bluuebunny/crossref_metadata_2025 huggingface dataset:
Korea's Strong Familism and Lowest‐Low Fertility
Authors: Suzuki Toru
Published: December 2008

Abstract:  The emergence of lowest‐low fertility in southern and eastern Europe dramatically changed the relationship between fertility and its covariates. Today, low fertility countries are characterized by low female labor force participation, low gender equity, robust marriage institution, and strong familism. It is assumed that the discrepancy between an advanced socioeconomic system and robust family patterns is an important cause of lowest‐low fertility. The Republic of Korea is a typical case where the conventional family pattern causes disharmony with socioeconomic development and depresses fertility. The direct cost of children has been rising rapidly because of the Confucian value of education and strong family ties. The tight labor market conditions and the increasing uncertainty about the future are depressing nuptiality as well as marital fertility. The robustness of traditional gender role division checks the improvement in compatibility between work and the family and sustains the high opportunity cost of childbearing. Although the Korean government announced an ambitious pronatal program in 2006, the budget is so limited that its effect is questionable. Furthermore, a large part of the difference between moderately low and lowest‐low fertility is attributed to cultural patterns and is beyond family policy.
Changing Italian Families in the Era of Fertility Decline
Authors: Tabuchi Rokuro
Published: December 2008

Abstract:  Over the past few decades, in examining the social causes of low fertility in advanced societies, sociologists and demographers have shown increasing interest in southern European countries. Italy has been recognized as one of these countries plagued by lowest‐low fertility. In general, the literature has depicted certain characteristics of Italian families as possible causes of fertility decline. This article examines the situation of contemporary Italian families and intergenerational relationships from a sociological point of view, particularly in comparison with Japanese families. It has sometimes been argued that strong familism characterizes Italian families and society. According to this view, one of the causes of fertility decline in Italy is the continuity of strong families. Empirical data suggest, however, that this familism perspective cannot explain the differences in family patterns observed among Italian regions. In addition, a comparison between Italy and Japan with respect to intergenerational relationships suggests that there are substantial differences between the two countries. It is suggested that a further exploration of the various aspects of social contexts is needed in order to clarify what is distinctive about contemporary Italian families.
JAL (RH48) blood group antigen: serologic observations
Authors: Lomas‐Francis Christine , Alcantara Denden , Westhoff Connie , Uehlinger Joan , Valvasori Marilia , Castilho Lillian , Reid Marion E.
Published: December 2008

BACKGROUND: JAL (RH48) is a low‐prevalence antigen in the Rh blood group system and anti‐JAL has caused hemolytic disease of the newborn. JAL is associated with either a haplotype carrying depressed C and e antigens or one carrying depressed c and e antigens. Blood samples from JAL+ people were tested, published serologic findings were confirmed, serologic studies were extended to include expression of other Rh antigens, and the antibody specificities produced by three sensitized JAL+ probands are reported.

STUDY DESIGN AND METHODS: Red blood cell (RBC) samples from 17 (12 probands) JAL+ persons were tested by hemagglutination using standard methods.

RESULTS: RBCs from both the Caucasian JAL+ probands had the (C)(e) haplotype and weakened C, e, hrB, and hrS antigens. JAL+ samples from black persons had the (c)(e) haplotype and expressed weakened c, e, f, V, VS, hrB, and hrS antigens. Plasma from three sensitized c+e+ JAL+ probands contained alloanti‐c, alloanti‐e, or alloantibody of apparent anti‐Rh17 specificity. This study shows that this alloanti‐Rh17−like antibody recognizes the high‐prevalence antigen antithetical to JAL that has been named CEST.

CONCLUSIONS: The presence of the JAL antigen has a quantitative (weakening) effect on the expression of C, e, hrB, and hrS antigens in Caucasian persons and of c, e, f, V, VS, hrB, and hrS antigens in people of black African ancestry. A qualitative effect also was demonstrated by the presence of alloanti‐c or alloanti‐e in the plasma of two transfused c+e+ patients and by an antibody (anti‐CEST) that recognizes the high‐prevalence antigen antithetical to JAL.
Effects of water‐borne copper on the gills and hepatopancreas of Macrobrachium rosenbergii
Authors: LI Na , MA Qiang , YANG Jian , ZHAO Yunlong , BROCHON Jean‐Claude
Published: December 2008

We focused on elucidating the toxic effects of water‐borne copper on the giant freshwater prawn Macrobrachium rosenbergii. After seven days of exposure to copper (Cu2+) at concentrations ranging from 0.01 mg L−1 to 0.5 mg L−1, three isozymes, malate dehydrogenase, alkaline phosphatase and esterase, were analyzed and compared using polyacrylamide electrophoresis (PAGE) and biochemical staining. The results indicated that the electrophoretic patterns of the isozymes showed a copper‐concentration‐related difference. Low doses of copper stimulated strong expression of the three isozymes. Electrophoretic patterns of malate dehydrogenase and alkaline phosphatase gradually became weaker or even lost as the level of copper increased. In contrast, esterase patterns exhibited an increased molecular heterogeneity at higher copper concentrations. A transmission electron microscope was used to study ultrastructure differences in the gills and hepatopancreas of M. rosenbergii, and the results showed significant structural damage at increased levels of copper compared with the control group. The basement membranes and mitochondira in the gills were seriously damaged, the cuticle electron density distribution was not homogeneous, and an infolded basement membrane, circularized nucleus, disintegrated nuclear membrane, and decreased mitochondria number and size were observed in the gills. Similarly, flowing out of karyoplasms, partly falling microvilli, decreased mitochondrion, partly disappeared mitochondrial cristae, and a thinned matrix were observed in the hepatopancreas. These findings indicate that exposure to elevated copper levels might damage the ultrastructure of the gills and hepatopancreas of M. rosenbergii and might further weaken their normal physical activities. Isozymes were quite sensitive to environmental stress and changes in isozyme elctrophoretic patterns might be effective biomarkers of environmental contamination.
Getting off the GoldVarb Standard: Introducing Rbrul for Mixed‐Effects Variable Rule Analysis
Authors: Johnson Daniel Ezra
Published: December 2008

