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Electromigration early failure void nucleation and growth phenomena in Cu and Cu(Mn) interconnects

: Hauschildt, M.; Hennesthal, C.; Talut, G.; Aubel, O.; Gall, M.; Yeap, K.B.; Zschech, E.


Institute of Electrical and Electronics Engineers -IEEE-:
IEEE International Reliability Physics Symposium, IRPS 2013. Vol.1 : Monterey, California, USA, 14 - 18 April 2013
New York, NY: IEEE, 2013
ISBN: 978-1-4799-0112-8 (Print)
ISBN: 978-1-4799-0111-1 (Online)
ISBN: 978-1-4799-0113-5
International Reliability Physics Symposium (IRPS) <2013, Monterey/Calif.>
Fraunhofer IZFP, Institutsteil Dresden ( IKTS-MD) ()

Electromigration early failure void nucleation and growth phenomena were studied using large-scale, statistical analysis methods. A total of about 496,000 interconnects were tested over a wide current density and temperature range (j = 3.4 to 41.2 µmA/m2, T = 200 to 350°C) to analyze the detailed behavior of the current density exponent n and the activation energy Ea. The results for the critical V1M1 downstream interface indicate a reduction from n = 1.55±0.10 to n = 1.15±0.15 when lowering the temperature towards 200°C for Cu-based interconnects. This suggests that the electromigration downstream early failure mechanism is shifting from a mix of nucleation-controlled (n = 2) and growth-controlled (n = 1) to a fully growth-controlled mode, assisted by the increased thermal stress at lower temperatures (especially at use conditions). For Cu(Mn)-based interconnects, a drop from n = 2.00±0.07 to n = 1.64±0.2 was found, indicating additional effects of a superimposed incuba tion time. Furthermore, at lower current densities, the Ea value seems to drop for both Cu and Cu(Mn) interconnects by a slight, but significant amount of 0.1 - 0.2eV. Implications for extrapolations of accelerated test data to use conditions are discussed. Furthermore, the scaling behavior of the early failure population at the NSD=-3 level (F about 0.1%) was analyzed, spanning 90, 65, 45, 40 and 28 nm technology nodes.