Pulsed DC and AC Electromigration Studies of Cu Dual Damascene Interconnects
- Hiroshima University, Graduate School of ADSM, Kagamiyama 1-3-1, Higashi-hiroshima 739-8530 (Japan)
Pulsed DC and AC electromigration (EM) studies were carried out in a range of a few tens of M Hz, using two level copper damascene via chain structures. For DC-EM studies, pulse off time dependence on EM MTF (median time to failure) was investigated. When the current off time was increased with constant current on time, a significant lifetime improvement was observed. We developed theoretical model that predicted EM MTF using time dependent one-dimensional drift-diffusion equation of vacancies, by taking the electron wind force into account. In this model, EM MTF is defined as the time when a maximum stress of Cu interconnects exceeds a critical value. This model well reproduced the tendency of prolongation of EM MTF with an increase in the pulse off time. It is strongly suggested that relaxation of vacancy concentration gradient during current off time is effective for prolongation of EM MTF. We investigated EM MTF under AC pulse condition. We observed that AC-EM MTF was two orders of magnitude longer than DC EM MTF, while simulated AC EM MTF using drift diffusion equation was infinity. The discrepancy is considered to come from the diffusion flux caused by temperature gradient.
- OSTI ID:
- 20630473
- Journal Information:
- AIP Conference Proceedings, Vol. 741, Issue 1; Conference: 7. international workshop on stress-induced phenomena in metallization, Austin, TX (United States), 14-16 Jun 2004; Other Information: DOI: 10.1063/1.1845848; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COPPER
DIFFUSION
DIFFUSION EQUATIONS
ELECTRIC CURRENTS
ELECTRONS
ELECTROPHORESIS
FAILURES
INTEGRATED CIRCUITS
LIFETIME
NUMERICAL ANALYSIS
ONE-DIMENSIONAL CALCULATIONS
PULSES
RELAXATION
STRESSES
TEMPERATURE GRADIENTS
TIME DEPENDENCE
VACANCIES