Thermal Stability of TaN-Based Thin Layers for Cu Metallization

The diffusion of Cu through TaN-based thin layers into a Si substrate has been studied. The barrier efficiency of TaN/Ta/TaN multilayer barrier of 50 nm:50 nm:50 nm in thickness has been investigated and is compared with that of TaN single layers. Thermal stabilities of these TaN-based thin layers were determined from glancing incidence angle X-ray diffraction and transmission electron microscopy, conducted in the temperature range of 773–973 K. The TaN/Ta/TaN barrier appeared to be more efficient than the TaN single layer in preventing Cu diffusion.