Category Archives: Touch Technologies

May 3, 2012 — Tablet PC shipments are expected to grow from 81.6 million units in 2011 to 424.9 million units by 2017, according to NPD DisplaySearch, overtaking notebook PCs. This rapid growth comes with diversification, in hardware like displays and in software like operating systems (OS).

Component manufacturing capacity is being increased to meet this new market demand. Many display manufacturers are transitioning tablet panel production to larger plants, including Gen 6 and Gen 8, which will lead to greater capacity for tablet displays, as well as lower prices. In addition, the share of AMOLED displays in tablets is forecast to increase from 3% in 2012 to 30% by 2017.

Also read: Media tablets join top 5 semiconductor end-markets in 2012

Figure. Worldwide tablet PC emerging and mature market shipment forecast. SOURCE: Q1 2012 NPD DisplaySearch Tablet Quarterly report.

 

The young market has been “dominated” by Apple’s iPad and similarly configured tablets from competitors, said Richard Shim, NPD DisplaySearch senior analyst.

NPD DisplaySearch expects retailers, brands, and consumers to experiment with emerging tablet opportunities. Increased investments in the tablet supply chain — amidst a lull in the growth of other device categories — will lead to more opportunities for new technologies to challenge incumbents. A key area where there is room for differentiation is operating systems, with Android taking share from iOS. Windows RT will also grow, but from a very small base.

NPD DisplaySearch’s Tablet Quarterly report tracks quarterly changes in tablet PC products and strategies, and forecasts the impact of those changes on the market. It covers the changing landscape of screen sizes, features that are expected to be included and excluded in future tablets, and operating systems. NPD DisplaySearch is a global market research and consulting firm specializing in the display supply chain, as well as the emerging photovoltaic/solar cell industries. Internet: http://www.displaysearch.com/.

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April 30, 2012 – BUSINESS WIRE — The global touch controller IC market is growing quickly, thanks to emerging natural user interface (NUI) devices and touchscreens’ rapid adoption in consumer electronics. In 2011, global touch controller revenue was only 0.4% of the total semiconductor industry’s $312.5 billion. In 2016, this share will increase to 1.65%.

Resistive- and capacitive-type touch panels were about 85% of the total touch controller IC market in 2011. Capacitive touch controllers will remain dominant, taking over about 55% of the total touch market in 2016.

Touch controller applications are broadly divided in to three segments: consumer, commercial, and industrial. Specific usage segments include retail, education, transport, medical, entertainment, and infotainment. In 2011, more than 80% of touchscreen controller IC revenues came from the consumer application segment, due to the huge volumes of touch-based mobile phones and tablets.

Also read: Touchscreen controller IC market tripling thanks to mobile devices

The demand for touch controller ICs from the Asia-Pacific (APAC) region should grow at a CAGR of 50% from 2011 to 2016. More than 60% of the product supply, however, comes from North America.

Access the report “Touch Controller IC Market Global Forecast & Analysis (2011 – 2016) by Technology, by Products Types, by Applications & by Geography” at http://marketpublishers.com/report/technologies_electronics/electronic_devices/touch_controller_ic_market_global_forecast_analysis_2011_2016_by_technology_by_products_types_by_applications_by_geography.html

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April 27, 2012 – BUSINESS WIRE — Multi-sensing touchscreen technology developer Neonode Inc. (OTC BB:NEON) was approved by The NASDAQ Stock Market LLC to begin listing its common stock on the NASDAQ Capital Market under the ticker symbol NEON, on May 1.

The NASDAQ listing will give “increased visibility” to Neonode, said its CEO Thomas Eriksson. The company’s zForce touch technology supports “multisensing,” will capabilities such as proximity-, pressure- and depth sensing, as well as object-size measuring. The technology suits devices like smartphones, tablets, toys and gaming consoles, printers and office equipment, e-readers and automotive or inflight infotainment systems.

Also read: Neonode enters consumer display sector with new licensing agreement and Neonode optical touch technology replaces resistive touch on office equipment line

Neonode’s customers include Sony, Barnes & Noble, Oregon Scientific, L&I, Daesung and Sonim.

Neonode Inc. (NEON) develops and licenses the next generation of proven optical MultiSensing technologies. For further information please visit www.neonode.com.

