Crystal orientation effect on local adhesion strength of the interface between a damascene copper line and the insulation layer

• Adhesion strength of the interface composed of a Cu grain and SiN in damascene interconnect was evaluated.
• Evaluated strength distributed on the crystal orientation map with a wide range of scatter.
• Crystal orientation of Cu grain played an important role to the local adhesion strength.

Local adhesion strength of the interface composed of a single copper grain and SiN insulation layer was evaluated by using subgrain-scale specimens fabricated on a damascene interconnect structure. Crystallographic information was also surveyed at the fracture sites of the specimens in view of possible correlations between the strength and the crystal orientation of copper. Evaluated strength distributed on the crystal orientation map with a wide range of scatter, which indicates that copper crystal orientation plays an important role on adhesion strength. In addition, the relationship between the evaluated adhesion strength and the crystal orientation of copper grain suggests the significant contribution of the energy to be dissipated to plastic deformation. The result of this fundamental evaluation supports the possible variation of local interface adhesion strength in damascene interconnects which consist of polycrystalline copper and the insulation layer.

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