Asahi Glass Research Articles

Hydrophilization of Amorphous Perfluoropolymer using Low-pressure Argon Plasma

The amorphous perfluoropolymer CytopTM (Asahi Glass Co., Ltd.) is an attractive material for use in microdevices for biological and chemical analysis because of its high optical transparency, excellent chemical stability, and low refractive index of 1.34, which is almost the same as that of water. In this study, to increase the applicability of this polymer for such microdevices, the modification of its surface properties was investigated using low-pressure argon plasma. Hydrophilicity control with a water contact angle in the range from 30° to 110° and, moreover, the long-term stability of the hydrophilized surface were achieved for the first time. Although oxygen plasma treatment caused etching instead of hydrophilization, exposure to argon plasma led to bond breaking, the formation of free radicals, and finally the incorporation of hydrophilic groups as a result of the reaction with the oxygen or water from the atmosphere after the polymer was removed from the plasma reactor. Furthermore, to evaluate the suitability of this material for applications involving cell cultivation, the cell adhesion and proliferation properties of the plasma-treated surface were also investigated.

Anisotropic etching of amorphous perfluoropolymer films in oxygen-based inductively coupled plasmas

An amorphous perfluoropolymer, “Cytop™” (Asahi Glass Co., Ltd.), is a preferable material for the fabrication of micro total analysis system devices because of its superior optical transparency over a wide wavelength range and low refractive index of 1.34, which is almost the same as that of water, as well as excellent chemical stability. To establish the precise microfabrication technology for this unique resin, the dry etching of the amorphous perfluoropolymer in Ar/O2 low-pressure inductively coupled plasma has been studied. A relatively high etch rate of approximately 6.3 μm/min at maximum and highly anisotropic etched features was attained. Plasma measurements by a single Langmuir probe technique and actinometry revealed that etching is dominated by ion-assisted surface desorption above a 10% O2 mixing ratio, whereas the supply of active oxygen species is the rate-limiting process below 10%. Moreover, angled x-ray photoelectron spectroscopy measurements of an etched trench pattern revealed that a high anisotropy is attributed to the formation of a carbon-rich sidewall protection layer.

Recyclable Fluorine-Based Cleaning Solvents for Resist Removal

The development of new functional cleaning agents is strongly required for leading-edge LSI fabrication, such as resist removal process without any damage to low-k materials. For example, as excessive acid cleaning agents would damage such materials. Consequently, a low damage cleaning technique with no collapsing fine structures is also desirable. On the other hand, the concept of recycle of cleaning agents is an urgent issue for the reduction of cleaning cost. Therefore, both cleaning ability and easy recyclable function are essential for next generation cleaning agents. Fluorine-based cleaning agents have been widely used for cleaning, rinsing and drying process in the electronics industry. Asahi Glass Corporation (AGC) has commercialized various fluorine-based cleaning agents as AC-series (Hydrofluorocarbon: HFC) and AE-series (Hydorofluoroether: HFE). Typical properties of these compounds are summarized in Table I. Here we report the application of fluorine-based cleaning agents to ArF resist removal and the evaluation of the recycles.

Comment on “Long‐Term Global Heating From Energy Use”

In a prominent article published in Tellus in 1969, Mikhail I. Budyko, with the Main Geophysical Observatory, Leningrad, Soviet Union, wrote that “all the energy used by man is transformed into heat, the main portion of this energy being an additional source of heat as compared to the present radiation gain” [Budyko, 1969, p. 618]. He pointed out that this heating was over and above any climate forcing from anthropogenic greenhouse gases and—since energy use was growing geometrically—it was likely to result in the retreat of the cryosphere, accompanied by excessive and potentially damaging global warming, perhaps in 200 years or less.Eric J. Chaisson, in Eos (“Long‐Term Global Heating From Energy Use,” 89(28), 253254, 2008), does not acknowledge Budyko's research. Chaisson cites cosmic history and the history of the human species, but he provides no references to the conceptual history of the idea that human energy use could result in global heating. Budyko first published on the Earth's heat budget in 1948 and in 1998 received the Blue Planet Prize, sponsored by the Asahi Glass Foundation, for his lifetime accomplishments in quantitative climatology.

