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

A modular and parametric approach to FE-modelling is presented which allows rapid virtual prototyping for MEMS and other microelectronics packages with respect to some topical reliability issues: Thermal management and thermo-mechanical fatigue. Thereby the method of automatic model generation by modular parametric modelling is outlined and some examples featuring the required solution techniques are given. This simulation procedure forms part of a comprehensive design optimisation process in the field of predictive engineering.

Modular parametric finite element modelling for reliability-studies in electronic and MEMS packaging

In this paper the potential of molecular dynamics simulation for structure-property correlations in epoxy-resins is discussed. This is a topic relevant for a multi-scale framework to lifetime prediction in microelectronics packaging. To achieve that objective, epoxy-resins are synthesised by systematically varying their chemical structure and then characterised by various thermo-mechanical testing methods. It was found that moisture diffusion showed the most distinct response with respect to material and loading parameters such as polarity, free volume, crosslinking density, moisture concentration and temperature. Starting with a parametric study, modeling approaches of different complexity have been able to show qualitative and quantitative agreement respectively. The paper comments further on the accuracy and limits of the method and correlates the calculations with experimental structural analysis results.

Molecular dynamics simulation and mechanical characterisation for the establishment of structure-property correlations for epoxy resins in microelectronics packaging applications

IR-thermography has become increasingly important for non-destructive testing of microelectronic devices and structures on chip, package and board-level. This paper focuses on the evaluation of best applicability for different pulse excitation modes to detect flaws and damages as well as to determine material properties. Pulse IR thermography using electrical and laser excitation was chosen as an analytic method to observe and quantify crack growths in vias under thermal cycling load. We found that cracks are detectable unambiguously and its advantage over the ohmic test. The laser excitation in contrast to the electrical excitation has a good potential for large-scale screening as the board can be stepwise thermally excited and screened in one go without having any additional measuring lines. A new concept detecting crack tips was demonstrated.

Material characterization and non-destructive failure analysis by transient pulse generation and IR-thermography

In the paper we present an approach based on this principle to design reliable thermal management solutions for high power applications. Thermal and thermo-mechanical reliability are measured and calculated for a flip-chip mounted die with a hot-spot using reverse-side micro-channel water cooling as cooling concept. Hereby the methodology starts by material characterisation and consistent numerical implementation. Then a numerical parametric study as to geometrical features and interface materials is carried out by coupled fluidic-thermal analysis in order to evaluate the most promising variant for optimum thermal performance within the employed technology. For experimental verification a computer-controlled closed-loop thermal-fluidic testing set-up was constructed. Good correlation was found between measured, simulated and analytical results.

Performance and thermo-mechanical reliability of micro-channel coolers - a parametric study

New packaging technologies are necessary to meet the demand for smaller and more reliable electronic devices. The so-called system-in-package (SiP) concept brings different technologies, material combinations and processes together in one package. To ensure the reliability of such a package reliable, fast and non-destructive failure analysis are needed.

Bernhard Wunderle

Papers

Modular parametric finite element modelling for reliability-studies in electronic and MEMS packaging

Molecular dynamics simulation and mechanical characterisation for the establishment of structure-property correlations for epoxy resins in microelectronics packaging applications

Material characterization and non-destructive failure analysis by transient pulse generation and IR-thermography

Performance and thermo-mechanical reliability of micro-channel coolers - a parametric study

Transient thermal analysis as failure analytical tool in electronic packaging