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April 25, 2012 — Touch sensors for displays grew to 66% to 9.6 million square meters in 2011, according to the NPD DisplaySearch Touch Sensor Manufacturing Capacity report. This includes resistive, projected capacitive, sensor-on-cover (SOC), and on-cell touch sensors. Touch sensors will continue growing, with 13.0 million square meters in 2012, and 16.4 million in 2014, says NPD DisplaySearch.

Figure. Touch sensor supply and demand. SOURCE: NPD DisplaySearch, April 2012.

By revenues, the touch panel industry grew from $4 billion in 2009 to over $13 billion in 2011. The market for touchscreen displays is strong, driven by mobile devices such as smartphones and tablet PCs, as well as PCs and point-of-information applications.

New display and color filter manufacturers, among other companies, are grabbing up market share in this rapidly growing display sector.

With rapid growth in resistive, projected capacitive, sensor-on-cover, and on-cell touch sensors, the industry’s development is under scrutiny, including the balance of supply and demand, how quickly sensor-on-cover projected capacitive touch can take share from conventional projected capacitive, and how on-cell and in-cell touch will impact add-on type touch screens, NPD DisplaySearch reports.

“Capacity in 2010 and 2011 was slightly higher — 13% — than demand, but this level of oversupply is healthy, given the rapid pace of growth in the touch industry,” said Jennifer Colegrove, Ph.D., VP, emerging display technologies for NPD DisplaySearch. “However, the glut is expected to more than double in 2012, to 27%, causing touch sensor prices to reduce rapidly. The oversupply will also force touch suppliers to move to larger size applications to utilize capacity, such as notebook and all-in-one PCs, ATM/finance and point of information,” Dr. Colegrove noted.

Resistive touch sensors were in oversupply in 2010. In 2011, most resistive touch manufacturers dramatically reduced their capacity; some converted their lines to projected capacitive touch. In 2012, resistive touch manufacturers continue to minimize capacity, leading to a balanced supply/demand outlook. While resistive continues to be strong in applications such as automotive, education/training, and industrial, it will slowly decline.

Projected capacitive touch manufacturing has increased dramatically, from 27 companies in 2009 to over 80 companies in 2011. Many projected capacitive suppliers are also establishing sensor-on-cover fabs.

SOC is forecast to grow fivefold (by area) in 2012. Due to its light weight and thinness, SOC is likely to be adopted in tablet and notebook PCs, including form factors such as sliding and convertible devices. Many leading touch module makers increased their cover glass capacity in 2011 in preparation for SOC production. NPD DisplaySearch forecasts SOC will capture an 8.6% share in 2012.

On-cell touch sensors are mainly used in AMOLED displays. In 2013, as large AMOLED fabs enter full production, there will be a significant oversupply (52%) of on-cell.

In-cell touch has been researched and demonstrated for many years, and in 2012, mass production will begin. Sony announced it is producing 4.3” in-cell LCDs. Synaptics is producing controller ICs for in-cell touch designs. As yield rates improve and tier one smartphone brands adopt the technology in 2013-2014, in-cell will experience strong growth.

Production of transparent conductive substrates (mostly ITO) for the four types of touch covered in the report will grow from 20.8 million square meters in 2011 to 30.9 million in 2014.

The Touch Sensor Manufacturing Capacity report includes information on nearly 100 fabs, including glass substrate generation, substrate size, substrate allocation, substrate input, yield rate, and yielded touch sensor area (in square meters). Transparent conductive substrate (ITO and ITO replacements) input information is also provided, and supply and demand for each of the four types of touch sensor is analyzed. NPD DisplaySearch surveyed over 60 suppliers of projected capacitive, sensor-on-cover, on-cell, and resistive touch sensors. The Touch Sensor Manufacturing Capacity report is a companion to the NPD DisplaySearch Touch Panel Market Analysis report, which profiles over 190 touch screen suppliers and analyzes each touch technology. NPD DisplaySearch is a leading global market research and consulting firm specializing in the display supply chain, as well as the emerging photovoltaic/solar cell industries. The NPD Group is the leading provider of reliable and comprehensive consumer and retail information for a wide range of industries. For more information on NPD DisplaySearch analysts, reports and industry events, visit http://www.displaysearch.com/.

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Blogger Mike Fury reports from the MRS Spring 2012 meeting in San Francisco. Highlights from the fourth day: electronic skin, energy storage with nanowires, printable inks, gas sensing, inkjet printing, semiconductor polymers for organic devices, CNTs, OFETs, touch screen fabrics, and the coffee breaks.