UV nanoimprint lithography process optimization for electron device manufacturing on nanosized scale

Imprint specific process parameters like the residual layer thickness and the etch resistance of the UV polymers for the substrate etch process have to be optimized to introduce UV nanoimprint lithography (UV NIL) as a high-resolution, low-cost patterning technique for research and industry into electron device manufacturing. Additionally, UV NIL processes have to be compatible with conventional silicon (Si) semiconductor processing. Within this work, the minimization of the residual layer thickness by using a multi-drop ink-jet system, which was integrated into the imprint stepper NPS300 from S-E-T-(formerly SUSS MicroTec), in combination with a low viscous UV polymer from Asahi Glass Company is shown. The etch resistance of different UV polymers against the poly-Si etch process was increased by 50% with an appropriate post-exposure bake. A poly-Si dry etch process was used to pattern the gates of short channel MOSFETs. After optimizing the poly-Si etch, properly working short channel MOSFETs with a minimum gate length of about 90 nm were fabricated demonstrating successfully the compatibility of UV NIL with conventional Si semiconductor processing on nanosized scale.

Asian production strategy of Asahi Glass Co. Ltd.

Asian production strategy of Asahi Glass Co. Ltd.

AWARDS

A BETTER PLANET. A pioneer of environmental law and a leading energy-conservation expert have won this year's Blue Planet prizes, awarded by Japan's Asahi Glass Foundation. Joseph L. Sax, a law professor at the University of California, Berkeley, receives the honor for helping to establish the idea of citizens' environmental rights, which became the basis of the first environmental act to be passed in the United States. And Amory Lovins, a physicist and co-founder of the Rocky Mountain Institute (RMI), wins the prize for his advocacy of renewable energy, including his invention of an ultra-light, fuel-efficient car and the design of an energy-efficient building as RMI's office headquarters in Boulder, Colorado. Each winner receives $400,000.

Low-temperature Deposition of Hydrogenated Microcrystalline Silicon Thin Films by Photochemical Vapor Deposition Technique and Their Application to Thin Film Solar Cells

Hydrogenated microcrystalline silicon (µc-Si:H) thin films were prepared by mercury-sensitized photochemical vapor deposition (photo-CVD) technique at various deposition temperatures. Crystalline volume fraction showed a monotonic decrease with increasing temperature from 125 to 200 °C caused by the enhanced desorption of surface hydrogen atoms. Since a similar decrease has been reported at higher temperatures than 400 °C in plasma-enhanced vapor deposition technique, we conclude that photon energy from ultraviolet radiation serves to activate surface species in photo-CVD process. In spite of the low deposition temperature, the obtained films had excellent material properties. Then, thin film solar cells were fabricated on a Type-U substrate with various haze ratios provided by Asahi Glass using such films as the i-layer. A substrate with a high haze ratio of about 50% was effective in realizing a better light-trapping structure. By decreasing the deposition temperature of the i-layer to 140 °C, conversion efficiency was improved markedly due to the improved film quality brought about by the contributions of photons from ultraviolet radiation to the enhancement of the surface migration of the radicals for reducing defects in the resulting film. Consequently, a maximum solar cell efficiency of 7.4% was obtained.

Growth of Highly Ordered Colloidal Crystals Using Self-Assembly at Liquid−Liquid Interfaces

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTGrowth of Highly Ordered Colloidal Crystals Using Self-Assembly at Liquid−Liquid InterfacesSatoshi Takeda and Pierre WiltziusView Author Information Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 North Mathews Avenue, Urbana, Illinois 61801, and Research Center, Asahi Glass Co., Ltd., 1150 Hazawa-cho, Kanagawa-ku, Yokohama 221-8755, Japan Cite this: Chem. Mater. 2006, 18, 24, 5643–5645Publication Date (Web):November 3, 2006Publication History Received5 July 2006Revised17 October 2006Published online3 November 2006Published inissue 28 November 2006https://doi.org/10.1021/cm0615525Copyright © 2006 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views739Altmetric-Citations22LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (275 KB) Get e-AlertsSUBJECTS:Amorphous materials,Crystals,Liquids,Microspheres,Solvents Get e-Alerts

Separation of different ions from wastewater at various operating conditions using electrodialysis

