bluuebunny/crossref_metadata_2025 huggingface dataset:
Sub-50nm resolution surface electron emission lithography using nano-Si ballistic electron emitter
Authors: Kojima A. , Ohyi H. , Koshida N.
Published: December 2008

It is demonstrated that parallel electron beam lithography using a nano-Si planar ballistic electron emitter (PBE) provided the resolution below 30nm even in a low accelerating voltage. This high resolving power is explained by the nature of ballistic electron transport in nanocrystalline silicon. The parallel EB lithography was performed on a 1:1 electron imaging system. The system was composed of the PBE as a patterned surface electron source, a target wafer parallel to the surface electron source, and vertical electromagnetic fields. The PBE projected a patterned electron image on the target. A replica of the pattern was transferred into a resist on the target wafer within less than 1s. The experimental exposure was performed over 10mm2 area. The PBE was composed of a thin metal surface electrode, nanosilicon layer, and semiconductor substrate. The electrons injected from semiconductor substrate were accelerated via cascade tunneling through the nanosilicon layer and reached the outer surface as ballistic or quasiballistic electrons. As a result, the chromatic aberration limiting resolution is expected to be quite small. The 1:1 electron imaging system based on the PBE provides promising solution for high resolution and high throughput lithography with low cost system with the simple electron optics for the next generation device fabrication in the sub-30nm scale.
Brightness measurements of a gallium liquid metal ion source
Authors: Hagen C. W. , Fokkema E. , Kruit P.
Published: December 2008

The virtual source size of a liquid metal ion source is an order of magnitude larger than the size of the region from which the ions are emitted at the source. This source size has a direct effect on the reduced brightness and, hence, on the performance of these sources. The variation of the virtual source size of a gallium liquid metal ion source as a function of the angular current density at the source has been measured. This was done by measuring the source image size from images of a pencil lead sample taken with an FEI focused ion beam system. The measurements indicate that the virtual source size grows from about 50–80nm when the emission current increases from 1to10μA. The experimental data on the virtual source size are compared with the theory on stochastic Coulomb interactions in the source region. On the basis of these measurements the authors show that the reduced brightness deteriorates with an increasing angular current density. The maximum reduced brightness measured was 1×106A∕(m2srV).
Dissolution characteristics of chemically amplified extreme ultraviolet resist
Authors: Itani Toshiro , Kaneyama Koji , Kozawa Takahiro , Tagawa Seiichi
Published: December 2008

The dissolution characteristics of the resist film into alkaline developer have been investigated in order to understand inherent extreme ultraviolet (EUV) resist characteristics and improve resist performance. The combined increase in dissolution “slope” and dissolution contrast (Rmax/Rmin) was confirmed to improve the resolution capability of an EUV resist. Also, a higher Rmin value, which means easy and smooth dissolution of the resist into the alkaline developer, will mean a lower line-width roughness (LWR). However, more evidence and further detailed investigation are necessary to prove this relationship between this dissolution characteristic and LWR. It was also found that the slope of dissolution rate curve for the poly(hydroxystyrene) resist increases as protecting ratios is increased. However, it was found that higher protection ratios increase the amount of released resist outgassing upon EUV exposure. The dissolution rate analysis of presently available high performance EUV resist Selete standard resist 2 (SSR2) was also performed. Based on these results, a high slope and dissolution contrast value of the SSR2 correlated with its improved resolution capability at the 26nm hp L/S.
Fabrication of Fresnel zone plates by holography in the extreme ultraviolet region
Authors: Sarkar Sankha S. , Sahoo Pratap K. , Solak Harun H. , David Christian , Van der Veen J. Friso
Published: December 2008

Fabrication of Fresnel zone plates (FZPs) with nanometer scale resolution is one of the major challenges in lithographic fabrication. The authors present a holographic approach to create FZPs where the interference pattern between a spherical beam and a plane wave is recorded to obtain the FZP structure. The spherical beam is obtained by diffraction from a circular aperture (pinhole) in a semiopaque membrane which is illuminated by a spatially coherent extreme ultraviolet beam. The beam transmitted by the membrane serves as the reference plane wave. The resulting pattern gives rise to a FZP with outermost zone width comparable to the dimension of the circular aperture. Fabrication and test results of a FZP obtained with this method are presented. The technique offers a solution to the pattern-placement problem encountered in serial ZP writing techniques as well as high resolution potential.
Fabrication of thin-film silicon on insulator by separation by implanted oxygen layer transfer
Authors: Wei Xing , Wu Ai Min , Chen Meng , Chen Jing , Zhang Miao , Wang Xi , Lin Cheng Lu
Published: December 2008

In this article, the authors propose an improved approach—separation by implanted oxygen (SIMOX) layer transfer process—to fabricate thin-film silicon on insulator (SOI). The top Si layer, a low-dose SIMOX wafer, was transferred upside down onto a thermally oxidized Si handle wafer by a bonding technique and etch-stop thinning process. Spectroscopic ellipsometry indicated a thin-film SOI with the device layer of 147.5±3.1nm. An atomic-scale sharp interface between the device layer and buried oxide layer was observed by high-resolution transmission electron microscopy.
Investigation of morphological changes in platinum-containing nanostructures created by electron-beam-induced deposition
Authors: Botman A. , Hesselberth M. , Mulders J. J. L.
Published: December 2008

