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Showing posts with label Cymer. Show all posts
Showing posts with label Cymer. Show all posts

Tuesday, March 11, 2014

A Perspective on EUV Lithography Feb. 2014 The NIF Shot Heard Around the World



http://www.youtube.com/watch?v=vIiqAcGr614&list=UU8T5Lc8XntcOTYqgXLJbwigSPIE Advanced Lithography V 2014 provided no encouraging news on further development of EUV power output for advanced semiconductor HVM. During the week of the conference it was announced that a recently shipped ASML NXE:3300B [A] stepper/scanner with a 30 Watt EUV source failed during its trial run at TSMC. Accidents happen. Over the years I have witnessed several spectacular meltdowns of high energy/high value wafer fab equipment. Recovery is rapid as wafer fab crash teams resolve such incidents in short order. 

The quest for higher power EUV has been a greater challenge than originally anticipated. Unfortunately this latest occurrence at TSMC punctuated a ten year continuance of forward looking statements in which ASML/Cymer repeatedly anticipated imminent arrival of EUV power levels of 100 watts or more.

The Ultimate Shot Noise

Interestingly, the search for advanced, future semiconductor EUV lithography technique has been an on-going effort that began many years ago. In 1994 the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory began the Laser Science and Technology (LS&T) Program [1] whose research would chart the course for many future advanced technology projects. The National Ignition Facility  [1A] team is to be congratulated on their most recent August 13, 2013 experiment which produced output power greater than that of input levels. The NIF utilizes 192 individual high energy lasers focused on a small deuterium target with the goal of emulating the physics of our sun and unleashing large amounts of fusion energy.

See Wikipedia NIF photos:

AMP

A subset of the Laser Science and Technology program was AMP, the Advanced Microtechnology Program, providing research and development resources in semiconductor imaging and detection. AMP was considered a show case example of the U.S. Department of Energy's (DOE) efforts to transfer and commercialize newly developed technologies to U.S. commercial interests. The semiconductor industry now had the attention of world experts in plasma and light source technology.
 
The Birth of Laser Produced Plasma EUV 

The NIF began work on Laser Produced Plasma EUV. Plasma produced from Sn (tin) or Xe (xenon) enables the creation of a 13.5nm EUV light source, an item of key interest to next generation lithographers in the semiconductor industry. The NIF built a 13.5nm Laser Produced Plasma (LPP) test stand which successfully provided this desired wavelength of vacuum EUV. AMP and its associated EUV research and development would become LS&T's largest program. 

Later, three DOE laboratories; Lawrence Livermore, Lawrence Berkeley, and Sandia Laboratories in California went on to form the Virtual National Laboratory (VNL) to further research and develop extreme ultraviolet lithography (EUVL) technology. The VNL was funded by the Extreme Ultraviolet LLC, a consortium of Intel, Motorola, Advanced Micro Devices, and Micron Technology. Semiconductor industry heavy weights were now interacting commercially with the formidable technology base of the U.S. Department of Energy. The three year, $250 million venture was dedicated to developing EUVL for commercial manufacturing of computer chips and to foster migration of the technology to semiconductor production facilities by 2010. Each national laboratory contributed expertise to this effort; Lawrence Livermore (optics, precision engineering, and multilayer coatings), Sandia Labs (systems engineering, photoresists, and light source). Berkeley contributed its Advanced Light Source capability, generating EUV light to characterize optics and resists at the nanometer scale. SEMATECH now similarly sponsors and benefits from the development of actinic EUV metrology at the Lawrence Berkeley Center for X-ray Optics (CXRO). 

A Fifteen Year Chronology of EUV
Source Development 

- On May 6, 1998 Arthur W. Zafiropoulo, Chairman, CEO and president of Ultratech, formed United States Advanced Lithography LLC, and reached an agreement with EUV LLC (the consortium of Intel, Motorola, Advanced Micro Devices, and Micron Technology) in order to further develop and transfer EUV technology to American lithography manufacturers. Zafiropoulo wanted to ensure U.S. semiconductor equipment vendors remained competitive in the world economy by producing EUV lithography tools on American soil. [1B]

- On June 24, 1999 ASML of the Netherlands reached an agreement with EUV LLC, (the consortium of Intel, Motorola, Advanced Micro Devices, and Micron Technology) to participate in the further development and transfer of EUV technology to semiconductor lithography manufacturers. By participating in the EUV program facilitated by EUV LLC, ASML became a defacto beneficiary of the EUV research conducted by the U.S. DOE. Martin van den Brink, executive vice president of marketing and technology at ASML was later quoted as saying “While EUV is expected to have the highest throughput and most extendable resolution, the complexity of non-optical techniques requires the parallel evaluation of multiple options."  ASML moved rapidly to secure its position in the future lithography market place.

- In June, 2006 Cymer put its first LPP EUV source into operation.

- In November 2007 Cymer reported achieving 100 watts of EUV burst power on its LPP source. [2]

- On May 14, 2008, Cymer reported the achievement of continuous EUV source operation for over one hour at an average power level of 25 watts. [3]

- In July 2009 Cymer announced the shipment of an LPP source to ASML, claiming it had achieved 75 watts of “EUV exposure power” and anticipated 100 watt power levels within 90 days enabling 60 wafer/hour throughput on 300mm wafers. [4] 

- In 2010 Cymer reported achieving 100 watts of EUV peak power for brief periods but was only able to provide 10 watts of continuous EUV output. ASML began evaluating three potential suppliers of EUV sources; Cymer, Gigaphoton and Extreme Technologies. [5]

- In July 2011, at a company earnings conference call Bob Akins, then Cymer's Chairman and CEO reported “As a result of increased source availability and stability improvements, the eight (EUV) sources have cumulatively produced greater than 40 megajoules of EUV since March of this year and it is sufficient to expose greater than 3,000 wafers”. [6]

- In February 2012, Cymer reported shipping three 8 Watt EUV sources but 20 watt upgrade shipments for NXE-3100 systems were delayed. [7]

- In May 2013, Cymer's EUV source power output was still short of HVM targets. ASML completed the Acquisition of Cymer in a cash and stock transaction estimated to be $3.7 Billion. [8]

- As reported on February 24, 2014 during SPIE Advanced Lithography V, an NXE:3300B, was shipped to TSMC with an integrated 30 Watt EUV source from ASML/Cymer, failed during testing but was later repaired. [9]


