Structural and Thermal Stability of TiN- and SiC-Based Multilayer Diffusion Barriers for Copper–Silicon Interfaces

In this study, the diffusion barrier performance of TiN and SiC layers was investigated in Si/TiN/Cu, Si/TiN/SiC/Cu, and Si/SiC/TiN/Cu multilayer structures to address copper diffusion issues at silicon interfaces in microelectronics. Samples were annealed in argon at 500–800 °C for 30 min, and diffusion behavior was analyzed using X-ray diffraction (XRD) and sheet resistance measurements. The Cu3Si phase formed at 600 °C in the Si/TiN/Cu system, while no Cu3Si appeared in the Si/SiC/TiN/Cu system up to 700 °C, indicating improved stability. Complete copper diffusion occurred in all systems at 800 °C. Sheet resistance measurements corroborated the XRD findings, demonstrating that multilayer structures incorporating TiN and SiC significantly enhance thermal stability and suppress copper diffusion. Comparison of Si/SiC/TiN/Cu and Si/TiN/SiC/Cu stacks annealed at 700 °C revealed that the stability of TiN depends on layer sequence, with SiC effectively blocking Cu migration into TiN when placed adjacent to Cu. Structural and morphological properties of TiN films were also examined, confirming their suitability as diffusion barriers. Additionally, the feasibility of forming a low-resistivity TiSi2 layer through a single annealing step to create a TiSi2/TiN system was explored, highlighting potential applications in advanced device integration.