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EUVL Masks may need to be Tool-Specific

March 7th, 2017

Extreme Ultra-Violet Lithography (EUVL) keeps hurting my brain. Just when I can understand how it could be used in profitable commercial high-volume manufacturing (HVM) I hear something that seriously strains my brain. First it was the mirrors and mask in vacuum, then it was the resist and pellicle, then it was the source power and availability, and in each case scientists and engineers did amazing work and showed a way to HVM. Now we hear that EUVL might require fabs to park work-in-progress (WIP) lots of wafers behind a single critical tool with an idealistic 80% availability on a good day, and lots of downtime bad days. Horrors!

For “5nm-node” designs the maximum allowable edge placement-error (EPE) in patterning overlay is only 2nm. While the physics of ~13.5nm wavelength EUVL means that aberration in the reflecting mirrors appears as up to 3nm variation in the fidelity of projected patterns. This variation can be measured and compensated for at the physical mask level, but then each mask would only be good for one specific exposure tool. John Sturtevant—SPIE Fellow, and director of RET product development in the Design to Silicon Division at Mentor Graphics—briefly discussed this on February 26th during Nikon LithoVision held just before SPIE Advanced Lithography.

Sturtevant explained that the Zernike coefficients for EUV are inherently almost 1 order-of-magnitude higher than for DUV at 193nm wavelength, as detailed in the SemiMD article “Edge Placement Error Control in Multi-Patterning.” How the inherent physical sources of aberration must be tightened to avoid image distortion and contrast loss as they scale with wavelength was discussed by by Fenger et al. in 2013 in the article “Extreme ultraviolet lithography resist-based aberration metrology” (doi:10.1117/1.JMM.12.4.043001).

—E.K.

Flagello to receive Zernike Award at SPIE Advanced Lithography

February 24th, 2017

Flagello-DonisDonis Flagello, president, CEO, and COO of Nikon Research Corporation of America (NRCA), will be presented with the 2017 Frits Zernike Award for Microlithography on Monday 27 February during SPIE Advanced Lithography in San Jose, California. The award, presented annually for outstanding accomplishments in microlithography technology, recognizes Flagello’s leading role in understanding and improving image formation in optical lithography for semiconductor manufacturing.

A prominent member of the industry since the early 1980s and a longtime SPIE Fellow, Flagello has primarily focused on the rigorous application of physics to lithography modeling and problem solving. Early in his career, while at IBM T.J. Watson Research Center, he developed the first practical test for measuring flare in optical lithography tools and made major contributions to high numerical aperture (NA) modeling including vector and polarization effects, and radiometric correction. At ASML he played an important role in providing analysis of aberrations for new systems and high-NA imaging effects due to polarization.

Another notable aspect of his career, Flagello’s presentations at lithography conferences and papers in various journals have inspired a better understanding of optics and resist behavior and helped drive optical lithography forward, colleagues said. “His presentations are known for their combination of humor with a deep understanding of the complex interactions between physical optics and lithographic process technology,” said David Williamson, an NRCA Fellow and previous Frits Zernike Award winner. “His combined theoretical and practical production experience and knowledge are rare in this field.”

—E.K.

Photoelectric measure of atomically thin stacks

February 17th, 2017

A team led by researchers at the University of Warwick have discovered a breakthrough in how to measure the electronic structures of stacked 2D semiconductors using the photoelectric (PE) effect. Materials scientists around the world have been investigating various heterostructures to create different 2D materials, and stacking different combinations of 2D materials creates new materials with new properties.

The new PE method measures the electronic properties of each layer in a stack, allowing researchers to establish the optimal structure for the fastest, most efficient transfer of electrical energy. “It is extremely exciting to be able to see, for the first time, how interactions between atomically thin layers change their electronic structure,” says Neil Wilson, who helped to develop the method. Wilson is from the physics department at the University of Warwick.

Wilson formulated the technique in collaboration with colleagues at the University of Warwick, University of Cambridge, University of Washington, and the Elettra Light Source in Italy. The team reported their findings in Science Advances (DOI: 10.1126/sciadv.1601832).

—E.K.