A Perspective on Extreme Ultra Violet Lithography 
March 11, 2014  

In 2008 Arthur W. Zafiropoulo, Chairman, CEO and President of Ultratech, estimated that EUV lithography systems could be premium priced as high as $15 to 20 million each, affording a significant market opportunity. The interplay of the NIF and EUV programs promulgating the current lithography initiative has exposed two starkly differing cost center/ROI models. The National Ignition Facility took tewlve years to build and houses 192 high power laser bays 300 yards long, producing 500 Terawatt laser “shots” (500 Trillion watts) focused on a single deuterium pellet with the goal of replicating the fusion energy created in the core of our sun. Funded by the U.S. Government's Department of Energy, the NIF facility cost $3.5 Billion to construct. Given current ASML pricing at $120 Million each, a quantity of 25 ASML EUV stepper/scanners, each anticipated to produce 150 watts of front end LPP EUV illumination, are now estimated to cost $3 Billion. If we utilize Mr. Zafiropoulo's original high end estimate of $20 Million per stepper, the cost for the same 25 EUV steppers is reduced to $500 Million (the number to the right of the decimal point on the NIF's construction cost). The collective investments in ASML made thus far by Intel, Samsung and TSMC actually exceed the NIF's $3.5 Billion construction cost. Is an ASML equipped semiconductor front end EUV lithography fab (25 EUV steppers) really at cost parity with a U.S. government sponsored fusion energy project?  Given current wafer fab construction costs approximating $5 to 6 Billion, ASML's recently quoted EUV lithography pricing is unprecedented.  This singular discrepancy in the semiconductor industry's cost continuum has displaced Moore's Law as a viable operand.  EUV technology originally developed within the U.S. DOE/NIF program has been transferred to cooperative multinational interests outside any U.S. based cost control infrastructure.  Electron beam lithography as an alternate HVM solution was never funded on a large scale leaving ASML as a defacto sole source for nanometer scale HVM. This is why the EUV program is on hold. It's time to call the accountants, get costs under control, and restore U.S. based best of breed lithography competition to the semiconductor industry.  We all applaud the efforts of our friends at ASML who have made extraordinary strides in the development of EUV.  However, with ASML as the primary beneficiary of the NIF's EUV Laser Produced Plasma program, the U.S. based semiconductor equipment industry should be competing with them for both economic and strategic considerations.
 
The current and on going status of EUV endures as a great drama for those of us with keen interest in the semiconductor industry and the phenomenon of Moore's Law. Although ASML stock holders should continue to benefit from their dominate front end market share, it would appear ASML's customer/investors are getting less return on their subsidy of EUV as progress on HVM power output development has stalled. Although there are few remaining EUV players (none with ASML's front end market share), the current economic complexity of the EUV program compounded by the throttling of the 450mm initiative has quashed enthusiasm for large scale investment in new, competitive EUV and alternative lithography technologies targeting CDs <28nm. The current over capacity status at many fabs has also delayed further investment in tweaking strategic product positioning, best illustrated by Intel's idling of newly constructed fab 42. 

With regard to next generation semiconductor products, we might choose to continue optimizing cloud based CPUs and servers as another way of offsetting increasingly heavy processing demands until nanometer scaling enabled by restoration of the EUV initiative or SEMATECH's alternate choice, electron beam lithography enables us to re-institute the spirit of Moore's Law.

Please join me in supporting the National Photonics Initiative, SPIE and the United Nations proclaimed International Year of Light 2015.

Thomas D. Jay 
Semiconductor Industry Consultant
Thomas.Dale.Jay@gmail.com
www.ThomasDaleJay.com
Thomas D. Jay YouTube Channel
 
 
http://www.youtube.com/watch?v=as4BFjU5MN0&list=UU8T5Lc8XntcOTYqgXLJbwig

 
 
www.lightourfuture.org

www.spie.org






http://spie.org/x93905.xml
























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.

Acknowledgements and Reference Links

 SPIE.org

 Photonics for a Better World.blogspot.com

National Photonics Initiative

 [A] ASML NXE:3300B, ASML Web Site

[A1] Ultratech

[1] Extreme Ultra Violet Lithography, Imaging the Future

[A-G] NIF Photos, Wikipedia 

[1A] National Ignition Facility, Lawrence Livermore National Laboratory  

[1B] May 6, 1998 Business Wire

[2] November 30, 2007 Business Wire 

[3] May 14, 2008 FABTECH

[4] EE Times July 13, 2009 

[5] August 19, 2011 Engineering and Technology Magazine, by Chris Edwards

[6] July 21, 2011, Morning Star 

[7] February 3, 2012 Semiconductor Engineering, by Mark LaPedus

[8] May 30 2013 UT San Diego, by Mike Freeman

[9] February 24, 2014 Semiconductor Engineering, by Mark LaPedus

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Wednesday, August 7, 2013

The Continuing Evolution of Extreme Ultra Violet Lithography


On July 17, 2013 in a qualified safe harbor statement, an ASML press release (NASDAQ:ASML) announced its second quarter earnings and also indicated that its EUV platform, scanner imaging and overlay performance improved to levels enabling engagement with customers on a strategy targeting insertion at the 10nm logic node.  Additional discussions concerned strategies in which the first NXE:3300B systems running at currently available EUV power levels are utilized for production of future nodes at reduced throughput in place of mask strategies utilizing 193i multi-patterning techniques. Customers will be able to upgrade their systems as higher power levels become available and avoid a costly process transition from 193i to EUV HVM.  Combined with currently available multiple-patterning capabilities on existing 193i platforms, ASML could provide the best possible options for customers.  In the second quarter, ASML achieved good performance, stability and reliability of the pre-pulse source concept at power levels up to 55 Watts, and remains confident of targeted throughput of 70 wafers per hour in 2014.  ASML projects availability of upgraded systems with 125 wafer per hour throughput in 2015 provided further development of EUV power output progresses as planned. Additional strategies are being considered for continued funding of additional R&D on EUV.   450mm HVM insertion is anticipated in 2018.  News Source: Seeking Alpha.com 7/17/2013.

The semiconductor equipment industry participants driving the evolution of EUV (Extreme Ultra Violet) and nanometer scale lithography might be characterized as "tag team" players as process enabling technologies provided by an interactive vendor base will often trigger a cascade of new concepts and innovation frequently spawning “disruptive technologies”  The semiconductor lithography market is technologically unique, supporting many diverse products demanding application specific process solutions.  Although this market place can seem extraordinarily complex it is commonly bound by the semiconductor industry phenomenon known as Moore's Law which states that the number of transistors on semiconductor devices doubles approximately every two years, reducing costs.  During the past several years semiconductor lithographers have been pursuing the means to create a sufficiently powerful source of EUV (Extreme Ultra Violet) light for use in next generation lithography stepper/scanners.  These complex machines are used to mass produce semiconductor “computer chips” utilizing a photolithography process similar to conventional film photography, the difference being the “photo negative” is actually comprised of many individual photo masks (as many as 50 or more), providing the discrete image negatives required for each process layer in a complex semiconductor device.  EUV light source technology is being pursued as the emitted 13.5nm light's wavelength is short enough to produce high resolution circuit imaging for present and future 14, 10 and 7 nanometer scale device structures. Although several well established companies in the field of semiconductor lithography have participated in the development of EUV technology the expense and diminishing returns on investment have narrowed the playing field to a few.  Lithography giant ASML based in the Netherlands recently purchased a key lithography light source supplier, Cymer, in an effort to consolidate EUV development efforts and secure the timely delivery of critical source components.  Underscoring the strategic value of EUV lithography are recent investments made in ASML by Intel, Samsung, and TSMC which total more than $6 Billion. To date, ASML and Cymer have produced excellent EUV lithography imaging with an available light source power output approximating 55 watts.  This is about half the power required to support the throughput of high volume manufacturing (HVM).  After years of industry anticipation, delayed development of EUV power output has put some semiconductor industry professionals in an uneasy holding pattern.  Although multiple patterning techniques for 193i lithography provide feasible lithography solutions in the interim, most would prefer a simplified EUV lithography process solution requiring fewer mask levels at reduced cost.  In light of ASML's recent announcements some are reconsidering the current status of EUV lithography development and the implementation of available alternatives such as double patterning and Directed Self Assembly (DSA) techniques.  In an effort to gain additional insight and inspiration from established experts in the EUV community my inquiries revealed that many are reluctant to speak to the current situation and perhaps for good reason. It is difficult to speculatively comment on the efforts of lithography industry experts who have diligently achieved the excellent results obtained thus far.  It appears we've hit a physical wall which has temporarily stalled EUV development and delayed the HVM insertion time line.  As we have learned over the years, difficult tasks sometimes take longer to complete.

