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Electromigration in Submicron Dual-damascene Cu/low-k Interconnects

Published online by Cambridge University Press:  01 February 2011

Ki-Don Lee
Affiliation:
Univ. of Texas at Austin, Microelectronics Research Center, PRC, Austin, TX 78712
Xia Lu
Affiliation:
Univ. of Texas at Austin, Microelectronics Research Center, PRC, Austin, TX 78712
Ennis T. Ogawa
Affiliation:
Univ. of Texas at Austin, Microelectronics Research Center, PRC, Austin, TX 78712
Hideki Matsuhashi
Affiliation:
Univ. of Texas at Austin, Microelectronics Research Center, PRC, Austin, TX 78712
Volker A. Blaschke
Affiliation:
International SEMATECH, 2706 Montopolis Dr., Austin, TX 78741-6499
Rod Augur
Affiliation:
International SEMATECH, 2706 Montopolis Dr., Austin, TX 78741-6499
Paul S. Ho
Affiliation:
Univ. of Texas at Austin, Microelectronics Research Center, PRC, Austin, TX 78712
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Abstract

Electromigration (EM) lifetime characteristics and failure mechanism were investigated for Cu/porous-low-k interconnects and compared to Cu/oxide. The porous low-k dielectric was JSR LKD-5109TM, an MSQ-based spin-on organosilicate material with k = 2.2. The activation energies for EM failure were found to be 0.9 - 1.0 eV for the porous MSQ and 0.8 eV for oxide while the current density exponents for both materials were found to be similar, 1.2 - 1.3. This range of activation energies are commonly associated with mass transport at the Cu/cap-layer interface and suggest a similar mass transport mechanism; interfacial diffusion. Porous MSQ structures showed the same distinct failure morphology as observed in other Cu/low-k interconnects: voiding at the cathode and lateral Cu extrusion at the anode under the cap layer, which seems to be related to the thermo-mechanical properties of Cu/low-k interconnects. The shorter lifetime characteristics of Cu/low-k interconnects comparing to Cu/oxide can be attributed to a smaller back stress, due to less thermomechanical confinement. Results of this study indicate that thermo-mechanical properties of low-k interconnects are important parameters in controlling EM reliability of Cu/low-k interconnects.

Type
Research Article
Copyright
Copyright © Materials Research Society 2002

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