Application of Cu–C and Cu–V alloys in barrier-less copper metallization

• The thermal stability of Cu–C/SiO2/Si and Cu–V/SiO2/Si systems were investigated.
• The resistivity of the annealed Cu–C film can reach the lowest 3.1 μΩ cm.
• C or V alloy atoms were segregated at the interface between Cu alloy film and SiO2.
• There was no diffraction peaks related to Cu3Si for both systems annealed at 500 °C.
• Adding C or V into Cu films can improve the thermal stability of Cu/SiO2/Si system.

Cu-alloy seed layers have been applied to barrier-less copper metallization to improve the thermal stability. The barrier property and thermal stability of Cu alloys with smaller atomic size element C and larger size element V were both studied for comparison. Thin Cu–C and Cu–V films were deposited onto SiO2/Si substrates by magnetron sputtering and vacuum-annealed. After annealing at 500 °C, resistivity values of the Cu–C and Cu–V films reduced to 3.1 and 4.5 μΩ·cm, respectively. For Cu–C/SiO2/Si and Cu–V/SiO2/Si samples, a self-formed thin layer was detected at the interface. No inter-diffusion was observed between the Cu-alloy and SiO2 layers. The Cu–V/SiO2/Si system lost its integrity at 600 °C, the failure temperature of the Cu–C/SiO2/Si system was 700 °C. While the pure Cu/SiO2/Si samples failed after 500 °C annealing. The Cu–C and Cu–V systems reflected improved barrier performance and thermal stability compared with pure Cu contact systems.

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