In the interim 24 months ahead we must also realize that the semiconductor industry will assimilate a new crop of scientists, electrical engineers, sales, marketing and application specialists along with the traditional complement of Wall Street industry analysts and investors.  To the new and uninitiated intelligentsia, EUV technology might require some explanation.  Educating new entrants to our industry is always a challenge.  As a technologist you might have a friend or relative who've asked about your work in semiconductors and observed their eyes glaze over as you explain.  As we pause to await news of higher EUV output power, I will utilize the available “dwell time” to provide an EUV primer for new industry participants and observers and hopefully fill in the blanks for our current, friends and colleagues.  Where to begin?                    


Plasma 101

Unlike solid, liquid or gas, plasma, the fourth state of matter exists within a narrow, low pressure domain approximating 1/760th of our atmosphere at sea level.  Positively ionized plasma can be created in this low pressure regime by inducing high energy electron collisions with gas molecules displacing orbital electrons normally found in the stable atoms comprising the gas.  The imparted electrical imbalance causes the gas molecules to gain a net positive charge as there are more positive protons remaining in the atoms/molecules than negatively charged electrons.  The resulting plasma is a glowing cloud of charged particles and gas molecules having a positive electrical potential and the conductivity of copper while simultaneously emitting light comprised of photons with the characteristic color of its elemental spectra.  Utilizing Italian physicist Torricelli’s scale, the pressure of the air at sea level is 760 Torr.  More specifically, the pressure at which electrical gas plasma can be created and sustained approximates 5x10-4 Torr, a near vacuum at less than 1/760th of the pressure of our atmosphere.  At an altitude of 84 kilometers above the earth and well below the international space station, the pressure in near outer space falls within this range and is conducive to the natural creation of plasma known as the aurora borealis.  This phenomenon occurs when high energy “solar wind” from the sun ionizes oxygen, nitrogen and other gases in the upper atmosphere in the presence of earth's magnetic field.  Back on terra firma, high vacuum technologists design and maintain carefully engineered process chambers simulating pressures ranging from ambient atmosphere to the ultra high vacuum of deep outer space.  Scientists and electrical engineers utilize these physical phenomena and resources to generate, contain and control high energy plasma by electrically ionizing specially selected process gases at precise pressures in high vacuum systems. Plasma etchers utilized in semiconductor wafer fabs were among the first process tools to adapt this technology.  In this application, plasma is generated to produce ions for etching semiconductor wafers.  The incidental light emitted from the plasma can be utilized to monitor the process.  The primary methods for ionizing these gases include hot cathode/filament electron discharge, microwave excitation, and RF (Radio Frequency) energy excitation.  Interestingly the Federal Communications Commission has designated special radio frequencies for use in plasma etch systems.   A common frequency utilized for RF plasma etchers is 13.56 MHz.  As a ham radio operator I am more spectrum conscious than most and when near a wafer fab I sometimes tune in with my mobile transceiver to listen for “etchers on the air”.  The received signal is not particularly exciting and is usually a continuous uninterrupted carrier wave sometimes producing a loud heterodyne when tuned in the single side band mode.

In this semiconductor manufacturing application of physics, positively charged high energy ions are created in these special plasma systems and utilized to etch semiconductor circuits on silicon wafers.  The ions having mass and kinetic energy bombard the surface of product wafers and selectively etch surfaces to form intricate device structures and circuit patterns from the metal film and materials left behind.  A variety of gases are utilized to etch process specific materials on product wafers.  Some of the gases utilized are also chemically reactive and can selectively enhance the etch rate of specific materials on a wafer's surface.  Other noble gases are chemically inert (non-reactive) and advantageous for a wide range of etch applications.  Plasma etch chambers emit a characteristic light whose primary color/wavelength is determined by the elemental composition of the process gas.  Argon gas for example emits a purple glow which is pleasing to the eye. This spectral phenomenon is often utilized as a process indicator to determine when a critical etch step must stop. While etching a thin film metal, a faint light emitting plasma with the metal's signature color/wavelength is also produced. Using optical end point detectors, process engineers can sample the spectrum of light emitted from the plasma to detect the metal's specific signature wavelength.  When this spectral signature disappears the metal etch process is deemed complete as there is no remaining metal being ionized.  This “end point” signal is typically used to automatically stop the etch cycle providing highly accurate process control and negates any manual intervention by wafer fab engineers.  A key observation of these phenomena are that elementally specific positively charged particle ions (mass specific) and photons (wavelength specific light) are created during the ionization process.  The science of plasma physics for etching semiconductor circuits has been refined over the years by companies like Applied Materials, Lam Research and Veeco Instruments (there are many others) however, the plasma physics required to produce 13.5nm EUV for lithography are quite different and much more challenging.  

Producing Extreme Ultra Violet Light With Plasma

For several years the semiconductor industry has been engaged in the research and development of next generation nanometer scale lithography requiring a precision stepper/scanner equipped with a 13.5nm light source.  For lithography applications, plasma is created for the purpose of generating light at specific wavelengths.  The production of ions and other charged particles is incidental and sometimes suppressed to avoid etching and erosion of sensitive components in the source and wafer stage. Utilizing the most current methods for producing this light, lithography research engineers create a plasma which emits 13.5nm EUV from the resulting ionization of xenon gas (Xe), or the solid metal tin (Sn).  As a gas, xenon ionizes easily but has a lower energy Conversion Efficiency (CE) than tin.  ASML has chosen solid tin as the plasma feed material for its EUV light source because of its higher energy conversion efficiency.  Creating an ionized tin plasma is more difficult and also creates unwanted particulates which can potentially contaminate EUV masks and product wafers. Although the 13.5nm spectra has been dubbed EUV (Extreme Ultra Violet) it can also be described as “soft x-ray” radiation or “vacuum EUV” as it is absorbed by many gases and propagates most efficiently in a high vacuum environment.  Extremely short wavelength EUV light will enable semiconductor lithographers to print ever smaller transistors and associated circuitry on computer chips reducing CD features (Critical Dimensions) down to nanometer scales and below.  Utilizing a current 22nm fabrication process, a state of the art Intel Quad core i7 microprocessor introduced in the year 2012 contains 1.4 billion transistors.  Moore's law marches on and future process nodes will soon shrink to 14, 10 and 7nm.  Imagine your smart phone's chip sets with the processing power of another billion or so transistors.