The variable rule program is one of the predominant data analysis tools used in sociolinguistics, employed successfully for over three decades to quantitatively assess the influence of multiple factors on linguistic variables. However, its most popular current version, GoldVarb, lacks flexibility and also isolates its users from the wider community of quantitative linguists. A new version of the variable rule program, Rbrul, attempts to resolve these concerns, and with mixed‐effects modelling also addresses a more serious problem whereby GoldVarb overestimates the significance of effects. Rbrul's superior performance is demonstrated on both simulated and real data sets.
Acute liver failure related to hepatitis B virus
Authors: Lee Han Chu
Published: December 2008

Hepatitis B virus (HBV) is an important cause of acute liver failure (ALF) worldwide. Two clinical entities are responsible for HBV‐related ALF: acute hepatitis B and acute exacerbation of chronic HBV infection. Differentiation between these clinical entities is sometimes difficult, especially when past status of hepatitis B surface antigen (HBsAg) is unknown. A quantitative analysis of serum immunoglobulin M (IgM) antibody to the hepatitis core antigen (anti‐HBc) may be helpful in the differential diagnosis. The recent definition of ALF in chronic HBV infection is somewhat problematic, because clinical, laboratory and radiological findings cannot reliably predict the presence of underlying liver cirrhosis in patients with acute exacerbation of chronic HBV infection. Explant liver shows underlying liver cirrhosis in >50% of these cases, even when there is no clinical evidence of liver cirrhosis. Therefore, it is advisable to exclude these patients in clinical trials because of the high incidence of underlying liver cirrhosis. The clinical course, however, is not different and neurologic complications are responsible for about half of the deaths, so a priority for liver transplantation should be maintained in these patients. The prognosis of HBV‐related ALF is quite grim without liver transplantation with transplant‐free survival rates ranging from 26% to 53%. To date, there is not enough evidence that antiviral therapy or artificial liver support devices can enhance the patient's survival, therefore, liver transplantation is still the only effective treatment option that can alter the grave prognosis of HBV‐related ALF.
Implication of cytokines: Roles of tumor necrosis factor‐α in liver injury
Authors: Nagaki Masahito , Moriwaki Hisataka
Published: December 2008

Acute liver failure caused by viruses, drugs, or liver resection, is marked by a massive degree of hepatocyte apoptosis and impaired hepatocyte proliferation, the mechanisms of which, however, still remain to be understood. The choice between life and death is associated with events in regulation of the immune system. The liver is continuously exposed to a large antigenic load that includes pathogens, toxins and dietary antigens. Bacterial toxins, including endotoxin and staphylococcal enterotoxin, have been implicated in the pathogenesis of multi‐organ failure associated with liver damage through production of cytokines and chemokines. Inflammation involves the sequential activation of signaling pathways leading to the production of both pro‐ and anti‐inflammatory mediators. Among pro‐inflammatory mediators, tumor necrosis factor‐α (TNF‐α)/TNF receptor (TNFR) systems play central roles in the physiological regulation of apoptosis as well as inflammation and immunity. These pleiotropic biological effects of TNF‐α result from its ability to initiate different intracellular signaling pathways, which induce both pro‐apoptotic and anti‐apoptotic molecules. Hepatocytes appear to be poorly responsive to pro‐apoptotic stimuli by TNF‐α. Tumor necrosis factor‐α, however, induces excessive hepatocyte apoptosis, once cells are sensitized by D‐galactosamine or actinomycin D, suggesting that TNF‐α itself also induces molecules that protect cells from apoptosis by TNF‐α. Besides the apoptosis‐inducing signal, the binding of TNF‐α to TNFR1 triggers a series of intracellular events that result in the activation of nuclear factor‐κB (NF‐κB), phosphatidylinositol 3‐kinase (PI3K)/Akt, and c‐Jun NH2‐terminal kinase (JNK). Inhibition of NF‐κB may be a two‐edged sword against liver injury, which inhibits pro‐inflammatory gene expression in leukocytes and causes the sensitization of hepatocytes to TNF‐α‐induced apoptosis. A variety of mechanisms exist to modulate the activity of intracellular molecules and thereby affect the ultimate outcome of a liver cell's fate.
Impaired liver regeneration in acute liver failure: the significance of cross‐communication of growth associated factors in liver regeneration
Authors: Tomiya Tomoaki , Omata Masao , Imamura Hiroshi , Fujiwara Kenji
Published: December 2008

