Developing thinner diffusion barriers for the microelectronics industry with energy dispersive x-ray spectroscopy (EDS)
Gatan instrument used
EDAX® Octane Elect Plus EDS system
Background
In the microelectronics industry, copper is often used for interconnects in integrated circuits due to its low resistivity. However, copper has a strong tendency to diffuse through devices, degrading performance strongly. To ease these problems, a 40 – 50 nm barrier layer of titanium nitride, for example, can be used to prevent the diffusion of copper. However, in attempts to reduce processing costs, manufacturers aim to develop improved barrier layers using more cost-effective methods. One process being investigated is the low-temperature deposition of thin titanium and silicon nitride films with subsequent annealing to form the titanium nitride barrier. To optimize process development, it is critical to characterize the layered structure to establish whether titanium nitride has been formed from the precursor materials. This requires the ability to reveal the elemental distribution with ~10 nm spatial resolution, which can be a challenge in the scanning electron microscope (SEM) due to the lateral spread of electrons in bulk specimens due to inelastic scattering.