Characterization of the Young's modulus, residual stress and fracture strength of Cu-Sn-In thin films using combinatorial deposition and micro-cantilevers

Microcantilevers coupled with combinatorial deposition were used to characterize the Young's modulus, residual stress and fracture strength of Cu-Sn-In thin films over a broad range of compositions. Measurement inaccuracies due to cantilever non-idealities were corrected using finite element simulations and deflection measurements at multiple locations. η-phase with a composition Cu₅₃Sn₂₅In₂₂ was discovered to have the highest fracture strength and therefore has potential in thin film solder bonding applications. This study provides a database for the mechanical properties of a wide range of Cu-Sn-In alloys. Moreover, the techniques developed in this study provide a highly efficient approach to finding an intermetallic compound composition with the most desired mechanical properties.