A Best Of Breed EUV Source?

As there has been significant wide ranging research on the subject of EUV source technology, I will focus on the most current technology utilized by ASML and will discuss possible alternately efficient means of EUV production. Having conducted research on past experimentation and published papers, I will direct attention to recent prior work having potential to enhance EUV source performance.  By “borrowing” concepts from the most promising efforts I will propose a possible “best of breed” hybrid EUV source design.  I suspect similar dialogue and debate has been conducted previously.  My intention is to foment new discussion which might yield solutions providing the EUV power output and performance required for HVM lithography (High Volume Manufacturing).   


ASML's EUV Source Design

ASML/Cymer's current technique for production of EUV light utilizes Laser Produced Plasma (LPP).  In this different approach to producing plasma, small droplets of tin approximating 30 microns in diameter are injected into an ionization source and targeted by a solid state “pre-pulse” laser.  The imparted energy from the pre-pulse laser enlarges the tin droplet and raises its energy state, providing a larger cross sectional profile for a more powerful 20 kilowatt CO2 laser.  After pre-pulse conditioning, the tin droplet is targeted with the larger CO2 laser resulting in the high energy evaporation and ionization of the tin, releasing 13.5nm EUV light as a result.  A continuous stream of tin droplets and sustained laser interaction produces stable EUV light output commensurate with requirements for precision lithography and dosimetry.  Utilizing this technique, current EUV power output levels of 55 watts have been achieved, about half the power required for HVM (High Volume Manufacturing).  In the quest for more EUV power output, I suspect ASML and Cymer will experiment with larger, more powerful lasers while optimizing other coincidental parameters.  While successfully producing EUV light, an Sn/LPP source produces a large number of tin particulates as the targeted tin droplet residue collects on exposed surface areas in the ion source and wafer stage. Reflective EUV optical mirror surfaces can lose efficiency (reflectivity) when coated with tin, while EUV masks and product wafers can be compromised if contaminated with particles as small as one nanometer.  A more recent technique for keeping surfaces clean is to direct a beam of hydrogen ions from a small, integral ion source at critical optics and wafer stage components.  Experiments implementing a hydrogen plasma clean cycle as part of a periodic maintenance regimen have also been suggested. The challenges in the design and implementation of EUV technology for high volume manufacturing are formidable.  


Z-Pinch Discharge Produced Plasma Source Technology

A Z-pinch source, consists of an insulated containment cylinder with electrodes attached on either end, mounted inside a vacuum chamber.  For the creation of EUV light emitting plasma, a gas such as SnH4 (Stannane) or xenon (Xe) is fed into the cylinder and pre-ionized with the resulting plasma having the electrical conductivity approximating that of copper.  A large pulse of electrical energy stored in a bank of capacitors or from a power supply is applied to the electrodes at the ends of the cylinder.  As a result, a large current flows through the electrically conductive plasma causing it to contract as a phenomenon known as the Lorentz force compels the mutual attraction of the ions flowing uniformly along the z-axis of the plasma. The term z-pinch is derived from the fact that the current flows along the z-axis of the plasma as it is being compressed and pinched. The contraction continues until the plasma becomes highly dense and further compression is resisted by the gas pressure comprising the plasma. Ultimately, the maximized “pinch” density releases a large burst of energy comprised of ions and characteristic spectral light.  In the case of SnH4 and Xe, Discharge Produced Plasma EUV light with a wavelength of 13.5 nanometers is emitted in the process.  A continuous, controlled flow of source gas and carefully timed high current pulses through the source cylinder repeat this cycle, sustaining the plasma and output of EUV light.  This is achieved by pulsing the power supply and the resulting high current flow through the conductive plasma between 6 and 8 thousand times a second.   A power supply pulsed at approximately 7 Khz usually delivers maximum output for this design.  Z-pinch operation can be further optimized by controlling the power supply frequency, pulse width and amplitude providing effective wave form control and regulation of power fed to the source.   With the power supply operating at a the relatively low frequency of 7 Khz, a computer operating at 1.5 to 2.0 GHz can be utilized to sample the sinusoidal/waveform input power and resulting EUV output at the wafer stage making it possible to close loop control associated lithography dosimetry and related functions.


Ushio's Sn/DPP EUV Source Design

At the SPIE 2007 International EUVL Symposium, Ushio published a paper on results obtained from experimentation conducted on a Discharge Produced Plasma EUV source utilizing SnH4 (Stannane) as the feed material: Development of Sn-fueled high-power DPP EUV Source Enabling HVM.  In this design a Z-pinch DPP source was fed with gaseous SnH4 providing the energy conversion efficiency of tin while affording the simplicity of source gas handling with conventional mass flow controllers and pressure measurement instruments.  Interestingly, Ushio's Discharge Produced Plasma (DPP) source produced 62 watts of EUV output utilizing gaseous SnH4 as compared with ASML's recently quoted EUV power output of 55 watts obtained with a Laser Produced Plasma sustained with source fed solid tin droplets.  A power output comparison of the two technologies builds a case for continued development of an SnH4 Discharge Produced Plasma EUV source with a more simplistic design.  An additional benefit of using SnH4 as a source feed material is it minimizes the erosion of electrodes and critical surfaces in the z-pinch tube.  

Zplasma's Xe/Stable DPP Z-Pinch Source With
Sheared Flow Stabilization (SFS)®

In my previous blog articles I've had the opportunity to interview Henry Berg, CEO of Zplasma, and discuss his company's Xenon based Discharge Produced Plasma EUV source.  Zplasma's Stable DPP source is quite different from the generic DPP description above.  Zplasma's stable pinch operation results from a patented, proprietary technique called Sheared Flow Stabilization (SFS)® which stabilizes the plasma and eliminates explosive pinch terminations. The stable pinch operation of an SFS design DPP source is required to produce the high power levels required for HVM lithography. As described by Henry Berg, there are six critical advantages to Zplasma's SFS source technology:

a) Longer Light Pulse: SFS pulses are 10 to 100 times longer due to their stable nature, allowing for more light collection.

b) High Power without High CE: Long SFS pulses and side-on optical collection access increase throughput and lower required CE, enabling HVM operation with xenon and eliminating the need for molten tin.

c) No Debris: SFS ends the plasma pinch without explosive termination, eliminating high-energy debris.

d) Low Instantaneous Power: SFS pulses allow for EUV light production without the high instantaneous power levels that cause electrode thermal stress and ablation.

e) Dose Uniformity: SFS allows the length of each EUV pulse to be adjusted under control of the power supply, allowing for extremely accurate dose uniformity.

f) Adjustable Geometry: SFS makes pinch geometry adjustable for optical matching to the stepper IF.
  
Given Discharge Produced Plasma (DPP) and Laser Produced Plasma (LPP) design concepts, how might we improve EUV power output and system performance?


