薄膜与小尺度材料及力学性能研究组

Thermomechanical properties of gold nanowires supported on a flexible substrate
Pages 273-276
Sven Olliges, Stephan Frank, Patric A. Gruber, Vaida Auzelyte, Karsten Kunze, Harun H. Solak, Ralph Spolenak

A new on-chip test structure for real time fatigue analysis in polysilicon MEMS

G. Langfelder^a, A. Longoni^a, F. Zaraga^a, A. Corigliano^b, A. Ghisi^b and A. Merassi^c

Competition between dislocation nucleation and void formation as the stress relaxation mechanism in passivated Cu interconnects

J. Zhang^a, J.Y. Zhang^a, G. Liu^a, Y. Zhao^a and J. Sun^a

^aState Key Laboratory for Mechanical Behavior of Materials and School of Materials Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China

Received 6 March 2008; revised 26 November 2008; accepted 10 December 2008. Available online 24 December 2008.

Abstract

We perform systematic calculations to study the competition between the dislocation nucleation and void formation as stress relaxation mechanism in Cu interconnects under thermal stress, which is related to the aspect ratio (ratio of the film thickness to width) of the Cu lines. It is quantitatively found from both elastic-perfectly plastic model and kinematic strain hardening model that there exists a critical aspect ratio, below and above which the stress relaxation is dominated by the dislocation nucleation and void formation, respectively. The critical aspect ratio is revealed to modulate by both the length scale of the interconnects and the interfacial strength between the Cu lines and surroundings, suggesting potential application to achieve artificial controlling on stress relaxation mechanism in Cu lines. Calculations are in good agreement with available experiments. 

Mechanical properties of porous silicon by depth-sensing nanoindentation techniques

Zhen-qian Fang^a, Ming Hu^a, Wei Zhang^a, Xu-rui Zhang^a and Hai-bo Yang^a

In-situ X-ray investigations of quench-condensed thin gold films

Dirk Lützenkirchen-Hecht^a, Sascha Gertz^a, Christian Markert^a and Ronald Frahm^a

Modeling of creep deformation and its effect on stress distribution in multilayer systems under residual stress and external bending

Qing-Qi Chen^a, Fu-Zhen Xuan^a and Shan-Tung Tu^a

Mechanical and deformation behaviour of titanium diboride thin films deposited by magnetron sputtering

P.K.P. Rupa^a, P.C. Chakraborty^b and S.K. Mishra^a

Electrostriction in elastic dielectrics undergoing large deformation

Xuanhe Zhao and Zhigang Suo
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA

We develop a thermodynamic model of electrostriction for elastic dielectrics capable of large deformation. The model reproduces the classical equations of state for dielectrics at small deformation, but shows that some electrostrictive effects negligible at small deformation may become pronounced at large deformation. The model is then specialized to account for recent experiments with an elastomer, where the electric displacement is linear in the electric field when the strain of the elastomer is held fixed, but the permittivity changes appreciably when the strain changes. Our model couples this quasilinear dielectric behavior with nonlinear elastic behavior. We explore the consequence of the model by deriving conditions under which the deformation-dependent permittivity suppresses electromechanical instability. ©2008 American Institute of Physics

Experimental and simulation studies of resistivity in nanoscale copper films

A. Emre Yarimbiyik^{a, b}, Harry A. Schafft^b, Richard A. Allen^b, Mark D. Vaudin^c and Mona E. Zaghloul^a

Micropillar compression studies on a bulk metallic glass in different structural states

A. Dubach^{a, b}, R. Raghavan^{b, c}, J.F. Löffler^a, J. Michler^b and U. Ramamurty^c

Received 10 November 2008; revised 3 December 2008; accepted 4 December 2008. Available online 24 December 2008.

Atypical three-stage-hardening mechanical behavior of Cu single-crystal micropillars

Z.L. Liu^a, X.M. Liu^a, Z. Zhuang^a and X.C. You^a

Received 18 October 2008; revised 8 December 2008; accepted 8 December 2008. Available online 24 December 2008.

Analysis, simulation and fabrication of MEMS springs for a micro-tensile system

Rui Liu, Hong Wang, Xueping Li, Jun Tang, Shengping Mao and Guifu Ding
Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, National Key Laboratory of Micro/Nano Fabrication Technology, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
E-mail: wanghongsjtu@yahoo.com.cn

A phase field study of morphological instabilities in multilayer thin films

B.G. Chirranjeevi^a, T.A. Abinandanan^b and M.P. Gururajan^{c, 1}

^aDepartment of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, India

^bDepartment of Materials Engineering, Indian Institute of Science, Bangalore, Karnataka 560 012, India

^cDepartment of Materials Science and Engineering, Northwestern University, Evanston, IL, USA

Received 14 February 2008; revised 22 October 2008; accepted 24 October 2008. Available online 7 December 2008.

