Effect of Zr and Cr Doping on the Structure and Properties of Copper Interconnection Thin Films
The effects of zirconium(Zr)and chromium(Cr)elements doping on the structure and properties of copper(Cu)interconnection thin films were investigated.Cu,Cu(Zr),Cu(Cr),and Cu(ZrCr)interconnection films were deposited on SiO2/Si substrates by direct current magnetron sputtering technique,and the films were annealed under vacuum condition at the temperature of 400-800 ℃ for 1 h.The surface morphologies,microstructure,and electrical properties of the films were tested and analyzed by SEM,XRD,and four probes method.The results show that single element doping of Zr or Cr improves the thermal stability of Cu interconnect films.The precipitation of Zr or Cr elements prevents mutual diffusion between Cu film and Si substrate,and suppresses the growth and aggregation of the grains,which make the films maintain good properties.After vacuum annealing at 700 ℃,the resistivity of the Cu(Zr)or Cu(Cr)film is less than 10 μΩ·cm(that of pure Cu film is 74.70 μΩ·cm).The co-doping of Zr and Cr elements further improves the thermal stability of Cu interconnection films while maintaining low resistivity and interconnect reliability.Especially after vacuum annealing at 800 ℃,the resistivity of Cu(ZrCr)film is as low as 3.23 μΩ·cm(that of pure Cu film is 103.50 μΩ cm).
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