The researchers investigated how treating TiN between Al and Si affects its ability to prevent diffusion. They found that treating TiN at 450˚C in N2 gas reduced the presence of oxygen and filled in gaps within the crystal structure. Untreated TiN failed after heat treatment, forming Al spikes and Si imprints, while treated TiN showed no such damage. This suggests that treating TiN improves its diffusion barrier performance between Al and Si by reducing the diffusion pathways within the crystal structure.