A flexible top metal structure to improve ultra low-k reliability

High stresses generated from chip-package interactions (CPI), especially when large die is flip mounted on organic substrate using Pb-free C4 bumps, can easily cause low-k delamination. A novel scheme by applying an elastic material can effectively reduce the transmitted stresses and, thus, resolve the interfacial delamination issue. Along with an optimized chip-package integration solution, a reliable interconnect structure with good electrical performance, has been successfully demonstrated.