Liver regeneration is considered to be retarded or suppressed in patients with acute liver failure. However, the mechanisms for this suppression remain to be elucidated. In order to evaluate deficiencies in liver regeneration in patients with acute liver failure, we focused on the cross‐communication of growth‐associated factors in experimental models. In primary cultured rat hepatocytes, the levels of cellular p53 and transforming growth factor‐alpha (TGF‐alpha), as well as DNA synthesis increased by the addition of hepatocyte growth factor (HGF). When p53 activity was suppressed, TGF‐alpha expression and DNA synthesis were reduced. DNA synthesis was also reduced when TGF‐alpha activity was suppressed. In rats after partial hepatectomy, hepatic HGF and p53 protein levels increased, followed by an increase of hepatic TGF‐alpha levels and hepatocyte proliferation. Circulating levels of HGF and TGF‐alpha correlated with changes in the hepatic levels. The suppression of TGF‐alpha activity reduced the proliferation of hepatocytes in these rats. In patients suffering from acute hepatitis, serum HGF levels increased followed by an increase of serum TGF‐alpha levels. In contrast, in patients with acute liver failure, the increase of serum TGF‐alpha levels was suppressed depending on the severity of hepatic failure, even though serum HGF levels markedly increased. The patients' hepatic levels were consistent with serum levels. Cross‐communication of growth associated factors may be important in the progression of liver regeneration, and impaired regenerative capacity in patients with acute liver failure may be attributable, at least in part, to a disruption of communication of growth‐associated factors.
Plasma exchange in combination with online‐hemodiafiltration as a promising method for purifying the blood of fulminant hepatitis patients
Authors: Inoue Kazuaki , Kourin Akishi , Watanabe Tsunamasa , Yamada Masaya , Yasuda Hiroshi , Yoshiba Makoto
Published: December 2008

Background:  Fulminant hepatitis is an intractable disease caused by various etiological agents. Artificial liver support (ALS) is a symptomatic treatment used to control serious symptoms, such as bleeding tendency, hepatic coma, and brain edema.

Methods:  The present study involved four patients with fulminant hepatitis who were admitted to Showa University Fujigaoka Hospital between January 2007 and June 2007. All four patients were subacute type disease of indeterminate etiology. The four patients were placed on an ALS system that comprised plasma exchange and online hemodiafiltration. The effect of the ALS on various symptoms of fulminant hepatitis was evaluated, and the levels of glutamine in the patients' plasma samples and the discarded buffer were assayed using automatic analyser.

Results:  Three of the four patients regained full consciousness and survived. The remaining patient died despite recovering from hepatic coma with ALS. The plasma glutamine levels were significantly reduced by artificial liver support. The estimated distribution volume of removed Gln ranged from 30 L to 60 L.

Conclusions:  Plasma exchange in combination with online hemodiafiltration is a promising and effective method for purifying the blood of patients with fulminant hepatitis.
Current status of autologous bone marrow cell infusion therapy for liver cirrhosis patients
Authors: Terai Shuji , Sakaida Isao
Published: December 2008

This article reviews recent translational research on the development of cell therapy using autologous bone marrow cell for liver cirrhosis patients. A clinical study of autologous bone marrow cell infusion (ABMI) therapy for liver cirrhosis patient was begun on Nov. 14, 2003. We previously reported nine liver cirrhosis (LC) cases that underwent ABMI from the peripheral vein and followed their progress up to 24 weeks. Subjects were LC patients with total bilirubin TB of < 3.0 mg/dL, platelets > 5 (1010/L) and no viable hepatocellular carcinoma on diagnostic imaging. Mononuclear cells (MNCs) were separated by cell washing and were infused via the peripheral vein. After ABMI therapy liver function and Child‐Pugh Score were significantly improved at 4 weeks and 24 weeks (P < 0.05). A total of 23 cases of ABMI therapy have been performed for LC patients to date. No major adverse effects were noted due to ABMI therapy. In conclusion, ABMI therapy should be considered as a novel treatment for LC patients.
Fabrication of 200nm period blazed transmission gratings on silicon-on-insulator wafers
Authors: Ahn Minseung , Heilmann Ralf K. , Schattenburg Mark L.
Published: December 2008

The authors report on the fabrication of 200nm period blazed transmission gratings on silicon-on-insulator (SOI) wafers. These critical angle transmission (CAT) gratings require 3–5μm tall freestanding grating bars with a very high aspect ratio (>100) and smooth sidewalls. In order to meet the challenging geometrical requirements, they modified and improved our previously reported process for the fabrication of a CAT grating prototype with 574nm period. They have used potassium hydroxide (KOH) solutions to fabricate high aspect ratio gratings on ⟨110⟩ SOI wafers. The KOH etching process was improved to minimize the lateral undercut through precise grating alignment to ⟨111⟩ planes within ±0.05° and a room temperature etch process with 50wt% KOH. In addition, an image-reversal technique with a high silicon content spin-on polymer was applied to increase process latitude with a high duty cycle nitride mask. A surfactant was also added to the KOH solution to promote hydrogen bubble release. With the improved process, they achieved a high etch anisotropy of above 300 on a ⟨110⟩ silicon wafer. They successfully fabricated 200nm period CAT gratings with support mesh periods of 25 and 40μm in a 9mm2 area of 4-μm-thick silicon membranes on ⟨110⟩ SOI wafers.
Fabrication of surface plasmon waveguides and integrated components on ultrathin freestanding membranes
Authors: Berini Pierre , Lahoud Nancy , Charbonneau Robert
Published: December 2008

