bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and tuning of nanoscale metallic ring and split-ring arrays
Authors: Sheridan A. K. , Clark A. W. , Glidle A. , Cooper J. M. , Cumming D. R. S.
Published: December 2007

Metallic structures with dimensions smaller than the wavelength of light demonstrate optical properties which depend strongly on the nanoparticle size, shape, and interparticle spacing. The optical properties are caused by the excitation of localized surface plasmon resonances that lead to strong enhancement and confinement of the optical field and can be exploited for many applications including surface-enhanced Raman spectroscopy, near-field scanning optical microscopy, and negative refractive index materials. In order to fully exploit the properties of these structures, both a highly reproducible and flexible fabrication technique and an in-depth understanding of the optical properties are needed. In this article, the authors demonstrate the fabrication of arrays of gold rings and split rings on glass using electron beam lithography. Electron beam lithography allows not only precise control of the size, shape, and spacing of the arrays but also the scope to design novel shapes at will. We characterize these arrays using polarization dependent spectroscopy. The structures can support multiple plasmon resonances, demonstrating that excellent uniformity across the array is achieved. These resonances are further characterized using a finite difference time domain method to model the electric field distribution around the ring structures.
Highly selective zero-bias plasma etching of GaN over AlGaN
Authors: Schuette Michael L. , Lu Wu
Published: December 2007

Highly selective, low-damage etching of GaN over AlGaN is realized by zero-bias, nitrogen-rich N2∕Cl2∕O2 inductively coupled plasma, affording sub-10-nm∕min etch rates and rms roughness of 3Å, favorable for gate recessing of GaN-based high electron mobility transistors (HEMTs). Selectivity is tuned by varying the O2 fraction, source power, and pressure. No AlGaN etching is detectable even after 30min, so the etching selectivity is considered to be infinite. The authors demonstrate linear recessing of a n+-GaN∕Al0.3Ga0.7N∕GaN device structure, which stops abruptly upon clearing the 10-nm-thick cap. SiO2 masking used in this study is compatible with HEMT processes, where a masking dielectric is used for passivation, gate footprint definition, and mechanical gate support. Current-voltage measurements on recessed Schottky diodes show a 40x decrease in reverse leakage current and a three-fold increase in forward saturation current, when compared to non-recessed diodes, as well as lack of sensitivity to etch duration. Diodes on this device structure also showed breakdown voltages greater than −200V, compared to −90V for nonrecessed diodes.
Large-scale growth of single-walled carbon nanotubes using cold-wall chemical vapor deposition
Authors: Shin K. Y. , Lee C. T. , Kao J. S. , Kei C. C. , Chang C. M. , Hsiao C. N. , Liang J. H. , Leou K. C. , Tsai C. H.
Published: December 2007

Carbon nanotubes have been considered as an alternative material for next generation nanoelectronic devices, such as the carbon nanotube field-effect transistor (CNT-FET) or nanosensor. Large-scale growth of single-walled carbon nanotubes (SWNTs) is particularly essential to the fabrication of the CNT-FET on a full wafer. In this study, SWNTs grown at designated positions on broken pieces in a conventional thermal furnace chemical vapor deposition (CVD) system and on a 4-in. full size silicon wafer in a cold-wall thermal CVD were compared. The distinct characteristics of SWNTs grown by the two systems are explained by the differences in the temperature distribution and the gas flow pattern, and their interplay with the catalysis and the feedstock gas decomposition. The adoption of cold-wall CVD process provides a simple method, but an essential step, toward commercial applications of SWNT-based devices.
Application of contrast enhancement layer to 193nm lithography
Authors: Kim Ryoung-han , Levinson Harry J.
Published: December 2007

The feasibility of contrast enhancement layer (CEL) for extending the practical limit of 193nm lithography was studied using an analytical model, exposed latent image inside the resist, and finite difference time-domain analysis. All studies showed that the CEL is applicable to 193nm regime and beneficial for obtaining a contrast enhancement effect which appeared to be nonlinear and more effective on the images of low incident contrast. However, because of its nonlinear behavior, material parameters should be carefully chosen and optimized to obtain a large contrast improvement. In addition, thick topcoat induced aberration was also taken into account to evaluate the feasibility of the CEL. As a conclusion, it is shown that the CEL is promising for the use of future technologies.
Rapid partial melt crystallization of silicon for monolithic three-dimensional integration
Authors: Witte D. J. , Pickard D. S. , Crnogorac F. , Pianetta P. , Pease R. F. W.
Published: December 2007

Controlling the crystallization process of semiconductor materials is essential for many applications, including monolithic three-dimensional integration of devices. In particular, crystallization must be done while keeping to the thermal budget of underlying device layers. Using a 532nm laser pulse of 10ms duration, we demonstrate partial melting of silicon, which yields crystallites several microns in size upon cooling. A ⟨100⟩ preferential orientation was observed in these crystallites, which may be a consequence of partial melting. By observing the melt evolution, we show that a partial melt can form on the millisecond time scale and does not require thermal equilibrium to exist. By reducing the laser pulse duration further, such a process could be compatible with the thermal constraints of three-dimensional integration.
Adaptive wiring for 20nm scale epitaxial silicon Ohmic contacts to silicon nanowires
Authors: Rooks M. J. , Cohen G. M. , Chu J. O. , Solomon P. M. , Ott J. A. , Miller R. J. , Viswanathan R. , Haensch W.
Published: December 2007

