Investigation of electromigration in copper interconnection of ULSI

With the development of higher integration and the improvement of integrated density of devices, copper interconnect technology become the current important connection technology. Its excellent mechanical and electrical characteristics attract the high-speed, power management devices and fine pitch applications. Copper interconnection has gained considerable attention because of its economic advantage, strong resistance to sweeping and superior electrical performance. The design and application of novel test interconnection to study electromigration (EM). The results show that the size, shape and microstructure of interconnection metallic line how to play an important role in the process of EM. Also, the temperature, current density and alloy elements have strongly effects on Mean Time of Failure (MTF) of EM. Through the EM experiment, the EM resistance of copper interconnection with different width was compared; The failure mechanism was explored. The failure distribution is concentrated at or above line-lengths longer than 150 um with a very distinct change. The evidences show that long length line of EM damage not only exists, but also present is damage that occurs in shorter-length interconnects.