Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.

Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor

A system includes a semiconductor device. The semiconductor device includes a first single crystal silicon layer comprising first transistors, first alignment marks, and at least one metal layer overlying the first single crystal silicon layer, wherein the at least one metal layer comprises copper or aluminum more than other materials; and a second single crystal silicon layer overlying the at least one metal layer. The second single crystal silicon layer comprises a plurality of second transistors arranged in substantially parallel bands. Each of a plurality of the bands comprises a portion of the second transistors along an axis in a repeating pattern.

System comprising a semiconductor device and structure

Review on Percolating and Neck-Based Underfills for Three-Dimensional Chip Stacks

In this paper we present our results of simulating a pull-out test of single walled carbon nanotubes (SWCNT) out of a single crystal gold lattice by means of molecular dynamics. We compare the obtained force-displacement data of the pullout test to results of simulated uniaxial tensile strain tests of SWCNTs. In doing so, we make a theoretical estimation about the quality of the clamping of SWCNTs in a gold crystal. We investigated the influence of chirality of SWCNTs and of the system temperature. Dependent on SWCNT chirality two different pull-out behaviours can be described. Zigzag nanotubes show stronger pull-out resistance than chiral or armchair nanotubes. Our results indicate a minor influence of embedding length of the SWCNT in the gold matrix on pull-out forces. The system temperature has only little effect on the maximum pull-out forces. The presented results have impact on design criteria of SWCNT-metal interfaces.

/pdf/pull-out-testing-of-swcnts-simulated-by-molecular-dynamics-3clznpwfhu.pdf

Pull-Out Testing of SWCNTs Simulated by Molecular Dynamics

In this paper, a novel concept of a thermo-mechanical MEMS actuator using aluminum thin-film heaters on a thermal oxide for electrical insulation is presented. The actuator is part of an universal tensile testing platform for thermo-mechanical material characterization of one dimensional materials on a micro- and nano-scopic scale under different environmental conditions, as varying temperatures, pressure, moisture or even vacuum and is realised in BDRIE technology. It is shown, that the actuator concept fulfills the requirements for the use in a tensile loading stage along with heterogeneously integrated nanofunctional elements, following a specimen centered approach in line with bottom-up self-assembly processes. Simulation and experiment agree very well in the thermal and mechanical domain and allow subsequent optimisation of the actuator performance.

Numerical characterization and experimental verification of an in-plane MEMS-actuator with thin-film aluminum heater

Interfacial delamination has become one of the key reliability issues in the microelectronics of portable devices and therefore is getting more and more attention. The analysis of delamination of a laminate structure with a crack along the interface is central to the characterization of interfacial toughness. Due to the mismatch in mechanical properties of the materials adjacent to the interface and also possible asymmetry of loading and geometry, usually the delamination propagates under mixed mode conditions. In this study, a modified mixed mode bending test using production line interface samples is proposed. The critical fracture properties are obtained by interpreting the experimental results through dedicated finite element modeling. The interface types being considered in the present work are between EMC's and copper lead frame.

Establishing Fracture Properties of EMC-Copper (-Oxide) Interfaces: Test Procedures and Simulations for Establishing the Interface Toughness, Depending on Temperature, Humidity and Mode Mixity

An ongoing root cause of failure in microelectronic industry is interface delamination. In order to explore the risk of interface damage, FE simulations for the fabrication steps as well as for the testing conditions are generally made in the design stage. In order to be able to judge the risk for interface fracture, the critical fracture properties of the interfaces being applied should be available, for the occurring combinations of temperature and moisture preconditioning. As a consequence there is an urgent need to establish these critical interface fracture parameters. For brittle interfaces such as between epoxy molding compound (EMC) and metal (-oxide) substrates the critical energy release rate (or delamination toughness) can be considered as the suitable material parameter. This material parameter is strongly dependent on the temperature, the moisture content of the materials involved and on the so-called mode-mixity of the stress state near the crack tip. The present study deals with experimental investigation of the delamination toughness of EMC-Copper lead-frame interfaces as can directly be obtained from the production line. The experimental set-up as designed for this purpose was previously reported, together with some measurement results and toughness evaluations for room temperature fracture tests. This study deals with experiment and simulation procedure of establishing the interfacial fracture toughness from fracture test results at high temperatures, especially in the glass transition temperature region of epoxy molding compound (EMC). In order to calculation accurate fracture toughness, the material property of molding compound is characterized as a function of temperature. A detailed discussion of how EMC responses at its glass transition region will be provided. The influence of the material property on interfacial fracture toughness will be given.

Bernhard Wunderle

Papers

Review on Percolating and Neck-Based Underfills for Three-Dimensional Chip Stacks

Pull-Out Testing of SWCNTs Simulated by Molecular Dynamics

Numerical characterization and experimental verification of an in-plane MEMS-actuator with thin-film aluminum heater

Establishing Fracture Properties of EMC-Copper (-Oxide) Interfaces: Test Procedures and Simulations for Establishing the Interface Toughness, Depending on Temperature, Humidity and Mode Mixity

Establishing fracture properties of EMC-Copper interfaces in the visco-elastic temperature region