Diffusion barrier property of MnSixOy layer formed by chemical vapor deposition for Cu advanced interconnect application

• Amorphous manganese silicate layer has been studied as a copper diffusion barrier.
• The 1.2 nm-thick Mn oxide layer is too thin to become a diffusion barrier.
• Good thermal stability of 2.0 nm-thick manganese silicate layer

An amorphous manganese oxide layers formed by chemical vapor deposition have been studied as a copper diffusion barrier. The thermal stability of the barrier layer was assessed by annealing Cu/MnSixOy/SiO2/Si samples at 400 °C for various times up to 10 h. Transmission electron microscopy, energy-dispersive X-ray spectroscopy (EDX), secondary ion mass spectroscopy (SIMS), capacitance-voltage and current–voltage measurements were performed. Failure of the barrier property is marked by observing the copper peak appearing in EDX and SIMS spectra data from the SiO2 region. Amorphous MnSixOy barrier with a thickness of 1.2 nm has failed in preventing Cu diffusion into SiO2 substrate after anneal at 400°C in vacuum for 1h, as proven by the presence of Cu in the dielectric (SiO2) layer. However, the amorphous MnSixOy with the thickness of 2.0 nm barrier was thermally stable and could prevent Cu from inter-diffusion to the SiO2 substrate after annealing at 400 °C even up to 10 h.