Morphology and Thermal Stability of Me-Si-N (Me=Re, W, Ta) for Microelectronics

Low pressure chemical vapor deposition (LPCVD) of Me-Si-N (Me= Re, W, Ta) thin films were investigated for use as diffusion barrier between Cu overlayer and oxidized silicon substrates. Their "amorphous" or nanocrystalline structure is expected to provide better performance than usual polycrystalline barriers. For the CVD process, gaseous precursors were silane, in situ fabricated metal chloride, ammonia, hydrogen and argon. Preliminary thermodynamic simulations of the Me-Si-N and the CVD Me-Si-N-C1-H-Ar systems (Me=Re, W, Ta), were combined to the experimental study. The Re-Si-N and W-Si-N layers crystallization temperature was found to be around 1173 K after annealing in vacuum by Rapid Thermal Annealing. Their morphology, thermal stability and resistivity were evaluated as a function of annealing temperature.