Nanoindentation of high-aspect ratio pillar structures on optical multilayer dielectric diffraction gratings

The mechanical response of optical multilayer dielectric (MLD) diffraction gratings has been studied using nanoindentation. The results are interpreted using a stress-strain model, which reveals a uniaxial yield stress of 4.1 GPa. It is shown that the indentation response of the high-aspect ratio “pillar” geometry (constrained in one transverse direction but free in the other) can be expressed in terms of yield stress rather than material hardness.