6KwBEiQA5V9ZoXa1_o6T48KX_XxsJ95irqG6EuLgXtaJmB7fkHAFaNsaAnzj8P8HAQ
IBM Aspera web site

[18] https://en.wikipedia.org/wiki/Softwaredefined_networking
Wikipedia

[19] http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6997998
IEEE Xplore web site


[20] https://www.youtube.com/watch?v=-R8jJ0wPM2Q
International Year of Light 2015, Official Trailer, YouTube

A Defining Inflection in the EUV Continuum

An April 22, 2015 ASML press release [1] announced an agreement with one of its major US customers (believed to be Intel) to purchase a minimum quantity of fifteen of its NXE:3350B EUV lithography systems with two of the units slated for delivery year end 2015. Intel has previously invested over $4 Billion in ASML. Given the size of the order, it would appear that Intel will proceed with a large scale strategic commitment to EUV lithography for future production process nodes =<10nm, with a path to 7nm and smaller CDs.

Although financial details of the purchase were not released, a sizable capital equipment expenditure has been made after many years of delay and uncertainty in the EUV program. This purchase transaction represents a large scale, high profile commitment to what has been a capital intensive development program delayed by uncooperative laws of physics, semiconductor sector business cycles, and capital market dynamics. It seems that the semiconductor production road map has been sufficiently refined, concomitant with related process technologies, and that confidence has been restored in long term EUV/HVM convergence/insertion forecasting. Although Intel's eventual commitment to production EUV had been anticipated, the waiting game is over. The remaining field of industry players who have withheld their commitments to EUV might now be motivated to secure anticipated purchase positioning with ASML before delivery date extensions become a concern.

SPIE Advanced Lithography 2015 was likely a key catalyst triggering this defining inflection point as process experts from around the globe converged to announce new and encouraging breakthroughs in lithography and related technologies which have heretofore gated the EUV program. We might review some of the important observations and breakthroughs which comprise the critical mass of the inflection:

EUV Inflection Triggers

Probable Key Factors in Intel's EUV Decision

- While lithographers have entertained DSA and electron beam lithography as developmental candidates for 7nm scaling, given current evolution, only 13.5nm stepper/scanners can provide the image resolution and throughput required for both pilot line and future HVM.

- SEMATECH recently announced the development of a metal oxide based photoresist which reduces the EUV power output required for EUVL dosimetry (typically 15 – 20 mJ/cm2) to less than 2 - 3 mJ/cm2. [2] The new resist enables process development at reduced EUV power levels, but will not eliminate the future requirement for higher HVM source power. In the interim, it's possible that process solutions can be built around this low dose resist, enabling further, accelerated development of EUV HVM.

- During SPIE Advanced Lithography on February 24, ASML announced TSMC's confirmation that it had processed 1022 wafers in twenty four hours [3] on its NXE:3300B with a sustained source power of 90 watts. There is encouraging new data illustrating improved MTBF while sustaining EUV source operation at higher power levels.

- ASML has made significant over all progress in EUV development and has recently updated its time line for implementation of key milestones. ASML released many new updates on their EUV program at SPIE Advanced Lithography 2015 which were quite voluminous (see the post conference SPIE abstract summary).

- Obstacles to 7nm and future nodes have been addressed. ASML and Carl Zeiss acknowledged in an invited paper at SPIE Advanced Lithography 2015, that higher resolutions will require 60mJ/cm2 for half pitch nodes <8nm. [4] ASML's work with Carl Zeiss has produced an optical system with a numeric aperture (NA) of 0.55 vs. ASML's current EUV NA of 0.33. The higher NA system will require 500 watts of EUV power to achieve the estimated 60 mJ/cm2 dosimetry required for throughput of 150 wafers/hour. While this ASML/Carl Zeiss achievement paves the way for =<7nm process nodes, current R&D programs are also under way to provide a visible path to a >500 watt free electron laser EUV source, identifying one of the last major puzzle pieces in ASML's EUV endeavor. While ASML continues to refine Laser Produced Plasma source technology, the future availability of a >500 watt free electron laser EUV source remains a critical item on the agenda, and will probably gate the time lines of related programs.