Focused electron-beam-induced deposition (EBID) allows the rapid fabrication of three-dimensional nanodevices and metallic wiring of nanostructures, and is a promising technique for many applications in nanoresearch. The authors present two topics on platinum-containing nanostructures created by EBID. First, they report on a TEM study of the microstructure of nanodeposits created from Pt(PF3)4. They have performed imaging and electron energy loss spectroscopy with a transmission electron microscope (TEM). The deposited material, composed mainly of platinum, phosphor, oxygen, and trace amounts of fluorine, is amorphous. Platinum is evenly distributed in the nanostructure, while phosphorus is observed to cluster. The size and amount of phosphorus clusters depend on the thickness of the structure. Second, they document an aging process in structures created from MeCpPtMe3, which have a resistivity which increases with the time they are exposed to air, from 2×105 to 1.8×108μΩcm over 55days. They demonstrate that covering the structures with an EBID-deposited insulating protective layer of TEOS can prevent this oxidation. In doing so, they achieved the lowest reported resistivity for EBID from this platinum precursor, of 1.5×103μΩcm.
Light transmission through a metallic/dielectric nano-optic lens
Authors: Ko Hyungduk , Kim Hyun Chul , Cheng Mosong
Published: December 2008

The authors analyze transmission of a normally incident plane wave through a Ag/dielectric layered concentric ring structure using finite-difference time-domain (FDTD) analysis. The authors study the dependency of the transmission efficiency on the refractive index in slit. The numerical analysis indicates that the focusing beyond diffraction limit is found even at the extended focal length comparable to the distance of 7λ from exit plane using a circularly polarized coherent plane wave, λ=405nm. Especially, compared to Ag-only structure, the Ag∕LiNbO3 structure exhibits over 2.85 orders of larger transmission power. Therefore, this Ag/dielectric layered lens has the potential for significantly the high resolution imaging and optical data storage.
Room temperature ferromagnetism of Fe-implanted ZnO film
Authors: Zhang B. , Li Q. H. , Shi L. Q. , Cheng H. S. , Wang J. Z.
Published: December 2008

The ZnO-based diluted magnetic semiconductors (DMSs) with room temperature ferromagnetism were achieved by ion implantation. Fe+ ions at 80keV with doses ranging from 1×1016to8×1016cm−2 were implanted into n-type ZnO films at room temperature. Subsequently, the samples were annealed at 700°C for 1h in air ambient. The Fe-implanted content was determined by proton induced x-ray emission. The magnetic property was measured by the Quantum Design MPMS superconducting quantum interference device magnetometer. No trace of secondary phases or clusters was observed within the sensitivity of x-ray diffraction. Raman spectrum showed that the Fe ions replaced Zn atoms and incorporated into the crystal lattice positions of ZnO. Apparent ferromagnetic hysteresis loops measured at 300K were observed, and the temperature-dependent magnetization showed that their Curie temperature exceeded room temperature.
Catalyst patterning for carbon nanotube growth on elevating posts by self-aligned double-layer electron beam lithography
Authors: Häffner M. , Heeren A. , Haug A. , Schuster E. , Sagar A. , Fleischer M. , Peisert H. , Burghard M. , Chassé T. , Kern D. P.
Published: December 2008

For gas-flow aligned growth of carbon nanotubes (CNTs), it is important to minimize interaction of the growing CNTs with the substrate. The authors present a method to fabricate thin catalyst films on top of protruding hydrogen silsesquioxane (HSQ) patterns. Self-alignment of the catalyst film with the HSQ pattern is achieved by exposing two layers of resist, polymethyl methacrylate (PMMA) on top of HSQ, simultaneously. By selecting appropriate development parameters for PMMA and HSQ, a common exposure dose can be applied. After a standard lift-off process HSQ is developed and CNTs are grown on the protruding HSQ patterns resulting in gas-flow aligned CNTs that can be further processed, e.g., for the fabrication of CNT based transistors.
The use of ionic liquid ion sources in focused ion beam applications
Authors: Zorzos Anthony N. , Lozano Paulo C.
Published: December 2008

A new monoenergetic, high-brightness ion source can be constructed using an arrangement similar to liquid metal ion sources by substituting the liquid metal with an ionic liquid or room-temperature molten salt. Ion beams produced by these ionic liquid ion sources (ILISs) have energy deficits and distributions that closely resemble their metallic counterparts, with the exception that they can be stably operated at current levels as low as a few nanoamperes if needed. ILISs are here presented as having two further key advantages: (1) the ability to obtain both positive and negative ion beams and (2) the ability to produce very diverse molecular ions in terms of their masses, compositions, and properties due to the fact that the number of available ionic liquids is large. In this article an overview of ILISs is presented, as well as preliminary results of their performance in a focused ion beam column.
Control of DNA motion in microchannels integrated with dual electrodes
Authors: Cardozo B. L. , Pang S. W.
Published: December 2008

The authors have fabricated a microfluidic system for the control of DNA motion consisting of 400 or 900nm wide Si channels covered by a bonded glass layer containing integrated dual electrodes. By applying an ac potential to an electrode pair on both sides of the channels, precise lateral positioning of DNA has been demonstrated for the first time. By modifying the amplitude or frequency of the ac potential applied to the electrode pairs, they control DNA motion within the channel, causing it to increase speed, decrease speed, reverse directions, or halt. The precise control of DNA average position within channels is expected to be an important step in the development of microfluidic single molecule analysis systems.
Improving lithography pattern fidelity and line-edge roughness by reducing laser speckle
Authors: Kritsun Oleg , Lalovic Ivan , Rokitski Slava , Partlo Bill , La Fontaine Bruno , Farrar Nigel , Levinson Harry
Published: December 2008

