Finite element analysis of thermal stress for Cu interconnect with different barrier layer

Finite element analysis software ANSYS is applied to simulate the stress distribution in the Cu line with structure Cu/barrier/SiO₂/Si,TaN and ZrN as diffusion barrier layer,respectively.The thermal loading is from 350℃ to 20℃,and the stress in Cu single damascus structures and Cu dual damascus structures is discussed.By observing the stress in the Cu line of Cu single damascus structures,Von Mises stress（700MPa） in the structure with ZrN as the diffusion barrier layer is smaller than Von Mises stress（800MPa） in the structure with TaN as the diffusion barrier layer.Compared with the thermal stress with TaN as the diffusion barrier layer in Cu dual damascus structures,σx,σy and σz,the thermal stress in all directions with ZrN as the diffusion barrier layer,is reduced by 50MPa,300MPa and 150MPa respectively.In addition,the effect of barrier layer thickness on thermal stress for Cu line structures with TaN and ZrN as diffusion barrier is studied in this paper.The thermal stress increases with increasing diffusion barrier thickness,and the thermal stress of various barrier thicknesses is smaller in the structure with ZrN as diffusion barrier layer.SX（ZrN）,SY（ZrN） and SZ（ZrN）,the stress in x,y and z directions,respectively is reduced by 50MPa,200MPa and 50MPa.