Applied Science and Convergence Technology 1996; 5(3): 229-238
Published online September 1, 1996
Copyright © The Korean Vacuum Society.
S. T. Bae,J. Y. Kim
The electromigration phenomrla. and the characterizations of the conductor lifetime (Time-To-Failure, TTF) in Al-1%Si thin film interconnections under D.C. and Pulseu D.C. conditions were investigated. Meander type test patterns were fabricated with the dimensions of 21080㎛ length, 3㎛ width, 0.7㎛ thickness and the 0.1㎛/0.8㎛ (SiO₂/PSG) dielectric overlayer. The current densities of 2×10^6 A/㎠ and 1×10^7 A/㎠ were stressed in Al-1%Si thin film interconnections under a D.C. condition. The peak current densities of 2×10^6 A/㎠ and 1×10^7 A/㎠ were also applied under a Pulsed D.C. condition at frequencies of 200㎑z, 800㎑, 1㎒, and 4㎒ with the duty factor of 0.5. The time-to-failure under a Pulsed D.C.(TTF_(pulsed D.C.)) was appeared to be larger than that under a D.C. condition. It was found that the TTF under both a D.C. and a Pulsed D.C. condition largely depends upon the appiled current densities respectively. This can be explained by a relaxation mechanism view due to a duty cycle under a Pulsed D.C. related to the wave on off. The relaxation phenomena during the pulsed off period result in the decay of excess vacancies generated in the AI-1 %Si thin film interconnections because of the electrical and mechanical stress gradient. Hillocks and voids formed by an electromigration were observed by using a SEM (Scanning Electron Microscopy).