Contacts to silicon nanowires are formed by etching holes through a dielectric stack of silicon dioxide and silicon nitride. P-type, in situ doped epitaxial silicon is grown through the holes, then polished flat and silicided or capped by metal to form the device electrodes. This novel contact method has been used in two ways, either in conjunction with adaptive wiring patterned with electron-beam lithography or in a random-connection process with a fixed wiring pattern printed with photolithography. By using the former process, the authors report the fabrication of closely spaced contacts to silicon nanowires. Electron-beam lithography allows the authors to adapt the wiring pattern to each individual target device, and is used to define 20nm scale contacts. In the latter process, the authors use a technique wherein a large array of contact lines is printed without alignment to individual nanowires. In this case, nanowires are connected by chance, relying on relatively long contact lines with relatively large spacing (down to 200nm). The authors compare the advantages of the two wiring techniques.
Surface characterization of imprinted resist above glass transition temperature
Authors: Lévéder T. , Landis S. , Davoust L. , Soulan S. , Tortai J.-H. , Chaix N.
Published: December 2007

Nanoimprint lithography is a high resolution and low cost patterning technique. Many difficulties have been overcome from the process point of view. This article is dedicated to the resist pattern characterization when they are annealed above the glass transition temperature of the material. This approach may be directly transposed to imprint process optimization when the demolding scheme is performed above the glass transition temperature. Simple model describing shape evolution with temperature is proposed and correlation with demolding process is presented. The results showed that a stamp release well above glass transition temperature is possible and may slightly impact the initial imprinted shape. Furthermore, this work may be transposed to determine temperature evolution of polymer dynamic viscosity.
Fabrication of terahertz holograms
Authors: Walsby E. D. , Alton J. , Worrall C. H. , Beere H. E. , Ritchie D. A. , Leach J. , Padgett M. , Cumming D. R. S.
Published: December 2007

The authors demonstrate the fabrication of polypropylene eight-level holograms with arbitrary patterns for use in terahertz beam forming and imaging applications. They make a binary master in silicon using multistage deep reactive ion etching. The pattern is then transferred into polypropylene using an imprint technique to make the final hologram. Patterns are tested using a 2THz quantum cascade laser. The results show that the desired image is formed with the inclusion of a zero order mode. The process is low cost and with high fidelity. The demonstration of holograms in low loss material opens a new field of opportunity for those working on terahertz applications.
Solid-state electrochemical nanoimprinting of copper
Authors: Schultz Peter L. , Hsu Keng H. , Fang Nicholas X. , Ferreira Placid M.
Published: December 2007

For the first time, the authors report highly selective dry etching of copper with a resolution of 80nm using solid-state electrochemical nanoimprint technology. By exploiting the high mobility of copper ions in solid electrolytes such as copper sulfide, they are able to obtain etching rates up to 5Å∕s without the use of contaminating liquids and excessive mechanical forces. Given the dearth of dry etch processes for metals in general and the fact that nanopatterning of metals is typically achieved indirectly using multistep processes, such a direct patterning technique offers potential application in a number of process steps in metallic interconnects and other nanoscale device fabrication.
Membrane stacking: A new approach for three-dimensional nanostructure fabrication
Authors: Patel Amil A. , Smith Henry I.
Published: December 2007

Future applications of nanotechnology, including integrated photonics, will require new three-dimensional (3D) fabrication techniques beyond those employed by the semiconductor industry. The authors investigate membrane stacking as a potential avenue for fabricating photonic crystals and other 3D structures with high yield. They fabricated membranes in silicon nitride with freestanding photonic structures and investigated the technology for stacking them.
Laser interferometric nanolithography using a new positive chemical amplified resist
Authors: Luttge R. , van Wolferen H. A. G. M. , Abelmann L.
Published: December 2007

The authors report on the progress of laser interference lithography at 266nm laser wavelength with a chemical amplified resist containing a polyvinyl derivate dissolved in propylene glycol monoethyl ether ester. A continuous-wave deep-UV source combined with a Lloyd mirror is a simple and useful tool for the fabrication of nanoscale periodic structures generally called nanoarrays. Aiming for a robust pattern transfer technique to fabricate nanoarrays into magnetic materials, the authors investigated the utility of a chemical amplification positive tone resist, despite the relatively high theoretical resolution limit of 133nm (λ∕2) pattern period for the laser source used. Taking advantage of this new type of resist, the authors demonstrated for the first time the fabrication of an 18Gbit∕in.2 dot pattern on a platinum thin film.
Direct measurement of the spatial extent of the in situ developed latent image by neutron reflectivity
Authors: Prabhu Vivek M. , Vogt Bryan D. , Kang Shuhui , Rao Ashwin , Lin Eric K. , Satija Sushil K.
Published: December 2007

The spatial distribution of polymer photoresist and deuterium labeled base developer highlights a fraction of the line edge that swells but does not dissolve. This residual swelling fraction remains swollen during both the in situ aqueous hydroxide dissolution (development) and water rinse steps uncovering that the final lithographic feature is resolved by a collapse mechanism during the drying step. These new insights into the mechanism of lithographic feature formation were enabled by contrast variant neutron reflectivity methods with nanometer resolution.
Geometry impact on ultrahigh resolution pattern collapse
Authors: Jouve A. , Simon J. , Gonon L. , Tortai J. H.
Published: December 2007

