Room-Temperature Bonding of Wafers with Smooth Au Thin Films in Ambient Air Using a Surface-Activated Bonding Method

Eiji HIGURASHI  Ken OKUMURA  Yutaka KUNIMUNE  Tadatomo SUGA  Kei HAGIWARA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E100-C   No.2   pp.156-160
Publication Date: 2017/02/01
Online ISSN: 1745-1353
Type of Manuscript: INVITED PAPER (Special Section on Fabrication Technologies Supporting the Photonic/Nanostructure Devices)
Category: 
Keyword: 
heterogeneous integration,  room-temperature bonding,  surface-activated bonding,  Au-Au bonding,  

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Summary: 
Wafers with smooth Au thin films (rms surface roughness: < 0.5nm, thickness: < 50nm) were successfully bonded in ambient air at room temperature after an Ar radio frequency plasma activation process. The room temperature bonded glass wafers without any heat treatment showed a sufficiently high die-shear strength of 47-70MPa. Transmission electron microscopy observations showed that direct bonding on the atomic scale was achieved. This surface-activated bonding method is expected to be a useful technique for future heterogeneous photonic integration.