- ASML has entered the pellicle business in the self interest of providing viable protection for EUV photomasks from particulate contamination. The polysilicon based pellicles are transparent to EUV with a one pass transmission loss approximating 14% and seem to exhibit sufficient durability for use in production. Previous uncertainty in EUV pellicle viability and availability have been resolved.

- As a key semiconductor industry supplier, Veeco Instruments has been successful in providing ion beam deposition tooling enabling EUV mask fabrication for advanced process nodes within acceptable defect limits. Defect free mask fabrication for advanced nodes has been a gating factor in the EUV program.

- Advancements in actinic inspection are progressing. Lawrence Berkeley National Laboratory's CXRO has been developing the SHARP EUV microscope in cooperation with SEMATECH . [5] A progress report on mask inspection was made at SPIE Advanced Lithography 2015. The SHARP EUV microscope is illuminated by an EUV synchrotron light source within the CXRO complex. The commercial availability of EUV obtained from free electron laser technology could enable the emulation of SHARP's capabilities given comparable optical and analytical performance.

- Future commercial availability of free electron laser EUV sources could also offset concerns gating the development of actinic inspection tools by KLA-Tencor and others. Given proper design, it's possible that a single free electron source beamline could provide EUV source illumination for both stepper/scanner clusters and in-line actinic inspection tools.

- Recent successes at TSMC with ASML's NXE:3300B EUV systems have prompted an additional order for two newer model NXE:3350B tools. As foundry commitments to EUV lithography continue, Intel has taken a major strategic step to ensure its competitive leadership positioning in the global wafer fabrication market.

No doubt there were many other considerations factored into Intel's EUV purchase decision. Ultimately the achievement and convergence of key process and equipment performance concerns have prompted a major commitment to both lithography and investment strategy over the longer term. In doing so, Intel has set a defining course for the semiconductor industry.

Please join me in supporting SPIE and the International Year of Light 2015 (click on the icons below for additional site links).

Thomas D. Jay
Semiconductor Industry Consultant
Thomas.Dale.Jay@gmail.com
www.ThomasDaleJay.blogspot.com
Thomas D. Jay YouTube Channel

Corporate, private entities or publications referenced or linked in this article are the respective owners of their logos, trademarks, service marks, media content and intellectual property.  Unless otherwise disclosed, Thomas D. Jay has no financial interest in companies referenced in blog articles or other published media communications. No representation is made to either buy or sell securities. Opinions expressed by Thomas D. Jay are his own. Thomas D. Jay does not employ or otherwise utilize/authorize third party agents to express his opinions, represent his interests or conduct business on his behalf except where formally contractually designated.

Acknowledgements and Reference Links

[1] ASML press release 

Link to ASML web site press release.

[2] photoresist which reduces the EUV power output required for EUVL dosimetry
Link to SEMATECH web site.

[3] ASML announced TSMC's confirmation that is had processed 1022 wafers in twenty four hours
Link to ASML web site press release.

[4] ASML and Carl Zeiss acknowledged in an invited paper at SPIE Advanced Lithography 2015, that higher resolutions will require 60mJ/cm2 for half pitch nodes <8nm.
Link to SPIE Digital Library abstracts, SPIE Advanced Lithography 2015.