The fabrication and physical characterisation of waveguides and integrated components on freestanding membranes are described. The waveguides consist of a thin (20–25nm) narrow (∼5μm) Au∕Cr stripe, on an ultrathin (20–30nm) large-area (∼1mm2) freestanding Si3N4 membrane clamped around its perimeter to an underlying Si substrate. The integrated components are implemented with this waveguide and consist of Mach-Zehnder interferometers and couplers. The waveguide and components are dimensioned such that they propagate long-range surface plasmon-polariton waves in a vacuum (air) or H2O background. The fabrication process flow adopted and some specific process steps are described. Physical characterisation was conducted on structures having undergone intermediate process steps and on finished structures, and characterisation results are given and discussed. The structures were found to be robust enough for careful use, and to routinely sustain ∼3μN of point force without shattering.
Molecular-dynamics investigation of the surface characteristics of Fe–Cu magnetic thin-film layers
Authors: Lee Soon-Gun , Chung Yong-Chae
Published: December 2008

Using molecular dynamics simulation, the structural characteristics of Fe and Cu thin films grown on Cu and Fe(001) substrates, respectively, were investigated with respect to the incident energy of adatoms and substrate temperature. In the case of Cu on Fe(001), no surface alloying at the interface was observed in the early stage of thin-film deposition, and growth generally followed the layer-by-layer growth mode. For Fe on a Cu(001) surface, a mixture confined to a single atomic layer at the Cu(001) surface was found to form at room temperature while films showed island growth. The steering effect due to atomic attraction was also observed at low incident energy, resulting in a rougher surface. Fe/Cu(001) growth changed to a layer-by-layer mode for an incident energy of 6 eV. The different aspects of surface morphology between Fe/Cu(001) and Cu/Fe(001) systems were explained in terms of surface free energy and impact cascade diffusion.
Film continuity and interface bonding of thin boron carbonitride films on Ge(100) and Si(100)
Authors: Fitzpatrick P. R. , Ekerdt J. G.
Published: December 2008

Motivated by the need for a passivation layer for Ge, thin (<10 nm) films of amorphous boron carbonitride (BCN) were deposited on Ge(100) surfaces to study film continuity and interface bonding. Chemical vapor deposition on Ge(100) and Si(100) (studied for comparison) produced BC0.75N0.07 and BCN0.07 stoichiometry films, respectively. When BCN is nominally 2.5–5 nm thick, the film’s coverage of Ge(100) is continuous. This range was determined by (i) 0.5 kV He+ ion scattering spectroscopy scans, in which the underlying Ge(100) substrate signal disappears upon continuous BCN coverage and (ii) the convergence to unity of the ratio of BCN thicknesses estimated by two angle resolved x-ray photoelectron spectroscopy (ARXPS) techniques. Only 1.5–2 nm BCN was required for continuous coverage of Si(100), possibly due to better nucleation on this surface. ARXPS analysis indicates that the BCN-Ge(100) interface is clean and abrupt, with no evidence of an interfacial layer due to elemental intermixing. Constituent bonding in the BCN bulk is maintained at the Ge(100) interface. Preservation of the Ge 3d and Ge 2p full width at half maximum values after BCN deposition suggests a lack of distortion of Ge surface bonds, a criterion necessary for passivation if low interface state densities are to be achieved. BCN-Si(100) interface characteristics were similar to BCN-Ge(100).
Ti surface alloying of an AISI 316L stainless steel by low energy high current pulsed electron beam treatment
Authors: Zhang K. M. , Zou J. X. , Grosdidier T. , Dong C. , Weber S.
Published: December 2008

Ti has been added into the surface layer of an AISI 316L stainless steel—by means of rapid surface alloying of Ti powder—using the low energy, high current pulsed electron beam (LEHCPEB) technique with the aim of enhancing its corrosion resistance. The alloyed layer contained a mixture of the α and γ phases and its depth increased with the number of pulses. Compared to the samples treated under the conventional LEHCPEB treatment (i.e., without surface alloying), Ti addition improved further the corrosion resistance. This can be attributed to the addition of Ti into the surface layer together with the removal of MnS inclusions. However, the homogeneity of the Ti distribution decreased when the number of pulses increased. Therefore, contrary to the conventional LEHCPEB treatment, as a result of this decreased homogeneity, the corrosion resistance decreased when the number of LEHCPEB was too high. Therefore, a good control of the processing parameters is required to take the full advantage of the surface Ti addition by LEHCPEB.
Application of vector scanning in focused ion beam photomask repair system
Authors: Yasaka Anto , Aramaki Fumio , Muramatsu Masashi , Kozakai Tomokazu , Matsuda Osamu , Sugiyama Yasuhiko , Doi Toshio , Takaoka Osamu , Hagiwara Ryoji , Nakamae Koji
Published: December 2008

