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Access Memory (access + memory)

Distribution by Scientific Domains
Physics and Astronomy42%
Polymers and Materials Science28%

Kinds of Access Memory

  • random access memory
    		•

    Selected Abstracts

    Multi-bit storage in reset process of Phase Change Access Memory (PRAM)

    PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 1 2007
    Yi Zhang
    Abstract A Phase Change Access Memory (PRAM) cell with stacked phase-change layers and heater layers is prepared. Multi-bit storage in the reset process of the PRAM is realized by this stacked structure including phase-change layers with uniform thickness and heater layers with different thickness. The thermal simulation results show three phase-change layers in three temperature zones, and they will transform from polycrystalline to amorphous state layer by layer. There are four levels of resistance appearing in the R ,V characteristics, and 2-bit storage is realized. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Capacitors with an Equivalent Oxide Thickness of <0.5 nm for Nanoscale Electronic Semiconductor Memory

    ADVANCED FUNCTIONAL MATERIALS, Issue 18 2010
    Seong Keun Kim
    Abstract The recent progress in the metal-insulator-metal (MIM) capacitor technology is reviewed in terms of the materials and processes mostly for dynamic random access memory (DRAM) applications. As TiN/ZrO2 -Al2O3 -ZrO2/TiN (ZAZ) type DRAM capacitors approach their technical limits, there has been renewed interest in the perovskite SrTiO3, which has a dielectric constant of >100, even at a thickness ,10 nm. However, there are many technical challenges to overcome before this type of MIM capacitor can be used in mass-production compatible processes despite the large advancements in atomic layer deposition (ALD) technology over the past decade. In the mean time, rutile structure TiO2 and Al-doped TiO2 films might find space to fill the gap between ZAZ and SrTiO3 MIM capacitors due to their exceptionally high dielectric constant among binary oxides. Achieving a uniform and dense rutile structure is the key technology for the TiO2 -based dielectrics, which depends on having a dense, uniform and smooth RuO2 layer as bottom electrode. Although the Ru (and RuO2) layers grown by ALD using metal-organic precursors are promising, recent technological breakthroughs using the RuO4 precursor made a thin, uniform, and denser Ru and RuO2 layer on a TiN electrode. A minimum equivalent oxide thickness as small as 0.45 nm with a low enough leakage current was confirmed, even in laboratory scale experiments. The bulk dielectric constant of ALD SrTiO3 films, grown at 370 °C, was ,150 even with thicknesses ,15 nm. The recent development of novel group II precursors made it possible to increase the growth rate largely while leaving the electrical properties of the ALD SrTiO3 film intact. This is an important advancement toward the commercial applications of these MIM capacitors to DRAM as well as to other fields, where an extremely high capacitor density and three-dimensional structures are necessary. [source]

    Fast iterative solution of large undrained soil-structure interaction problems

    INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 3 2003
    Kok-Kwang Phoon
    Abstract In view of rapid developments in iterative solvers, it is timely to re-examine the merits of using mixed formulation for incompressible problems. This paper presents extensive numerical studies to compare the accuracy of undrained solutions resulting from the standard displacement formulation with a penalty term and the two-field mixed formulation. The standard displacement and two-field mixed formulations are solved using both direct and iterative approaches to assess if it is cost-effective to achieve more accurate solutions. Numerical studies of a simple footing problem show that the mixed formulation is able to solve the incompressible problem ,exactly', does not create pressure and stress instabilities, and obviate the need for an ad hoc penalty number. In addition, for large-scale problems where it is not possible to perform direct solutions entirely within available random access memory, it turns out that the larger system of equations from mixed formulation also can be solved much more efficiently than the smaller system of equations arising from standard formulation by using the symmetric quasi-minimal residual (SQMR) method with the generalized Jacobi (GJ) preconditioner. Iterative solution by SQMR with GJ preconditioning also is more elegant, faster, and more accurate than the popular Uzawa method. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Runaway Implantable Defibrillator,A Rare Complication of Radiation Therapy

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 5 2007
    EMEC M.D., F.A.C.C., JAN N
    A case of a patient with runaway implantable cardioverter defibrillator (ICD) due to radiation therapy of a lung cancer is reported. This manifested as poorly tolerated wide complex tachycardia due to inappropriate rapid ventricular pacing, The event terminated with polymorphic VT, which inhibited pacing and ceased spontaneously before ICD discharge. The likely cause was corruption of device random access memory by ionizing radiation. [source]

    A CMOS macro-model for MTJ resistor of MRAM cell

    PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2004
    Chung-Hyun Cho
    Abstract When a matured magneto-resistive random access memory (MRAM) process is not available, a CMOS macro-model for MRAM cell can be a good tool for developing efficient MRAM architectures and their competitive peripheral circuits. This paper proposes a novel CMOS modelling circuit emulating voltage-dependent characteristics of MTJ resistance in a 2T2MTJ cell and its applications in the MRAM full-chip. The variable resistance characteristic is realized by applying the feedback voltage to the gate of the MOS resistor. A test MRAM full-chip adopting the proposed model was implemented in a 0.35 ,m CMOS process. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    In Situ Monitoring of Silicon Plasma Etching Using a Quantum Cascade Laser Arrangement,

    CHEMICAL VAPOR DEPOSITION, Issue 6-7 2007
    D. Stancu
    Abstract In etch plasmas used for semiconductor processing, concentrations of the precursor gas NF3 and of the etch product SiF4 are measured online and in situ using a new diagnostic arrangement, the Q-MACS Etch system, which is based on quantum cascade laser absorption spectroscopy (QCLAS). In addition, the etch rates of SiO2 layers and of the silicon wafer are monitored including plasma-etching endpoint detection. For this purpose the Q-MACS Etch system is working as an interferometer arrangement. The experiments are performed in an industrial, dual-frequency, capacitively coupled, magnetically enhanced, reactive ion etcher (MERIE), which is a plasma reactor developed for dynamic random access memory (DRAM) technologies. In the spectral range 1028 ± 0.3 cm,1, the absorption cross-sections of SiF4 and NF3 are determined to be ,,=,(7.7 ± 0.7) × 10,18 cm2 molecule,1 and ,,=,(8.7 ± 0.8) × 10,20 cm2 molecule,1, respectively. [source]