Abstract

We studied the microstructural evolution of multiple layers of elastically stiff films embedded in an elastically soft matrix using a phase field model. The coherent and planar film/matrix interfaces are rendered unstable by the elastic stresses due to a lattice parameter mismatch between the film and matrix phases, resulting in the break-up of the films into particles. With an increasing volume fraction of the stiff phase, the elastic interactions between neighbouring layers lead to: (i) interlayer correlations from an early stage; (ii) a longer wavelength for the maximally growing wave; and therefore (iii) a delayed break-up. Further, they promote a crossover in the mode of instability from a predominantly anti-symmetric (in phase) one to a symmetric (out of phase) one. We have computed a stability diagram for the most probable mode of break-up in terms of elastic modulus mismatch and volume fraction. We rationalize our results in terms of the initial driving force for destabilization, and corroborate our conclusions using simulations in elastically anisotropic systems.

Keywords: Phase field modelling; Thin films; Asaro–Tiller–Grinfeld instability; Microstructural evolution; Elastically stressed solids

Predicting Young's modulus of nanowires from first-principles calculations on their surface and bulk materials

Guofeng Wang¹ and Xiaodong Li²

¹Department of Mechanical Engineering, Indiana University–Purdue University Indianapolis, Indianapolis, Indiana 46202, USA
²Department of Mechanical Engineering, University of South Carolina, Columbia, South Carolina 29208, USA

Mechanics of nanoscale metallic multilayers: from atomic-scale to micro-scale

J. Wang^a, R.G. Hoagland^a and A. Misra^b

Received 30 September 2008; revised 15 November 2008; accepted 18 November 2008. Available online 7 December 2008.

Thickness-dependent phase transformation in nanoindented germanium thin films

D J Oliver¹, J E Bradby¹, J S Williams¹, M V Swain² and P Munroe^3
1 Department of Electronic Materials Engineering, Research School of Physical Sciences and Engineering, The Australian National University, Canberra ACT 0200, Australia
² Biomaterials Science Research Unit, Faculty of Dentistry, The University of Sydney, Eveleigh, NSW 1430, Australia
³ Electron Microscope Unit, University of New South Wales, Sydney, NSW 2052, Australia
E-mail: djo109@rsphysse.anu.edu.au

Characterization of Deformation Behaviors and Elastic Moduli of Multilayered Films in Piezoelectric Inkjet Head

Seong-Gu Hong   Minho Kim   Soon-Bok Lee   Chong Soo Lee

Dept. of Mater. Sci. & Eng., Pohang Univ. of Sci. & Technol., Pohan

Abstract

A bulge testing system was developed to mechanically characterize the deformation behaviors and elastic moduli of multilayered films, mainly composed of polycrystalline silicon (polysilicon) and lead zirconate titanate (PZT), used in a multilayer actuator of a piezoelectric inkjet head. In the tests, commercial inkjet heads including a few tens of multilayer actuators were directly pressurized by air, and the corresponding deflections were measured via full-field optical measurement techniques. An analytic solution derived from a thin-plate theory and finite-element analysis were used to describe pressure-deflection behaviors of films, and the results were compared with the experimental data to evaluate the elastic modulus of individual film. The results showed that the elastic moduli of polysilicon and PZT films are ~110 and ~49 GPa, respectively. These values were consistent with the nanoindentation results. For polysilicon films, about 30% reduction in elastic modulus, compared with that calculated from single-crystal elastic constants, was observed, and this was most likely attributed to the presence of microdefects like voids and microcracks at grain boundaries between columnar grains.

Keywords: Bulge test   full-field optical measurement   multilayered films   piezoelectric inkjet head

Micron-Scale Friction and Sliding Wear of Polycrystalline Silicon Thin Structural Films in Ambient Air

Alsem, D. H.   Dugger, M. T.   Stach, E. A.   Ritchie, R. O.