In this article the authors discuss the impact of coherence, or laser speckle, of current generation 193nm argon fluoride (ArF) excimer sources on lithographic patterning. They report a new metrology capability to characterize single-pulse speckle patterns at the exit of the laser aperture and quantify the speckle dependence on time integral square (TIS) pulse duration for different system configurations. The authors performed lithographic exposures on high-numerical-aperture immersion and dry ArF systems as a function of source pulse duration and have quantified the speckle impacts on measured photoresist line-edge roughness (LER) and linewidth roughness (LWR) using immersion and dry lithography processes. Measurements were obtained for multiple feature sizes, pitches, and illumination modes using both static and scanning exposures. They have compared the measured LWR due to laser speckle to results of a line-roughness image model, which accounts for the LER, LWR, and critical dimension uniformity due to the effective dose variation from laser speckle. Finally, the authors present measurements that demonstrate the proportionality between laser speckle contrast and the inverse root of the TIS pulse duration and find that the lithographic LWR exhibits a similar relationship with pulse duration.
Metal transfer assisted nanolithography on rigid and flexible substrates
Authors: Kang Myung-Gyu , Guo L. Jay
Published: December 2008

A nanolithography technique based on metal transfer printing is demonstrated. The transferred metal conveniently acts as an etch mask for pattern transfer to a substrate. This lithography technique can be used on flexible plastic substrate as well as on rigid substrate due to the low pressure and temperature used in the metal transfer process. Dense nanosize metal particle arrays with different shapes such as square, diamond, and nanobar were created with high yield over large area, and localized surface plasmon spectra of those particle arrays were measured. Pattern linewidth was reduced to 50 nm in metal grating by depositing metals on the poly(dimethysiloxane) grating sidewall using a shadow evaporation process.
The coexistence of surface reconstruction domains on strained heteroepitaxial films
Authors: Sears Lee E. , Millunchick Joanna Mirecki , Pearson Chris
Published: December 2008

Thin films of In0.81Ga0.19As∕InP, grown by molecular beam epitaxy and imaged by in vacuo scanning tunneling microscopy, are observed to possess surfaces that consist of multiple reconstruction domains; small anisotropic regions of β2(2×4) in a matrix of a disordered (n×3) reconstruction. The shape and size distribution of these domains is consistent with anisotropic elastic relaxation at the domain boundaries. The boundary energy anisotropy varies with the growth temperature, indicating that the configurational entropy along the [11¯0] direction is higher than for the [110].
Fabrication and testing of through-silicon vias used in three-dimensional integration
Authors: Abhulimen I. U. , Kamto A. , Liu Y. , Burkett S. L. , Schaper L.
Published: December 2008

The formation of through-silicon vias (TSVs) provides a vertical interconnect scheme that can be used in three-dimensional stacking technologies. A sloped via sidewall is essential for conformal coverage of via lining materials deposited in subsequent steps that provide insulation (SiO2), barrier (TaN), and metal seed (Cu) layers. In this article, via sidewall angles in the range of 83°–90° are investigated resulting in variable degrees of conformal lining of the insulation, barrier, and seed layers. Via insulation is deposited by plasma enhanced chemical vapor deposition, while barrier and seed layers are deposited by sputtering. A modified Bosch process, using a deep reactive ion etch tool, allows formation of differing via profiles in silicon substrates. Cross-sectional views of via profiles showing the coverage of lining materials (SiO2, TaN, and Cu) are examined with a scanning electron microscope. For a constant via sidewall angle, variable aspect ratios allow us to determine the specific via profile that can be conformally lined and filled by Cu electroplating without the presence of voids. The aspect ratios of the vias under study are in the range of 2–4. Electrical performance of the fabricated TSVs is reported and is consistent with expected performance.
Gigahertz surface acoustic wave generation on ZnO thin films deposited by radio frequency magnetron sputtering on III-V semiconductor substrates
Authors: Wang Qi Jie , Pflügl Christian , Andress William F. , Ham Donhee , Capasso Federico , Yamanishi Masamichi
Published: December 2008

The authors demonstrate 1.6GHz surface acoustic wave (SAW) generation using interdigital transducers patterned by e-beam lithography on a thin ZnO piezoelectric film deposited on an InP substrate. The highly oriented, dense, and fine-grain ZnO film with high resistivity was deposited by radio frequency magnetron sputtering and was characterized by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and a four-point probe station. The acoustic wavelength of the 1.6GHz SAW generated by exciting the interdigital transducer on ZnO∕InP with a microwave signal is 1.6μm. This SAW filter device could be monolithically integrated with optoelectronic devices, opening new opportunities to use SAWs for applications such as gigahertz-frequency filters on optoelectronic devices and novel widely tunable quantum cascade lasers.
Large-area dielectric and metallic freestanding gratings for midinfrared optical filtering applications
Authors: Vincent Grégory , Collin Stéphane , Bardou Nathalie , Pelouard Jean-Luc , Haïdar Riad
Published: December 2008

