Electroplated Al Press Marking for Wafer-Level Bonding

Heterogeneous integration of micro-electro mechanical systems (MEMS) and complementary metal oxide semiconductor (CMOS) integrated circuits (ICs) by 3D stacking or wafer bonding is an emerging approach to advance the functionality of microdevices. Aluminum (Al) has been of interest as one of the waf...

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Bibliographic Details
Published in:Micromachines (Basel) 2022-07, Vol.13 (8), p.1221
Main Authors: Al Farisi, Muhammad Salman, Tsukamoto, Takashiro, Tanaka, Shuji
Format: Article
Language:English
Subjects:
Aluminum
Bonding strength
CMOS
Complementary metal oxide semiconductors
Deformation
electroplating
Grain boundaries
Grooves
High temperature
Integrated circuits
Internet of Things
Marking
Mechanical systems
MEMS
Metal oxides
Microelectromechanical systems
Plasma
Plating
press marking
Semiconductor chips
Shear strength
Substrates
wafer bonding
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Summary:Heterogeneous integration of micro-electro mechanical systems (MEMS) and complementary metal oxide semiconductor (CMOS) integrated circuits (ICs) by 3D stacking or wafer bonding is an emerging approach to advance the functionality of microdevices. Aluminum (Al) has been of interest as one of the wafer bonding materials due to its low cost and compatibility with CMOS processes. However, Al wafer bonding typically requires a high temperature of 450 °C or more due to the stable native oxide which presents on the Al surface. In this study, a wafer bonding technique for heterogeneous integration using electroplated Al bonding frame is demonstrated. The bonding mechanism relies on the mechanical deformation of the electroplated Al bonding frame through a localized bonding pressure by the groove structures on the counter wafer, i.e., press marking. The native oxide on the surface was removed and a fresh Al surface at the bonding interface was released through such a large mechanical deformation. The wafer bonding was demonstrated at the bonding temperatures of 250–450 °C. The influence of the bonding temperature to the quality of the bonded substrates was investigated. The bonding shear strength of 8–100 MPa was obtained, which is comparable with the other Al bonding techniques requiring high bonding temperature.
ISSN:2072-666X
2072-666X
DOI:10.3390/mi13081221