A Study Of Preparation And Thermal Stability Of Nb_xSi_1-x Diffusion Barrier Layer In The Cu Interconnect Of Integrated Circuit

With the development of deep sub-micron technology in the manufacture of integrated circuit, Cu has been used as a new kind of interconnection materials for its lower resistivity and better electro-migration resistance. However, the diffusion contamination between Cu and Si is inevitable. A diffusion barrier under the Cu interconnect-lines was needed to prevent the diffusion of Cu and improve the adhesion between Cu and Si. Searching appropriate diffusion barrier has been a hot research topic of Cu interconnection technology for years.At first, the development and challenges of Cu interconnection were reviewed,and then, the fabrication methods and the development of diffusion barrier were given in this article. RF magnetron sputtering technology and DC magnetron sputtering technology were used to manufacture the Nb_xSi_1-x film and the Cu/Nb_xSi_1-x films on the surface of monocrystalline silicon. The Cu/Nb_xSi_1-x/Si samples were annealed at 600?, 650?,700? and 725? for 60 min in vacuum environment. X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscope, transmission electron microscope and four-point probe were used to research the chemical bonds,the phase compositions, the morphology, the microstructure and the electrical resistivity of Nb_xSi_1-x film. Four-point probe, X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy were used to research the electrical resistivity and the thermal stability of Cu/Nb_xSi_1-x/Si samples annealed at different temperatures.The experimental results showed that the thickness of Nb_xSi_1-x films manufactured by magnetron sputtering technology were about 20nm. The surfaces of deposited Nb_xSi_1-x films are smooth. The XRD results and the TEM results showed that the Nb₉₅Si₅ barrier films were mixed with crystalline grain of Nb₅Si₃. The others Nb_xSi_1-x barrier films were mainly amorphous. The Nb₈₉Si₁₁ barrier films were mixed with Nb₃Si microcrystal. The chemical bonds of Nb_xSi_1-x barrier films were Nb-O,Nb-N,Nb-Si and Si-O. The results of four-point probe sheet resistance measurement,XRD and X-ray photoelectron spectroscopy showed the Cu/Nb₉₅Si₅/Si samples failed at 650? and the Cu/Nb₆₃Si₃₇/Si samples failed at 700?. The others Cu/Nb_xSi_1-x/Si samples were stable until annealing to 700?. In conjunction with these measurements discussed above, it implied that Nb,Si_1-x barrier films could be used as a new kind of diffusion barrier film for Cu interconnects system. Nbg₉Si₁₁ film has better thermal stability and lower resistivity.