With continuous reduction in linewidth of the VLSI devices, the pattern integrity of photomasks becomes considerably more important than ever. Consequently, requirement for the defect repair technology on photomasks is more severe and strict. Focused ion beam (FIB) technology has been widely used for defect repairing in photomask industry. Therefore, the performance of the FIB mask repair tool has to be improved especially in repair accuracy and precision. The FIB repair processes are classified into two kinds; one is additive repair using FIB induced deposition for missing patterns, the other is subtractive repair using gas assisted FIB etching for extra patterns. In both processes, precursor gas is applied onto the processing area through a small nozzle. Thus, the repair processes are controlled by the FIB irradiation and the precursor gas supply. Important characteristics of the repairs, such as size, shape, and placement of the repair area, are defined by the FIB scanning control. As conventional FIB systems used raster type of beam scanning for the repair processes, the size, shape, and placement could be controlled with the unit of pixel size (typically about 6–12nm). However, in order to satisfy the recent requirement, more precise beam control is needed. The authors have developed a vector scanning system to meet the requirement. The vector scanning system enables us to control ion beams more precisely and more arbitrarily. Furthermore, unicursal beam scanning can be applied to the repair processes, which minimizes beam blanking times. By adopting the vector scanning, repair precision is improved. Additionally, sidewall angle of the repair region is also improved because the repair shape is formed without beam blanking.
Chip-based microfabricated electrospinning nozzles
Authors: Bellan Leon M. , Alpha Chris , Corso Tom , Henion Jack , Craighead Harold G.
Published: December 2008

The authors have used microfabricated nozzles with inner diameters as small as 5 μm to produce electrospinning jets. A chip containing an array of individually addressable nozzles was incorporated with a commercial automated fluid delivery system and a floating high voltage supply. Using this system, the authors were able to produce polymeric nanofibers with various geometries, including beads-on-a-string, straight continuous fiber, and fibers that had broken in flight. The authors have shown that the use of this small electrospinning nozzle produces a smaller, more uniform spot compared to other source geometries.
Resistivity change of the diamondlike carbon, deposited by focused-ion-beam chemical vapor deposition, induced by the annealing treatment
Authors: Kometani Reo , Ichihashi Toshinari , Kanda Kazuhiro , Suzuki Tsuneo , Niihara Koichi , Ishihara Sunao , Kaito Takashi , Matsui Shinji
Published: December 2008

Diamondlike carbon (DLC) deposited by focused-ion-beam chemical vapor deposition (FIB-CVD) has the interesting material characteristics because DLC deposited by FIB-CVD using the gallium (Ga) FIB contained Ga. The DLC wires were subjected to annealing, and it was found that their resistivity and the Ga content of DLC decreased. To understand the reason for the decrease in resistivity, changes in the fine structure and composition of DLC due to annealing were examined by transmission electron microscope electron energy loss spectroscopy and Rutherford backscattering spectroscopy/elastic recoil detection analysis, respectively. The results revealed that the graphite content of DLC increased due to hydrogen (H) elimination induced by annealing. Thus, it was concluded that the resistivity of the annealed DLC wires decreased due to the increase in the graphite content of DLC.
High-speed optical beam-steering based on phase-arrayed waveguides
Authors: Jarrahi Mona , Fabian R. , Pease W. , Miller David A. B. , Lee Thomas H.
Published: December 2008

The authors present a high-speed optical beam-steering system employing phase-arrayed waveguides. They demonstrate a 100mrad deflection angle at the fastest ever reported instrument-limited deflection speed of 18GHz and power consumption of 1.8mW.
Image quality improvement in focused ion beam photomask repair system
Authors: Yasaka Anto , Aramaki Fumio , Muramatsu Masashi , Kozakai Tomokazu , Matsuda Osamu , Sugiyama Yasuhiko , Doi Toshio , Takaoka Osamu , Hagiwara Ryoji , Nakamae Koji
Published: December 2008

Focused ion beam (FIB) technology has widely been adopted as a defect repair tool on photomasks for semiconductor manufacturing. In the FIB mask repair process, scanning ion image (FIB image) is used for the defect area recognition. Quality of the FIB images is one of the most important factors in order to improve the repair accuracy. Precise imaging of the small features on the photomasks, however, is a challenging subject due to the surface charge buildup induced by FIB scanning, even though simultaneous electron beam irradiation is used for the charge compensation. The authors have developed new method of the FIB scanning for better image quality. This method utilizes software accumulation of multiple images with different scan directions and results in higher peak-to-background ratio and higher contrast images with isolated mask patterns on the quartz substrate, compared to the images acquired from conventional single scanning. The images also show better uniformity and symmetry of the secondary electron intensity.
In situ monitoring of material processing by a pulsed laser beam coupled via a lensed fiber into a scanning electron microscope
Authors: Hwang David J. , Misra Nipun , Grigoropoulos Costas P. , Minor Andrew M. , Mao Samuel S.
Published: December 2008

In this study, a new method coupling laser irradiation into a dual-beam scanning electron microscope (SEM) and focused-ion-beam (FIB) system is developed. By using a lensed fiber, pulsed laser illumination could be successfully delivered onto the sample under SEM imaging, providing in situ monitoring for laser material processing applications including local modification of micro-/nanostructures and laser-assisted chemical vapor deposition. In situ characterization of the laser-induced features by high resolution SEM imaging and energy dispersive x-ray spectrometry was successfully carried out. Furthermore, in situ repair of a contaminated lensed fiber probe during laser-assisted chemical vapor deposition was demonstrated via FIB milling. The results demonstrate the full compatibility of the lensed fiber apparatus with the dual-beam apparatus without disturbing the original functions of the system. The combination of guided laser radiation with SEM and FIB instruments offers a powerful capability for in situ monitoring of multilevel laser-based micro- and nanoscale material processing.
Optical properties of carbonaceous nanoparticles produced in sputtering discharges
Authors: Zeinert A. , Arnas C. , Dominique C. , Mouberi A.
Published: December 2008

