Nanoindentation is used in a variety of fields to measure material hardness and elastic modulus. This test technique is especially attractive for thin films because of the difficulty of conducting tensile or other conventional mechanical characterization tests on thin film specimens, and because it requires only a small surface area for testing. However, the standardization process for this new measurement method is still in progress. To test the ability of current measurement procedures to provide comparable results, a round robin was conducted. Invitations to participate were sent to over 100 laboratories. Two specimens, a copper film on a silicon substrate and an uncoated substrate, were distributed to each of 33 laboratories. The choice of measurement procedure was left to the performing organizations. By the end of the reporting period, 27 sets of results were received. While the average reported uncertainty (1 standard deviation) among the individual participants was 4 % of the average hardness, the interlaboratory standard deviation of the hardness values was 15 %. Similarly, the average reported uncertainty of the modulus was 5 % of the interlaboratory average value, but the interlaboratory standard deviation of the modulus was 19 %. None of the measurement variables examined in this round robin, including instrument type, analysis procedure, time since instrument calibration, chip mounting procedure, and tip condition, and neither of the potential covariant effects, chip location in the wafer and test date, were found to have a statistically significant effect on the reported hardness or modulus.
Citation: Metal. Mater. Trans.
Pub Type: Journals
copper, elastic modulus, film, hardness, indentation, instrumented indentation, interlaboratory, nanoindentation, precision, repeatability, reproducibility, silicon, thin film