Wafer thinning, bonding, and interconnects induced local strain/stress in 3D-LSIs with fine-pitch high-density microbumps and through-Si vias

M. Murugesan, H. Kino, H. Nohira, J. C. Bea, A. Horibe, F. Yamada, C. Miyazaki, H. Kobayashi, T. Fukushima, T. Tanaka, M. Koyanagi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

50 Citations (Scopus)

Abstract

Mechanical strain/stress and crystal defects are produced in extremely thin wafers (thickness ∼10 μm) of 3D-LSIs not only during wafer thinning, but also after wafer bonding using fine-pitch, high-density microbumps and curing. Furthermore, the metal of through-Si via (TSV) and microbump not only becomes the cause of contamination, but also induces strain/stress (due to the difference in the co-efficient of thermal expansion (CTE) between Si and metal) in thinned Si substrate. X-ray photoelectron spectroscopy (XPS) results showed that the crystal quality of Si is highly deteriorated in the ultra-poly ground (UPG) surface after wafer thinning and stress relief. Micro-Raman spectroscopy (μRS) data revealed that a local tensile strain amount to 1.8 GPa was induced by 4×4 μm2 square sized Si microbumps in 10 μm-thick LSI wafers after bonding and curing. We have noticed that this locally induced strain/stress caused more than 10% change in the ON current of p-MOS transistor. CuSn microbumps have also induced strain/stress at Si wafer surface, and it penetrates deeper for larger bump size and wider for smaller bump pitch.

Original languageEnglish
Title of host publication2010 IEEE International Electron Devices Meeting, IEDM 2010
Pages2.3.1-2.3.4
DOIs
Publication statusPublished - 2010 Dec 1
Event2010 IEEE International Electron Devices Meeting, IEDM 2010 - San Francisco, CA, United States
Duration: 2010 Dec 62010 Dec 8

Publication series

NameTechnical Digest - International Electron Devices Meeting, IEDM
ISSN (Print)0163-1918

Other

Other2010 IEEE International Electron Devices Meeting, IEDM 2010
CountryUnited States
CitySan Francisco, CA
Period10/12/610/12/8

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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