The fifth and final day of the MRS Spring 2012 meeting opened Friday the 13th at Moscone West in San Francisco opened under bright mostly sunny skies following an evening of thunderstorms and torrential rain. Thunderstorms are not a common event in San Francisco, and this one brought some spectacular lightning strikes on the Transamerica pyramid and the Oakland Bay Bridge. The lightning rods worked as advertised. Praise Science!!

K9.1 Ali Javey of UC Berkeley opened with a discussion of printed nanomaterials for artificial electronic skin (which might imply that work is underway on organic electronic skin, but I suspect that this is not actually the case) and its ability to detect and respond to external stimuli. Many types of basic sensing elements can now be integrated into thin film organic electronics. For example, covering an airliner with a strain gauge skin and detecting early signs of structural weakening might reduce the incidence of fuselages peeling off in flight in our aging fleet. Many of his structures are based on CNT TFT on pollyimide, with mobilities of 40-50cm2/Vs. Stretchability up to 10% is achieved by laser ablating holes in the substrate much like honeycomb decoration paper, and placing the TFT devices at substrate locations that have minimum strain when stretched. A pressure sensing honeycomb glove has a tactile sensitivity and response comparable to human skin. Additional work is underway on programmable, reconfigurable materials from which a 3D shape can be self-assembled from a planar substrate by patterning folds and junctions and activating them in the proper sequence — effectively nano origami. Such devices have applications as actuators of all kinds and can respond to temperature, moisture, pH or light. Imagine curtains that can close themselves when the run is bright.

N11.1 Liqiang Mai of the Wutan U (China) – Harvard Joint Nano Key Lab talked about energy storage at several scales using nanowire electrochemical devices. A test device was developed for characterizing the battery electrode properties of a single nanowires with an ion gel electrolyte. Materials studies include VO2, MoO3, FeSe2, MnMoO4, CoMoO4 and Li-doped variants of these. One intriguing variant was CoMoO4 nanowires that were grown on MnMoO4 nanowires that were somewhat larger, resulting in a porcupine structure. The specific area increased to 54.06m2/g compared to <10 for the MnMoO4 substrate itself. Functional battery work remains to be done, but a strategy for increasing electroactivity has been nicely demonstrated.

J15.2 Darin Laird of Plextronics described some printable inks for OPV and OPD (diode detector) devices and their integrated applications. Minimization of dark current is critical for an effective OPD. Current level for a sample Ca/Al electrode device is >100nA/cm2 at 1V, but a proprietary cathode material brings this down to 66±38. The Plextronics PV2000 OPV ink is based on bis-indene, which is a derivatized C60 buckyball that was developed and commercialized in 2006 (contrary to reports elsewhere of first introduction of this material several years later).

BB10.6 Ulrich Simon of Aachen U (Germany) talked about polyol-mediated synthesis and high throughput impedance spectroscopy screening of gas sensing metal oxide nanoparticles. In addition to the familiar list of common industrial and household gases that are sensed to control safety and comfort issues, there are a host of more exotic gases in the medical and security fields that are garnering increased attention. Nanocrystals are desirable for such applications due to their higher active surface area and thus sensitivity. Over 200 metal oxides have been synthesized and screened using a high throughput experimentation protocol developed in his lab. Thick film amorphous oxides are synthesized in parallel on a 64 cell multi-electrode ceramic substrate and fired concurrently, mimicking the use of parallel analysis for drug screening.

K9.7 Craig Arnold of Princeton U demonstrated the utility of laser-induced blister dynamics for actuating inkjet printing of organometallic molecules for electroluminescent devices. His modeling of multicomponent inks shows that inadequate initiation of the drop formation can result in droplet formation of a surface solvent layer without incorporating a representative portion of pigment molecules in the correct proportions. This printing method is particularly suitable for molecules that cannot survive printing with conventional inkjet methods.

Z12.8 Christine Luscombe of U Washington developed a variety of star-shaped and hyperbranched semiconducting polymers for organic electronic devices using a Ni(PPh3)4 ligand exchange protocol to control conformation and molecular weight distribution. A hyperbranched structure is a less regular analog of a dendrimer. Absorbance ~550nm is 2x greater for the star P3HT than for the corresponding linear P3HT, and preliminary but promising OPV performance was shown.

