As the size of integrated circuit devices continues to decrease, the ratio of interfacial area to volume increases and the dimension of thin films shrinks to the order of tens of nanometers. In such circumstances, the interfacial reactions, which are frequently accompanied with nanometer scale local failures, become a dominant mechanism for the breakdowns of the devices at high temperatures. This makes transmission electron microscopy (TEM) take a unique role in the research of Si metallization. In situ techniques have succeeded to reproduce and observe such real time reactions in the TEM. Moreover, after the introduction of the field emission gun systems(FEG), there have been enormous improvements in the spatial resolution and performance of x-ray energy dispersive spectroscopy (EDS) and electron microdiffraction. In the present work, two case studies of local failure were successfully investigated by combining these techniques: TiN diffusion barrier breakdown between Si and Al, and TiN electrodes on tantalum pentoxide (Ta2O5) capacitors for 1 Gigabit DRAM.