Evaluation for interface strength fluctuations induced by inhomogeneous grain structure of Cu line in LSI Interconnects

Chuantong Chen, Nobuyuki Shishido, Shoji Kamiya, Kozo Koiwa, Hisashi Sato, Masaki Omiya, Masahiro Nishida, Takashi Suzuki, Tomoji Nakamura, Takeshi Nokuo, Toshiaki Suzuki

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Abstract

Local adhesion strength of the interface between Cu line and SiN cap layer in a Cu damascene interconnect structure of LSI has a significant fluctuation when evaluated with in-plane dimensions of 1 × 1 μm specimens, which was 4.78 ± 1.63 J/m2. The reproducibility of the evaluation technique was investigated by evaluating the strength of the Cu/SiN interface for the specimens fabricated on a plate of Cu single crystal, where the interface strength was measured as 0.62 ± 0.02 J/m2. The relative standard deviation of interface strength distribution in LSI interconnect structure was 34% which was more than ten times larger than the value 2.5% for the specimens fabricated on the plate of Cu single crystal. The significant fluctuation of interface strength was induced clearly not by the random error of the evaluation technique, but by the inhomogeneous grain structure of Cu line with various crystal orientations and grain boundaries. By means of elastic-plastic interface crack extension simulations, it was revealed that the difference in the amount of energy dissipated in plastic deformation of Cu layer mainly leads to a significant fluctuation of the apparent strength. Plastic deformation of Cu layer plays a dominant role on the local strength of interface Cu/SiN in LSI interconnects.

Original languageEnglish
Pages (from-to)52-58
Number of pages7
JournalMicroelectronic Engineering
Volume120
DOIs
Publication statusPublished - 2014 May 25

Keywords

  • Cu single crystal
  • Elastic-plastic simulation
  • Local interface strength

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering

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    Chen, C., Shishido, N., Kamiya, S., Koiwa, K., Sato, H., Omiya, M., Nishida, M., Suzuki, T., Nakamura, T., Nokuo, T., & Suzuki, T. (2014). Evaluation for interface strength fluctuations induced by inhomogeneous grain structure of Cu line in LSI Interconnects. Microelectronic Engineering, 120, 52-58. https://doi.org/10.1016/j.mee.2013.10.018