[5] Lawrence Berkeley National Laboratory's CXRO has been developing the SHARP EUV microscope in cooperation with SEMATECH
Link to SPIE Digital Library abstracts, SPIE Advanced Lithography 2015

The Cloud of Nations

Our world has been transformed by photonics. Our government, businesses and many of our personal activities are assisted or managed by what has been termed a “cloud” based infrastructure of computers, servers and a global communications network enabled by advanced photonic devices, lasers and fiber optics.  (Students: Click on the blue TDJ logo above for more on advanced photonics; become a scientist or engineer and help design our photonic future)  It can be argued that in addition to the physical world, governments and society also maintain a shadow, hyperspace existence in the cloud. The continued research, development and evolution of these technologies is integral to the growth of our economy, society and national defense. In recognition of this significance, SPIE, (The International Society for Optics and Photonics), OSA (The Optical Society), LIA (Laser Institute of America), IEEE Photonics Society and the American Physical Society have teamed to form the National Photonics Initiative (NPI). The NPI has embarked on a campaign to gain visibility with our government, key funding agencies and other industry partners to:

• Drive funding and investment in areas of photonics critical to maintaining US competitiveness and national security.

• Develop federal programs that encourage greater collaboration between US industry, academia, and government labs.

• Increase investment in education and job training programs.

• Expand federal investments supporting university and industry collaborative research.

• Collaborate with US industry to review international trade practices.

The discussion points above were excerpted from the NPI's recent white paper. For a more detailed description of the NPI agenda visit www.lightourfuture.org. [1]

Photonic technologies have made a major impact on our society, simultaneously enabling advanced capabilities in computing, communications, manufacturing and their disruptive derivatives. Disruptive derivatives can vary in magnitude, yielding both laser guided weapons and unexpected video calls on your smart phone. For the purpose of this article, I will briefly review the history and development of the significant photonic technologies which have enabled what we now call the “cloud” and discuss some of the social-political ramifications.

The Development of the Laser

The fundamental physics behind the laser were theorized by Albert Einstein and Max Plank. Their theories were later confirmed by Rudolph W. Leydenburg, Valentin A. Fabrikant, Willis E. Lam and R.C. Retherford. In later years Charles Hard Townes developed the MASER (Microwave Amplification by Stimulated Emission of Radiation) a microwave amplifier, and later at Bell Laboratories worked with Arthur Leonard Schalow to conceptually define infrared and optical lasers. In 1958 Bell Labs applied for a patent on an optical MASER based on their work. At Columbia University Gordon Gould was conducting graduate work on thallium emissions and in November 1957 coined the acronym LASER to define Light Amplification by Stimulated Emission of Radiation. Conducting concurrent competitive research, Theodore H. Maiman operated the first solid state flash lamp pumped 694 nanometer synthetic ruby LASER at Hughes Research in Malibu California on May 16, 1960. [2]

The Fiber of the Cloud

Ten years later in 1970, Corning, Inc. announced that researchers Robert D. Maurer, Donald Keck, Peter C. Schultz, and Frank Zimar had developed and tested an optical fiber with a low optical attenuation of 17 dB per kilometer by doping silica glass with titanium. After conducting additional research they later produced a fiber with an attenuation of only 4 dB/km, using germanium oxide as the core dopant. This low loss quality over longer distances made fiber optic cable practical for telecommunications and networking. Corning became the world's leading manufacturer of optical fiber. [3]  

Continued improvements in fiber-optic materials have reduced line losses and capacity is being further optimized by utilizing multi-wavelength lasers for data transmission.  In 1990, Bell Laboratories transmitted a 2.5 Gb/s signal over a distance of 7,500 km without repeater regeneration by utilizing a soliton laser and an erbium-doped fiber amplifier.  In 1998, AT&T researchers transmitted 100 simultaneous optical signals, each at a data rate of 10 gigabits per second over a distance of 400 km utilizing dense wavelength-division multiplexing (DWDM) technology, allowing multiple wavelengths to be combined into one optical signal.  This technique increased the total data rate on one fiber to one terabit per second. [3A]