Minimizing Source Plasma Opacity
Maximizing EUV light Output

EUV light emitted from a tin or xenon plasma discharge is partially absorbed by the opacity of source plasma.  More specifically, the 13.5nm light is readily absorbed by many gases and solid materials, inclusive of the low pressure vapor state of the tin or xenon utilized to create the plasma. This means that the intensity of the emitted EUV light diminishes as it is partially absorbed and diffused during its transit through the plasma cloud and transport to the stepper's intermediate focus (where the EUV light is collected).  A reduction in the rate of absorption and diffusion by the plasma can sometimes be achieved by reducing the pressure of the gas comprising the plasma. This has the effect of reducing the density of the plasma, lessening its opacity, and potentially increasing power output by increasing the transmission efficiency of the emitted EUV light.  This pressure adjustment is critical as the plasma will be extinguished if the pressure is too low (insufficient gas density/pressure to sustain the plasma) and will similarly cease to ionize if the pressure is too high. Experimentation is required to determine the optimal pressure and plasma density for maximum production and transmission of EUV light.  I suspect ASML has optimized this parameter on their Sn/LPP EUV source.  This technique is discussed in a 2005 paper:  Comparison of experimental and simulated extreme ultraviolet spectra of xenon and tin discharges by E.R. Keift, K. Garloff, J.J.A.M. van der Mullen and V. Banine.  


Maximizing the Transmission Efficiency
 of EUV Light to the Wafer Stage

To carry the EUV transmission efficiency discussion further, in some EUV system designs the wafer stage chamber is maintained at the same vacuum pressure (approximately 5x10-4 Torr), as the plasma source chamber and share the vacuum environment sustained by the pressure controllers and vacuum pumps supporting the EUV plasma. The pressure inside the wafer stage area is also critical as additional absorption and diffusion of the EUV light can occur there during transit from the intermediate focus coupling (IF) to the wafer stage.  Reductions of EUV energy propagation efficiency in the wafer stage chamber can be pressure related and contribute to path loss concerns exemplified in the source plasma opacity discussion above.  It is probable that higher levels of EUV dosing can be obtained by maintaining the wafer stage chamber under high vacuum pressure at <1x10-7 Torr. 

An excellent example of increased energy transfer efficiency under high vacuum conditions and the resulting effects on lithography are illustrated in a 2006 Nano Letters paper by Benjamin D. Myers and Vinayak P. Dravid, Variable Pressure Electron Beam Lithography (VP-eBL): A New Tool For Direct Patterning of Nanometer Scale Features on Substrates With Low Electrical Conductivity.  I found this paper quite interesting in that it addresses concerns common to both EUV and eBeam technologies.  The primary purpose of this paper was to illustrate a methodology for mitigating surface charging effects on electrically insulated wafer substrates patterned with eBeam lithography while simultaneously optimizing the resolution of the patterned images.  The paper also illustrates how differences in vacuum pressure effect eBeam (energy) propagation.  In the experiment, a differentially pumped vacuum system maintained an electron beam column under high vacuum while enabling operation of the wafer stage within pressures ranging from high vacuum to 3 Torr.  It was determined that a decrease in beam-gas path length (BGPL) and resulting electron beam scattering occurring at higher pressures mitigated surface charging and secondary electron proximity effects while enhancing image resolution.  However, the beam scattering also reduced the number of electrons available to dose the patterned resist requiring longer write times.  Longer write times or specialized dose requirements can now be optimized with computational lithography techniques inclusive of shot tasking and dose modulation.  To follow the discussion of exhibits in this paper, click on the link above. In Figure 1, exhibit (A) illustrates the insulated substrate surface charge induced displacement and distortion of eBeam imaging at high vacuum pressure.  Subsequent improvement in image resolution and accuracy are illustrated in exhibit (B) at .4 Torr, and in exhibit (C) at 1 Torr.  In Figure 2, Exhibits (A) through (D) and similarly Figure 3, Exhibits (A) through (C), illustrate eBeam induced surface trenching in the resist which decreases when the pressure is increased.  These examples illustrate the increase in energy transfer efficiency under high vacuum conditions and resulting decrease at higher pressures.  Figure 4, illustrates how electron beam dose requirements increase at higher gas pressures along with the interactive effect on minimum line width.  While there have been studies and process gas specific absorption coefficients established for electron beams and spectral light across a range of pressure regimes, it is well recognized that both forms of energy propagate most efficiently in a high vacuum environment, hence the term “vacuum EUV”. 

It follows that an EUV source and wafer stage chamber maintained at separate optimal pressure levels, approximately 5x10-4 Torr for the source (plasma opacity optimized),  and <10-7 Torr for the wafer stage chamber, more efficient transfer of EUV light can likely be obtained. This scenario requires a means of isolating the two vacuum chambers, perhaps by differential pumping, and transferring the EUV light through a transparent window or aperture at the intermediate focus (IF).  There are candidates for low loss EUV window material which could facilitate such a design.  In addition, there is a patented EUV source design featuring a differentially pumped source and wafer stage chamber coupled by a gas flow/conduction limiting optical aperture which efficiently conducts the EUV light across the two pressure regimes. http://www.google.com/patents/US6576912


Dueling Etendue – A Hybrid Dual DPP Source Design
 to Double Power Output

The search for high power EUV production techniques has been primarily focused on identification of energy conversion efficient source materials (solid and gaseous) and the most efficient means of ionizing them.  Recent research has determined that the best two ionization techniques are Discharge Produced Plasma (DPP) and Laser Produced Plasma (LPP).  As I point out in this article, the two techniques seem to be tied at maximum EUV power levels of 62 watts for DPP and 55 watts for LPP.  An approach to achieving higher power levels might be to operate two DPP sources simultaneously within one vacuum system, theoretically generating twice the power output.  The challenge would be optically coupling two sources to the stepper IF to truly double the power.  This might not be easily achieved.   Simultaneously capturing the maximum brilliance of two plasma sources could be challenging as the hardware interface to the IF must accommodate the optimal plasma profile angles for two discrete light sources to effect the most efficient etendue.  It's possible Bragg Cell EUV mirrors could be utilized to assist in effecting dual source DPP etendue.  Any concerns with absorptive losses from the Bragg Cell mirrors would be negated by the additional power afforded by the dual source design.

In my opinion a good candidate design technology for a hybrid EUV source resides with Zplasma.  The original system built by Zplasma utilized Xe as its source gas feed which produced a 2% bandwidth energy conversion efficiency (CE) of 0.5% which is low, however the efficiency will increase to 1.5% with a power supply optimized for the source.  By substituting Xe with SnH4, the energy conversion efficiency could be increased further to become competitive with Sn Laser Produced Plasma efforts to date. In addition to the increase in CE, higher EUV output power levels might be obtained if Zplasma's patented Sheared Flow Stabilization Z-pinch performs as well with SnH4 as it does with Xe.  Zplasma's system design might also accommodate the concept of Dual DPP sources as etendue match concerns might be minimized by its z-pinch source characteristics affording side on collection of light from the plasma.  In addition, the DPP configuration could accommodate an optional H2 plasma clean maintenance regimen.  A successful technique utilized by Gigaphoton in its source development program minimizes tin (Sn) particulate contamination by optimal positioning of a superconducting magnet in the source which deflects tin particles away from critical wafer stage and optical components.  Assuming a viable hybrid EUV source design is identified, how might further R&D funding be obtained given the current economic climate?


