Investigation of machine compliance uniformity for nanoindentation screening of wafer-supported libraries

Abstract

The reliability of nanoindentation results can depend critically on an accurate assessment of the machine compliance term. The common practice is to determine the machine compliance from a small reference specimen, then apply its value to a much larger wafer-supported library. The present study investigates the validity of this approach by thoroughly testing bare 76.2 mm diameter, 410μm thick Si(100) wafers mounted on two vacuum chucks of different design. We find that the small-sample value of the machine compliance is adequate for the majority of the wafer, including areas directly over vacuum rings and a circular center port of ordinary dimensions. However, vacuum chucks with a tweezer slot should be avoided in combinatorial materials science applications. But even in the absence of a tweezer slot, it may be necessary to generate an accurate machine compliance map for the wafer perimeter if the thin-film library extends beyond the outermost vacuum ring to the wafer edge. The Young’s modulus and the hardness of silicon are found to be 169±3GPa and 12.2±0.2GPa, respectively, over well-mounted regions of the wafer; both values are in good agreement with the literature.

Experimental method to account for structural compliance in nanoindentation measurements

“…Using the standard OliverPharr data analysis method, both Warren et al 32 33 With the standard analysis we calculate E s and H values of 166 ± 2 and 13.4 ± 0.1 GPa, respectively, for the series of indents placed on the supported region of the silicon (series no. 1).…”

Phase composition and transformations in magnetron-sputtered (Al,V)2O3 coatings

“…The measurement equipment has an automatic correction for thermal drift prior to each indent. The hardness was evaluated according to the Oliver and Pharr method [45], using upper 95 to lower 20 % of the unloading segment for the unloading stiffness fit procedure (for Si substrate 95 to 30% due to phase transformation when unloading [46]). The polished Si on the rim of the pure Al2O3-sample is the internal reference of the hardness measurement, making it more reliable to evaluate the hardness and modulus over extended time as is demanded for such an annealing study.…”

Combinatorial Materials Science: Measures of Success

“…[87] Ultimately, this information promises to help make nanoindentation data quantitative, and it may be the key for extending nanoindentation to challenging soft, viscoelastic materials like polymers. However, in the short term, this capability is being developed because it enables high-throughput screening that is independent of other instruments, and that is amenable to a wider range of hard materials libraries for which nanoindentation is currently suited [88,89].…”