Nanomechanical characterization of thin Ti–Pt–Au multilayers deposited on top of LiNbO3 wafer

Nanomechanical characterization of LiNbO3–Ti(20 nm)–Pt(10 nm)–Au(100 nm), substrate/multilayers, was studied by depth-sensing diamond nanoindentation/scratch technique. Nanoindentation tests were performed using a Berkovich indenter of 50 nm of the tip radius. The average measured values of hardness and elastic modulus of each film were evaluated discretely. It was found that at diamond penetration depth exceeding 20% the thickness of the film, the mechanical properties of the film were influenced by those of the LiNbO3 substrate. Discontinuities were also observed in the loading part of the load–depth curves, and were found to be in correlation with the substrate/films practical adhesion. Nanoscratch tests were performed using a cube-corner diamond tip. They consisted mainly of three failure modes: ductile, ductile to brittle transition, and brittle. The critical load for practical adhesive failure measured for the LiNbO3–Ti(20 nm) was found relatively higher than that measured for the LiNbO3–Ti(20 nm)–Pt(10 nm).