A Proposal for a New National Photonics Initiative Agenda Funding High Priority Challenges
 to Manufacturing

An important SPIE co-sponsored initiative took place on February 28, 2013 in Washington, DC, titled, “Optics and Photonics: Lighting a Path to the Future.”  Other organizations co-sponsoring the event included the IEEE Photonics Society, Optical Society of America (OSA), IEEE Photonics Society,  American Physical Society, and the Laser Institute of America.  The event was attended by many government agencies who traditionally sponsor research. The goal of the conference was to foster better government collaboration with American optics and photonics industries and forge a National Photonics Initiative (NPI).  The value of this proposed initiative is best exemplified by recent (non-government) semiconductor industry manufacturers' investments in ASML and Cymer.  The collaboration of industry and government in key photonic and optical science endeavors could distribute R&D expenditures among participants and reduce costs across many disciplines. While I was researching and writing this blog article, the benefits of a coordinated NPI program became more apparent.  After reviewing the many technical papers written on the subject of EUV and related technologies, I believe it is accurate to say that the level of participation by private industry, universities and government sponsored funding is probably unprecedented, and has created a reciprocally proportionate wealth of intellectual property and patent filings spanning many entities and corporations.  While we all support the concept of independent research, competitive concerns with ownership of applicable intellectual property may have slowed investment in the development of the EUV program. It is my opinion that a hybrid EUV source with superior power output and HVM performance might be assembled from the assortment of promising technologies and IP developed thus far.  Should a hybrid EUV concept be successfully proven, ensuing IP cross licensing concerns could potentially inhibit cooperation and progress.  This concern has been addressed previously by SEMATECH and other groups cooperatively sponsoring other past and present research programs.  The current pause in the pace of EUV development should foment renewed enthusiasm for jointly developed technology, intellectual property and reduction of R&D costs outside the domain of the foundries in order to prevent further stratification and/or dissolution of the traditional semiconductor equipment vendor base.  

On July 25, 2013 I received the following communication from NIST from which I have excerpted the following:

MEMORANDUM FOR Advanced Manufacturing Distribution 
From: The NIST Advanced Manufacturing Technology Consortia (AMTech) Program Team

“It is my pleasure to inform you that the National Institute of Standards and Technology (NIST) has released a Federal Funding Opportunity (FFO) for the Advanced Manufacturing Technology Consortia (AMTech) Program.  This is a new competition for awards to establish new or strengthen existing industry-led consortia in planning research that addresses high-priority challenges impeding the growth of advanced manufacturing in the United States.  NIST anticipates awarding $4 million in early 2014 as a result of this AMTech announcement.  Awards are expected to be up to two-years in duration and range between about $250,000 and $500,000.  As a leading voice in advanced manufacturing, we believe your members or constituents may have interest in AMTech and this newly announced funding opportunity.  AMTech-supported consortia will identify and prioritize long-term, pre-competitive industrial research needs; enable technology development; and create the infrastructure necessary for more efficient transfer of technology.  Teaming and partnerships are strongly encouraged including participation by the full value chain, including small-and mid-sized firms.  By convening key players across the entire innovation life cycle, the objectives of the AMTech Program are to eliminate critical barriers to innovation; increase the efficiency of domestic innovation efforts; and collapse the time scale to deliver new products and services based on scientific and technological advances. The end goal will be a growth of advanced manufacturing in the U.S. and an increase in the global competitiveness of U.S. Companies.  The AMTech Program will host two webinars on August 15, 2013, and August 20, 2013, at 2:00 p.m. Eastern time.  Participants are required to register in advance.  The events will offer guidance on the AMTech Program and preparing proposals, and will provide an opportunity to answer questions from the public about the program.  Participation in the free event is not required to submit an application.  Information on and registration for the event is available at www.nist.gov/ampo.  To assist in identifying potential collaborators for a consortium, the AMTech Program is creating a LinkedIn group where individuals can provide their area(s) of interest and communicate with each other.  Visit www.nist.gov/ampo for more information about joining.”

In considering this proactive initiative by NIST, I believe it is accurate to state that timely availability of EUV lithography technology is one of the high-priority challenges impeding the growth of more advanced manufacturing in the United States.

I propose that SPIE and the industry groups comprising the National Photonics Initiative consider establishing an additional agenda coordinated with SEMATECH to pursue government funding of advanced research in EUV development.  Further, there should be emphasis on directing available grant funding to the many promising start up companies whose entrepreneurial potential for technological contribution have been precluded by the prevailing economic climate in Silicon Valley, Wall Street and the larger U.S. economy.  We all applaud the cooperation of major players such as Intel, Samsung, and TSMC as they collectively support the efforts of ASML, but we must also ensure proactive support for promising, small business based entrepreneurial start up companies that have traditionally made the best and brightest contributions to Silicon Valley and the semiconductor industry.

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








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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.

Correction:  A previous reference in this article was made crediting Ushio for a technique utilizing a superconducting magnetic field to mitigate tin particulate debris.  This statement was made in error and corrected on August 8, 2013.  Gigaphoton developed the superconducting magnet particulate mitigation technique as reported by Business Wire on July 1, 2013.  My apologies to Gigaphoton and Ushio for this unintentional error.  
Thomas D. Jay, August 8, 2013

Acknowledgments and Links

ASML News Release Source: Seeking Alpha.com 7/17/2013

Intel's Quad Core i7 Microprocessor
Intel Corporation, You Tube

ASML/Cymer's current technique for production of EUV light, ASML, You Tube

The challenges in the design and implementation of EUV technology for high volume manufacturing are formidable,
Jos Benschop, ASML, You Tube

Z-Pinch DPP Source Reference, Wikipedia.org

Development of Sn-fueled high-power DPP EUV Source Enabling HVM, Yusuke Teramoto, Zenzo Narihiro, Daiki Yamatani, Takuma Yokoyama, Kazunori Bessho,
Yuki Joshima, Takahiro Shirai, Shinsuke Mouri, Takahiro Inoue, Hiroshi Mizokoshi, Gohta Niimi*, Tomonao Hosokai*, Hironobu Yabuta, Kohkan C. Paul, Tetsu Takemura, Toshio Yokota, Kiyoyuki Kabuki, Koji Miyauchi, Kazuaki Hotta, and Hiroto Sato Gotenba Branch, Hiratsuka Research and Development Center, Extreme Ultraviolet Lithography System Development Association  *Ushio Inc.

www.zplasma.com, Henry Berg, CEO, Zplasma, Inc.

