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 μΩ·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 350°C, 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 250°C and current density from 5 × 10⁵ to 2 × 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. © 2008 IEEE