Xi Wang, Yves Bellouard, Joost J. Vlassak

Published in Acta Materialia 53 (2005) p4955-4961.

Abstract — We present the results of a crystallization study on NiTi shape memory thin films in which amorphous films are annealed by a scanning laser. This technique has the advantage that shape memory properties can be spatially distributed as required by the application. A kinetics study shows that nucleation of the crystalline phase occurs homogenously in the films. Consequently, the laser annealing process produces polycrystalline films with a random crystallographic texture. The crystallized films have a uniform microstructure across the annealed areas. The material in the crystalline regions transforms reversibly to martensite on cooling from elevated temperature and stress measurements show that a significant recovery stress is achieved in the films upon transformation.

Cells function based on a complex set of interactions that control pathways resulting in ultimate cell fates including proliferation, differentiation, and apoptosis. The interworkings of his immensely dense network of intracellular molecules are influenced by more than random protein and nucleic acid distribution where their interactions culminate in distinct cellular function.

Low dielectric constant (low-k) is achieved often at the cost of degraded mechanical properties, making it difficult to integrate the dielectric in the back end of line (BEOL) and to package low-k chips. Development of low-k technology becomes costly and time-consuming. Therefore, more frequently than before, people resort to modeling to understand mechanical issues and avoid failures. In this paper we present three multilevel patterned film models to examine channel cracking in low-k BEOL. The effects of copper features, caps and multilevel interconnects are investigated and their implications to BEOL fabrication are discussed.

Low-k BEOL Mechanical Modeling
Liu, Xiao Hu; Lane, Michael W; Shaw, Thomas M; Liniger, Eric G; Rosenberg, Robert R; Edelstein, Daniel C
Advanced Metallization Conference 2004 (AMC 2004); San Diego, CA and Tokyo; USa and Japan; 19-21 Oct. 2004 and 28-29 Sept. 2004. pp. 361-367. 2005

DEPARTMENT OF MECHANICAL ENGINEERING AND MATERIALS SCIENCE

PRATT SCHOOL OF ENGINEERING

The Department of Mechanical Engineering and Materials Science invites applications for tenure-track faculty positions. Two tenure-track appointments are anticipated and are open to all ranks, Assistant, Associate and Full Professor level. Applications are invited from candidates with research interests in autonomous vehicles and robotic systems, conventional and alternative energy technology, and MEMS/NEMS devices. Applications will also be accepted for allied mechanical engineering disciplines such as nonlinear dynamics and control, sensor technology, small and micro-scale propulsion systems, aerodynamics and aeroelasticity, thermal sciences, and vehicle dynamics.

Successful candidates are expected to establish a vibrant research program, obtain competitive external research funding, and participate actively in teaching at both the undergraduate and graduate levels. Applicants should submit a cover letter describing their research interests and qualifications, a curriculum vitae, and the names and addresses of three references. Please submit your application to mems-search [at] mems.duke.edu as a PDF (preferred) or Word file attached to your email. Duke University is an Affirmative Action/Equal Opportunity Employer.

Experiments with a multidimensional nano-contact system (Lucas, Hay, and Oliver, J. Mater. Res. 2004) have shown that, prior to kinetic frictional sliding, there is a significant reduction of the tangential contact stiffness relative to the elastic prediction. The reduction occurs at contact sizes below about 50~200nm for aluminum single crystals and several other materials. Using a cohesive interface model, we find that this reduction corresponds to a transition from a small-scale-slip to large-scale-slip condition of the interface.

The effect of long-range (LR) elastic interactions on the toroidal moment of polarization in a two-dimensional ferroelectric particle is investigated using a phase field model. The phase field simulations exhibit vortex patterns with purely toroidal moments of polarization and negligible macroscopic polarization when the spontaneous strains are low and the simulated ferroelectric size is small. However, a monodomain structure with a zero toroidal moment of polarization is formed when the spontaneous strains are high in small simulated ferroelectrics, indicating that, because of the LR elastic interactions, high values of spontaneous strains hinder the formation of polarization vortices in ferroelectric particles. Applied Physics Letters 88, 182904 (2006)

The Multi-Physics Modeling and Simulation Department at Sandia National Laboratories, California, is seeking a technical staff member to develop finite element-based simulation codes for linear and nonlinear solid mechanics and/or to perform solid mechanics and structural dynamics modeling and simulation. Typical departmental programs include: detailed analyses of weapon systems; design guidance of weapon components through analysis; development of forging and welding modeling capabilities; pressure vessel analysis including aging and failure; penetration modeling; ground shock and hydrodynamics modeling and simulations; failure model development and implementation (metals and composites); thermal and dynamic analysis of artillery projectiles; and electromagnetics and EM wave propagation analysis.

The Mechanics of Materials Department performs experimental and analytical studies to understand the mechanical behavior of materials. Our experimental work covers the entire discoverycharacterization-
validation spectrum. Motivated by observations, we develop models to simulate material responses under various loading and environmental conditions. The fidelity of our models and simulations vary from atomic to continuum scales corresponding to the requirement of Sandia applications. Accuracy of the models for specific applications is validated by experimental data. Numerical codes are developed to allow implementation of the
material models for high performance computing simulations.

The highly motivated scientist or engineer with expertise in experimental mechanics will work as a part of a diverse team in our state-of-the-art laboratories. The applicant is expected to develop and apply experimental research methods in one or more of several research areas, including: material model development, failure
model development, rate-dependent material effects and advanced experimental methods/diagnostic technique development.

Introduction:

This is the Fifteenth Conference in Mechanical Engineering series that started in 1992. The conference is concerned with the latest in theoretical, mathematical and scientific developments in Mechanical Engineering as well as application of established techniques to new domains. Following tradition of conference, ISME 2007 will provide an international technical forum for experts and researches from both the academia and industry to meet and exchange new ideas and present their findings of ongoing research in various Mechanical engineering disciplines.

Although nanostructures, such as nanoparticles, nanotubes, nanowires, nanobelts, and nanometer thick films, nanostructured materials and nanocomposites have been synthesized and fabricated by various techniques, their mechanical properties have not been well explored. These nanostructures are being used as structural and functional building blocks to construct micro/nanodevices. Some nanostructured materials exhibit the breakdown of Hall-Petch behavior. The failure of conventional reinforcing models has been found in nanocomposites. The extremely small dimensions of nanomaterials and micro/nanodevices impose tremendous challenges to many existing experimental techniques and modeling tools. An in-depth understanding of mechanics at the nanoscale is greatly needed. Development of mechanical testing, and manipulation instruments and techniques, is also a technological necessity. This symposium will focus on research on mechanical properties of nanostructures, nanostructured materials and nanocomposites, and reliability testing of micro/nanodevices.