The authors present a fabrication process of large-area (1.7×1.7 mm2) dielectric and metal-coated lamellar freestanding gratings structured at the micrometer scale. Both the stress management and the drying problems have been carefully optimized for the fabrication of drilled membranes. Transmission spectra measurements of freestanding gold-coated gratings demonstrate the achievement of high quality, accurately controlled optical filters in the midinfrared wavelength range.
Feature profile evolution during shallow trench isolation etch in chlorine-based plasmas. II. Coupling reactor and feature scale models
Authors: Hsu Cheng-Che , Hoang John , Le Vu , Chang Jane P.
Published: December 2008

A two-dimensional numerical fluid model was developed to investigate the effects of reactor design on the radial profiles of plasma species, namely, etch products and positive ions, during shallow trench isolation etching in Cl2∕O2∕Ar inductively coupled plasmas. Specifically, the dual-coil and dual gas-feed designs of the reactor were examined. The former parameter was determined to be effective in tailoring the radial ion flux profile at pressures higher than 20mT, while the latter parameter was shown to alter the etch product transport in the convection-dominant flow regime. Coupling of the reactor scale model to a feature scale model allowed investigation of minor center to edge variations in the etched feature profile. This hybrid model suggests that the general radial decrease in the etch depth seen from a set of design of experiments is caused by an inherent decrease in the spatial distribution of chlorine radicals. In addition, the increase in the silicon sidewall angle from center to edge can be qualitatively explained by the radial profile of the etch products.
Effect of gas mixing ratio on etch behavior of ZrO2 thin films in Cl2-based inductively coupled plasmas
Authors: Efremov Alexander , Min Nam-Ki , Yun Sun Jin , Kwon Kwang-Ho
Published: December 2008

The analysis of the ZrO2 thin film etch mechanism in the Cl2∕Ar, Cl2∕He, and Cl2∕N2 inductively coupled plasmas was carried out. It was found that an increase in additive gas fraction at fixed gas pressure and input power results in increasing ZrO2 etch rate, which changes from 1.2nm∕min for pure Cl2 plasma up to 3.15, 2.40, and 2.31nm∕min for 80% Ar, N2, and He, respectively. Langmuir probe diagnostics and zero-dimensional plasma modeling indicated that both plasma parameters and active species kinetics are noticeably influenced by the initial composition of the gas mixture. From the model-based analysis of etch kinetics, it was shown that, similarly to the case of BCl3-based plasmas, the behavior of the ZrO2 etch rate corresponds to the ion-flux-limited etch regime.
Interface states mediated reverse leakage through metal/AlxGa1−xN∕GaN Schottky diodes
Authors: Lu Changzhi , Zhang Xiaoling , Xie Xuesong , Feng Shiwei , Diagne Ibrahima , Khan Arif , Noor Mohammad S.
Published: December 2008

Interface states modulated reverse leakage current through metal/AlxGa1−xN∕GaN diodes has been studied. Reverse leakage current and breakdown voltage have been measured over wide temperature ranges. The investigation suggests that the piezoelectric polarization and the spontaneous polarization at the AlxGa1−xN∕GaN heterostructure create polarization induced charges in AlxGa1−xN, and influence the two-dimensional electron gas at the GaN∕AlxGa1−xN interface. Both of them dictate the barrier height of the strained AlxGa1−xN Schottky contact. High density of defect states at the metal/AlxGa1−xN interface leads to high reverse leakage current via Fowler-Nordheim emission and/or Frankel-Poole emission. The most notable finding is the reduction in the leakage current almost to zero at high temperatures due to strain relaxation, reduction in defect states, and barrier height enhancement at the metal/AlxGa1−xN interface. Such finding may have significant impact on the way we design high-power microwave devices.
Carbon nanotube–based magnetic actuation of origami membranes
Authors: In Hyun Jin , Lee Hyungwoo , Nichol Anthony J. , Kim Sang-Gook , Barbastathis George
Published: December 2008

Multiwalled carbon nanotubes (CNTs) with nickel and cobalt catalyst tips have been grown on foldable titanium nitride membranes. Once magnetized to saturation under an external magnetic field, these ferromagnetic tips, which reside atop each CNT, can be used to actuate the entire membrane on which the nanotubes are grown. Magnetic modeling is performed to analyze the magnetic properties of the teardrop-shaped CNT tips, and initial experimental results show that magnetic torques and forces arising from the CNT tips are sufficient to rotate the membrane up to 180° and keep it latched without springing back.
Enhancement in hyper-numerical-aperture imaging through selective TM polarization
Authors: Smith Bruce , Zhou Jianming , Xie Peng
Published: December 2008

The degradation of projected images using TM polarization is not intrinsic because losses in image contrast can be recoverable. By controlling the photoresist/substrate interface reflectivity, high modulation for TM polarization can be maintained for angles approaching 90° in a photoresist. Although there is calculated loss of image contrast with increasing polarization angle using suppressed reflection (i.e., with an antireflection coating), the loss is not nearly as large when imaging over a reflective substrate. These results can potentially impact the design of illumination, possibly away from most recent TE-only schemes for oblique imaging angles and high numerical apertures (NA). Several cases of TM illumination are presented combined with tuned substrate reflectivity for 0.93NA, 1.20NA, and 1.35NA and compared to results using TE illumination. Additionally, a scheme for frequency doubling with a single TM polarized exposure is presented. Using a single exposure and selective TM polarization, the reflective component produced at the photoresist/substrate interface is utilized for a four-beam imaging scenario. In doing so, patterns deposited into a photoresist film with double density are made possible.
Characterization of a sol-gel based high-k dielectric field effect transistor for cryogenic operation
Authors: Khan M. Ziaur Rahman , Hasko D. G. , Saifullah M. S. M. , Welland M. E.
Published: December 2008