Comparison of experimental and simulated extreme ultraviolet spectra of xenon and tin discharges by E.R. Keift, K. Garloff, J.J.A.M. van der Mullen and V. Banine

Variable Pressure Electron Beam Lithography (VP-eBL): A New Tool For Direct Patterning of Nanometer Scale Features on Substrates With Low Electrical Conductivity, Benjamin D. Myers and Vinayak P. Dravid

http://www.google.com/patents/US6576912

www.nist.gov/ampo

National Photonics Initiative

NPI Agenda

SEMATECH





Wednesday, March 20, 2013

Report on Recent SPIE Activities – Spring 2013


Commentary on SPIE Advanced Lithography IV 2013
SPIE Advanced Lithography IV concluded February 28, a few weeks ago.  I did not attend the conference this year but was in frequent contact with colleagues who were on the scene.  I was able to obtain some interesting perspective (albeit remotely) on EUV events thanks to first person accounts, daily news and video updates on the SPIE web site and from other SEMI industry news media.  My instinct to publish blog commentary immediately after the SPIE conference proceedings was throttled by additional background research in which I rediscovered recent, relevant historic data preceding and supplementing this years SPIE Advanced Lithography event.

ASML made a compelling fifty page presentation at SPIE which outlined their progress in sustaining the evolution of nanometer scale lithography while simultaneously supporting high volume manufacturing (HVM).  The report outlined the status of ASML's current EUV lithography program demonstrating measured incremental progress in EUV power output but underscored its ability to deliver the precision and accuracy necessary for evolving nanometer scale lithography.  Additionally, supportive data reinforced ASML's ability to implement complementary 193nm double patterned strategies as part of its EUV transition program.  Tool to tool accuracy and precision data were presented, ensuring the availability of interim process solution sets concurrent with the evolution of EUV development.  The EUV source power question was deferred to the continuing research and development effort at Cymer where gains have been progressing incrementally.

Following SPIE on March 12, at a recent UBS technology conference in Europe (Source: Seeking Alpha.com),  ASML was asked if the Cymer supplied EUV light source was the only available option for its EUV lithography system.  The ASML response was that they had designed a standard light source interface to the stepper but welcomed customers to optionally supply their own production proven EUV light source. Realistically, other than a few EUV source/systems under evaluation at imec, customers currently have few options and are probably best served by an ASML/Cymer source with an attached performance guarantee.

The SPIE conference again reminded us that the most pressing EUV lithography issues continue to be EUV laser/plasma based source technology, mask fabrication, resist performance and particle contamination concerns prompting a pellicle solution. The complex interaction of these critical issues create a matrix of challenges. The EUV resist component of this matrix was first comprehensively addressed in a 2011 paper: Stochastic Exposure Kinetics of Extreme Ultraviolet Photoresists: Simulation Study, by Chris A. Mack, James W. Thackeray, John J. Biafore and Mark D. Smith.  You might think a paper from 2011 is old news, however, in my opinion it is perhaps the best summary of critical EUV resist issues and remains a valuable work of reference applicable to current EUV process concerns.  Utilizing data derived from then available EUV resist materials a statistical analysis was performed to characterize lithography performance providing recommendations on possible process enhancing resist modifications.  The paper summarizes seven parameters which could be optimized to improve EUV resist performance (itemized below).  For complex structures and contact holes with dose exposure/shot noise sensitivity, the paper proposes that modification of resist chemistry and subsequent performance can be enhanced by:
  • Increase resist absorption of EUV light.
  • Reduce the electron affinity of the matrix polymer (reduce electron energy loss that does not result In PAG (Photo Acid Generator) excitation, thus increasing de and C)
  • Increase the electron affinity (and thus the reaction cross-section) of the PAG.
  • Minimize electron blur by increasing resist atomic density (thus reducing re).
  • Minimize acid diffusivity by using lower activation energy leaving groups and reduced post exposure bake temperatures
  • Reduce the spatial distribution fluctuations of PAG in the resist.
  • Reduce resist sensitivity to out-of-band radiation.
Fast forward two years to SPIE Advanced Lithography 2013.  A few minutes after reading this 2011 paper I discovered James Thackeray's recent You Tube video posted on 2/25/2013 describing how Dow Chemical's recent improvements in EUV resist compounds effectively addressed the issues described in the paper of two years ago.  You might ask, why does it take two years to resolve a photoresist design problem?  The chemistries themselves are complex and comprised of nanoscale molecular components which must react selectively to 13.5nm EUV at 14X below typical exposure levels while maintaining integrity under high vacuum conditions with minimal outgassing.  The search for materials exhibiting these extraordinary physical and performance characteristics is time consuming and requires an exhaustive R&D program.  It's gratifying to observe that those who have effectively identified and communicated a complex problem set are also contributing the solutions.

Chris A. Mack's 2012 SPIE invited paper Line Edge Roughness and the Ultimate Limits of Lithography resets the EUV resist issue yet again.  The recent encouraging news from James Thackeray and Dow Chemical might satisfy interim goals in the pursuit of shrinking nanometer scale geometries but the effort to further scale process technology is never ending (we think).  Chris Mack's recent paper speaks to the continuing struggle with LER.  After thoughtful dissertation on process parameters effecting LER he again suggests ways in which EUV resists might be further improved.  EUV exposure/dose is another parameter which can improve LER if only more power were available to provide viable exposure times demanded by HVM throughput requirements.  An anemic EUV photon count contributes to LER, poor contact hole resolution, shot noise, reduction in throughput and the gamut of related effects.  James Thackeray's  recent You Tube  video employs a popular illustration utilized to depict this problem.  Two adjacent plasma chambers exhibit marked differences in photon density with EUV depicted as 14X less.  Dr. Thackeray comments that with 14X less “information” EUV dosage at desired levels remains a challenge.  As an FCC licensed amateur radio operator, I'll site my own analogy.  Ham operators communicate using radio, mostly by voice but also transmit encoded “information” employing radio teletype, slow and fast scan television.  We sometimes talk to the astronauts on the International Space Station on a special link.  As a gentleman's hobby, the rule is to use minimal power necessary to maintain communications so as not to interfere with other stations or adjacent radio services.  On occasion, path loss between stations, atmospheric conditions and noise levels mandate adjustment to this guide line.  One thousand five hundred watts of effectively radiated peak envelope power usually delivers sufficient RF signal strength to “burn a path” to the receiving station.  Signal to noise problems are mitigated and the message gets through.  It's time for Cymer to crank up the output power.

Although there have been many positive developments reported at this years SPIE Advanced Lithography conference, many of the same critical EUV lithography issues remain on the agenda. Some items have been resolved only to be replaced by newer design and performance challenges.  The engineering funnel feeding Moore's Law flexes to accommodate bumps in the road map as the physical limits of materials and energy science are pressed ever further.  Forward looking HVM road maps project that performance improvements in resist LER (Line Edge Roughness), EUV power output and shot noise will eventually converge to resolve the HVM (High Volume Manufacturing) yield and throughput issues given time.  With continued investment, EUV nanometer scale lithography HVM could well emerge to sustain Moore's Law.  In the interim, parallel research continues in e-beam and direct imprint lithography as well as DSA (Directed Self Assembly) techniques for patterning nanoscale device structures.  ReRAM technology has recently been adapted for key next generation products which are candidates for these alternate manufacturing techniques.