EE10.1 Sung Hun Jin from U Illinois Urbana (John Rogers group) presented a method for aligning SWCNT and subsequently removing the metallic tubes (m-CNT) to leave only semiconducting tubes (S-CNT). After aligning the tubes, they are pinned at each end with an electrode, and the entire CNT array is coated with an organic film. When a current is applied, heating resistance of the m-CNT melts the coating and exposes them to the surface. Plasma ashing then removes the exposed m-CNT; when the coating is stripped, a high performance array of only S-CNT remains. The technique has been dubbed ‘metallic nanotube removal’ or MNR, and was shown to be scalable to a channel nearly 1mm long. A near term objective is to use this S-CNT array to fabricate high frequency RF devices.

EE10.2 Chongwu Zhou of USC explained a method for DNA separation of CNT seeds based on chirality, followed by a catalyst-free CVD cloning technique to extend the seeds from 0.3µm to 30-40µm in length. This chirality-controlled CNT cloning in combination with semiconductor enrichment enabled fabrication of separated nanotube (SN-) TFT devices with 98% yield, 25kΩ/square sheet resistance, 10µA/µm current density and 67cm2/Vs mobility across 3 inch Si/SiO2 wafers. Another demonstration produced a working display element with 500 pixels and 1,000 transistors.

K10.4 Shimpei Ono of the Central Research Institute of the Electric Power Industry (Japan) described a high performance OFET with ultra-thin gate dielectric. The device uses rubrene single crystals with a 50nm ALD HfO2 gate dielectric and Au metal gate. The HfO2 dielectric exhibits a high carrier accumulation of 5×1013cm-2, 5x the number of charge carriers as a comparable SiO2 device. The high current at 2V applied voltage indicates a high quality HfO2 dielectric. Top gate devices are stable in air, while inverted bottom gate devices with the rubrene exposed to air are not.

K10.5 Toshitake Takahashi of UC Berkeley talked about smart skin as one implementation of a CNT active matrix backplane for conformal electronics and sensors using semiconductor-enriched CNT scheme. The CNT network density is controlled by managing the rate of solvent spreading and evaporation as the mixed S-CNT (~99%) and m-CNT source material is applied drop wise to the polyimide substrate. Electrical properties showed no degradation in bending down to a 2.5mm radius. The flexible, stretchable substrate with devices fabricated at the points of minimum substrate strain is the same as described in K9.1 above.  The transistors showed Ion/Ioff ~104 and a mobility of 20cm2/Vs with an ALD Al2O3 gate oxide.

K10.6 Kazuhiro Kudo of Chiba U (Japan) talked about printed common gate vertical channel transistors using nanoimprint patterning. Evaporated devices comprised pentacene channels, 120nm parylene-C gate dielectric, Al gate, and Au S/D. An analogous wet process device deposited all active layers in a planar stack, then formed two vertical channels using imprint to create a depressed channel with a vertical sidewall on each side. SVC-OFETs can be used for active matrix displays and RFID tags with active loop antennae.

E11.6 Umberto Celano of IMEC talked about Cu migration in conductive bridging memories. The CuTe layer exhibited improved homogeneity with the addition of a Ti interlayer. The migration of Cu into the solid electrolyte is confirmed as the driving mechanism for device operation.

K10.8 Hiam Sinno of Linkoping U (Sweden) used a block copolymer as a surface modifier improving the printing of polyelectrolyte gated OFETs. The problem arises because the electrolyte (e.g. PSSH) is typically hydrophilic, and the semiconductor (e.g. P3HT) is hydrophobic. The block copolymer treatment enhances the surface presence of thiophene components in the PSSH. The electrical functionality of the transistor was not impacted. This electrolyte gated OFET device has the best acronym of the week: EGOFET. Freud would be pleased.

K10.9 Peyman Servati of U British Columbia wrapped up the symposium with a presentation on transparent, flexible composite nanofiber electronics for touch screen fabrics as a replacement for ITO. Candidate materials include SWCNT, Ag nanowires and graphene, but each has its down side. The approach taken here is to mimic natural fiber networks by using an electrospinning process on a solution of composite nanofibers (CNF) where the CNF can comprise several different types of materials. The spray head can induce some level of nanotube alignment which is useful for enhancing performance. Following spinning, the fibers are carbonized at ~700°C, producing a conductive CNF mesh. The resulting mesh can be 80% transparent at 100Ω/o. Early OPV devices performed at 2% efficiency vs. 4% for a comparable ITO device, due to surface roughness issues that remain to be addressed.

