Measurement and Simulation of Mechanical Strength of Back-End-Of-Line Layer in Advanced CMOS Dies

The back-end-of-line (BEOL) layers of ICs are subjected to considerably high mechanical forces during processing and when operating in harsh conditions. Without proper design and flip chip process control, the forces induced from flip chip bumps may exceed the ultimate strength of the BEOL resulting in critical failures. It is therefore of high interest to have a measurement method to quantify the strength of the BEOL structure of a functional IC. Ultimate fracture stress values are extracted from these measurements which can be used in thermo-mechanical simulations of flip chip assemblies for survivability evaluations.