XMC becomes YRST or Changjiang Storage

January 19th, 2017

As reported by Digitimes, a major enterprise in Wuhan, China has broken ground on the first of three mega-fabs to produce 3D-NAND chips. The final fab name-plate may ultimately read XMC or YMTC or YRST or possibly Changjiang Storage (not to be confused with GuangDong ChangJiang Storage Battery), but it is over half owned by the Chinese government’s Tsinghua Unigroup.

Total investment in XMC/YRST by Tsinghua Unigroup is reported by Digitimes to be US$24 billion. In 2015 Tsinghua Unigroup bid US$23 billion to buy Micron Technology Corp, but the company was not for sale.

In 2013 as reported at EETimes, the fab re-branded itself as XMC from the former Wuhan XinXin Semiconductor Manufacturing (WXIC). Dr. Simon Yang was CEO of WXIC/XMC from 2012 to last November when he resigned to become the CEO of Yangtze Memory Technologies Co. Ltd.

Two months later the new company is reportedly to be called Yangtze River Storage Technology (YRST), according to DIGITIMES. Meanwhile, Nikkei Asian Review reports that YRST is also known as Changjiang Storage.

High-Volume Manufacturing (HVM) in the first fab is planned for 2018, and the third fab on the campus is expected to bring 300k 300mm wafer-starts-per-month online by 2020. Rick Tsai the ex-CEO of Taiwan Semiconductor Manufacturing (TSMC) and Shih-Wei Sun the ex-CEO of United Microelectronics (UMC) have both reportedly joined Tsinghua Unigroup.

—E.K.

China to be 15% of World Fab Capacity by 2018

November 29th, 2016

Currently there are eight Chinese 300mm-diameter silicon IC fabs in operation as 2016 comes to a close. Chinese IC fab capacity now accounts for approximately 7% of worldwide 300mm capacity, as reported by VLSIresearch in a recent edition of its Critical Subsystems report (https://www.vlsiresearch.com/public/csubs/). This will expand rapidly, as ten are now under construction and two more have been announced. China’s 300mm fabs are located in ten cities.

“Total Chinese capacity is expected to be around 13 million by end 2018,” said John West of VLSI Research. Worldwide 300mm wafer fabrication capacity will exceed 85 million wafers per year in 2018, putting China in control of 15% of worldwide 300mm capacity in 2018. While new Chinese fabs have yet to prove they can produce leading edge silicon ICs with high yields, it should be only a matter of time before they prove they stand among the world’s great semiconductor production regions.

West recently presented a China market outlook for semiconductors, original equipment manufacturers (OEM), and critical subsystems at the recent Critical Materials Council (CMC) Seminar (http:cmcfabs.org/seminars) held in Shanghai. At the same event, representatives from Intel and TI discussed supply-chain dynamics in China, and Secretary General Ingrid Shi of the Integrated Circuit Materials Industry Technology Innovative Alliance (ICMITIA) presented on “The China Materials Supply Consortium and China’s 5 Year Technology Plan.”

The 2016 CMC Seminar also saw a presentation of China’s first semiconductor-grade 300mm silicon wafer supplier:  the recently unveiled Zing Semiconductor (www.zingsemi.com). Founder and CEO Richard Chang, co-founder of SMIC, has assembled a team and funding to start creating wafers in the Pudong region of Shanghai. He showed a photo of his company’s first 300mm silicon boule at the event.

[DISCLOSURE:  Ed Korczynski is also Marketing Director for TECHCET CA, an advisor firm that administers the Critical Materials Council and CMC events.]

—E.K.

Reliable ICs from unreliable devices

November 10th, 2016

In an article published in the most recent issue of imec’s online magazine (http://magazine.imec.be/) titled “Chips must learn how to feel pain and how to cure themselves,” researchers Francky Chatthoor and Guido Groeseneken discuss how to build reliable “5nm-node” ICs out of inherently unreliable transistors. Variability in “zero time” and “over time” performance of individual transistors cannot be controlled below the “7nm-node” using traditional guard-banding in IC design.

“Maybe it means the end of the guard-band approach, but certainly not the end of scaling,” says Groeseneken in the article. “In our research group we measure and tried to understand reliability issues in scaled devices. In the 40nm technology, it is still possible to cope with the reliability issues of the devices and make a good system. But at 7nm, the unreliability of the devices risks to affect the whole system. And conventional design techniques can’t stop this from happening. New design paradigms are therefore urgently needed.” These researchers predict that industry will have to manufacture self-healing chips by the year 2025.

