| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 97 === Electromigration tests of dual-damascene Cu interconnect structures with or without an NH3/He plasma treatment between Cu and SiCN etch stop layer have been performed in this study at 400゜C under a current density of 8 MA/cm2 to investigate the influence of interface structures to electrical reliability. From the electrical resistance-to-time traces, it was observed that the electrical resistance of the interconnects with the plasma treatment increased slowly. From the cumulative failure probabilities of 1.1 R0, 1.3 R0, 1.5 R0 (R0: initial resistance), and wire opening, it was found that the interconnects with the plasma treatment exhibited a higher median time to failure, and the electrical reliability of the interconnects was effectively enhanced by the plasma treatment. An oxide layer existed at the Cu/SiCN interface without the plasma treatment, whereas it was removed by the plasma treatment, and Cu-N or Cu-Si bonds formed, consequently enhancing the adhesion of interface. From the observations of EM-induced voiding behaviors in the interconnects, it was found that voids nucleated at the Cu/SiCN interface without the plasma treatment and then grew gradually with testing intervals. In comparison, voids nucleated inside the Cu wires, rather than at the interface, after the plasma treatment, indicating that the NH3/He plasma treatment strengthened the adhesion of the interface and then inhibited the electromigration behavior which occurred at the interface.
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