Tip-radius effect in finite element modeling of sub-50 nm shallow nanoindentation

An accurate representation of the indenter geometry is essential for correct finite element simulations of shallow indentations of less than 50 nm using a 90degrees cube-corner indenter. A nonlinear regression method for estimating the tip radius of an indenter is presented, which takes into account that initially the contact is only with the spherical surface of the tip and subsequently also includes contact with the equivalent conical surface. The tip radius of a Berkovich indenter is estimated by a finite element modeling (FEM) best-fitting method. Using the estimates of tip radii, the yield strength of gold in the film of a gold/silicon system was estimated from the best fit between FEM simulations and nanoindentation experiments using the 90degrees cube corner indenter. which compared favorably with an FEM simulation and nanoindentation data using a Berkovich indenter. (C) 2003 Elsevier B.V. All rights reserved.