In this paper, effect of influential factors on separation of monovalent (Na +), divalent (Cu 2+, Zn 2+, Pb 2+) and trivalent (Cr 3+) ions from wastewater was investigated. Two types of different membranes (AMV and CMV made by Asahi Glass and AR204SXR412 and CR67MK111 made by Ionics) with different ion exchange capacities (IEC) were used. Taguchi experimental design was used to plan a minimum number of experiments. A L 9 orthogonal array (OA, four factors in three levels) was employed to evaluate effect of concentration (100, 500, and 1000 ppm), temperature (25, 40, and 60 °C), flow rate (0.07, 0.7, and 1.2 mL/s) and voltage (10, 20, and 30 V) on separation percent (SP) of the individual ions in the solution. A L 16 OA (five factors in four levels) was applied to enquire the effect of ion valence in a mixture of ions on the response (SP). Statistical analysis, ANOVA, was also employed to determine the relationship between experimental conditions and yield levels. The results show that increasing concentration, voltage and temperature improves cell performance; however, SP decreases with increasing flow rate. At concentrations of more than 500 ppm, dependency of SP on concentration diminishes. The optimum levels of influential factors, determined for all ions are: concentration 1000 ppm, temperature 60 °C, flow rate 0.07 mL/s and voltage 30 V. According to the results, using a membrane pair with higher IEC improves SP. It was found that performance of an electrodialysis (ED) cell is almost independent on the type of ions and only depends on the operating conditions and the cell structure. This result was confirmed by the experiments conducted on a mixture of ions. It was also found that SP of monovalent ions is larger than divalent and trivalent ions ( S Cr < S Cu, S Zn, S Pb < S Na). For ions of similar valence, SP was found to be restricted by molecular weight and electrochemical activation energy of the ions ( S Pb < S Cu < S Zn).

Evaluation of changes on ion-selective membranes in contact with zinc-cyanide complexes

Morphological and structural changes on anion selective membrane Selemion 1 1 Selemion is a registered trademark of the Asahi Glass Co. AMV and cation-exchange-membrane Selemion CMT were evaluated, when these membranes were in contact with solutions containing zinc complexes. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and thermogravimetric analysis (TGA) were used to investigate the membranes. The effect of interactions among zinc complexes and membranes on the ionic transport was evaluated. To this investigation, the sodium ion transport, through the anion-exchange-membrane AMV, and the cyanide transport, through the cation-exchange-membrane CMT, were analysed. Two solutions were used on this paper: alkaline (NaOH) and alkaline with cyanide (NaCN). Results show an important loss of permselectivity of the ion-exchange membranes in the presence of zinc-cyanide complexes, what demonstrates that the interactions among complexes and membranes can cause significative changes on these membranes.

Study on fluoride reduction in artesian well—water from electrodialysis process

The possibility of removing fluoride from potable water from artesian wells to reduce the concentration of fluoride International Standard Methods (l.5 mg l −1), has been investigated. Many methods have been used to remove excessive fluoride from drinking water such as chemical adsorption, chemical precipitation, ion exchange and physical removal [reverse osmosis (RO) and electrodialysis process (ED)] because it causes harmful effects such as dental and skeletal fluorosis. In this paper two ion-exchange membranes have been examined for ED. The Selemium AMP® anionic membrane (Asahi Glass Co.) and photo-polymeric anionic membrane (MZA™) were tested in an experimental apparatus of a mini-ED cell having two acrylic compartments. The AMP® membrane, with 0.1 A dm −2 current density, removed 69% of the fluoride anion and, with 0.7 A dm −2, removed 97% of the fluoride anion. The MZA™ membrane removed 40% with that current density, without pretreatments. The analytical method for determining the fluoride anion, in every step of the electrodialysis process, was the Ion Analyzer Chromatographic System (DX-80 Dionex with conductivity detector). The results have shows the possibility of using the ED process to remove fluoride from water from artesian wells, thereby improving the quality the potable water in this region.

Salt production from coal-mine brine in ED–evaporation–crystallization system

ED-EDR double step electrodialytic pre-treatment and pre-concentration of “Debiensko” coal-mine brine was examined. Univalent ion permeable Tokuyama Co. ACS and CMS membranes were applied in the first electrodialysis step and normal grade CMV, AMV Asahi Glass membranes in the second. Coal-mine brine with 32.8 g/L Cl − content was desalinated and concentrated at a current density of 344–688 A/m 2 in the first step and 300 A/m 2 in the second. The total ED-EDR energy consumption found was in the range for 9.4–14.4 kWh/m 3 of inlet brine depending on applied electric current density. The performance of crystallization step was then estimated based on chemical compositions of ED concentrates and compared with data from the “Debiensko” Desalination Plant, where currently a salt crystallizer is supplied with brine concentrated by RCC evaporation method. This comparison shows that unit energy consumption decreases from ca 970 kWh per 1 ton of evaporated salt for brine treated by RCC method to ca 500 kWh/t in the case of ED-EDR treated brine. At the same time the amount of salt in lye decreases from 110 kg per 1 ton of evaporated salt produced to 20 kg/t.