Pattern collapse is one critical issue that lithography must overcome to address future high resolution nodes (32 and 22nm). Published pattern collapse models showed that lines collapse when the capillary pressure exerted by the liquid overcomes the mechanical strength of the material. To simplify equations, those models consider that the maximum capillary pressure is exerted only on one side of the pattern, when the rinse liquid fills the space on one side of the pattern while no liquid remains on the other side. The collapsing behavior of 60nm dense lines printed with extreme ultraviolet interferometric lithography (EUV-IL) and electron beam lithography (EBL) has been studied. These experiments confirm that this phenomenon can be correctly modeled with an asymmetric rinse liquid filling configuration. Then the influence of the pattern shape of sub-60-nm dense lines on collapse behavior is checked. The authors demonstrate that reentering slope deteriorates the pattern holding, whereas top rounding improves it. Finally, they observe that exposure defaults due to the tool properties such as stitching (EBL) or exposure dose heterogeneity (EUV-IL) considerably influence pattern collapse and should be considered for a better prediction.
Cathode ray tube type electron gun as a source for multibeam electron lithography
Authors: van den Brom A. J. , van Veen A. H. V. , Weeda W. M. , Berglund G. Z. M. , Wieland M. , Kruit P.
Published: December 2007

The authors have investigated the potential of using a dispenser cathode in space charge limited regime for employment in an electron beam lithography electron source. The space charge limitation guarantees stable and uniform emission even if there are small work function variations or bumps and depressions on the surface. Employment of a dispenser cathode in the space charge limited regime enables high beam currents and splitting of the electron beam into many sub-beams for parallel multibeam electron lithography. In the reported experiment, the electron beam is split into 194 sub-beams. The reduced brightness, defined as current divided by normalized emittance, was measured at different cathode temperatures and extraction potentials for a cathode ray tube type electron source equipped with an I-type dispenser cathode. In the central 25 sub-beams, reduced brightness values of up to 106Am−2sr−1V−1 were observed. Such a high reduced brightness in combination with a high total emission current (up to 20mA) indicates potential application in electron beam lithography systems. In accord with theory, the experimentally observed reduced brightness is directly proportional to the emission current density. It was found, however, that the brightness drops if the emission current density is increased beyond the level where the emitter leaves the space charge limited regime. Within the space charge regime, increasing reduced brightness as a function of increasing current density is found to be caused by a decreasing virtual source size, while the angular current density remains nearly invariant.
Semitransparent Cu electrode on a flexible substrate and its application in organic light emitting diodes
Authors: Kang Myung-Gyu , Guo L. Jay
Published: December 2007

A semitransparent nanomesh Cu electrode on a polyethylene terephthalate (PET) substrate using metal transfer from a polydimethylsiloxane (PDMS) stamp and nanoimprint lithography is reported. A nanoscale dense mesh pattern is replicated by using a high modulus PDMS stamp. It is found that a uniform pressure of 30 psi and a temperature of 100 °C are needed for the transfer of the Cu mesh structure from the PDMS stamp onto the PET substrate. A fabricated semitransparent Cu electrode exhibits high transmittance in the visible range and good electrical conductivity. The authors show that the transmittance is increased by reducing the linewidth of the mesh pattern and an average transmittance of 75% is achieved. An organic light emitting diode on a flexible substrate is fabricated to demonstrate the potential use of a semitransparent Cu electrode as a transparent conducting electrode.
Influence of solubility switching mechanism on resist performance in molecular glass resists
Authors: Lawson Richard A. , Lee Cheng-Tsung , Henderson Clifford L. , Whetsell Robert , Tolbert Laren , Yueh Wang
Published: December 2007

Five different molecular glass chemically amplified photoresists which utilized different solubility switching mechanisms and chemistries, based on a tris(4-hydroxyphenyl)ethane (THPE) core, were synthesized and their performance compared. Three different positive tone systems were designed based on acid catalyzed deprotection of a phenolic hydroxyl group protected with one of the following groups: tert-butoxycarbonyl (tBoc), tetrahydropyranyl, or ethoxyethyl. Two negative tone systems were designed; one using cationic epoxide polymerization of pendant epoxides and one using condensation of the unprotected THPE with a multifunctional cross-linking additive. The tBoc system and negative tone systems showed good performance under deep UV and large field e-beam patterning, but the epoxide system showed far superior performance for high resolution electron beam patterning. It was able to produce 50nm 1:1 line/space patterns and 30nm lines on 1:3 line/space patterns with high sensitivity, good contrast, and a very low line edge roughness (3σ) of 2.3nm using 100keV electron beam patterning.
Ultrathin magnetic multilayer films for low-field microwave notch filters
Authors: Kuanr Bijoy K. , Kuanr Alka V. , Fal T. , Camley R. E. , Celinski Z.
Published: December 2007

