Effect of Au Film Thickness and Surface Roughness on Room-Temperature Wafer Bonding and Wafer-Scale Vacuum Sealing by Au-Au Surface Activated Bonding

Au-Au surface activated bonding (SAB) using ultrathin Au films is effective for room-temperature pressureless wafer bonding. This paper reports the effect of the film thickness (15-500 nm) and surface roughness (0.3-1.6 nm) on room-temperature pressureless wafer bonding and sealing. The root-mean-sq...

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Bibliographic Details
Published in:Micromachines (Basel) 2020-04, Vol.11 (5), p.454
Main Authors: Yamamoto, Michitaka, Matsumae, Takashi, Kurashima, Yuichi, Takagi, Hideki, Suga, Tadatomo, Takamatsu, Seiichi, Itoh, Toshihiro, Higurashi, Eiji
Format: Article
Language:English
Subjects:
Au-Au bonding
heterogeneous integration
room-temperature bonding
surface activated bonding
wafer bonding
wafer sealing
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Summary:Au-Au surface activated bonding (SAB) using ultrathin Au films is effective for room-temperature pressureless wafer bonding. This paper reports the effect of the film thickness (15-500 nm) and surface roughness (0.3-1.6 nm) on room-temperature pressureless wafer bonding and sealing. The root-mean-square surface roughness and grain size of sputtered Au thin films on Si and glass wafers increased with the film thickness. The bonded area was more than 85% of the total wafer area when the film thickness was 100 nm or less and decreased as the thickness increased. Room-temperature wafer-scale vacuum sealing was achieved when Au thin films with a thickness of 50 nm or less were used. These results suggest that Au-Au SAB using ultrathin Au films is useful in achieving room-temperature wafer-level hermetic and vacuum packaging of microelectromechanical systems and optoelectronic devices.
ISSN:2072-666X
2072-666X
DOI:10.3390/mi11050454