Modeling of optical and electrical properties of In 2O 3 : Sn coatings made by various techniques

The optical and electrical properties of two types of wet chemical processed tin doped indium oxide (ITO) films deposited by spin coating technique as well as of a commercial sputtered ITO film have been measured. The transmission and reflection spectra in the wavelength range 0.25 to 20 μm have been simulated using the Scout 2 software with different dielectric function models. The electrical parameters obtained from the modeling are compared with those obtained experimentally. The optical data of a low porosity (28%), low specific resistivity ( ρ = 6.3 × 10 − 4 Ω cm) sol–gel film deposited from an ethylene glycol solution of In and Sn salts and sintered at 550 °C, as well as those of an Asahi Glass sputtered film ( ρ = 1.9 × 10 − 4 Ω cm) have been successfully fitted with the Drude model and the electrical parameters deduced from the fitting are in good agreement with the measured ones. On the other hand, the best fit of the optical data of a thick single coating prepared using dispersed crystalline nanoparticles was obtained using the Bruggemann effective medium theory coupled with the extended Drude model. The electrical and structural parameters deduced from the fitting are also in good agreement with those measured. The results are discussed in terms of the morphology of the coatings.

Bringing Clarity to the Patent Settlement Debate: Judge Posner's Asahi Decision

One of the most controversial issues in the biotech and pharmaceutical industries is when can parties settle patent litigation without violating the antitrust laws. In the past few years there have been numerous government enforcement actions and private antitrust cases challenging patent settlements, primarily between innovator and generic pharmaceutical manufacturers.1 A recent decision by Circuit Court Judge Richard Posner, Asahi Glass Co. v. Pentech Pharms., Inc.,2 addressing many of the controversial issues in these cases. The decision granted Glaxo and Pentech’s motion to dismiss Asahi’s suit seeking a declaration that their patent for a version of the popular anti-depressant drug Paxil was invalid, and that their settlement agreement was a violation of antitrust law. Because Judge Posner is one of the most esteemed antitrust jurists, it this decision may provide important guidance in future settlement litigation.

Electrodialytic desalination and concentration of coal-mine brine

Electrodialysis (ED) of coal-mine brine was investigated as the first stage of an ED-evaporation-crystallization system. Univalent ion permeable ACS and CMS membranes (Tokuyama) were applied in the first step while normalgrade CMV and AMV Asahi Glass membranes and electrodialysis reversal (EDR) were used in the second step (for the first step diluate treating). Electrodialysis in the countercurrent flow mode and electrodialysers with small intermembrane distances were applied to diminish problems that result from major differences in ED concentrate and diluate concentrations. A single-pass low residence operating time mode was applied to avoid gypsum crystallization in the EDR concentrate. A coal-mine brine with 32.8 g/L Cl− content was desalinated and concentrated at a current density of 344–688 A/m2 in the first step and 300 A/m2 in the second. First step diluate was treated by EDR yielding 85% recovery. The total energy consumption found was equal to 7.8-14.4 kWh/m3 inlet brine depending on the first step current density and the first step ED concentrate composition (TDS equal to 136–290 g/L). It was found that ED concentrate met requirements concerning low Ca2+ and SO42− concentrations to avoid gypsum crystallization during further evaporation. The comparison of RCC vapour compression evaporation and proposed electrodialytic concentration showed an advantage of ED treatment.

Micro protein patterning using a lift-off process with fluorocarbon thin film

This paper discusses micro protein patterning using fluorocarbon (FC) thin films patterned by a lift-off process to prevent the nonspecific binding of protein. 3M’s Fluorad™ and Asahi Glass’s CYTOP™ were evaluated in FC film patterning using the lift-off process. Surface characterization of patterned FC films was performed for various static and dynamic contact angles, surface energy, roughness, surface morphology, and fluorescence intensity after each step of the lift-off process and surface modification for protein patterning. The CYTOP™ films were found to have better biochemical resistance than the Fluorad™ films for surface characterization. The CYTOP™ films preserved the surface properties, demonstrating a narrow variation of static and dynamic contact angles, contact angle hysteresis, and surface roughness in repeated surface modifications for the protein patterning over 17 h. In a nonspecific binding test of BSA, it was found that the nonspecific binding on the CYTOP™ film appeared considerably above 2 μg/ml from the surface characterization. We fabricated 100 μm diameter circular silicon nitride (SiN) patterns with the CYTOP™ film background. FITC-labeled BSA was patterned on the silicon nitride surface after chemical oxidation for SiOH group activation, silanization, and aldehyde treatment.

Ecraprost: AS 013, Circulase.

