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Micromachines 2011, 2(1), 49-68; doi:10.3390/mi2010049

Self-Assembly of Chip-Size Components with Cavity Structures: High-Precision Alignment and Direct Bonding without Thermal Compression for Hetero Integration

1
New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8579, Japan
2
Department of Bioengineering and Robotics, Graduate School of Engineering, Tohoku University, Sendai, Japan
3
Micro/Nano-Machinning Research and Education Center (MNC), Graduate School of Engineering, Tohoku University, Sendai, Japan
4
Department of Biomedical Engineering, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
*
Author to whom correspondence should be addressed.
Received: 7 December 2010 / Revised: 16 January 2011 / Accepted: 17 January 2011 / Published: 18 February 2011
(This article belongs to the Special Issue Self-Assembly)

Abstract

New surface mounting and packaging technologies, using self-assembly with chips having cavity structures, were investigated for three-dimensional (3D) and hetero integration of complementary metal-oxide semiconductors (CMOS) and microelectromechanical systems (MEMS). By the surface tension of small droplets of 0.5 wt% hydrogen fluoride (HF) aqueous solution, the cavity chips, with a side length of 3 mm, were precisely aligned to hydrophilic bonding regions on the surface of plateaus formed on Si substrates. The plateaus have micro-channels to readily evaporate and fully remove the liquid from the cavities. The average alignment accuracy of the chips with a 1 mm square cavity was found to be 0.4 mm. The alignment accuracy depends, not only on the area of the bonding regions on the substrates and the length of chip periphery without the widths of channels in the plateaus, but also the area wetted by the liquid on the bonding regions. The precisely aligned chips were then directly bonded to the substrates at room temperature without thermal compression, resulting in a high shear bonding strength of more than 10 MPa. View Full-Text
Keywords: self-assembly; room-temperature bonding; direct bonding; liquid; surface tension; cavity chip; hetero integration self-assembly; room-temperature bonding; direct bonding; liquid; surface tension; cavity chip; hetero integration
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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MDPI and ACS Style

Fukushima, T.; Konno, T.; Iwata, E.; Kobayashi, R.; Kojima, T.; Murugesan, M.; Bea, J.-C.; Lee, K.-W.; Tanaka, T.; Koyanagi, M. Self-Assembly of Chip-Size Components with Cavity Structures: High-Precision Alignment and Direct Bonding without Thermal Compression for Hetero Integration. Micromachines 2011, 2, 49-68.

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