Abstract

Micron-scale static friction and wear coefficients, surface roughness, and resulting wear debris have been studied for sliding wear in polycrystalline silicon in ambient air at micro-Newton normal loads using on-chip sidewall test specimens, fabricated with the Sandia SUMMiT V$^{rm TM}$ process. With increasing number of wear cycles friction coefficients increased by a factor of two up to a steady-state regime, concomitant with a decay (after an initial sharp increase) in the wear coefficients and roughness. Wear coefficients were orders of magnitude smaller than reported macroscale values, suggesting that the wear resistance is higher at micrometer dimensions. Based on our observations, a sequence of micron-scale wear mechanisms is proposed involving: 1) a short adhesive wear regime ( $≪ 10^{4}$ cycles), where the oxide is worn away and the first silicon debris particles form and 2) a regime dominated by abrasive wear, where silicon particles (50–100 nm) are created by fracture through the grains ( $sim$500 nm). These particles subsequently oxidize and agglomerate into larger debris clusters, while “ploughing” by this debris leads to abrasive grooves associated with local cracking events rather than plastic deformation.

Keywords: Friction   microelectromechanical systems (MEMS)   silicon   thin films   wear  

Density functional theory study on stacking faults and twinning in Ni nanofilms
Pages 124-127
Aditi Datta, U.V. Waghmare and U. Ramamurty

Unusual thermal fatigue behaviors in 60 nm thick Cu interconnects

J. Zhang^a, J.Y. Zhang^a, G. Liu^a, Y. Zhao^a, X.D. Ding^a, G.P. Zhang^b and J. Sun^a

Effects of focused ion beam milling on the compressive behavior of directionally solidified micropillars and the nanoindentation response of an electropolished surface

S. Shim^{a, b}, H. Bei^a, M.K. Miller^a, G.M. Pharr^{a, b} and E.P. George^{a, b}

Evaluation of the crack-initiation strain of a Cu–Ni multilayer on a flexible substrate

X.F. Zhu^a, B. Zhang^b, J. Gao^b and G.P. Zhang^a

^aShenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China

^bSchool of Materials & Metallurgy, Northeastern University, 3-11 Wenhua Road, Shenyang 110004, China

Received 9 September 2008; revised 2 October 2008; accepted 2 October 2008. Available online 14 October 2008.

In-situ investigation on the deformation and damage behaviour of Diamond-like Carbon coated thin films under uniaxial loading

Jens Schaufler^a, Karsten Durst^a, Orlaw Massler^b and Mathias Göken^a

^aUniversity Erlangen-Nürnberg, Department of Materials Science and Engineering, Erlangen, Germany

^bOerlikon Balzers AG, Liechtenstein

Received 15 April 2008; revised 25 September 2008; accepted 25 September 2008. Available online 12 October 2008.

Stress relaxation through interfacial sliding in nanocrystalline films

N V Skiba, I A Ovid'ko and A G Sheinerman
Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, Bolshoj 61, Vasiljevskii Ostrov, St Petersburg 199178, Russia
E-mail: ovidko@def.ipme.ru

Shape memory behaviour of annealed Ti_48.5Ni_(51.5-x)Cu_x (x = 6.2-33.5) thin films

A. Ishida ^a; M. Sato ^a

^a National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan

Abstract

The shape memory behaviour of (Ni,Cu)-rich Ti-Ni-Cu thin films (Ti_48.9Ni_44.9Cu_6.2, Ti_48.5Ni₄₀Cu_11.5, Ti_48.6Ni_35.9Cu_15.5, Ti_48.3Ni_28.4Cu_23.3, Ti_48.3Ni_23.9Cu_27.8 and Ti_48.5Ni₁₈Cu_33.5) annealed at 773, 873 and 973 K for 1 h was investigated. The films with 6.2, 11.5-15.5 and 23.3-33.5 at% Cu showed a single-stage deformation due to a B2 ↔ B19' transformation, a two-stage deformation due to the B2 ↔ B19 ↔ B19' transformation and a single-stage deformation due to the B2 ↔ B19' transformation, respectively. The martensitic transformation start temperature (M_s) increased with increasing Cu content and then levelled off for more than 15 at% Cu, indicating a high Ms temperature of 345 K. Temperature hystereses were almost 15 K for all films with more than 10 at% Cu. The critical stress for slip increased with increasing Cu content and increased significantly for the Ti_48.5Ni₁₈Cu_33.5 film, whereas the maximum recoverable strain significantly decreased for the Ti_48.5Ni₁₈Cu_33.5 film. With decreasing annealing temperature, the critical stress for slip increased, but the M_s temperature decreased. It was found that films with 11.5 at% Cu or more, annealed at 873 K, showed a high martensitic transformation temperature and a high critical stress for slip.

