Microstructure, impurity and metal cap effects on Cu electromigration
Abstract
Electromigration (EM) lifetimes and void growth of pure Cu, Cu(Mn) alloy, and pure Cu damascene lines with a CoWP cap were measured as a function of grain structure (bamboo, near bamboo, and polycrystalline) and sample temperature. The bamboo grains in a bamboo-polycrystalline grained line play the key role in reducing Cu mass flow. The variation in Cu grain size distribution among the wafers was achieved by varying the metal line height and wafer annealing process step after electroplating Cu and before or after chemical mechanical polishing. The Cu grain size was found to have a large impact on Cu EM lifetime and activation energy, especially for the lines capped with CoWP. The EM activation energy for pure Cu with a CoWP cap from near-bamboo, bamboo-polycrystalline, mostly polycrystalline to polycrystalline only line grain structures was reduced from 2.2 ± 0.2 eV, to 1.7 ± 0.1 eV, to 1.5 ± 0.1 eV, to 0.72 ± 0.05 eV, respectively. The effect of Mn in Cu grain boundary diffusion was found to be dependent on Mn concentration in Cu. The depletion of Cu at the cathode end of the Cu(Mn) line is preceded by an incubation period. Unlike pure Cu lines with void growthmore »
- Authors:
-
- IBM T. J. Watson Research Center, Yorktown Heights, NY 10598 (United States)
- IBM Microelectronic Division, Hopewell Junction, NY 12533 (United States)
- Publication Date:
- OSTI Identifier:
- 22311265
- Resource Type:
- Journal Article
- Journal Name:
- AIP Conference Proceedings
- Additional Journal Information:
- Journal Volume: 1601; Journal Issue: 1; Conference: International conference on stress induced phenomena and reliability in 3D microelectronics, Kyoto (Japan), 28-30 May 2012; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ACTIVATION ENERGY; ANNEALING; BINDING ENERGY; CATHODES; CONCENTRATION RATIO; COPPER; DIFFUSION; ELECTROPHORESIS; ELECTROPLATING; EV RANGE; GRAIN BOUNDARIES; GRAIN SIZE; LIFETIME; MANGANESE; MECHANICAL POLISHING; POLYCRYSTALS; TRAPPING
Citation Formats
Hu, C. -K., Gignac, L. G., Ohm, J., Breslin, C. M., Huang, E., Bonilla, G., Liniger, E., Rosenberg, R., Choi, S., and Simon, A. H. Microstructure, impurity and metal cap effects on Cu electromigration. United States: N. p., 2014.
Web. doi:10.1063/1.4881341.
Hu, C. -K., Gignac, L. G., Ohm, J., Breslin, C. M., Huang, E., Bonilla, G., Liniger, E., Rosenberg, R., Choi, S., & Simon, A. H. Microstructure, impurity and metal cap effects on Cu electromigration. United States. https://doi.org/10.1063/1.4881341
Hu, C. -K., Gignac, L. G., Ohm, J., Breslin, C. M., Huang, E., Bonilla, G., Liniger, E., Rosenberg, R., Choi, S., and Simon, A. H. 2014.
"Microstructure, impurity and metal cap effects on Cu electromigration". United States. https://doi.org/10.1063/1.4881341.
@article{osti_22311265,
title = {Microstructure, impurity and metal cap effects on Cu electromigration},
author = {Hu, C. -K. and Gignac, L. G. and Ohm, J. and Breslin, C. M. and Huang, E. and Bonilla, G. and Liniger, E. and Rosenberg, R. and Choi, S. and Simon, A. H.},
abstractNote = {Electromigration (EM) lifetimes and void growth of pure Cu, Cu(Mn) alloy, and pure Cu damascene lines with a CoWP cap were measured as a function of grain structure (bamboo, near bamboo, and polycrystalline) and sample temperature. The bamboo grains in a bamboo-polycrystalline grained line play the key role in reducing Cu mass flow. The variation in Cu grain size distribution among the wafers was achieved by varying the metal line height and wafer annealing process step after electroplating Cu and before or after chemical mechanical polishing. The Cu grain size was found to have a large impact on Cu EM lifetime and activation energy, especially for the lines capped with CoWP. The EM activation energy for pure Cu with a CoWP cap from near-bamboo, bamboo-polycrystalline, mostly polycrystalline to polycrystalline only line grain structures was reduced from 2.2 ± 0.2 eV, to 1.7 ± 0.1 eV, to 1.5 ± 0.1 eV, to 0.72 ± 0.05 eV, respectively. The effect of Mn in Cu grain boundary diffusion was found to be dependent on Mn concentration in Cu. The depletion of Cu at the cathode end of the Cu(Mn) line is preceded by an incubation period. Unlike pure Cu lines with void growth at the cathode end and hillocks at the anode end of the line, the hillocks grew at a starting position roughly equal to the Blech critical length from the cathode end of the Cu(Mn) polycrystalline line. The effectiveness of Mn on Cu grain boundary migration can also be qualitatively accounted for by a simple trapping model. The free migration of Cu atoms at grain boundaries is reduced by the presence of Mn due to Cu-solute binding. A large binding energy of 0.5 ± 0.1 eV was observed.},
doi = {10.1063/1.4881341},
url = {https://www.osti.gov/biblio/22311265},
journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 1601,
place = {United States},
year = {Thu Jun 19 00:00:00 EDT 2014},
month = {Thu Jun 19 00:00:00 EDT 2014}
}