Lawrence Berkeley National Labs CXRO Update
Later this year 2013, the enhanced performance SHARP (SEMATECH High-NA Actinic Reticle review Project) is scheduled to go on line.  The effort will be led by Kenneth Goldberg, Ph. D. at Lawrence Berkeley National Labs CXRO (Center for X-Ray Optics).  The enhanced EUV microscope/inspection station with 0.5 NA will be available for SEMATECH members conducting EUV lithography research. The system has undergone many hardware upgrades and performance enhancements and should prove extremely valuable in the continuing EUV process development agenda.  Patrick Naulleau, Ph.D. is the Director of LBNL CXRO and chaired this years SPIE Advanced Lithography IV program, providing unique insight on the industry wide EUV initiative.   

SPIE at Optics and Photonics: Lighting a Path to the Future
In addition to SPIE Advanced Lithography, another important SPIE co-sponsored initiative took place on February 28, in Washington, DC, titled, “Optics and Photonics: Lighting a Path to the Future.”  Other organizations co-sponsoring the event included the IEEE Photonics Society, Optical Society (OSA), American Physical Society, and the Laser Institute of America.  The event was attended by many government agencies who traditionally sponsor research.  The goal of the conference was to foster better government collaboration with American optics and photonics industries and forge a National Photonics Initiative (NPI).  The value of this proposed initiative is best exemplified by recent semiconductor industry manufacturers' investments in ASML and Cymer.  The collaboration of industry and government in key photonic and optical science endeavors could dramatically distribute R&D expenditures and reduce costs across many disciplines. 

SPIE at CREOL Industrial Affiliates Symposium
On March 8, SPIE members also participated in The CREOL Industrial Affiliates Symposium (College of Optics and Photonics at the University of Central Florida) held each spring (currently numbering 70 members).  Themed “Light in Action” the event was also attended by Dr. Eugene Arthurs and Steve Anderson of SPIE.  The following day Dr. MJ and Cheryl Soileau hosted the annual CREOL “Spring Thing” event, an annual Cajun cuisine cook out at their residence on Lake Jesup.  Dr. MJ Soileau is the current Vice President of Research and Commercialization at UCF.  Having attended the “Spring Thing” event at MJ's in the past, (unfortunately not this year) I can vouch for its Cajun authenticity.  “MJ” goes into rare form, rolls up his sleeves and stirs up a pot of spicy vittles which is always a delectable crowd pleaser.  Unknown to most, MJ also keeps a secret supply of his world famous hot sauce in his desk at UCF.  Those seeking inspiration are encouraged to sample this formula known only to MJ.  I once advised him on its stored energy potential commenting that “While not exactly fusion in a bottle, I suspected Pons and Fleischmann would be proud.”  Thanks MJ for your inspiration and all you do for UCF.

Zplasma Update
My blog entry last month featured an Interview with Henry Berg, CEO of Zplasma who is currently seeking funding for further development of a Xenon based Z-pinch EUV source.  During the SPIE Advanced Lithography conference there was interest in Zplasma EUV technology but no immediate success in securing funding.  Feedback from my recent interview with Henry provides insight he gathered from the conference while providing perspective on possible future opportunities for Zplasma.
  
Henry Berg – CEO, Zplasma: 
“It was very exciting to bring Zplasma’s SFS technology to SPIE and talk to companies that will benefit from our Stable DPP source.  We are addressing the four key areas where previous DPP sources ran into difficulties:

Electrode Melting: Previous DPP sources used a short, unstable pinch that required high instantaneous power levels that raised electrode surface temperatures above the melting point of tungsten (3695 K).  Zplasma’s SFS pulses are 10-100 times longer, so the required instantaneous power levels are 10 times lower, which keeps electrode surface temperatures below the melting point.

Electrode Pitting and Erosion: The unstable plasma used in previous DPP sources was subject to current interruptions caused by plasma instabilities.  The current interruptions caused high voltage spikes that ripped charge carriers out of the electrodes, causing pitting and erosion.  Zplasma SFS stable plasma eliminates the voltage spikes that were the root cause of the pitting and erosion.

Etendue Match and Collectible EUV Light: Poor etendue match and the use of grazing incidence collectors meant that previous DPP sources could not collect enough light.  SFS emission volume is adjustable for a high etendue match, and SFS geometry supports side-on collection with an ellipsoidal multilayer mirror, so the Zplasma Stable DPP source can deliver high EUV power levels to the stepper IF. 

Dose Uniformity: Previous DPP sources had unpredictable plasma instabilities, which made controlling dose uniformity difficult.  SFS stable plasma allows for EUV emission under control of the power supply to provide dose uniformity control better than the industry target of 0.2% 3-sigma deviation over 50 pulses.

We had some great discussions about the advantages of Zplasma’s source, with particular interest in the simplicity of Stable DPP and the resulting increase in reliability and reduction in cost of ownership.  We are talking to several companies now about supporting the development of our source.  We are also exploring several new secondary applications as a result of meetings at SPIE.”

SPIE Advanced Lithography IV 2013 provided a wealth of information and insight on the current status of EUV lithography and has also set the stage for the continuing development of required complementary technologies.  KLA-Tencor introduced its Spectra Shape 9000 laser/plasma based inspection station and is said to be developing an EUV actinic inspection tool.  As the complexity and sophistication of these instruments increase, so does the cost to manufacturing.  The result is further stratification of the semiconductor equipment industry and the likely continued expansion of the foundry business model.  Interestingly the business models for most of these scenarios are sometimes analyzed on iPhones, but look out Apple, the Samsung S4 will arrive next month.  Competition is a wonderful thing.  But then we all know that.


For those interested in my ham radio comments: Yes hams really can talk to the astronauts on the International Space Station. Most of the astronauts are also licensed hams with their own call signs.  The astronauts have a very busy schedule and operate the ISS ham station in their spare time which is not very often (usually after their dinner).  To contact the ISS it must be overhead for direct path VHF/UHF communications.  Visit the NASA link for ISS ham radio frequencies and transmission modes and the American Radio Relay League for more information on Amateur Radio: http://spaceflight.nasa.gov/station/reference/radio/
www.arrl.org

Ham Radio Update 3/28/2013.  Two Hams are scheduled to arrive at the ISS.  NASA TV will televise coverage of vehicle docking with the ISS at 10:30 PM EST Thursday evening 3/28. Check the ARRL link below for more information on the astronauts. http://www.arrl.org/news/two-hams-scheduled-to-head-to-iss-this-week


As semiconductor equipment manufacturers expend considerable funding to create exotic plasma systems, the ISS crew is sailing above a sea of plasma easily viewed from their moving vantage point.  I suggest you visit the NASA link below for an incredible view of our planet:

Plasma display courtesy of NASA and the ISS:http://www.youtube.com/watch?v=hWz5ltE_I4c&feature=player_embedded

Thomas D. Jay
Semiconductor Industry Consultant
Thomas.Dale.Jay@gmail.com
www.linkedin.com/pub/thomas-d-jay/26/aa3/499
www.thomasdalejay.blogspot.com

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