A silicon on insulator field effect transistor for cryogenic operation has been fabricated using a sol-gel derived TiO2 electron beam resist as a high-k gate dielectric and characterized over a range of temperatures. The TiO2 dielectric layer allows too large a gate leakage current for good device operation at room temperature, but the leakage current is strongly suppressed at cryogenic temperatures and good transistor characteristics were observed. The temperature dependence of the gate leakage current suggests that Frenkel-Poole and trap-assisted tunneling dominates the conduction in the dielectric layer. The drain current shows peaks at certain frequencies under continuous wave microwave irradiation, which may be caused by the resonance of electrons trapped in defects at the TiO2/SiO2 interface. These resonances offer the possibility to manipulate single electrons for nonclassical information processing.
Formation and stability of NiSi in the presence of Co and Fe alloying elements
Authors: Deduytsche D. , Detavernier C. , Van Meirhaeghe R. L. , Jordan-Sweet J. L. , Lavoie C.
Published: December 2008

The formation and degradation of NiSi in the presence of Co and Fe alloying elements have been investigated. Alloyed Ni layers were characterized with in situ techniques to determine the stability of the NiSi phase on single crystalline and on polycrystalline Si substrates. It is shown that the phase stability is decreased with the addition of Co or Fe. The formation of the NiSi2 phase on Si(100) is initiated at a temperature that is more than 200 °C lower for the Ni alloys than for a reference Ni layer. Thereby a few percent of Co or Fe results in the formation of a polycrystalline NiSi2 phase on a single crystalline substrate. The low formation temperature of the NiSi2 phase in the presence of Co or Fe can be attributed to a mixing entropy effect. The morphological stability of the silicide films on Si(100) and on polycrystalline Si is improved due to the early formation of NiSi2 and is related to an increased film thickness and also to a higher deformation temperature for the poly-Si.
Damage mechanism in low-dielectric (low-k) films during plasma processes
Authors: Jinnai Butsurin , Nozawa Toshihisa , Samukawa Seiji
Published: December 2008

Plasma is extensively used for the etching/ashing of low-dielectric (low-k) films. However, since low-k films, such as SiOC films, are vulnerable to plasma irradiation, they are severely damaged during plasma processes, such as the extraction of methyl groups from low-k films. As a result, plasma irradiation increases the dielectric constant of low-k films and reduces the reliability of Cu/low-k interconnects. In previous work, the authors achieved highly selective and low-damage etching processes for low-k films by using their developed neutral beam process instead of the conventional plasma process. They have now investigated the damage mechanism in low-k films (porous SiOC films) during plasma processes by clarifying the effects of ions, radicals, and photons in plasma. First, they compared the damage in SiOC films etched by the conventional plasma process and the neutral beam process. Their results show that plasma processes change the structure of the SiOC film deeply within the film (over 100nm in depth) and increase the film’s dielectric constant, whereas the neutral beam process maintains the structure of the SiOC film. Additionally, they found that when a combination of the neutral beam process and a 172nm excimer lamp is used, photon irradiation enhances the extraction of methyl groups from the SiOC film by breaking Si–C bonds in the film. These results show that photon irradiation plays a very important role in the damage mechanism in low-k films during plasma processes.
Fluorinated diamondlike carbon templates for high resolution nanoimprint lithography
Authors: Schvartzman M. , Mathur A. , Kang Y. , Jahnes C. , Hone J. , Wind S. J.
Published: December 2008

Nanoimprint templates were fabricated from diamondlike carbon (DLC) films grown on Si, using negative-tone e-beam lithography and oxygen plasma etching. An antiadhesion coating was provided through fluorocarbon-based plasma treatment, which was found to form a Teflon-like thin layer on the treated DLC surface. The fluorinated templates were used to imprint arrays of dots with diameters down to 10nm in polymethyl-methacrylate. Application of the fluorocarbon plasma treatment was also demonstrated in the antiadhesion treatment of the nanoimprint resist and in elastomer molding.
Fabrication of Ag-tetracyanoquinodimethane nanostructures using ink-jet printing/vapor-solid chemical reaction process
Authors: Aggarwal Ravi , Narayan Roger J. , Xiao Kai , Geohegan David B.
Published: December 2008

In this study, microscale patterns of the charge-transfer organic compound silver-tetracyanoquinodimethane (Ag-TCNQ) were prepared using a novel two-step ink-jet printing/vapor-solid chemical reaction process. First, silver nanoparticles were patterned on silicon using a piezoelectric ink-jet printer. Ag-TCNQ nanostructures were then processed on these patterned surfaces using a vapor-solid chemical reaction growth process. Scanning electron microscopy revealed that 50–100nm wide, ∼2μm long Ag-TCNQ nanocones, crystallites, and ribbons were fabricated using this two-step process. Patterns with a higher number density of silver nanoparticles demonstrated a greater number of nanocone structures. Micro-Raman spectroscopy results confirmed charge transfer between silver and TCNQ in the Ag-TCNQ nanostructure. Patterned Ag-TCNQ nanostructures fabricated using this novel two-step ink-jet printing/vapor-solid chemical reaction process could find use in high density, high-speed optical memory devices, magnetic devices, field effect transistors, organic light emitting diodes, metal/insulator/metal photoswitches, biosensors, and other advanced devices.
Bias power dependence of reactive ion etching lag in contact hole etching using inductively coupled fluorocarbon plasma
Authors: Imai Shin-ichi
Published: December 2008

