Structure and composition of the Cu/low k interconnects de-layered with FIB

By the gas-assisted focused ion beam (FIB) method, we de-process the device from top layer to bottom layer. It is a highly efficient failure analysis method on the precise location. After removing the dielectric layers under the bombardment of an ion beam, the chemical composition of the top layer was altered with the reduced oxygen content. Further energy-dispersive X-ray spectroscopy and FTIR analysis revealed that the oxygen reduction lead to appreciable silicon suboxide formation. Our findings with structural and composition alteration of dielectric layer after FIB de-layering open up a new insight avenue for the failure analysis in IC devices.