In this work, the authors report on the optical properties of carbonaceous nanoparticles produced in argon sputtering dc discharges. These particles are the result of a nucleation-condensation mechanism in gas phase and form porous particulates with a mean diameter greater than 20nm. The resulting powderlike deposit, which can be collected in the chamber, is analyzed in terms of an effective medium approximation that allows the determination of their optical constants. These parameters are then used in a simple application of the Lorenz-Mie theory, in combination with a laser-extinction experiment, to provide the particle density in the plasma.
Angular distribution of elemental composition of films deposited by laser ablation of a SrZrO3 target
Authors: Konomi I. , Motohiro T. , Horii M. , Kawasumi M.
Published: December 2008

The angular distributions of elemental composition of films prepared by laser ablation of perovskite oxide SrZrO3 have been investigated using electron probe microanalysis with wavelength-dispersive spectroscopy. Each constituent element showed two modal distribution composed of a broad cosmθ (m=2–3) distribution and a sharp cosnθ (n=8–23) distribution. Oxygen showed a broader distribution than that of Sr and Zr. At the polar angle close to surface normal direction (polar angle <12°), Zr concentration was higher than that of Sr in vacuum whereas in oxygen-containing atmosphere their concentrations were about the same. Below oxygen pressure of 1.3Pa, Sr and Zr concentration increased and decreased with the increase in polar angle, respectively, whereas in oxygen partial pressure of 10Pa, both elements showed no angular dependences. Broadening of angular distribution of all the elements was observed when deposition was performed under oxygen partial pressure of 10Pa, which is considered to be caused by collisional scatterings of more than ten times with ambient gas molecules.
Neutral atom and molecule focusing using a Fresnel zone plate
Authors: Reisinger Thomas , Holst Bodil
Published: December 2008

Focusing of neutral atoms and molecules has several potential applications. The very first microscopy images using helium as an imaging probe were published earlier this year. Another possible application is to study the diffusion of atoms and molecules through materials with high spatial resolution by stepping a porous or permeable sample across the focused beam. With this application in mind, the authors present the best resolution transmission images hitherto achieved with helium atoms (less than 2 μm) of a thin carbon film with 2 μm holes. Furthermore, they present the first experiment using a Fresnel zone plate to focus neutral molecules. They used a beam of deuterium (D2) which was focused down to 15.2±0.5 μm. D2 was chosen because it fits in mass to the geometry of our system, which is optimized for helium. However, the method can be extended to hydrogen (H2) or other molecules by using a suitably adapted zone plate. In both cases the focus was limited by chromatic aberrations, caused by the velocity spread of the beams. Finally, they present calculations exploring the resolution limits for focusing of molecular beams using Fresnel zone plates. The calculations show that Fresnel focusing down to 170 nm full width at half maximum is possible with presently available techniques.
Experimental and numerical analyses on recovery of polymer deformation after demolding in the hot embossing process
Authors: Takagi Hideki , Takahashi Masaharu , Maeda Ryutaro , Onishi Yuki , Iriye Yasuroh , Iwasaki Takuya , Hirai Yoshihiko
Published: December 2008

In a hot embossing process, optimization of the demolding temperature is quite important to achieve high throughput because the cooling step before demolding takes a relatively long time in the process cycle. The authors experimentally examined the influence of demolding temperature on polymer deformation. Polymer deformation was also examined using a finite element simulation tool which assumed the polymer as a viscoelastic body represented by the generalized Maxwell model. In both experiments and numerical simulations, demolding at higher temperature resulted in smaller deformation. Numerical simulations revealed that recovery of polymer deformation occurred in the cooling step after demolding at temperatures higher than the glass transition temperature of polymer. In addition, numerical simulation enables detailed analysis of the impacts of various parameters on the recovery phenomena. This numerical simulation method is expected to be a powerful tool for optimization of the hot embossing process cycle.
Impact of trench width roughness on the graphoepitaxial assembly of block copolymers
Authors: Welander Adam M. , Nealey Paul F. , Cao Heidi , Bristol Robert
Published: December 2008

In this paper, the authors investigated constraints on the quality of topographic features needed for graphoepitaxial assembly of cylinder forming poly(styrene-b-methyl methacrylate) (PS-b-PMMA) thin films, showing the impact of trench width roughness (TWR) on feature size uniformity and defect formation. Topographically patterned substrates were prepared using chemically amplified photoresist and reactive ion etching in conjunction with commercially available lithographic tools and masks. A dose/focus array was utilized to systematically produce trenches with widths between 40 and 400nm with roughness of 5–35nm on top of which block copolymers were assembled. Scanning electron microscopy images were taken and analyzed using IMAGEJ software for the metrology of the trenches and ordered block copolymer domains after the removal of the PMMA cylinders. Analysis showed little or no change in domain size variation of the block copolymer with respect to the TWR of lithographically defined features. The impact of TWR on defect formation is qualitatively investigated by classifying all images as having few, some, or many defects. From this analysis, the commensurability between the natural length scale of the block copolymer (l0) and the trench width (W) had a significant effect on defectivity, whereas TWR did not play a dominant role.
Contact angles in a thermal imprint process
Authors: Bogdanski Nicolas , Möllenbeck Saskia , Scheer Hella-Christin
Published: December 2008

