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

We achieve low-temperature Cu-to-Cu direct bonding using highly (111)-orientated Cu films. The bonding temperature can be lowered to 200°C at a stress of 114psi for 30min at 10−3torr. The temperature is lower than the reflow temperature of 250°C for Pb-free solders. Our breakthrough is based on the...

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Bibliographic Details
Published inScripta materialia Vol. 78-79; pp. 65 - 68
Main Authors Liu, Chien-Min, Lin, Han-wen, Chu, Yi-Cheng, Chen, Chih, Lyu, Dian-Rong, Chen, Kuan-Neng, Tu, K.N.
Format Journal Article
LanguageEnglish
Published Elsevier Ltd 01.05.2014
Subjects
BONDING
Copper
Creep
Creep (materials)
CREEP PROPERTIES
Cu-to-Cu direct bonding
DIFFUSION
Diffusivity
Lead (metal)
Planes
Preferred orientation
SOLDERING ALLOYS
Solders
Surface diffusion
Creep
Diffusion
Cu-to-Cu direct bonding
Preferred orientation
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Summary:We achieve low-temperature Cu-to-Cu direct bonding using highly (111)-orientated Cu films. The bonding temperature can be lowered to 200°C at a stress of 114psi for 30min at 10−3torr. The temperature is lower than the reflow temperature of 250°C for Pb-free solders. Our breakthrough is based on the finding that the Cu (111) surface diffusivity is the fastest among all the planes of Cu and the bonding process can occur through surface diffusion creep on the (111) surfaces.
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ISSN:1359-6462
1872-8456
DOI:10.1016/j.scriptamat.2014.01.040