Atomic-scale structural evolution of Ta–Ni–Si amorphous metal thin films

• The thermal stability of a potential Ta-based Cu diffusion barrier was investigated.
• The ternary amorphous metal thin film remain substantially amorphous up to 800 °C.
• At 900 °C a ternary nano-crystalline phase forms, Ta3Ni2Si, in an amorphous matrix.
• Ta2.4Ni2.2Si high glass forming ability limits growth of unary and binary phases.

We investigated the thermal stability of a new ternary amorphous metal thin film, Ta2.4Ni2.2Si, and assessed its suitability as a Cu diffusion barrier for semiconductor device applications. Transmission electron microscopy was coupled with atom probe tomography to provide a detailed understanding of the atomic-scale evolution of both structure and composition as a function of annealing temperature. We show that the amorphous structure is stable up to >800 °C under ultrahigh vacuum, while annealing to 900 °C induces nano-crystallization of a single ternary phase in an amorphous matrix. The implications of crystallization and solute partitioning are examined in the context of high-temperature stability to aid in the design and understanding of this new class of thin film materials.

Figure optionsDownload as PowerPoint slide