This article describes the bias power dependence of reactive ion etching (RIE) lag from 1300to700W bias power in contact hole etching using inductively coupled C2F6 fluorocarbon plasma without additive gases at 2600W source power, 5mTorr operational pressure, and a total gas flow of 40SCCM (SCCM denotes cubic centimeter per minute at STP). RIE lag is estimated by etching multiple feature sizes on one wafer. In the discussion of the bias power dependence of RIE lag, the authors used an RIE lag model based on a solid angle model modified by a specular reflection on the wall of a contact hole. The RIE lag model indicates that the RIE lag characteristic is caused by the three-dimensional structure of the contact hole. The etched depth relates to a term of a cubic root of etch time. Moreover, a decrease in bias power slows the etch rates, but the maximum etched depth increases in contact hole etching. By decreasing the bias power from 1300to700W, the RIE lag characteristic can be dramatically improved in a limitation aspect ratio from 27 to 133.
Charging and error budgets in electron beam lithography tools
Authors: Hartley John G. , Lyons Adam
Published: December 2008

Given a set of end user requirements that establish the overall performance goals of a system, the error budget allows a system architect to seek an optimum balance between various subsystems to achieve the most efficient design. When factors that contribute to the overall error budget are poorly understood the result is likely a suboptimal design that relies on the designer’s knowledge of the “art” as opposed to the desired but absent scientific understanding. This typically leads to overengineering of other subsystems to compensate. One factor not strongly quantified is drift due to charging. In this article, the authors explicitly examine contributions due to particle contamination, voids in conductive coatings that expose insulating material, and contamination induced insulating films on conductors in the electron optic subsystem.
Optical focusing of plasmonic Fresnel zone plate-based metallic structure covered with a dielectric layer
Authors: Kim Hyun Chul , Ko Hyungduk , Cheng Mosong
Published: December 2008

By modulating the zone width of a plasmonic Fresnel zone plate, consisting of metallic nanostructures covered with a dielectric layer, the authors demonstrated numerically that a focused beam can be achieved with higher intensity and smaller spot size than the diffraction-limited conventional Fresnel zone plate. Rigorous electromagnetic simulation predicts a full width at half maximum of 162nm (equivalent to an effective numerical aperture of 1.30) at 0.5μm focal length, using 405nm wavelength illumination. This sub-diffraction-limit focusing has potential in applications such as maskless nanolithography, high resolution scanning optical microscopy, optical data storage, and optical antenna. This focusing capability is related to extraordinary optical transmission, which is explained by the complex propagation constant in the zones afforded by higher refractive index dielectric layer and surface plasmons.
Fabrication strategies for filter banks based on microring resonators
Authors: Holzwarth C. W. , Amatya R. , Dahlem M. , Khilo A. , Kärtner F. X. , Ippen E. P. , Ram R. J. , Smith Henry I.
Published: December 2008

Wavelength-division demultiplexers are a fundamental component needed for many proposed integrated photonic systems. By using filter banks based on microring resonators it is possible to create demultiplexers that are two orders of magnitude smaller and achieve better performance than the discrete component demultiplexers currently used. To create a filter bank out of microring resonators the resonant-frequency spacing must be controlled to within 1GHz. This is achieved by controlling the electron-dose during scanning-electron-beam lithography in order to change the average ring waveguide width on the tens of picometer scale. Using this method a second-order twenty-channel dual filter bank (80 microrings) is fabricated with a average channel spacing of 83GHz demonstrating the capability to make changes in the average ring waveguide width with an accuracy of 75pm. It is shown that any frequency errors that remain after fabrication can be corrected using thermal tuning with integrated microheaters. The amount of power needed to correct for all frequency errors in the fabricated filter banks is 0.09W, compared to the 2.4W that is needed if no attempt is made to control the frequency spacing during fabrication. Also a temperature stabilization circuit is demonstrated that can stabilize the temperature of the filters to 80mK (280MHz).
Assisted convective-capillary force assembly of gold colloids in a microfluidic cell: Plasmonic properties of deterministic nanostructures
Authors: Pinedo Rivera T. , Lecarme O. , Hartmann J. , Rossitto E. , Berton K. , Peyrade D.
Published: December 2008

A new colloidal assembly technique in a microfluidic cell is proposed in this work. This technique is based on classic capillary force assembly (CFA) assisted by air-suction flow and temperature control during the assembly process. Their influence on the assembly macroscopic (triple contact-line speed, receding contact angle) and microscopic (colloidal motion at the triple contact line) parameters is examined. It is shown that the extent and the performance of the assembly process are significantly enhanced by this approach. Finally, the plasmonic properties of deterministic linear (2–5 colloid long) and tripod gold nanostructures created with this technique are investigated.
Biphasic Modulation of Apoptotic Pathways in
Cryptosporidium parvum
-Infected Human Intestinal Epithelial Cells
Authors: Liu Jin , Deng Mingqi , Lancto Cheryl A. , Abrahamsen Mitchell S. , Rutherford Mark S. , Enomoto Shinichiro
Published: December 2008