Our Global Photonic Schematic

Today, the backbone of our global communication system is comprised of an interconnected fiber optic cable infrastructure spanning the oceans, continents and civilized peripheries. The first undersea cable networks laid by ships supported telegraphy only, later evolving and expanding to accommodate voice communications via telephone. Network traffic was limited by the number of conductor pairs in the cables and long distance communication was sometimes problematic. Electronic relays were required to maintain call quality over long distances and troubleshooting was challenging as transoceanic cables lying on the sea bottom were difficult to locate, retrieve and repair. Over time, copper conductors were replaced with fiber optic cables and the communications revolution we are witnessing today began in earnest.  The AT&T Tech Channel features an informative video describing the evolution of the undersea fiber optic cable system [4] currently connecting our world.  Today there are over 321 major cables connecting the continents [5] (most under the sea) providing audio, high definition video and data transmission for our global community. Access to this advanced network can be had for the price of a smart phone. Utilizing services like Apple's FaceTime, Google Voice or Microsoft's Skype, it's possible to make real time two way video calls to friends, relatives or businesses almost anywhere on the Earth. This connectivity extends to most of the 3G and 4G cellular networks as well as the Wi-Fi systems we find at the corner coffee shop.

The Cloud of Nations

The early 1980s began the evolutionary period in our history in which we saw the rapid expanse of the internet along with the conception and realization of the “Cloud”. E-commerce and the idea of utilizing large data storage centers to strategically manage inventory and facilitate business transactions changed a fundamental business model which continues to evolve. The concept of in-country brick and mortar manufacturing sites and retail store distribution are being rethought every day. The acceleration to a web centric existence has transformed banking, trading, manufacturing, retail markets, personal communications and governments.  How so?

The internet connected cloud enabled by photonics has become the continuum in which multinational corporations and many governments reside. Independent of the necessity for fixed, localized manufacturing and distribution, large multinational corporations and small businesses can participate in an electronic global market place. A company in the US can own factories in Asia which produce and ship products world wide. Similarly, many foreign based companies own large manufacturing facilities in the US simplifying the distribution of their products here. The financial industry has been transformed as the international stock exchanges and banking institutions can now complete transactions in milliseconds or less. The undersea cable system made overnight international wire transfers possible. After business hours, banks in the U.S. can wire transfer large monetary holdings to banks in Australia or Asia where a more favorable overnight interest rate might be obtained (Australian banks typically pay a better overnight interest rate). Having earned significant interest overnight, these large monetary sums can be returned to the originating U.S. bank restoring local liquidity in time for opening business hours the following morning. The evolution in global business and trade among nations has brought our world closer together as an inter-dependent community made possible by the ubiquity of the world wide web, complements of advanced photonics.

Recent history has taught us that idealistic global business models don't always work to resolve disputes.  During the first Persian gulf conflict there was an exodus of Kuwait's displaced population to Europe and the United States. Interestingly, the Kuwaitis took their country with them. With electronic access to their country's wealth and the international banking system, Kuwait continued to function as a country and business entity in the cloud [6] via the web. For the first time in the world's history a nation existed and functioned electronically in hyperspace, untethered from its physical geography. Kuwait's political existence extended to its world wide connectivity with banking institutions, embassies and the United Nations. Similarly, Kuwait's finances and trading activities were all remotely accessible through the stock exchanges and SWIFT computers connecting the international banking system. Many of Kuwait's displaced citizens abroad established temporary residency in Europe and the U.S. aided by the continued financial support of their Kingdom which was fully functional on the web. This impressive logistical feat was managed remotely from hotel suites and conference rooms with laptop computers and direct access to major financial institutions outside the middle east.

Partly Cloudy

We like to think our internet system is fast and efficient, however high speed data crossing the oceans in milliseconds from distant continents at the speed of light are often stalled during local distribution and routing by network hubs which provide last mile connectivity to your home or business. A good example of this phenomenon can be found at fast food restaurants or coffee shops which provide wireless internet service to patrons. Sometimes while having coffee at a local establishment I'll use the wireless service to watch business news often featuring live programming feeds from Asia or Europe. Although this programming reaches the US in a fraction of a second, local network and distribution routers ration the data packets as they time share the program feed among thousands (or millions) of on line recipients. The resulting multiplexing and buffering of the programming can start and stop the video program on your computer every few seconds revealing the latency in the local distribution server as it slows to accommodate everyone, sometimes providing only a few program frames at a time. In these situations some news programming and streaming movies are not viewable and must be downloaded or viewed later on a faster network. Having experienced this phenomenon, I sometimes find myself exclaiming the virtues of 35mm movie film which runs at full program speed without interruption. Much of our wired internet infrastructure has not kept pace with 4G wireless and new 802.11ac distribution speeds and needs to be upgraded.