Microwave filters that use thin films of ferromagnetic metals are now being established as a valuable option compared to yttrium iron garnet based filters due to their higher frequency response. In these filters the signal propagation is inhibited over a wide frequency band, depending on the applied dc magnetic field. However, the continuous application of an applied field to achieve an operating frequency in the higher gigahertz range increases the power consumption of the device. The main contribution of this article is to provide techniques which significantly boost the operating frequency of notch filters in zero or very low applied magnetic fields. To do this, the authors fabricated high quality epitaxial Fe films which are interlayer exchange coupled through nonmagnetic Si layer of different thicknesses. The films were used in flip-chip geometry on top of a Cu-coplanar waveguide to create band-stop filters. In contrast to filters based on Fe alone, the multilayer filters can operate above 25GHz with a very small applied magnetic field. The observed upshift in frequency is attributed to the induced interlayer exchange coupling energy mediated through the nonmagnetic Si layer between the two Fe layers. These frequency shifts are in good agreement with theoretical calculations of the ferromagnetic resonance modes taking into account anisotropy, exchange, and Zeeman energies.
Exploring the manufacturability of using block copolymers as resist materials in conjunction with advanced lithographic tools
Authors: Craig Gordon S. W. , Nealey Paul F.
Published: December 2007

The authors discuss studies of the capabilities and advantages of using self-assembling block copolymers in the lithographic process. Directing the assembly of these materials on lithographically defined chemically nanopatterned surfaces offers the potential to improve the dimensional control of features at the nanoscale while retaining essential attributes of the lithographic process, such as registration, patterning of regular fabric architectures, and a high degree of pattern perfection.
Nickel nanowires for planer microwave circuit applications and characterization
Authors: Marson Ryan L. , Kuanr Bijoy K. , Mishra Sanjay R. , Camley R. E. , Celinski Z.
Published: December 2007

The dynamic properties of uniform one-dimensional arrays of high aspect ratio nickel nanowires have been studied by ferromagnetic resonance (FMR) technique at 24GHz. The fundamental magnetic parameters such as spontaneous magnetization, gyromagnetic ratio (γ), and magnetic anisotropies of the nanowires are derived from the angular variation of resonance field Hr(θH) positions. The effective fields of the nanowire system were observed to decrease with increasing length of the nanowires. Further, the use of nanowires as a tunable stop-band notch filter in a coplanar waveguide geometry has been assessed. The stop-band frequency (fr) is observed to be tunable up to 14GHz with an applied field (H) of up to 4kOe. The kink in the fr(H) data gives the measure of the effective field (Heff) of the nanowire system. The theoretical fitting of fr(H) data to resonance relation yields values of Heff and γ which are a little higher than the conventional FMR results.
Thermal model for a superstrate cooling apparatus for an integrated in-line manufacturing process for thin film photovoltaic devices
Authors: Enzenroth R. A. , Barth K. L. , Sampath W. S. , Manivannan V.
Published: December 2007

An efficient apparatus to cool glass substrates in vacuum has been developed. The regions near the substrate are maintained at a higher pressure than the surrounding vacuum environment. Heat is transferred from the substrate by thermal conduction through the gas phase to a closely spaced water cooled plate. This article presents a model to predict the heat transfer rate as a function of the Knudsen number and the substrate to cooled plate distance.
Structure and magnetic property of c-axis oriented L10-FePt nanoparticles on TiN/a-Si underlayers
Authors: Tsuji Yoshiko , Noda Suguru , Yamaguchi Yukio
Published: December 2007

L 1 0 -FePt is a promising material for high-density perpendicular magnetic recording media. The authors previously reported that c-axis oriented L10-FePt nanoparticle monolayers can be formed on (200)-oriented polycrystalline template TiN underlayers on SiO2 by using a conventional sputtering method. In this study, TiN nanostructures, such as the degree of (200) orientation, were improved by first depositing a buffer layer, such as amorphous Si onto SiO2, and the grain size could be controlled by adjusting either the deposition temperature or TiN thickness. When FePt nanoparticles were formed on a template TiN underlayer with a buffer layer of amorphous Si, both their degree of c-axis orientation and their magnetic properties were improved; FePt nanoparticles with nominal thickness of 1.4 nm had coercivity of 12.9 kOe in the out-of-plane direction at 300 K.
Influence of different surface-passivation dielectrics on high-temperature strain relaxation of AlGaN in AlGaN∕GaN heterostructures
Authors: Chen D. J. , Tao Y. Q. , Chen C. , Xie Z. L. , Zhai Z. Y. , Wu X. S. , Han P. , Zhang R. , Zheng Y. D.
Published: December 2007

The influence of AlN, Si3N4 and SiO2 surface-passivation dielectrics on high-temperature strain relaxation of AlGaN in AlGaN∕GaN heterostructures was investigated in the range from room temperature to 600°C by means of x-ray diffraction. The Si3N4 and SiO2 films produce an additional biaxial tensile stress to the underlying AlGaN barrier layer, whereas the AlN film produces an additional biaxial compressive stress. The authors found that the process of long-time heating and cooling results in a nonreversible lattice relaxation in the AlGaN layer. The passivation dielectrics used in this work can mitigate this high-temperature strain relaxation. The AlN dielectric manifested a better effect than the Si3N4 and SiO2 dielectrics.
Photopolymerization kinetic study of UV nanoimprint lithography dedicated resists
Authors: Voisin P. , Zelsmann M. , Ridaoui H. , Chouiki M. , Gourgon C. , Boussey J. , Zahouily K.
Published: December 2007