In a thermal imprint process, contact angles may evolve in two situations, between the stamp and the polymer, when a cavity remains unfilled, or, in cases where the polymer locally dewets the substrate, between the substrate and the polymer. For two polymers of different polarity, such contact angles are determined experimentally and compared to values calculated from surface energy data. In doing so, the specific temperature dependence of surface energies of a thermoplastic polymer as well as the typical course of an imprint process, where cooling times often exceed the imprint times, are considered. The differences between experimental and theoretical values are critically discussed. The results indicate that the respective adhesive layers govern the surface status of the substrate and the stamp as well.
Effects of oxygen on low-temperature growth and band alignment of ZnO∕GaN heterostructures
Authors: Liu H. F. , Hu G. X. , Gong H. , Zang K. Y. , Chua S. J.
Published: December 2008

Continuous ZnO thin films have been grown at low temperature (400°C) on GaN∕c-sapphire substrates in a radio-frequency magnetron-sputtering chamber employing a substoichiometric ZnO target with and without extra oxygen feeding. The effects of oxygen on the growth and band alignment of the ZnO∕GaN heterostructures were investigated by using scanning-electron microscopy, x-ray diffraction, photoluminescence and transmittance/absorbance, ultraviolet-resonant Raman scattering, and x-ray photoelectron spectroscopy. Very remarkable changes of the structural and optical properties resulted from the introduction of oxygen: the surface hexahedral facets were diminished; the size of the surface islands and, hence, the compressive strains were reduced; ultraviolet transparency of the ZnO film was enhanced, together with an increased band gap due to the reduced intrinsic shallow-donor defects; and hence, the free-electron concentration. The offset in valence bands of the ZnO∕GaN heterostructure was increased by ∼90meV at certain conditions. This is likely due to the increased Ga–O bonds at the ZnO∕GaN interface by the incorporation of extra oxygen at the initial growth of ZnO.
Aberration correction for electron beam inspection, metrology, and lithography
Authors: Munro Eric , Rouse John , Liu Haoning , Wang Liping
Published: December 2008

This article investigates, with computer simulations, whether electron optical aberration correctors could be used to improve the performance of electron beam equipment for the semiconductor manufacturing industry. The simulations are performed using the differential algebraic method. Three types of aberration corrector are investigated: (1) a quadrupole-octopole corrector for critical dimension scanning electron microscopy for metrology and inspection (it is shown that this type of corrector, which corrects spherical and chromatic aberrations, can provide a smaller probe diameter with a larger numerical aperture, thereby improving resolving power and throughput), (2) a hexapole planator for projection electron beam lithography (it is demonstrated that field curvature, astigmatism, and spherical aberration can be corrected, thereby permitting a larger field size), and (3) a mirror corrector for reflective electron beam lithography (it is shown how field curvature and chromatic aberration in such systems can be corrected by using an electron mirror).
Multilevel visualization of local electric field at probe apex using scanning electron microscopy
Authors: Fujita Jun-ichi , Ikeda Yuta , Suzuki Ikumi
Published: December 2008

The authors have found that the locally enhanced field at a probe apex can be visualized using conventional scanning electron microscopy (SEM) under a low accelerating voltage. The local electric field deflects the primary electrons in the vicinity of the apex. They placed a gold grid detector just beside the beam axis to detect these deflected primary electrons. The secondary electrons thus generated from the grid simultaneously created a concentric contour ring around the probe apex in the SEM image. Thus, a simple Rutherford scattering model could be adopted to analyze the local electric field distribution at the tip apex.
Field-programmable gate array implementation of real-time spatial-phase locking for electron-beam lithography
Authors: Yang Yugu , Hastings J. T.
Published: December 2008

Spatial-phase locked electron-beam lithography provides feedback control of electron-beam position by monitoring the signal from a fiducial grid on the substrate. Formerly, a real-time spatial-phase-locking algorithm has been implemented on general purpose microprocessor to provide control for raster-scan system. However, it would be advantageous to provide real-time spatial-phase locking for both vector- and raster-scan systems with accelerated sampling and computational rate demanded by many modern electron-beam lithography tools. In addition, it is desirable for the phase-locking system to be easily parallelizable for multibeam/multicolumn systems. Implementation of vector- and raster-scan spatial-phase locking algorithms on a field-programmable gate array (FPGA) addresses both of these issues. Initial experimental results demonstrate that the FPGA implementation can provide real-time spatial-phase locking effectively at accelerated speed even when the algorithm is performed in the noise limited regime.
Novel SU-8 optical waveguide microgripper for simultaneous micromanipulation and optical detection
Authors: Panepucci Roberto R. , Martinez Jose A.
Published: December 2008