Ecraprost [AS 013, Circulase] is a prodrug of prostaglandin E(1) within lipid microspheres that is being developed in Japan by Mitsubishi Pharma Corporation and Asahi Glass. It was originally in development with Welfide Corporation. On 1 October 2001, Welfide Corporation (formerly Yoshitomi) merged with Mitsubishi-Tokyo Pharmaceuticals to form Mitsubishi Pharma Corporation. The new company is a subsidiary of Mitsubishi Chemical. Taisho and Seikagaku Corporation had been involved in the development of ecraprost but discontinued their licences to do so. The effects of ecraprost on reperfusion injury, in preclinical studies, had been reported by Taisho. Ecraprost is in phase II in Japan and was in phase II in Europe for the treatment of peripheral arterial disease. It was also in a phase II study in the treatment of diabetic neuropathies. However, this is no longer an active indication. A phase III trial using a lipid emulsion of ecraprost [Circulase] is underway with Mitsubishi Pharma Corporation in the US, using ecraprost for the treatment of patients with severe peripheral arterial disease, which, because of decreased blood flow to the extremities, can lead to painful ulcers on the legs and feet and subsequent amputation. Alpha Therapeutic Corporation (a former subsidiary of Mitsubishi Pharma) was initially involved in trials of ecraprost in the US, but this responsibility has been taken over by the parent company.

Cost effective electrodialytic seawater desalination

The share of electrodialysis in seawater desalination is very small in contrast to reverse osmosis. It is stated that ED may compete with RO in the range of feed water salinity up to 8–10 g/L only because ED desalination cost is proportional to the amount of salt, which must be carried through the membrane. It is assumed in the papers comparing RO and ED that exergy loss in RO is equal to 0.983 while in ED to 12.87 kWh/m 3 in the process of seawater desalination. The cited results were however achieved assuming 35 atm excess pressure in RO and 0.8 V excess voltage in an electrodialysis stack. Diminishing the aforementioned ΔP value would indeed result in a decrease in RO flux and, as a consequence, an increase in desalination costs. The voltage drop in ED may be however diminished by applying low-resistance membranes and decreasing an intermembrane distance in an ED stack. Electrodialytic desalination of seawater was investigated in a laboratory using ED stack (developed by the author) equipped with 0.19 mm spacer. The pressure drop vs. linear velocity in the ED channel is small because of a special shape of a spacer net. Asahi Glass CMV and AMV membranes were applied. Seawater was desalinated in a cascade of two electrodialyzers at current density 300–600 A/m 2 in the first stage and 300 A/m 2 in the second. The total energy consumption estimated for industrial plant was equal to 6.6–8.7 kWh/m 3 of desalinated water (TDS 0.45 g/L) depending on the first stage current density. The desalinated water cost was equal to 1.05 $/m 3 assuming 0.06 $/kWh.

Dual-purpose desalination-salt production electrodialysis

Electrodialysis (ED) is applied in Japan for seawater concentrating to ca. TDS 200 followed by thermal concentration and salt crystallization. A partially desalinated water (ED diluate) is obtained at the same time. Its further desalination for potable water production may be considered to decrease costs of ED by obtaining two valuable products instead of mere salt. Univalent ion permeable ion-exchange membranes are however applied in ED process and as a result the contents of calcium, magnesium and sulfate ions in diluate are relatively high (in relation to chloride), which makes any further processing difficult. Electrodialysis reversal (EDR) may overcome these shortcomings. The salinity of partially desalinated water is as high as TDS 22.9. If dual-purpose desalination-salt production electrodialysis concern is high degree of desalination, which is however necessary, this implicates many problems in the ED process that are the result of major differences in ED concentrate and diluate concentrations and the small conductivity of potable water grade diluate. Electrodialysis of seawater was investigated in a two-step stand with ED-MSF-Crystallization system being the first stage. Univalent ion permeable Tokuyama Co. ACS and CMS membranes were applied in the first step and normal grade CMV, AMV Asahi Glass membranes in the second step (for the first step diluate treating). ED stack developed by the author and equipped with 0.19 mm spacer was applied. A single-pass low residence time mode of operation was applied to avoid gypsum crystallization in the second step ED concentrate. The first step diluate containing, in g/L, Ca 2+—0.38, Mg 2+—1.26, Cl −—4.08, SO 4 2-—2.78 was treated by EDR yielding 90% recovery. Potable water grade EDR diluate was obtained. No gypsum crystallization in the EDR concentrate was observed despite its 360% saturation. The total water recovery of ED-MSF-crystallization system is equal to 90%. As there are two valuable products in the described process, the cost of each of them is obviously related to their selling price. IF $30 per one ton of salt is assumed, the potable water cost is estimated to be only $0.44/m 3.