Impact of Interconnections on Vertically Stacked 20 um-Thick DRAM Chips

M. Murugesan, T. Fukushima, J. C. Bea, S. Tanikawa, T. Tanaka, H. Hashimoto, M. Koyanagi

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

Abstract

Effect of thermo-mechanical stress (TMS) originating from CuSn micro-bumps (μ-bumps) and Cu through-Si-vias (TSVs) on the retention characteristics of 20-μm-Thick, vertically stacked dynamic random access memory (DRAM) chip has been investigated. At cumulative probability of 50 %, the retention period decreased nearly 47% for the DRAM chip having thickness value of 20 μm as compared to the retention period of 200 μm-Thick DRAM chip. Annealing at 300 °C, a compressive stress value of-200 MPa caused by Cu-TSVs was observed as the remnant stress at the periphery of the keep-out-zone, and faded quickly by moving away from the keep-out-zone. We did observe tle dependency of DRAM retention time on the TMS caused by TSVs. In the case of μ-bump, we observed a large amount of tensile stress (> +300 MPa) on the back-side of DRAM chip at right above the CuSn μ-bumps, and it led to a crack in the DRAM chip. As compared to CuSn μ-bumps, the polyimide dummy μ-bumps present in between two chip layers induced less amount of residual stress in the DRAM chip.

Original languageEnglish
Title of host publicationProceedings - ECTC 2016
Subtitle of host publication66th Electronic Components and Technology Conference
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages50-55
Number of pages6
ISBN (Electronic)9781509012039
DOIs
Publication statusPublished - 2016 Aug 16
Event66th IEEE Electronic Components and Technology Conference, ECTC 2016 - Las Vegas, United States
Duration: 2016 May 312016 Jun 3

Publication series

NameProceedings - Electronic Components and Technology Conference
Volume2016-August
ISSN (Print)0569-5503

Other

Other66th IEEE Electronic Components and Technology Conference, ECTC 2016
CountryUnited States
CityLas Vegas
Period16/5/3116/6/3

Keywords

  • Cu-TSV
  • CuSn ?-bump
  • Thermo-mechanical stress
  • Thinned DRAM

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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