This article reports on the properties of ultraviolet nanoimprint lithography dedicated imprinting materials. Studied solutions are composed of a diacrylate-based monomer and a variable amount (1%, 2%, and 4% in weight) of three different photoinitiators from Ciba Specialty Chemicals (Irgacure 819, Irgacure OXE02, and Irgacure 379). Photopolymerization kinetic studies were conducted on these solutions. Quantity and type of photoinitiator could be optimized in order to obtain a polymerization rate higher than 95% with an exposure dose as low as 20mJ∕cm2. The etch resistance of this home-developed imprinting resist was characterized under standard plasma etching conditions. We observed that the polymerization rate has a large influence on the plasma etch resistance, and we show that the etch rates of our best material is comparable to the one measured for 193nm photolithography resists and makes it a very good candidate as a masking layer for direct pattern transfer.
Dual-domain scanning illuminator for the SEMATECH Berkeley microfield exposure tool
Authors: Anderson Christopher N. , Naulleau Patrick P. , Denham Paul , Kemp Drew , Rekawa Senajith
Published: December 2007

Illumination uniformity and reproducibility in extreme ultraviolet (EUV) microfield exposure tools are critical to many aspects of the EUV lithography development task. Here, the authors present a scanning-field-averaging illuminator delivering consistent, uniform illumination to synchrotron-based microfield exposure tools. The system is integrated into the existing Fourier-synthesis custom coherence illuminator at the SEMATECH Berkeley microfield exposure tool and its effectiveness is demonstrated lithographically. Following the upgrade, the authors report a 6.5% peak-to-valley intensity variation across the full 200×600μm2 wafer-side field of view.
Monolithic multichannel secondary electron detector for distributed axis electron beam lithography and inspection
Authors: Pickard D. S. , Kenney C. , Tanimoto S. , Crane T. , Groves T. , Pease R. F. W.
Published: December 2007

The attractiveness of electron beam systems would be greatly enhanced if the throughput could be improved. One approach, described previously by the authors employs a uniform axial magnetic field to focus thousands of electron beams simultaneously [D. S. Pickard et al., J. Vac. Sci. Technol. B 21, 2709 (2003); T. R. Groves and R. A. Kendall, ibid., 16, 3168 (1998)]. The beamlets never combine to form a common crossover, thereby avoiding the throughput limitations due to space charge blurring. With this approach, one challenge was to fashion a detection scheme that maintains a tight beamlet packing density (250μm pitch) while minimizing cross-talk between adjacent secondary electron signals, either by crossing trajectories or within the detector. A pin-diode-based detector was investigated as a potential component of the multielement detection scheme for the authors’ system. The detector features a two-dimensional array of elements on high resistivity float-zone silicon. The detector attributes that were attractive to their application include modest internal amplification (>5000 at 25kV), fast response time (measured at <10ns), ability to be made compact and with dense packed electrodes (<250μm), low electrode capacitance (<1pF), and ability for (complementary metal-oxide semiconductor) circuitry to be integrated directly onto the detector array so that low noise amplification of each signal can be performed. This detector requires a retarding field for the primary beam, which accelerates the secondary electrons to energies sufficient to excite a large number of internal secondaries.
Fabrication of high aspect ratio Si nanogratings with smooth sidewalls for a deep UV-blocking particle filter
Authors: Mukherjee Pran , Kang Myung-Gyu , Zurbuchen Thomas H. , Guo L. Jay , Herrero Fred A.
Published: December 2007

To measure space plasmas and neutral particles one must filter out high-energy ultraviolet photons that would increase background count or damage sensors. To enable sensitive neutral particle measurements, a photon-to-particle rejection rate of 1014 is desired, far exceeding the requirements of prior filters. The authors propose a high-aspect ratio Si grating with densely packed, sub-100 nm slits. In this article, the authors report the development of a new technique for fabricating sturdy, self-supported transmission gratings in silicon using nanoimprint lithography and deep reactive ion etching, resulting in grating slits with scalloping under 7 nm and high (8.5:1) aspect ratios.
Double patterning overlay budget for 45nm technology node single and double mask approach
Authors: Rigolli Pierluigi , Turco Catia , Iessi Umberto , Capetti Gianfranco , Canestrari Paolo , Fradilli Aldo
Published: December 2007

Double patterning (double exposure and double etch) is definitely a viable solution for overcoming the physical resolution limit of k1=0.25 of imaging systems. This article presents the overlay budget for a double patterning technique using a 45nm technology node flash memory device with k1∼0.20 and 193nm dry lithography. Adopting double exposure, the final pattern is composed of two lithography patterns within the resolution capability of the exposure tool and then combined with the double etching processes. The photoetch photoetch approach creates the overlay between the two exposures which is the most critical issue to be addressed. This article presents the adopted scanner setup, mask requirements, and efficient overlay metrology setup in order to achieve the overlay roadmap of 6nm for the 45nm technology node.
Fabrication of spiral-phase diffractive elements using scanning-electron-beam lithography
Authors: Tsai Hsin-Yu , Smith Henry I. , Menon Rajesh
Published: December 2007

