Characterization of single crystal silicon and electroplated nickel films by uniaxial tensile test with in situ X-ray diffraction measurement

In this study, mechanical properties of micron-thick single crystalline silicon (Si) and electroplated nickel (Ni) films at intermediate temperatures are investigated by means of X-ray diffraction (XRD) tensile testing. The developed tensile test technique enables us to directly measure lateral (out-of-plane) elastic strain of microscale crystalline specimen using XRD during tensile loading, and determines Young's modulus, Poisson's ratio and tensile strength of the Si and Ni specimens. The specimens, measuring 10 μm thick, 300 μm wide and 3 mm long, are prepared through a conventional micro-machining process, and the ultraviolet lithographie galvanoformung abformung (UV-LIGA) process including a molding and an electroplating. The Si specimens, showing brittle fracture at room temperature (R.T.), have average Young's modulus and Poisson's ratio of 169 GPa and 0.35, respectively, in very good agreement with analytical values. The Ni specimens, showing ductile fracture, have those of 190 GPa and 0.24, lower than bulk coarse grained Ni. Young's moduli of both the Si and Ni specimens decrease with increasing temperature, but Poisson's ratios are independent of temperature. The influence of specimen size on elastic-plastic properties of the specimens is discussed.

[1]  H. J. Mcskimin.  Measurement of Elastic Constants at Low Temperatures by Means of Ultrasonic Waves–Data for Silicon and Germanium Single Crystals, and for Fused Silica , 1953 .

[2]  Yoshitada Isono,et al.  Plastic deformation of nanometric single crystal silicon wire in AFM bending test at intermediate temperatures , 2002 .

[3]  Paul Ludwik,et al.  Elemente der technologischen Mechanik , 1909 .

[4]  O. Tabata,et al.  Specimen size effect on tensile strength of surface-micromachined polycrystalline silicon thin films , 1998 .

[5]  S. Inoue,et al.  Mechanical Properties of Polycrystalline Titanium Nitride Films Measured by XRD Tensile Testing , 2005 .

[6]  J. Chaboche,et al.  Mechanics of Solid Materials , 1990 .

[7]  Y. Isono,et al.  Evaluation of size effect on mechanical properties of single crystal silicon by nanoscale bending test using AFM , 2000, Journal of Microelectromechanical Systems.

[8]  Frans Spaepen,et al.  Tensile testing of free-standing Cu, Ag and Al thin films and Ag/Cu multilayers , 2000 .

[9]  Y. Isono,et al.  Development of AFM tensile test technique for evaluating mechanical properties of sub-micron thick DLC films , 2006, Journal of Microelectromechanical Systems.

[10]  John P. Sullivan,et al.  Young's modulus, Poisson's ratio and failure properties of tetrahedral amorphous diamond-like carbon for MEMS devices , 2005 .

[11]  G. Pharr,et al.  An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments , 1992 .

[12]  C. Kim,et al.  Measurement of mechanical properties for MEMS materials , 1999 .

[13]  L. S. Stephens,et al.  Mechanical property evaluation and failure analysis of cantilevered LIGA nickel microposts , 2001 .

[14]  Uwe Erb,et al.  Effect of porosity on Young's modulus of nanocrystalline materials , 1993 .