Non-linear deformation mechanisms during nanoindentation

Nanoindentation of patterned metal lines on a Si substrate

“…5 show that the response of these cases are essentially indistinguishable up to a load of 400 lN. The initial stage of nanoindentation is often explained by the Ôpunch-outÕ of dislocation loops around the indenter tip [4,5]. When the indenter depth increases, the dislocation density increases by the nucleation of new dislocations and/or the expansion of existing dislocations.…”

“…It has been shown [5,7] that a force balance of JohnsonÕs elasto-plastic indentation model can be used to estimate the plastic zone size, c, as a function of the applied load and tensile yield strength, r ys of the material as:…”

“…A particularly appealing attribute of nanoindentation is that, at least in principle, it offers a means to probe the elastic and plastic deformation characteristics as well as residual stresses in small features that are patterned onto substrates under constraints, which are representative of real applications including micro-electro-mechanical systems (MEMS) and microelectronic devices and packages. However, the interpretation of material response during indentation remains a complex issue [5,6]. In this paper, we present instrumented nanoindentation results of patterned aluminum lines on a silicon substrate, to explore the effects of two length scales (line width and thickness) on the indentation loaddisplacement (P -h) response.…”

Nanoindentation-induced defect–interface interactions: phenomena, methods and limitations

“…As the tip encountered these on contact, no Hertzian regime was experienced with a plastic response at the lowest detected loads. A similar set of coupled experiments was conducted on W single crystals with similar results [14].…”

“…The ®rst comes from a staircase yielding phenomenon as seen in Fig. 3 and discussed in more detail elsewhere for Au [13,15,16,20] and W [14]. For gold, Corcoran et al [16] found the force for the ®rst displacement excursion to depend heavily on crystal orientation.…”