As compared with much of the world, the US is behind the curve in providing high speed Internet service.  A November 27, 2013 study reported by Techspot.com indicates the U.S. currently ranks 31st place in the world's Internet connection speed rankings. [7]  Current international speed ranking data can be found here [8] as conducted by Speedtest.net.  In addition we are behind in implementing the new IPv6 internet protocol which will enhance security and network standardization with the rest of the world.  As a technology leader among nations, we can do much better. Some might think this comparison unfair as the United States has a much larger land mass and population making a continual nation wide upgrade of Internet capacities and ISP inter-connectivity a capital intensive proposition. Realistically this cost consideration is not an impediment as our larger U.S. economy and consumer markets will rapidly consume any capacity upgrades made by Internet service providers. An abundant dark fiber infrastructure (previously installed and underutilized fiber optic cable) is readily available for augmentation of existing internet capacity. Rather than reconstruct my thoughts on this subject I will quote myself from recent comments I made while responding to an article appearing on Seeking Alpha.com, an investment newsletter web site.  Thomas D. Jay commentary posted on Seeking Alpha.com September 12, 2013 [9]

“Demands for Internet bandwidth will grow rapidly as new technology comes on line. The new Samsung S4 smart phone and Apple MacBook Air both feature the new 802.11ac wireless standard which operates on both 2.4 and 5 GHz at three times the speed of 802.11n. New 802.11ac routers are now available for commercial and home use. New smart phones and computers will soon get a wireless speed upgrade of 3X. Cable companies will be shifting strategies to accommodate consumers who stream video on the net in addition to those who subscribe to the standard menu of channels on their systems. The move is toward the wide scale implementation (much capacity has already been installed) of 256 bit QAM (Quadrature Amplitude Modulation) providing a greater number of cable channels and capacity. 4K video (4X 1080P resolution) is here now with 16K expected in about 18 months. Kudos to Verizon Fios and Google's 1 Gbit fiber optic system, however Sony is already deploying a 2 Gbit system in Tokyo [10] in anticipation of the need for extra system bandwidth. The US has been far behind in upgrading internet bandwidth and is in need of enhanced server center capacity in addition to fiber-optic distribution networks to homes and businesses. Fios 500 Mbit bandwidth at your home is of no use if the server you're connected to is overwhelmed with the demands of thousands of 20 Mbit subscribers. The price of bandwidth will gradually decrease if network capacity successfully paces growth forecasts. [18] An old programmers' law states that computer programs will grow in size to consume all available processing power and memory. Similarly, streaming internet applications and on line services will grow to consume all available bandwidth. The challenge is to build capacity ahead of the bandwidth demand curve and reduce cost. The principal of Moore's Law should be adapted by Internet Service Providers, by doubling network capacity every two years. Big data and network demand will require it.”  An additional note on QAM:  Where high spectral bandwidth and speed is required, networks usually employ 4096 QAM which has a greater constellation density (see Wikipedia, QAM) [11].