Self-healing chips could use the workload variation of the system for their benefit. Based on a deterministic predictor of the future, future slack is determined and used to compensate for the delay error and mitigate at peak load. (Source: imec) Self-healing chips could use the workload variation of the system for their benefit. Based on a deterministic predictor of the future, future slack is determined and used to compensate for the delay error and mitigate at peak load. (Source: imec)

The ultimate goal of imec and its academic partners is to develop a fully proactive parametric reliability mitigation technique with distributed monitors, a control system and actuators, fully preventing the consequence of delay faults and potentially also of functional faults. Said Catthour, “the secret to the solution lies in the work load variation of the system. Based on a deterministic predictor of the future, you determine future slack and use this to compensate for the delay error at peak load. Based on this info on the future, you change the scheduling order and the assignment of operations.” The Figure shows how self-healing chips can use future slack to compensate for delay error and mitigate at peak load.

—E.K.

CSP Market Forecast – Strong

October 29th, 2016

Chip-Scale Packages (CSP) continue to be in strong demand for IC needing the smallest form-factors for applications including automotive, industrial applications to mobile phones and wearable electronics, according to leading market research firm TechSearch International. TechSearch’s latest CSP market forecast shows a 8% CAGR from 2015 to 2020, despite a slowing growth rate for smartphones.

One of the categories with the strongest growth is the quad flat no-lead (QFN) package with a CAGR of 8.6%. QFNs are a low-cost, low-profile package found in a wide range of products from automotive and power devices. An analysis of the Out-Sourced Assembly and Test (OSAT) market in China provides insight into expansion plans and market shares.

Fan-Out Wafer-Level Packages (FO-WLP) with many variations are now winning slots in many new mobile devices. New advanced packages such as JCAP’s FO-WLP are highlighted in the latest Advanced Packaging Update, along with the use of TSMC’s FO-WLP for Apple’s A10 application processor. The report also examines trends in stacked die CSPs, laminate-substrate CSPs, and package-on-package (PoP) with a market forecast for each. See:  http//www.techsearchinc.com.

—E.K.

Dan Rose departs material realm

October 14th, 2016
Daniel J. Rose, Ph.D. November 7, 1937 – September 20, 2016 Daniel J. Rose, Ph.D.
November 7, 1937 – September 20, 2016

With sadness I post that Daniel J. Rose, Ph.D.—founder of Rose Associates—passed away on September 20, 2016, due to complications of Alzheimer’s disease. Dan Rose received a Ph.D. in materials engineering from the University of British Columbia, and subsequently spent five years managing packaging manufacturing operations at Fairchild Semiconductor. He worked with and become friends with industry luminaries such as Intel’s founder Robert Noyce, and National Semiconductor’s founder Charlie Sporck.

In February of 1970, he founded Rose Associates, which initially provided engineering and manufacturing support to the semiconductor industry, establishing factories in the US and assembly plants in the Far East. In 1977, Rose Associates began conducting market research in electronic materials. In January of 1985, Rose Associates began publishing the Electronic Materials Report (EMR) monthly newsletter, and In 1986 held its first annual Electronic Materials Conference.

Dan Tracy, Ph.D.— SEMI Senior Director, Industry Research & Statistics—was one of Rose’s associates who joined the trade organization in 2000 when it acquired Rose Associates’ business. Tracy wrote a wonderfully heartfelt remembrance as a LinkedIn Pulse article (https://www.linkedin.com/pulse/dr-daniel-j-rose-phd-dan-tracy?trk=hb_ntf_MEGAPHONE_ARTICLE_POST).

—E.K.

Fish-Scale Piezo Generators

September 26th, 2016

Piezoelectric generators are based on thin-films of structured materials that can convert pressure into electricity. Inorganic crystals such as aluminum-nitride (AlN) barium titanate (BT) and lead-zirconium-titanate (PZT) have long been explored as piezoelectric films for various applications. Now researchers Sujoy Kumar Ghosh and Dipankar Mandal at the Jadavpur University in Kolkata, India have shown that fish scales (FSC) can be used to build a flexible bio-piezoelectric nanogenerator (BPNG) capable of producing a maximum output power density of 1.14 μW/cm2 under repeated compressive normal stress of 0.17 MPa.