The authors report on the fabrication of binary spiral zone plates and investigate an approach using gray scale scanning-electron-beam lithography to fabricate spiral-phase plates. The optical performance of the spiral zone plates is characterized via photoresist exposures and compared to theory.
First-principles calculation of electronic structure and magnetic properties of copper adsorbed polar-ZnO surface
Authors: Kim Yoon-Suk , Chung Yong-Chae
Published: December 2007

The electronic structure and magnetic properties of a Cu adsorbed polar-ZnO surface system were investigated using the ab initio projector-augmented-wave method. It is found that the H3 site is the most stable adsorption site of Cu adsorbed polar-ZnO surfaces with stable ferromagnetism. The Zn-terminated ZnO:Cu surface system (H3 site adsorption) is predicted to have a half-metallic property and stable ferromagnetism of 0.72 μB magnetic moments.
Electron beam and optical proximity effect reduction for nanolithography: New results
Authors: Peckerar Martin , Sander David , Srivastava Ankur , Foli Adakou , Vishkin Uzi
Published: December 2007

Proximity effect correction by dose modulation is widely practiced in electron-beam lithography. Optical proximity control is also possible using a combination of shape adjustment and phase control. Assigning “the right” dose (or fill factor and phase for optics) is a well known mathematical inverse problem. Linear programming, by definition, is the appropriate method for determining dose. In the past, the technique was too slow for full-scale implementation in mask making. Here, the authors discuss how recent developments in computer speed and architecture have improved the prospects for full-scale implementation. In addition, the authors discuss some numerical techniques, analogous to gridding and relaxation, that make linear programming more attractive in mask making.
Improved release strategy for UV nanoimprint lithography
Authors: Garidel Sophie , Zelsmann Marc , Chaix Nicolas , Voisin Pauline , Boussey Jumana , Beaurain Arnaud , Pelissier Bernard
Published: December 2007

The adhesion between the fused silica mold and the resist remains a key issue in ultraviolet nanoimprint lithography (UV-NIL), especially in step and repeat processes. In this paper, we present results on antisticking layers (ASLs) of tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (F13-TCS) deposited in vapor phase and of a commercial product, Optool DSX™, from Daikin Chemical, deposited in liquid phase. The antisticking properties and structural morphologies of the formed self-assembled monolayer are investigated using contact angle, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy (XPS) measurements. Obtained surface energies are as low as 10mN∕m for both types of ASL. The stability of these formed layers during the UV-NIL process remains the main important issue. It was tested on an EVG® step and repeat UV-NIL equipment using acrylate-based resists. After only 50 prints, we observed a high increase in the surface energy of the mold, which indicates a drastic degradation of the antisticking (ASL). XPS measurements show that fluorine is removed from the mold surface. This surface modification is attributed to free radicals created during the UV cure of the resist that easily cleaved fluorocarbon chains. This can be confirmed by the fact that the polar component of the surface energy was increased by a larger factor than the dispersive one. To overcome this problem, the acrylate-based resist was modified by the adjunction of a fluorine surfactant. To go further in the mold/resist interaction, we developed an original setup that directly measures the adhesion force. Almost no degradation of the organic ASL was observed in terms of surface energy and fluorine density after more than 50 prints when using a sufficiently high amount of surfactant in the resist.
Stretching and selective immobilization of DNA in SU-8 micro- and nanochannels
Authors: Yang B. , Dukkipati V. R. , Li D. , Cardozo B. L. , Pang S. W.
Published: December 2007

Nanoimprint lithography is used to fabricate 200nm–10μm wide SU-8 channels reversal imprinted onto Si substrates. The immobilization and stretching of double stranded λ-DNA molecules within the micro- and nanochannels are demonstrated and controlled by varying the hydrophobicity of SU-8 using oxygen plasma exposure. Site-directed immobilization of DNA is achieved by the integration of 10μm wide SU-8 patterns with 6μm gaps into 100μm wide and 1μm deep Si channels.
High-Pressure Creep of Serpentine, Interseismic Deformation, and Initiation of Subduction
Authors: Hilairet Nadege , Reynard Bruno , Wang Yanbin , Daniel Isabelle , Merkel Sebastien , Nishiyama Norimasa , Petitgirard Sylvain
Published: December 2007

The supposed low viscosity of serpentine may strongly influence subduction-zone dynamics at all time scales, but until now its role could not be quantified because measurements relevant to intermediate-depth settings were lacking. Deformation experiments on the serpentine antigorite at high pressures and temperatures (1 to 4 gigapascals, 200° to 500°C) showed that the viscosity of serpentine is much lower than that of the major mantle-forming minerals. Regardless of the temperature, low-viscosity serpentinized mantle at the slab surface can localize deformation, impede stress buildup, and limit the downdip propagation of large earthquakes at subduction zones. Antigorite enables viscous relaxation with characteristic times comparable to those of long-term postseismic deformations after large earthquakes and slow earthquakes. Antigorite viscosity is sufficiently low to make serpentinized faults in the oceanic lithosphere a site for subduction initiation.
Rapid Changes in Throughput from Single Motor Cortex Neurons to Muscle Activity
Authors: Davidson Adam G. , Chan Vanessa , O'Dell Ryan , Schieber Marc H.
Published: December 2007