The Need for Speed

Latency in program distribution for both national (the US) and international carriers is problematic. The cumulative wide ranging delays in program arrival time experienced by viewers on the Internet can create an unfair playing field for consumers as well as private investors. On Wall Street, investment firms strategically locate their trading computers and servers as close as possible to the NYSE/EURONEXT and NASDAQ exchanges to gain precious millisecond (or better) advantages in price quote retrieval time and trade execution speed. Investment firms closest to the exchanges have an unfair (but legitimate) trading speed advantage over competitive firms and their investors. While monitoring the media, a slow internet connection can delay the arrival of streamed investment news by as much as twenty seconds or more. As a concerned former trader I've actually confirmed this phenomenon by comparing the arrival time of CNBC's cable broadcast programming with the identical program content streamed on the Internet. Again, the big investment houses win this scenario by employing the use of supercomputers which monitor stocks, market conditions, news events, and other exchanges in real time.  IBM has worked with TD Bank Financial Group to develop high speed computer architectures for use in financial decision making and transactions. [12]  A TD Financial Group computer can monitor markets, quotes, international news, and a wide range of critical investment decision parameters. Programmed with carefully developed algorithms the system makes trading decisions dynamically based on real time data input to the system. Investment firms utilizing supercomputers enable high frequency trading which is frowned upon by some, while many exchanges welcome the liquidity these trading firms provide.

Recently the Singapore Stock Exchange (SGX) Asia's largest bourse operator, expressed interest in attracting a larger number of high speed traders to help bring additional volume and liquidity to their market. SGX has invested over $250 Million in a computer trading platform which can execute transactions in 90 microseconds. Before large scale high frequency trading takes root on Singapore's SGX, trading circuit breakers must be implemented to prevent unforeseen market volatility from adversely impacting the market. Interestingly, high frequency traders have also avoided the SGX as it extracts a transaction fee of 20 basis points (0.2%) for shares traded on the exchange. (Source: Bloomberg News 10/29/2013) [13]

Global Clock Skew

For the purposes of global trading, communications and navigation, it is imperative that clocks are synchronized everywhere on the earth. In addition to navigation assistance, our GPS (Global Positioning System) satellites also provide a time standard beacon, complements of our friends at NIST (National Institute of Standards and Technology). You can program your PC clock to sync directly with NIST instead of your network server. On a global scale we observe that light travels approximately 186,282 miles per second and can circle the earth in 134 milliseconds (about one tenth of a second). If we consider the earth as a large computer, the continents might be compared to microprocessors interconnected by our global internet, milliseconds apart. If we observe our immediate, personal photometric sphere of existence, we find that in one nanosecond light travels one foot. How precise must our world be?

Chip Level Clock Skew

In the metrics of semiconductors nanosecond measurements are woefully imprecise and we must calibrate metrology in picoseconds in order to measure the speed of data traversing millimeter sized computer chips. In the semiconductor industry we refer to differences in data arrival time on a computer chip as clock skew. On a real semiconductor device, electrical signals on copper conductors travel at approximately 66-70% of light speed. An acceptable clock skew range approximating 20 to 200 picoseconds (pico = 10^-12) usually provides acceptable device performance but this specification can vary across device types and design. For each tick of the chip's master system clock, billions of transistor gates must be switched on and off in precise unison. A microprocessor operating at a 2 gigahertz clock speed must have sufficient temporal uniformity across the device so that the arrival time of gate switching signals are all within an acceptable time window. If the switching signal's arrival time falls outside this window, the microprocessor and the program it's running will crash. Careful design considerations go into device fabrication technique and wafer processing to ensure product and performance quality. More information on computer chip clock skew can be found in the paper “Skew Variability in 3-D ICs with Multiple Clock Domains” [14] Hu Xu, Vasilis F. Pavlidis, and Giovanni De Micheli, LSI - EPFL, CH-1015, Switzerland Email: {hu.xu, vasileios.pavlidis, giovanni.demicheli}@epfl.ch

As clock speeds increase and device geometries decrease, the <10nm design node will pose additional technical challenges in device timing and data throughput. Recognizing this challenge, IBM designed computer chips that are interconnected with photonics, [15] enabling superior, high speed inter and intra-device communication utilizing beams of light instead of electrical signals carried on copper conductors. The evolution of light speed photonic interconnects for on and off chip communication will minimize concerns with clock skew across chips and networks as device structures shrink to critical dimensions (CD) <10nm and become stacked in dense arrays.

