Copper/carbon nanotube composite interconnect for enhanced electromigration resistance

Bottom-up growth of carbon nanotubes (CNTs) and electrochemical plating approaches were combined to produce homogeneous copper/CNT composite. The measured resistivity of the copper/CNT composite at room temperature was 2.2 muOmegaldr cm. The electrical resistivity of copper/CNT composite at room temperature increases slightly with the increasing loading of the CNTs in the copper matrix. From room temperature to 350degC, all the composites exhibit the typical metallic increase of the electrical resistivity. Conventional Blech-Kinsbron test structure were fabricated and used to characterize the electromigration (EM) induced void growth rate. EM comparison testing of Cu and Cu/CNT composites were carried out over temperature range of 100 to 250degC and current density from 5 times 10⁵ to 2 times 10⁶ A/cm². The void growth rate for the Cu/CNT composite stripe was measured and found to be around four times lower than that of the pure Cu stripe. The result suggests that Cu/CNT composite is potentially a good candidate for advanced integrated circuit interconnect application where both lower electrical resistivity and better EM resistance are required.