The impact of
Cryptosporidium parvum
infection on host cell gene expression was investigated by microarray analysis with an in vitro model using human ileocecal HCT-8 adenocarcinoma cells. We found changes in 333 (2.6%) transcripts at at least two of the five (6, 12, 24, 48, and 72 h) postinfection time points. Fifty-one of the regulated genes were associated with apoptosis and were grouped into five clusters based on their expression patterns. Early in infection (6 and 12 h), genes with antiapoptotic roles were upregulated and genes with apoptotic roles were downregulated. Later in infection (24, 48, and 72 h), proapoptotic genes were induced and antiapoptotic genes were downregulated, suggesting a biphasic regulation of apoptosis: antiapoptotic state early and moderately proapoptotic state late in infection. This transcriptional profile matched the actual occurrence of apoptosis in the infected cultures. Apoptosis was first detected at 12 h postinfection and increased to a plateau at 24 h, when 20% of infected cells showed nuclear condensation. In contrast, experimental silencing of Bcl-2 induced apoptosis in 50% of infected cells at 12 h postinfection. This resulted in a decrease in the infection rate and a reduction in the accumulation of meront-containing cells. To test the significance of the moderately proapoptotic state late in the infection, we inhibited apoptosis using pancaspase inhibitor Z-VAD-FMK. This treatment also affected the progression of
C. parvum
infection, as reinfection, normally seen late (24 h to 48 h), did not occur and accumulation of mature meronts was impaired. Control of host apoptosis is complex and crucial to the life of
C. parvum
. Apoptosis control has at least two components, early inhibition and late moderate promotion. For a successful infection, both aspects appear to be required.
Telomerization of 3,3,3-Trifluoroprop-1-ene and Functionalization of Its Telomers
Authors: Kostov George K. , Améduri Bruno , Brandstadter Stephan
Published: December 2008

The synthesis of four 3,3,3-trifluoroprop-1-ene telomers (RF(C3H3F3)nI, n = 1, 2, RF = n-C6F13- or (CF3)2CF-) and their allyl derivatives RF(C3H3F3)nCH2CH=CH2 are presented. The allyl telomers were prepared by a three-step reaction. The first step involved the thermal and peroxide-induced bulk telomerization of 3,3,3-trifluoroprop-1-ene (TFP) with heptafluoro-2-iodopropane or tridecafluoro-6-iodohexane leading to monoadduct and diadduct, the ratio of which depends on the R0 = [RFI]0/[TFP]0 initial molar ratio and the reaction temperature. The amount of monoadduct increased up to 50-60% and of the diadduct to 25-30% at temperatures up to 180 °C (thermal-initiated) and 150 °C (initiated with di-tert-butyl peroxide, DTBP), R0 up to 1.5. It was observed that the addition of the (CF3)2CF• radical onto the =CH2 of TFP was regioselective leading to selective formation of a single isomer in contrast to the addition of the n-C6F13• radical. Then, the telomers reacted with allyl acetate yielding RF(C3H3F3)nCH2CH(I)CH2OCOCH3 (n = 1, 2) in 50-80% yields. The third step consisted of a deiododeacetatization of these iodoacetates into RF(C3H3F3)nCH2-CH=CH2 (C,n) giving 50-80% yields. All the intermediates were characterized by 1H, 19F and products by 13C NMR spectroscopy.
Synthesis of Fluorinated Steroids Using a Novel Fluorinating Reagent Tetrabutylammonium Difluorodimethylphenylsilicate (TAMPS)
Authors: Herrmann Pavel , Kvíčala Jaroslav , Pouzar Vladimír , Chodounská Hana
Published: December 2008

Steroidal 3-fluoroderivatives were prepared from corresponding tosylates using tetrabutylammonium difluorodimethylphenylsilicate as fluorinating agent. The reaction was tested on all four possible C-3 and C-5 stereoisomers of cholestane and 17-oxoandrostane skeletons. In this reaction only one isomer was always formed with opposite configuration at C-3 to starting tosylate. The reaction is accompanied by elimination which affords a mixture of corresponding olefines.
Physical characteristics of novice and experienced women marathon runners.
Authors: Christensen C. L. , Ruhling R. O.
Published: December 2008

The physiological and anthropometric characteristics of 23 non-elite women marathoners were studied. Ten of these women had never run a marathon before (novices) and 13 had run at least one marathon during the previous year (experienced). A comparison of characteristics of these two groups to each other and to elite women marathoners, as reported in the literature, disclosed no significant (p greater than 0.01) among the groups in age, % body fat, body weight, height, lean body mass or HR max. Significant differences (p less than 0.01) were noted, however, in VO2 max (45.8, 51.8, 59.1 ml.kg-1 min-1), VE max (76.3, 94.7, 108.9 L.min-1), and years of training (0.54, 2.06, 4.55 years) with the novice runners having the smallest values, the experienced runners having the next larger values, and the elite runners having the largest values. For our subjects, estimated percentage of body fat did not correlate with finish time, but VO2 max and finish time were significantly related (r = -0.72, p less than 0.01). This suggest that women marathon runners are similar in anthropometric measurements, and that improved performance is associated with higher aerobic capacity and years of training rather than with body dimensions.
An evaluation of a bioelectrical impedance analyser for the estimation of body fat content.
Authors: Maughan R J
Published: December 2008