Motor cortex output is capable of considerable reorganization, which involves modulation of excitability within the cortex. Does such reorganization also involve changes beyond the cortex, at the level of throughput from single motor cortex neurons to muscle activity? We examined such throughput during a paradigm that provided incentive for enhancing functional connectivity from motor cortex neurons to muscles. Short-latency throughput from a recorded neuron to muscle activity not present during some behavioral epochs often appeared during others. Such changes in throughput could not always be attributed to a higher neuron firing rate, to more ongoing muscle activity, or to neuronal synchronization, indicating that reorganization of motor cortex output may involve rapid changes in functional connectivity from single motor cortex neurons to α-motoneuron pools.
The impairment/disability distinction: a response to Shakespeare
Authors: Edwards S D
Published: December 2007

Tom Shakespeare’s important new book includes, among other topics, a persuasive critique of the social model of disability. A key component in his case against that model consists in an argument against the impairment/disability distinction as this is understood within the social model. The present paper focuses on the case Shakespeare makes against that distinction. Three arguments mounted by Shakespeare are summarised and responded to. It is argued that the responses adequately rebut Shakespeare’s case on this specific issue. Moreover, as the engagement with Shakespeare’s argument illustrates, his claim to employ a critical realist perspective appears to be in considerable tension with the case he offers against the impairment/disability distinction.
MULTIVARIATE INTEGRAL PERTURBATION TECHNIQUES I: THEORY
Authors: DASH JAN W.
Published: December 2007

We present a quasi-analytic perturbation expansion for multivariate N-dimensional Gaussian integrals. The perturbation expansion is an infinite series of lower-dimensional integrals (one-dimensional in the simplest approximation). This perturbative idea can also be applied to multivariate Student-t integrals. We evaluate the perturbation expansion explicitly through 2nd order, and discuss the convergence, including enhancement using Padé approximants. Brief comments on potential applications in finance are given, including options, models for credit risk and derivatives, and correlation sensitivities.
PARAMETRIZATION AND CORRECTION OF ELECTROCARDIOGRAM SIGNALS USING INDEPENDENT COMPONENT ANALYSIS
Authors: CHAWLA M. P. S.
Published: December 2007

Electrocardiogram (ECG) signals are largely employed as a diagnostic tool in clinical practice in order to assess the cardiac status of a specimen. Independent component analysis (ICA) of measured ECG signals yields the independent sources, provided that certain requirements are fulfilled. Properly parametrized ECG signals provide a better view of the extracted ECG signals, while reducing the amount of ECG data. Independent components (ICs) of parametrized ECG signals may also be more readily interpretable than original ECG measurements or even their ICs. The purpose of this analysis is to evaluate the effectiveness of ICA in removing artifacts and noise from ECG signals for a clear interpretation of ECG data in diagnostic applications. In this work, ICA is tested on the Common Standards for Electrocardiography (CSE) database files corrupted by abrupt changes, high frequency noise, power line interference, etc. The joint approximation for diagonalization of eigen matrices (JADE) algorithm for ICA is applied to three-channel ECG, and the sources are separated as ICs. In this analysis, an extension is applied to the algorithm for further correction of the extracted components. The values of R-peak before and after application of ICA are found using quadratic spline wavelet, which facilitates the estimation of the reconstruction errors. The results indicate that, in most of the cases, the percentage reconstruction error is small at around 3%. The paper also highlights the advantages, limitations, and diagnostic feature extraction capability of ICA for clinicians and medical practitioners. Kurtosis is varied in the range of 3.0–7.0, and variance of variance (Varvar) is varied in the range of 0.2–0.5.
MULTIPHASE FLOW OF BLOOD THROUGH ARTERIES WITH A BRANCH CAPILLARY: A THEORETICAL STUDY
Authors: MISRA J. C. , ADHIKARY S. D. , SHIT G. C.
Published: December 2007

In this paper, we present a theoretical analysis of the problem of hematocrit reduction (due to plasma skimming) in a capillary that emerges from an artery making an angle α with the parent artery. The analysis bears the potential to explore a variety of information regarding some phenomenological aspects of this important physiological problem. The flow is considered to consist of three distinct phases, viz., the peripheral plasma layer, the cell-depleted middle layer, and the core region which usually has a high concentration of erythrocytes. This study deals with both steady and pulsatile flow of blood, which is treated as a non-Newtonian fluid of Herschel–Bulkley type. A computational procedure is developed for a quantitative measure of the velocity profile, the volumetric flow rate, and the hematocrit of blood in a specific situation. The procedure also gives us an opportunity to examine the nature of variation of these important hemodynamic factors; this observation holds true irrespective of whether the flow of blood is steady or pulsatile. The study reveals that the velocity of blood in the parent artery reduces when the fluid index/yield stress increases. It is further revealed that the volumetric flow rate of blood in the capillary also decreases with an increase in the value of the fluid index/yield stress of blood.
Lateral erosion (‘toe-cutting’) of alluvial fans by axial rivers: implications for basin analysis and architecture
Authors: LEEDER M. R. , MACK G. H.
Published: December 2007