Keywords: martensitic transformation; mechanical behaviour; shape memory alloys; shape memory effect; sputtering; thin films; Ti-Ni-Cu

Transmission electron microscopy investigation of the atomic structure of interfaces in nanoscale Cu-Nb multilayers

K. Yu-Zhang ^a;  J. D. Embury ^b;  K. Han ^c; A. Misra ^d

^a Dpartement de Physique, Laboratoire de Microscopies et d'Etude de Nanostructures, Universit de Reims, Reims Cedex 02, France

^b Department of Materials Science and Engineering, McMaster University, Hamilton, Canada

^c National High Magnetic Field Laboratory/Florida State University, Tallahassee, USA

^d Los Alamos National Laboratory, Los Alamos, NM 87545, USA

Abstract

Multilayers of Cu-Nb have been grown on a Nb seed layer on a Si (100) substrate using a magnetron sputtering technique. The bilayer period (Λ) was varied from 10 to 2.4 nm. Cross-sectional transmission electron microscopy (XTEM) and high-resolution TEM (HRTEM) were used to study the detailed structure as a function of the bilayer period. Although the majority of the structures conformed to a Kurdjumov-Sachs (K-S) orientation relationship between the Cu and Nb layers, the structures exhibit considerable spatial variation. In some local regions, a Nishiyama-Wasserman (N-W) orientation relationship was found. In addition, considerable distortions were observed in both the Cu and Nb regions close to the interface. Using both HRTEM imaging and fast Fourier transform (FFT) of HRTEM images, early stage of the fcc to bcc transition in Cu was detected. The results suggest that, in multilayer structures, the detailed structure of the interface and large local distortions may play an important role in interface-controlled plasticity.

Keywords: multilayer; CulNb; deformation; nanostructure; lattice distortion; orientation relationship

Microstructure of annealed Ti_48.5Ni_(51.5-x)Cu_x (x = 6.2-33.5) thin films

Ishida ^a;  M. Sato ^a; K. Ogawa ^a

^a National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan

Abstract

(Ni, Cu)-rich Ti-Ni-Cu amorphous films with a Cu content of 6.2-33.5 at. % formed by sputtering were annealed at 773, 873 and 973 K for 1 h and their microstructures investigated. Two types of precipitate were observed in the annealed films: a Ti(NiCu)₂ phase for the Ti_48.5Ni₄₀Cu_11.5, Ti_48.6Ni_35.9Cu_15.5, Ti_48.3Ni_28.4Cu_23.3 and Ti_48.3Ni_23.9Cu_27.8 films, plus a TiCu phase for the Ti_48.5Ni₁₈Cu_33.5 films. These precipitates were found to have coherency with the B2 matrix in the films annealed at 773 K and were densely distributed within the grains. However, in the films annealed at 873 K, their size increased 10-fold and their density decreased. Annealing at 973 K promoted grain-boundary precipitation and, accordingly, the density of the precipitates in the grain interiors decreased. On the other hand, the annealed Ti_48.9Ni_44.9Cu_6.2 films showed no precipitates in their grain interiors, but the number of grain-boundary precipitates increased with increasing annealing temperature. It was also found that grain size decreased with increasing Cu content and was significantly decreased for the Ti_48.5Ni₁₈Cu_33.5 films.

Keywords: annealing; microstructural characterization; shape memory alloys; sputtering; thin films; Ti-Ni-Cu

An argument for proof testing brittle microsystems in high-reliability applications

B L Boyce^1,4, R Ballarini² and I Chasiotis^3
1 Materials Science and Engineering Center, Sandia National Laboratories, PO Box 5800, MS0889, Albuquerque, NM 87185-0889, USA
² Department of Civil Engineering, University of Minnesota, Minneapolis, MN 55455, USA
³ Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
⁴ Author to whom any correspondence should be addressed (tel. no. (505) 845-7525)
E-mail: blboyce@sandia.gov

On the importance of sample compliance in uniaxial microtesting

D. Kiener^{a, b}, W. Grosinger^b and G. Dehm^{b, c}

^aMaterials Center Leoben, Forschungs GmbH, A-8700 Leoben, Austria

^bErich Schmid Institute of Materials Science, Austrian Academy of Sciences, A-8700 Leoben, Austria

^cDepartment of Materials Physics, Montanuniversität Leoben, Leoben, Austria

Received 1 July 2008; revised 4 September 2008; accepted 19 September 2008. Available online 8 October 2008.

Density functional theory study on stacking faults and twinning in Ni nanofilms

Aditi Datta^a, U.V. Waghmare^b and U. Ramamurty^a

^aDepartment of Materials Engineering, Indian Institute of Science, Bangalore 560012, India ^bTheoretical Sciences Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore 560064, India

Received 12 August 2008; revised 22 September 2008; accepted 23 September 2008. Available online 2 October 2008.