A novel microgripper device structure with optical waveguides as arms is presented. The devices shown here have waveguide dimensions of 50×30μm2. The device fabrication, using SU-8 polymer, is described. Its capability to perform micromanipulation while simultaneously carrying out optical detection is demonstrated.
Self-assembled monolayer fiducial grids for spatial-phase-locked electron-beam lithography
Authors: Samantaray C. B. , Hastings J. T.
Published: December 2008

The authors characterize a new fiducial grid based on a self-assembled monolayer (SAM) that is well suited to low-energy (⩽10keV) spatial-phase locked electron-beam lithography (SPLEBL). SAMs significantly alter the secondary electron yield of the metal films on which they are formed. In addition, SAMs are not expected to strongly scatter the primary beam, even at low energies, because they are less than 2-nm-thick and are composed of low atomic number elements. In this work the authors evaluate the signal-to-noise ratio (SNR) of SAM grids on gold and copper coated electron-beam resist. 400nm period octadecanethiol fiducial grids were microcontact printed onto the gold and copper metal layers using polydimethylsiloxane stamps. Gold serves as a model system and provides excellent SNR; however, its strong forward scattering makes it impractical in many applications. Copper offers reduced forward scattering but exhibits inverted secondary electron contrast and greatly reduced SNRs. In all cases, SNR decreases with increasing beam energy as overall secondary electron yield decreases. These results suggest that SAM fiducial grids are promising for low-energy SPLEBL; however, further optimization of the interlayer and SAM composition is warranted.
Preferential orientation effects in partial melt laser crystallization of silicon
Authors: Witte D. J. , Masbou M. P. A. , Crnogorac F. , Pease R. F. W. , Pickard D. S.
Published: December 2008

The ability to produce a known crystalline orientation in semiconductor materials is essential for many applications, including monolithic three-dimensional integration of devices. In particular, crystallization must be done without exceeding the thermal budget of surrounding or underlying devices. Using a 532nm laser pulse of 2ms duration on a 185nm thick amorphous silicon film, the authors demonstrate that partial melting of silicon can yield crystallites several microns in size with a strong ⟨001⟩ preferential orientation. They investigate the effects of laser pulse duration, film thickness, and heat flow rate on the degree of texturing. By using a thinner silicon film and reducing the laser pulse duration further, such a process could be compatible with the thermal constraints of three-dimensional integration.
Epoxy silsesquioxane resists for UV nanoimprint lithography
Authors: De Girolamo J. , Chouiki M. , Tortai J.-H. , Sourd C. , Derrough S. , Zelsmann M. , Boussey J.
Published: December 2008

Photopolymerizable epoxy polyhedral oligomeric silsesquioxane monomers with variable aliphatic spacer have been prepared and cured under UV radiation. Due to their organic/inorganic composition, these materials are promising candidates for microelectronic applications which requires high thermal and mechanical stabilities as well as a low dielectric constant, for example, for the fabrication of electrical interconnects. The authors pointed out by ellipsometric measurements that the use of a sensitizer in addition to the photoinitiator enhances the kinetic of the cationic polymerization of epoxy groups. The polymerization performed either in an EVG770® nanoimprint lithography stepper or under normal atmospheric conditions has been investigated by infrared spectroscopy, delivering information concerning polymerization mechanisms and allowing the optimization of the resin composition. Thermogravimetric analyses have shown that an annealing step is necessary after the UV curing of the resin to eliminate inert residues of the photoinitiator dissociation and thus improving the thermal resistance of the polymer. Finally they have demonstrated that the obtained polymers form interpenetrated networks and that their mechanical properties are retained up to a temperature of 375°C.
Light modulation with nanopatterned diffractive microelectromechanical system pixels
Authors: Skinner Jack L. , Talin A. Alec , Horsley David A.
Published: December 2008

The design, fabrication, and testing of a microelectromechanical system (MEMS) optical modulator is presented. Polarization effects of noncircular holes on reflectivity are examined. Thermal nanoimprint lithography is used to form an array of 150nm diameter nanoholes in a 60nm thick metal film on a silicon-on-insulator wafer. A quartz superstrate with an indium tin oxide electrode and a photoresist spacer is used to electrostatically actuate the MEMS pixel. The motion of the pixel in relation to the superstrate causes shifts in the wavelengths of optical interference from the periodic nanohole array. An optical modulation depth of over 67% is demonstrated with this modulation method. Dynamic modal analysis is also presented.
Study of machine to machine overlay error for sub-60-nm memory devices
Authors: Shin Jangho , Lee Sihyeung , Yeo Jeongho , Kim Hochul , Lee Junghyeon , Han Woosung
Published: December 2008

According to the 2007 international technology roadmap for semiconductors, the overlay budget of 60nm memory devices is 11.3nm. To meet such a tight requirement, each overlay error budget should be controlled carefully. It turns out that scanner contributions due to machine to machine overlay (MMO) error are nearly half of the total overlay error budget. In a conventional way, overlay errors are corrected by ten linear terms: offset x and y, wafer rotation x and y, wafer magnification x and y, shot rotation x and y, and shot magnification x and y. Especially for the shot correction, average correction values are applied commonly for all shots. MMO cannot be compensated by only linear correction to meet such a tight specification any longer. In this article, a grid matching strategy through per-shot-correction (PSC) is investigated so that scanner contributions are minimized. In PSC, shot correction is implemented for each shot with different correction parameter values. By matching wafer grids from machine to machine, overlay budget is feasible for sub-60-nm memory devices.