Low-temperature and low pressure copper-to-copper direct bonding enabled by creep on highly (111)-oriented Cu surfaces

Chih Han Tseng, Chien Min Liu, Han Wen Lin, Yi Cheng Chu, Chih Chen*, Dian Rong Lyu, Kuan-Neng Chen, King-Ning Tu

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

2 Scopus citations

Abstract

Cu-to-Cu microbumps have many advantages, such as better electrical and thermal conductivities. The Cu-to-Cu microbumps may be a potential solution to the heat dissipation problem in 3D IC integration. In addition, for packaging of CMOS image sensors, the bonding temperature is preferred to below 200 °C. Therefore, low temperature and low pressure Cu-to-Cu direct is of great interests for packaging industry. However, it is a challenging issue because Cu atoms diffuse slowly below 200 °C. In this study, we achieved low temperature and low pressure Cu bonding using highly (111)-orientated Cu films. Because the diffusivity of Cu atoms on the (111) surface diffusivity is the fastest among all the crystallographic planes of Cu. The bonding temperature can be lowered to 150°C at a compressive stress of 114 psi held for 60 min at 10-3 torr. Since the melting points of popular Pb-free solders such as SnAg and SnAgCu are over 230°C. Therefore the present technique can be applied to packaging of CMOS image sensors and 3D IC integration.

Original languageEnglish
Title of host publicationICEP-IAAC 2015 - 2015 International Conference on Electronic Packaging and iMAPS All Asia Conference
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages523-526
Number of pages4
ISBN (Electronic)9784904090138
DOIs
StatePublished - 20 May 2015
Event2015 International Conference on Electronic Packaging and iMAPS All Asia Conference, ICEP-IAAC 2015 - Kyoto, Japan
Duration: 14 Apr 201517 Apr 2015

Publication series

NameICEP-IAAC 2015 - 2015 International Conference on Electronic Packaging and iMAPS All Asia Conference

Conference

Conference2015 International Conference on Electronic Packaging and iMAPS All Asia Conference, ICEP-IAAC 2015
CountryJapan
CityKyoto
Period14/04/1517/04/15

Keywords

  • 3DIC
  • Cu-Cu
  • direct bonding
  • nanotwin

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