Managing the schedule for so many concurrent technical sessions is always a challenge, especially given the preponderance of academic speakers in this conference; I refer of course to the notion of herding cats. One element of the conference that always runs like clockwork is the coffee breaks. They start on time, which is a great reliability feature since not all symposia are coordinated to exactly the same break times. Equally as impressive, but with the opposite pleasure polarity, is the fact that they end precisely on time. If Seinfeld were still producing new episodes, I would expect the iconic soup Nazi to be joined before long by these coffee Nazis. Ruthless but precise. Just doing their jobs.

April 13, 2012 — Demand is sharply increasing for projected capacitive (PROCAP) touchscreen display panels, used in smartphones and tablets, but capacitive touch panel structures are unique to each company. This core technology must be advanced and differentiated to enable more touch devices, says Displaybank. Technical issues and a lack of cooperation could restrain touchscreen growth.

In general, capacitive touch can be classified into glass- or film-substrate produced. Glass-substrate capacitive touchscreens are found in Apple’s iPhone and Samsung’s Galaxy S phone. The iPhone uses a glass-glass (GG) structure that forms the X-axis sensing electrode on the upper surface of a glass substrate and Y-axis sensing electrode on the bottom. While Apple’s GG method and other mobile phone makers’ glass/film (GFF) designs are becoming mainstream, attempts to develop products such as G1F, and G2 with better transmittance and thinness will continue. G2 is cover window integrated touch, which does not require separate touch sensor.

Figure. PROCAP touchscreen architectures. SOURCE: Displaybank.

The advantages of GFF are low capital cost, suitable for small quantity batch production, and light structure. GG is suitable for mass production and has better appearance properties, but it has high investment costs and is heavier than film-based panels.

Learn more about the various PROCAP touchscreen options and merits in Diverse touchscreen technologies drive industry transition

Displaybank looked at the evolution of touchscreen technologies by examining Apple’s related patents: the main ideas of these patents, technical information, and technology flow. They selected 7 key patents for Apple’s double-sided indium tin oxide (DITO) and single-sided ITO (SITO), and also referred to Apple and Motorola’s patent dispute issue and product analysis result of Apple’s iPhone 4S.

Learn more about the report, Apple Touch Sensor Panel (TSP) Key Technology – GG (DITO & SITO) Key Patent Analysis, at http://www.displaybank.com/_eng/research/report_view.html?id=865&cate=4

April 11, 2012 — Dawar unveiled its all-glass Multi-Touch Projected Capacitive Touch (PCT) Screen technology with advanced optics for medical, instrumentation, and industrial displays.

Figure. Dawar’s Multi-Touch PCT Screens reportedly offer functionality, sensitivity and advanced optics in an all-glass touchscreen.

The multi-touch PCT screens support 4 simultaneous touch points with full gesture support for tap, flick, pinch, click, expand, and rotate actions from a finger, glove or conductive stylus. Its optics enable 90% light transmission and clarity above 97%. No linearity calibration is required. The all-glass display’s surface durability is greater than 9H pencil hardness over a wide operating temperature range.

The display product is made in the US with US engineering support. Screen sizes include 4.3” to 24” diagonal for controller board solutions and 4.3” to 17” diagonal for Chip-on-Flex. Dawar offers screens in standard (4:3) and wide aspect ratios. Custom features are available.

All are Windows 7 HID compliant, with drivers available for most other operating systems.  They support multiple interfaces (USB, RS232 and I2C). Dawar controller boards, drivers, interface cables and other components are available, along with custom solutions.

Dawar offers user-interface technologies and electronic components. Learn more at www.dawar.com.

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Blogger Mike Fury reports from the MRS Spring 2012 meeting in San Francisco. Highlights from the second day: OLED TFT displays, single transistor DRAMs, silicon photonic wires, CNTs, 3D optical interconnects, graphene for RF and sensing, transparent ZnO, epidermal electronic systems, stretchable electronics, ultra-low-k dielectrics, patterning of electroceramics, PRAM (an alternative to NRAM), and inkjet printing of superconducting films.

Day 2 of the MRS Spring 2012 meeting opened Tuesday in Moscone West in San Francisco under overcast skies and a light drizzle. The halls were packed at 8am as so many of the symposia lead off with presentations that have high audience appeal.