Free Space Optical Communications (FSO)

Free Space Optical Communication refers to the use of optical (visible) and the near optical (near visible) spectrum of light for line of sight transmission of communications and data. FSO is advantageous in areas where traditional radio frequency (RF) traffic is dense precluding the efficient use of available radio spectrum. FSO can also enable precisely directed communications by laser providing undetected, low profile communications for military or other secure communications. An FSO device is also a cool way of describing your infra-red TV remote control.

Wi-Fi and now Li-Fi

Recently there has been much hoopla over new computer networking hardware utilizing Li-Fi, a complementary technology to Wi-Fi (Wireless Fidelity). Li-Fi (Light Fidelity) utilizes LEDs (Light Emitting Diodes) producing visible or near visible infra-red light to propagate data transmissions in place of the typical RF (Radio Frequency) based 2.4 or 5 GHz 802.11n routers that have become ubiquitous. Some time ago I watched a TED presentation in which LED propagation of voice and data was pitched as a visionary concept. The fact is, the semiconductor industry recognized the significance of this idea and put it to work in the wafer fab many years ago.

Wafer Fab Free Space Optical Communications (WFFSO)

In the 1980's a major wafer fab equipment manufacturer provided automated guided vehicles to transport wafer lots and load process tools. The vehicles featured robotic arms and transported wafer cassette boxes. The mobile robots could open an on board cassette box and load/unload a process tool while communicating the wafer lot's status to the fab's Work In Process (WIP) tracking computer. The robots' communications with the fab was achieved with FSO cellular infrared LED clusters which were immune to radio frequency noise and interference from nearby process tools. The high intensity IR LED signals also bounced off the fab walls and ceilings to reach vehicles that were sometimes outside a direct optical path, or in shadowed areas created by fab technicians or equipment. Upload and download of vehicle and WIP programming was easily achieved using the IR data links. RF plasma etchers and other fab tools can create RF interference at their fundamental and harmonic frequencies and sometimes create “birdies” (spurious emissions) all over the RF spectrum. In most cases FSO/IR communications effectively eliminates this problem. The infrared cellular transceivers were ceiling mounted and unobtrusive. Quick visual confirmation of the system's activity was accomplished by “eyeballing” the ceiling mounted IR transceivers with a special IR sensitive viewing lens. Today it's easy to confirm IR LED activity with a smart phone. Most smart phone cameras are sensitive to a wide range of IR LEDs. Point your smart phone camera at an active IR LED (your TV remote for example) and you can see a corresponding bright white spot on your phone's display which is otherwise invisible to the human eye.

More recently it's been possible to operate long distance point to point FSO computer networks using lasers. The GeoDesy [16] wireless, directed laser system was introduced in 1996 and has been improved to provide competitive error free network connectivity without wires or radio frequency devices providing gigabit speeds. Two stationary laser units target each other with narrow directed beams at distances up to five kilometers to create a network link.

The First Cloud Over the Moon

Although fiber optic cables connect the continents of our earth, there has been no such lunar connectivity. However, very recently an earth based laser system was utilized to establish long distance connectivity with a space craft orbiting the moon. In October 2013, NASA's LADEE Laser Communications Demonstration [17] (LLCD) experiment made history by pulsing laser data 239,000 miles from the moon to the earth at a rate of 622 megabits per second (Mbps). The LLCD is on aboard NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE), launched in September from NASA's Wallops Flight Facility on Wallops Island, Virginia. The LLCD is NASA's first laser based communication system for use with space craft. A ground station in New Mexico also successfully uploaded data to the LLCD system on board the LADEE lunar orbiter at an error free rate of 20 Mbps. LLCD is the precursor to future laser communications in space. In 2017 NASA plans to launch the Laser Communications Relay Demonstration (LCRD) as part of an expansive effort to advance communications in the space program.

