Fabrication of (111) nanotwinned Cu and its applications in interconnects of microelectronic devices

Chih Chen*, Chien-Min Liu, Tien-Lin Lu, Han-wen Lin, Yi-Cheng Chu, Chia-Ling Lu, Jing-Ye Juang, Kuan-Neng Chen, King-Ning Tu

*Corresponding author for this work

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

Abstract

As the miniaturization trend of microelectronic devices continues, the dimension of interconnects also decreases gradually. The dimensions of Cu lines and solder joints shrink dramatically. Several challenges arise due to the scaling. First, the diameter of solder joints reduces from 70 μm to 20 μm, and it will be further scaled down in the future. Due to the dramatic decrease in solder volume, the yield and the brittleness of intermetallic compounds will become challenges in the fabrication of microbumps. Therefore, solders might be removed from the joints in the future and Cu joints may replace the solder joints for fine-pitch packaging. Low-temperature Cu-to-Cu direct bonding appears to be one of the solutions for fine-pitch microbumps for 3D IC packaging. However, the high bonding temperature and pressure are the main problems of this approach. We achieve low-temperature Cu-to-Cu direct bonding at low pressure and ordinary vacuum by highly (111) nanotwinned Cu (nt-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, or at 200°C for 30 min. Excellent bonding interface can be obtained by bonding two highly (111)-oriented nt-Cu films. Our breakthrough is based on the finding that the diffusivity of Cu atoms on (111) surfaces is approximately 3-4 orders higher than other major planes.
Original languageEnglish
Title of host publication2016 IEEE INTERNATIONAL INTERCONNECT TECHNOLOGY CONFERENCE / ADVANCED METALLIZATION CONFERENCE (IITC/AMC)
PublisherIEEE
Pages27-27
Number of pages1
DOIs
StatePublished - 11 Jul 2016
EventIEEE International Interconnect Technology Conference / Advanced Metallization Conference (IITC/AMC) - San Jose, Canada
Duration: 23 May 201626 May 2016

Publication series

NameIEEE International Interconnect Technology Conference IITC
PublisherIEEE
ISSN (Print)2380-632X

Conference

ConferenceIEEE International Interconnect Technology Conference / Advanced Metallization Conference (IITC/AMC)
CountryCanada
CitySan Jose
Period23/05/1626/05/16

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