K1.1 Kazumasa Nomoto of Sony offered Sony’s outlook for the future of ultra flexible AM-OLED TFT displays, enough so to merit the labels foldable and rollable. In a full color 4.1 inch 121 ppi FWQVGA format, an 80µm thick AM-OLED display has a bending radius of 4mm. In a 13.3 inch 150 dpi UXGA format, a 120µm thick electrophoretic display (EPD) has a bending radius of 5mm. This is facilitated by integrating flexible OTFT gate driver circuitry into the backplane. The 20nm thick PXX gate oxide consists of alternative self-assembled layers. Both screen printing and inkjet printing techniques are employed in the process flow.

E1.1 Sorin Cristoloveanu of IMEP-LAHC Minatec guided us along the path to single transistor DRAM (1-T DRAM) in which the capacitor storage cell scales proportionally to the drive transistor. Metastable dip (MSD) DRAM is a hysteresis device that has no associated capacitor. Another variation is ARAM. Below a storage channel width of 10nm, it is not longer possible to sustain a separation of holes and electrons. Inserting a 3nm separator between the two sides of the channel (suggesting a squared off “A”) makes it possible to reduce the total width below 10nm. A new device called Z2-FET is a PIN junction with zero subthreshold swing and zero impact ionization. The fabrication process is compatible with SOI CMOS. URAM is the combination of a 1-T DRAM with a non-volatile memory (NVM) element. Several additional concepts were presented more rapidly than I could keep up.

L1.1 Siegfried Janz of NRC Canada talked about the use of silicon photonic wires as optical sensor elements. Folded waveguides can be configured in dense spirals or grids to achieve, for example, a 2mm long sensing element in a 150µm2 area. These elements can be applied to photonic wire evanescent field (PWEF) affinity binding sensors for DNA, protein and bacteria analysis to 200 pico molar sensitivity. The entire waveguide detector system is fabricated in an oxide layer 200nm thick. Microfluidic channels 200µm wide are aligned and pressed over the PWEF array to flow analyte over the sensor elements. The PWEF sensor arrays are manufactured with 500 chips per wafer in the CMOS foundry at LETI.

J3.1 Rahul Sen of Nantero described the use of CNT formulations in electronic devices. Materials are 300mm CMOS compatible spin coated films that can be lithographically patterned with conventional oxygen plasma techniques. Facilities fabricating with these films include ON Semi and SVTC. The CNT solution has <25ppb metal impurities; the final film has <1×1011 atoms/cm2 for BEOL compatibility. Sporadically high calcium levels >30ppb was resolved with an ion exchange process. One application of this material is the development of an NRAM™ universal memory device using CNT as the switching element.

M1.6 Soenke Steenhusen of Fraunhofer ISC took us from research to reality as regards 3D optical interconnects. The energy required to operate processers suggests a limit of 1.25 TFLOPS/chip which translates to an energy threshold of 6 GFLOPS/watt using conventional metal interconnects. This becomes the fundamental driver for integrating optical interconnects in their stead. The optical waveguide fabrication methodology described involved 2 photon polymerization (2PP) of polymer materials using femtosecond laser pulses.

DD5.2 Tomás Palacios of MIT presented the use of graphene for RF and sensing devices. His approach is to fabricate graphene devices on top of completed CMOS structures, or to make the graphene devices directly on flexible substrates. He uses the PMMA transfer method for graphene grown at 1000°C from CH4 on Cu. His applications of interest cover the whole range of known markets that have been discussed elsewhere. For on-chip interconnects in the range of 100nm wide down to 1nm wide, graphene has a low constant resistivity; in this range, the resistivity of copper spikes exponentially. By fabricating a top-gated GFET on an insulating substrate rather than conductive silicon, the GFET device can exhibit a high fT >20GHz in which the parasitic capacitance is low, meaning that the de-embedded fT is quite comparable to the non-de-embedded value.

BB1.11 Chia-Lin Chuang of National Taiwan U discussed a highly transparent p-ZnO prepared from a non-toxic sol gel. Generally, p-type ZnO is difficult to fabricate for a variety of reasons including native donor defects, deep acceptor levels and unintentional hydrogen doping. Their non-toxic composition included zinc acetate, indium nitrate, IPA, MEA and ammonium acetate. The resulting films have a resistivity of 4.43 Ω∙cm with a carrier concentration of 1.36×1018/cm3.