Closing Thoughts

The National Photonics Initiative has established a presence in Washington, DC and is engaging key political figures, government agencies and seeking alliances to pursue policies which can accelerate the funding and development of advanced photonic technologies. Although the NPI is a lobbying advocate for a wide range of industrial photonic applications, the development of fiber optic and laser based communications systems have probably made the most significant contribution to improving our daily lives.  A major subset of the NPI agenda might also include a National High Speed Internet Initiative similar to the government's subsidized interstate highway projects started in the 1960s. The world wide migration to the cloud has altered the landscape of the globe. The concept and coexistence of cloud based commerce and national sovereignty is continuously changing in complexity as borders can be breached electronically with no passport required. We are able to trade internationally while probing a potential adversary's information systems, currency exchanges, and telecommunications. Thus the current debate concerning computer network sovereignty at national and international levels are complicated by the security and intelligence gathering initiatives of the many nations populating the web in a dynamic global market place. The solution set to this concern is problematic, engaging heads of state, and established international law. As Americans we also value personal privacy. Our government security agencies and commercial entities must be vigilant and ensure a delicate balance of national security and personal privacy. In addition to NPI's opening white paper discussion points the National Photonics Initiative must also assist in speeding the development of complementary photonic technologies which will ensure the security and integrity of our communications infrastructure.

The speed of light is sufficient for most of today's technological endeavors.  As we extend our reach further from the Earth with instruments and manned space craft, interplanetary clock skew will become (is) the next challenge. Exceeding the speed of light as defined by Einstein's limit will soon become a priority as our need for speed accelerates.  A quantum level initiative may define our future. In the interim I invite you to join me in supporting the National Photonics Initiative.

Thomas D. Jay

Semiconductor Industry Consultant
Thomas.Dale.Jay@gmail.com
Thomas Dale Jay.com
Thomas D. Jay YouTube Channel 

  


     




























Corporate or private entities mentioned in this article are the respective owners of their logos, trademarks, service marks and intellectual property. Unless otherwise disclosed, Thomas D. Jay has no financial interest in companies referenced in blog articles or other published media communications. No representation is made to either buy or sell securities. Opinions expressed by Thomas D. Jay are his own. Thomas D. Jay does not employ or otherwise utilize/authorize third party agents to express his opinions, represent his interests or conduct business on his behalf except where formally contractually designated.

Acknowledgments and Reference Links

[1] The National Photonics Initiative White Paper

[2] The history of the laser, Wikipedia

[3] The history of fiber optics, Wikipedia

[3A] www.fiber-optics.info/history/p3

[4] AT&T Tech Channel, "Lightwave Undersea Cable System"
Courtesy AT&T Archives and History Center, Warren, NJ

[5] Telegeography Submarine Cable Map

[6] Kuwait conducts business in exile 1990, New York Times

[7] Techspot reports world internet speed rankings

[8] Current World Internet Speed Rankings, Speedtest.net

[9] Thomas D. Jay Commentary, on Seeking Alpha.com

[10] World's fastest internet arrives in Tokyo, Tech Spot.com

[11] Quadrature Amplitude Modulation, Wikipedia

[12] "From Gigahertz to Systems to Solutions; Our Industry in Transition", Bernard S. Meyerson, Ph.D., IBM, .PDF Published 2010

[13] Singapore SGX High Speed Computer Trading, Source:  Bloomberg News

[14] Skew Variability in 3-D ICs with Multiple Clock Domains” Hu Xu, Vasilis F. Pavlidis, and Giovanni De Micheli, LSI - EPFL, CH-1015, Switzerland Email: {hu.xu, vasileios.pavlidis, giovanni.demicheli}@epfl.ch

[15] IBM Silicon Nanophotonic devices, IBM

[16] GeoDesy FSO PTP Laser Networking

[17] LADEE Laser Communications Demonstration, NASA

[18] Telegeography News Update