Quantitative In-Situ Nanoindentation of Thin Films in a Transmission Electron Microscope

Abstract

<jats:p>A unique <jats:italic>in situ</jats:italic> nanoindentation stage has been built and developed at the National Center for Electron Microscopy in Berkeley, CA. By using piezoceramic actuators to finely position a 3-sided, boron-doped diamond indenter, we are able to image in real time the nanoindentation induced deformation of thin films. Recent work has included the force-calibration of the indenter, using silicon cantilevers to establish a relationship between the voltage applied to the piezoactuators, the displacement of the diamond tip, and the force generated.</jats:p><jats:p>In this work, we present real time, <jats:italic>in situ</jats:italic> TEM observations of the plastic deformation of Al thin films grown on top of lithographically-prepared silicon substrates. The <jats:italic>in situ</jats:italic> nanoindentations require a unique sample geometry (see Figure 1) in which the indenter approaches the specimen normal to the electron beam. in order to meet this requirement, special wedge-shaped silicon samples were designed and microfabricated so that the tip of the wedge is sharp enough to be electron transparent.</jats:p>

Ex SituTransmission Electron Microscopy: A Fixed-Bed Reactor Approach

“…Recent work continues to improve physical property understanding by exploring dislocation behavior under strain at room temperature~Chiou & Mitra, 2000;McCabe et al, 2002;Haque et al, 2003;Hattar et al, 2004!. Construction of in situ nanoindentation holders significantly extends the area of fundamental research in dislocation formation and mo-tion~Wall & Dahmen, 1997;Minor et al, 2001aMinor et al, , 2001bMinor et al, , 2003 Cryogenic stages, also developed in the middle portion of the last century, permit effective characterization of structures in aqueous-based solutions, low melting point materials, some electron-beam-sensitive structures, and certain phase transformations~Butler & Hale, 1981!. Structural characterization of materials in aqueous-based media progressed significantly with improvements in vitrification techniques encompassing materials ranging from surfactants to clay particles~Bellare, 1988; Luo et al, 2001!.…”

Local Deformation Behavior of the Copper Harmonic Structure near Grain Boundaries Investigated through Nanoindentation

“…Pop-in phenomena can be observed as sudden displacement bursts, which appear as a plateau in the loading curve. The pop-in phenomenon can be understood as dislocation nucleation and propagation under an initial elastic strain and requires shear stresses in the range of the theoretical strength of a defect-free metal [ 34 , 35 , 36 , 37 , 38 ]. Therefore, the maximum shear stress, , underneath the indenter during loading is given as [ 33 ] …”

Nanoindentation in Materials Science

“…In order to reveal mechanical behavior of materials under the indentation load in detail and explain discontinuities during the initial loading segment better, more direct observation methods during indentation tests should be developed (Ghisleni et al, 2009). In recent years, based on the transmission electron microscope (TEM) and scanning electron microscope (SEM), in situ indentation technique is presented by researchers Minor et al, 2001;Zhou et al, 2006). In situ TEM indentation has the capability to visually observe microstructure variations beneath the indenter such as phase transformation, dislocation formation and propagation , and dislocationgrain boundary interaction (De Hosson et al, 2006).…”