K2.1 Nanshu Lu (now at UT Austin) of the John Rogers group at U Illinois Urbana presented the groups’ recent achievements in epidermal electronic systems. Micro-transfer printing is the method of choice for interconnecting small rigid silicon electronics elements with thin nanoribbons of silicon or metal. Depositing onto a pre-stretched elastomer substrate provides a resting state in which the interconnects are buckled or canted and can endure up to 100% elongation while imparting ≤1% stress to the rigid circuit elements. The trick of fabricating extremely thin silicon for flexibility applies to the PDMS polymer substrate as well when the objective is to apply the device to the skin and tolerate stretching and bending without adhesion loss. The thin polymer stability is maintained until it is applied using technology similar to that used in applying temporary tattoos. For some device types, the rigid silicon electronics can be eliminated by integrating the active device elements into the serpentine interconnects themselves. For development of integrated devices, functions that have been demonstrated include amplifiers, temperature sensors, strain gauges, solar power sources, induction couplers and wireless transmitters & receivers for device control. Current devices, however, use wires to connect to external control and power sources. The only three elements in contact with the skin are gold, silicon and polyimide, all of which are FDA approved.

K2.2 Michael Melzer of IFW Dresden extended the family of stretchable electronics from silicon and optoelectronics to now include magneto electronics. Stretchable GMR multilayers are fabricated by depositing GMR thin films on a pre-strained PDMS substrate. Data indicates no loss of magnetic performance through this process to 2.5% strain even though resistance starts to rise above 1.6% strain. For greater detection sensitivity, stretchable spin valves were developed using the same process flow as for the GMR multilayers. After some refinement of the process, they were able to achieve 29% strain without losing functionality or sensitivity.

K2.5 A Gaikwad of City College NY described a stretchable battery embedded in cloth with Zn and MnO2 as the active materials. Cracking and delamination due to flexing and stretching was addressed by embedding these materials in a non-conducting nylon mesh in an earlier version. In the new version, a silver coated nylon cloth is used as the substrate for the Zn electrode and separately for the MnO2 electrode. No delamination or electrical degradation was observed at 100% strain in either the x- or the y-direction. The capacity of 4 mAh/cm2 was maintained even with this stretching 100% level.

C2.6 Yusuke Matsuda of Reinhold Dauskardt’s group at Stanford presented a new class of ULK dielectric materials in work done jointly with IBM and RPI. Moisture-assisted cracking is a pervasive problem with current silica-based ULK material options. Polycarbosilane dielectrics (CLPCS) are introduced, their salient feature being a network of Si-CH2-Si bonds. The films have a dielectric constant 2.3-2.5 with no porosity. In comparison with MSSQ and CDO films, CLPCS has a higher fracture strength, lower density  and no sensitivity to moisture-assisted cracking. However, there is some crack growth due to viscoelastic relaxation of C-C bonds.

BB2.6 Susan Trolier-McKinstry of Penn State described a low cost, damage-free microcontact printing method for patterning electroceramic films. PDMS stamps for PZT patterning can be used only one time, but the transfer integrity is good for PZT films 110-130nm thick at ~3µm lines/spaces. Dots 3-4µm with 2-3µm spaces can also be printed faithfully. Alternate stamp material research has led to polyurethane (PU) and composite PU/PDMS enables up to 50 passes for multiple use with a simple solvent wash in between. The PU stamp can print large areas >1cm2 and feature sizes from 5µm to 1cm. Electrical and piezoelectric properties of films so deposited overlapped nicely with films of equivalent thickness deposited by conventional methods.

F4.4 Youn-Seon Kang of Samsung R&D provided a glimpse into the coming 20nm node for PRAM. Challenges include contact size, cell to cell distance, reset current and operating voltage. The 20nm diode contact process includes growth of epitaxial Si in the vias, ion implantation, silicidation, tungsten capping and CMP. Use of a confined structure allows a lower reset current with a larger bottom electrode, suggesting that further reduction is possible. Double pattern lithography is used for the minimum feature sizes. Thermal disturbance between neighbor cells is not observed up to 108 cycles. Samsung is optimistic that PRAM will be a robust NVRAM competitor below 20nm.

BB2.8 Isabel Van Driessche of Ghent U (Belgium) used aqueous solutions of YBa2Cu3O7 for inkjet deposition and patterning of superconducting coatings. Fluorine-free aqueous formulations for chemical solution deposition (CSD) were used to eliminate the toxic BaF2 used in traditional approaches. Conventional methods were used to optimize the solution rheology for inkjet image control. Atmospheric control during annealing reduces the detrimental formation of BaCO3 that is problematic in other systems. Features as small as 40µm were successfully demonstrated; smaller features are likely with further ink formulation.