Measurement of body composition is an important part of any assessment of health or fitness. Hydrostatic weighing is generally accepted as the most reliable method for the measurement of body fat content, but is inconvenient. Electrical impedance analysers have recently been proposed as an alternative to the measurement of skinfold thickness. Both these latter methods are convenient, but give values based on estimates obtained from population studies. This study compared values of body fat content obtained by hydrostatic weighing, skinfold thickness measurement and electrical impedance on 50 (28 women, 22 men) healthy volunteers. Mean(s.e.m.) values obtained by the three methods were: hydrostatic weighing, 20.5(1.2)%; skinfold thickness, 21.8(1.0)%; impedance, 20.8(0.9)%. The results indicate that the correlation between the skinfold method and hydrostatic weighing (0.931) is somewhat higher than that between the impedance method and hydrostatic weighing (0.830). This is, perhaps, not surprising given the fact that the impedance method is based on an estimate of total body water which is then used to calculate body fat content. The skinfold method gives an estimate of body density, and the assumptions involved in the conversion from body density to body fat content are the same for both methods.
Injury surveillance in a rugby tournament.
Authors: Wekesa M , Asembo J M , Njororai W W
Published: December 2008

OBJECTIVE--To investigate injuries in international rugby football. METHODS--All injuries that led to temporary stoppage of the game or to the substitution of a player during the Rugby World Cup prequalifying tournament were recorded. Six matches were played, involving the Arabian Gulf, Kenya, Namibia, and Zimbabwe. RESULTS--47 injuries were recorded, giving an injury rate of eight per match. The number of injuries decreased from 38.3% in the first matches to 23.4% in the final ones. The most serious injury was a concussion and the majority of the injuries affected soft tissues. Anatomically, the lower limbs suffered most injuries (46.8%), followed by the head (21.3%), trunk (17.0%), and upper limbs (12.8%). Slightly more injuries occurred in the defensive half of the field of play (53.2%) than in the offensive half (46.8%). More injuries occurred in the second half (61.7%) than in the first half (38.3%). CONCLUSIONS--Protective equipment should be introduced to minimise the number and seriousness of injuries in rugby.
Integrative genomic and gene expression analysis of chromosome 7 identified novel oncogene loci in non-small cell lung cancer
Authors: Campbell Jennifer M. , Lockwood William W. , Buys Timon P.H. , Chari Raj , Coe Bradley P. , Lam Stephen , Lam Wan L.
Published: December 2008

Lung cancer accounts for over a quarter of cancer deaths, with non-small cell lung cancer (NSCLC) accounting for approximately 80% of cases. Several genome studies have been undertaken in both cell models of NSCLC and clinical samples to identify alterations underlying disease behaviour, and many have identified recurring aberrations of chromosome 7. The presence of recurring chromosome 7 alterations that do not span the well-studied oncogenes EGFR (at 7p11.2) and MET (at 7q31.2) has raised the hypothesis of additional genes on this chromosome that contribute to tumourigenesis. In this study, we demonstrated that multiple loci on chromosome 7 are indeed amplified in NSCLC, and through integrative analysis of gene dosage alterations and parallel gene expression changes, we identified new lung cancer oncogene candidates, including FTSJ2, NUDT1, TAF6, and POLR2J. Activation of these key genes was confirmed in panels of clinical lung tumour tissue as compared with matched normal lung tissue. The detection of gene activation in multiple cohorts of samples strongly supports the presence of key genes involved in lung cancer that are distinct from the EGFR and MET loci on chromosome 7.
Comment on “Comparative genomic analysis of the whale (Pseudorca crassidens) PRNP locus”Appears in Genome, 51: 452–464.
Authors: Acutis Pier Luigi , Peletto Simone , Grego Elena , Colussi Silvia , Riina Maria Vittoria , Rosati Sergio , Mignone Walter , Caramelli Maria
Published: December 2008

A reminder that another paper on the cetacean PRNP locus has been published before Kim et al.’s paper (2008. Genome, 51: 452–464) is presented along with a consideration of the related results.
Differences in left ventricular mass between overweight and normal-weight preadolescent children
Authors: Peralta-Huertas Jose , Livingstone Kristina , Banach Alayna , Klentrou Panagiota , O’Leary Deborah
Published: December 2008

This study examined cardiac and arterial differences between overweight and normal-weight preadolescent children. Twenty children (10.2 ± 0.4 years of age) classified as overweight, on the basis of age-appropriate body mass index (BMI) cutoffs, were compared with 43 normal-weight controls. Height, mass, and body surface area were measured. Relative body fat and lean body mass were estimated from skinfold thickness. Each child’s weekly physical activity metabolic equivalent (PAME) was calculated using a standardized questionnaire, and his or her sexual maturation was self-assessed using the Tanner scale. Peak aerobic power was assessed using a cycle ergometer and normalized to lean body mass. Mean arterial pressure was calculated from systolic and diastolic blood pressure (DBP) measurements taken with a Finapres. Cardiac dimensions were measured, using Μ-mode 2-dimensional echocardiography, and normalized to body surface area and height2.7. Left carotid artery pulse pressure (CaPP) was assessed with applanation tomometry. Overweight boys and girls had a higher left ventricular mass (LVM) and LVMHT2.7 than normal-weight boys and girls. CaPP was signficantly lower in the overweight than in the normal-weight groups, whereas PAME and relative peak aerobic power were significantly higher in the boys than the girls. Although overweight children had significantly higher stroke volumes and cardiac outputs than normal-weight children, ejection fraction was similar in the weight groups. Adjusted LVMHT2.7 was associated with cardiac volume measurements, BMI, and DBP in normal-weight children, whereas in the overweight children LVMHT2.7 did not significantly correlate with any variable. In conclusion, we found that cardiovascular adaptations can be seen in prepubescent overweight children as young as 10 years of age.