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Low ppm failure analysis for advanced Cu and Cu alloy on-chip wiring

 
: Kraatz, Matthias; Hauschildt, Meike; Gall, Martin; Zschech, Ehrenfried

Kraemer, R. ; Informationstechnische Gesellschaft -ITG-:
Zuverlässigkeit und Entwurf. 9. ITG/GMM/GI-Fachtagung 2017 : 18.-20. September 2017, Cottbus
Berlin: VDE-Verlag, 2017 (ITG-Fachbericht 274)
ISBN: 978-3-8007-4444-2
ISBN: 3-8007-4444-9
7 S.
Fachtagung "Zuverlässigkeit und Entwurf" (ZuE) <9, 2017, Cottbus>
Englisch
Konferenzbeitrag
Fraunhofer IKTS ()

Abstract
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 mA/μm2, 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 incubation 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 – 0.2 eV. Implications for extrapolations of accelerated test data to use conditions are discussed.

: http://publica.fraunhofer.de/dokumente/N-484235.html