Abstract:
We document the neglected phenomenon of lateral erosion (‘toe-cutting’) of alluvial fans by non-incising axial river channels. Field examples from the Holocene of the Big Lost River basin, Idaho and the Plio-Pleistocene of the Rio Grande Rift, New Mexico help to establish architectural models with more general application to basin analysis. The process of toe-cutting can lead to complete fan destruction and may be a response to climate change, tectonic tilting, fault propagation or a combination of these variables. It gives rise to: near horizontal erosion surfaces cut in fan sediment; steep fan-margin scarps; progressive up-fan incision from the scarp by a network of channels; soil formation up-fan away from the incised channel network; a deposit of axial alluvium that overlies the erosion surface and onlaps the scarp. Once avulsion occurs to take the axial channel away from the bajada margin, distinctive ‘healing-wedges’ of fan alluvium prograde across abandoned axial river channel and floodplain deposits, gradually onlapping the eroded scarp and its upstream network of incised channels. Toe-cutting has important stratigraphic basin analysis and economic consequences: bajada deposits subject to the process exhibit appreciable extra groundwater and petroleum reservoir potential in the intercalations of more porous and permeable axial fluvial sediments.
Turbidite provenance in the Lower Palaeozoic Manx Group, Isle of Man: implications for the tectonic setting of Eastern Avalonia
Authors: BURNETT D. J. , QUIRK D. G.
Published: December 2007

The provenance of turbidites from the predominantly Arenig-aged Manx Group has been constrained using petrographical and geochemical techniques. Petrographical analysis of sandstones reveals that mono- and poly-crystalline quartz grains of cratonic origin are dominant. Major, trace and rare earth element concentrations in both sandstones and mudstones complement the petrographical data indicating that the source of the sediments consisted of quartzose basement and mature sedimentary rocks. There is little evidence of a juvenile volcanic input but a minor palaeovolcanic component of active continental margin affinity is present. There are indications of a more immature character in the oldest units but, on the whole, geochemical data from the Manx Group suggest an overall passive margin setting. These results suggest that Eastern Avalonia was attached to Gondwana during deposition of the Manx Group and that Iapetus oceanic crust did not subduct beneath the region before the end of the Arenig.
Ascent mechanism of the Dzhabyk batholith, southern Urals: constraints from URSEIS reflection seismic profiling
Authors: BROWN D. , TRYGGVASON A.
Published: December 2007

In order to determine which of the two conflicting models for the ascent of a granitic magma (diapiric rise, or along descrete pathways) may apply in any particular case it is important to see the crust through which the melt ascended. Reflection seismic data provides a means to do this. The URSEIS seismic profile images the 2D crustal profile from the surface outcrop of the Dzhabyk batholith to the upper mantle. The batholith is

c.

5 km thick, and the crust beneath it shows continuous reflectivity to depths of 20–35 km. The continuous reflectivity indicates the absence of a diapir tail, and suggests that melt ascent along descrete pathways was the more likely ascent mechanism in this case.
The aureole of the Rum Tertiary Igneous Complex, Scotland
Authors: Holness M.B. , Isherwood C.E.
Published: December 2007

The aureole of the Tertiary Rum Igneous Complex formed at shallow levels in amphibolite-facies migmatitic Lewisian gneisses and previously unmetamorphosed Precambrian arkose of the Torridonian Group. Contact metamorphism of arkose resulted in the breakdown of chlorite-rich cement and detrital muscovite, feldspar disordering, and melting. A simplified thermal model shows that magma chamber filling may have occurred over a few hundred years. Contact metamorphism of Lewisian gneiss, exposed only within the Main Ring Fault of the complex, resulted in the breakdown of hornblende to pyroxene, plagioclase, biotite and magnetite. Biotite in high-grade gneisses is replaced by feldspar and orthopyroxene. Extensive melting of the gneiss occurred only locally. Prominent migmatitic structures predate contact metamorphism. Significant mobility of Fe, Mg and Al occurred in the aureole, probably effected via circulation of aqueous fluids confined to the metamorphic peak within the Main Ring Fault but extending to lower temperatures outside. Significant differences between cooling rate of rocks within and outside the Main Ring Fault are inferred from textural observations. These probably relate to a combination of a relatively extended metamorphic event for the innermost rocks and a greater cooling influence of circulating aqueous fluids on the outermost rocks.
Deep structure of the Armorican Basin (Bay of Biscay): a review of Norgasis seismic reflection and refraction data
Authors: Thinon I. , Matias L. , RÉhault J.P. , Hirn A. , Fidalgo-GonzÁlez L. , Avedik F.
Published: December 2007

The Bay of Biscay is bounded to the north by the North Biscay margin, which comprises the Western Approaches and Armorican segments. In the 1970s and 1980s, most researchers considered this margin typical of a non-volcanic passive margin: it is characterized by a striking succession of tilted blocks beneath which occurs the S reflector and the continent–ocean boundary is abrupt. This paper examines the Armorican segment and is based on a study of all early seismic profiles together with new multichannel reflection and refraction seismic data (Norgasis cruise). An important result is the discovery of a 80 km wide ocean–continent transition zone that coincides with the Armorican Basin (a deep sedimentary basin). It is characterized by a high-velocity lower-crustal layer (7.4–7.5 km s
−1
) overlain by sediments. The other results are: (1) the main crustal thinning occurs exclusively under the narrow continental slope; (2) the tilted blocks and the S reflector are observed only at the base of the continental slope in the narrow domain called the ‘neck area’; (3) the North Biscay Ridge is a large oceanic plateau present only off the NW Armorican margin rather than a long ridge elongated off the whole North Biscay margin.