Fabrication of flexible (BPNG) from bio-waste fish-scale (FSC) a) photographs of the bio-waste raw FSC, and demineralised FSC, b) flexibility of the BPNG shown by human fingers, and c) schematic diagram of simple BPNG device structure. (Source: APL) Fabrication of flexible (BPNG) from bio-waste fish-scale (FSC) a) photographs of the bio-waste raw FSC, and demineralised FSC, b) flexibility of the BPNG shown by human fingers, and c) schematic diagram of simple BPNG device structure. (Source: APL)

As recently published in Applied Physics Letters with the title, “High-performance bio-piezoelectric nanogenerator made with fish scale,” the Figure shows that they started with the skin trimmings of Indian carp (Catla catla), that were acid washed and demineralized to extract collagen of nominal thickness ∼250 ± 10 μm, which is then sandwiched between 90nm thick sputtered gold electrodes, followed by lamination with polypropylene (PP) film ∼125 μm thick.
Energy harvesting is enabled by the self-assembled and ordered collagen nano-fibrils, which exhibit intrinsic piezoelectric strength of −5.0 pC/N.

…the most abundant piezoelectric biomaterial present in animal tissues such as skin, tendon, cartilage, bone, and even in human heart, is the type I collagen, which is a biocompatible and biodegradable polymer enabling fabrication of the flexible BPNG. The cost effective collagen source is the fish constituents such as skin, fins, maws, and swim bladder which are mainly treated as “bio waste” materials because different fish species are consumed daily in large quantities worldwide. The disposal of these bio-wastes causes an increasing environmental pollution. The recycling of the fish by-products into the BPNG via one step process is a promising solution for the development of value-added products and also to reduce the e-waste elements.

The BPNG is able to convert several forms of mechanical energy into electricity. For example, gentle press-hold-release motions of a single human finger (∼3.75 kPa and strain rate of 0.017% s−1) results in ∼680 mV output voltage with perfect switching of polarity. It scavenges mechanical energy from high level vibration from machines and also from very low level vibration, arises from sound (∼0.2–2.0 Pa) and wind motions (∼3.6 m/s). When slapped repeatedly by a human hand (∼ 0.17 MPa with 0.77% s−1 strain rate) this BPNG generates a rectified open circuit voltage (Voc) of 4 V, and multiple layers can be stacked to multiply the Voc. Due to high sensitivity, good stability, and efficient piezoelectric power-generating performance, these BPNG may open a new era in sustainable energy harvesting.

—E.K.

Patterning with Films and Chemicals

August 24th, 2016

Somewhere around 40nm is the limit on the smallest half-pitch feature that can be formed with a single-exposure of 193-nm wavelength laser light using water immersion (193i) lithography. While multiple-patterning (MP) is needed to achieve tighter half-pitches, smaller features at the same pitch can be formed using technology extensions of 193i. “Chemistry is key player in lithography process,” is the title of a short video presentation by Dow Electronic Materials corporate fellow Peter Trefonas now hosted on the SPIE website (DOI: 10.1117/2.201608.02).

Trefonas as been working on chemistries for lithography for decades, including photoresists, antireflectant coatings, underlayers, developers, ancillary products, and environmentally safer green products. He is an inventor on 61 US patents, has over 25 additional published active U.S. patent applications, is an author of 99 journal and technical publications, and is a recipient of the 2014 ACS Heroes of Chemistry Award and the 2013 SPIE C. Grant Willson Best Paper Award in Patterning Materials and Processes. Now a Senior Member of SPIE, he earned his Ph.D. in inorganic chemistry with Prof. Robert West at the University of Wisconsin-Madison in 1985.

Trefonas explains how traditional Chemically-Amplified (CA) resists are engineered with Photo-Acid Generators (PAG) to balance the properties for advanced lithography. However, in recent years the ~40-nm half-pitch resolution limit has been extended with chemistries to shrink contact holes, smooth line-width roughness, and to do frequency-multiplication using Directed Self-Assembly (DSA). All of these resolution extension technologies rely upon chemistry to create the final desired pattern fidelity.

—E.K.

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