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Proceedings Paper

Low-temperature bonding of a LiNbO3 waveguide chip to a Si substrate in ambient air for hybrid-integrated optical devices
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Paper Abstract

We report the low-temperature bonding of a lithium niobate (LiNbO3) chip with gold (Au) thin film to a silicon (Si) substrate with patterned Au film for hybrid-integrated optical devices. The bonding was achieved by introducing the surface activation by plasma irradiation into the flip-chip bonding process. After the Au thin film (thickness: 500 nm) on the LiNbO3 chip (6 mm by 6 mm) and the patterned Au film (thickness: 2 μm) on the Si substrate (12 mm by 12 mm) were cleaned by using argon (Ar) radio-frequency (RF) plasma, Au-Au bonding was carried out in ambient air with applied static pressure (~50 kgf). The LiNbO3 chips were successfully bonded to the Si substrates at relatively low temperature (< 100 °C). However, when the bonding temperature was increased to be greater than 150 °C, the LiNbO3 chips cracked during bonding. The tensile strength (calculated by dividing the total cross-sectional area of the initial, undeformed micropatterns) of the interface was estimated to be about 70 MPa (bonding temperature: 100 °C). It was sufficient for use in optical applications. These results show the potential for producing highly functional optical devices and for low-cost packaging of LiNbO3 devices.

Paper Details

Date Published: 18 October 2006
PDF: 7 pages
Proc. SPIE 6376, Optomechatronic Micro/Nano Devices and Components II, 637603 (18 October 2006); doi: 10.1117/12.690741
Show Author Affiliations
Ryo Takigawa, The Univ. of Tokyo (Japan)
Eiji Higurashi, The Univ. of Tokyo (Japan)
Tadatomo Suga, The Univ. of Tokyo (Japan)
Satoshi Shinada, National Institute of Information and Communications Technology (Japan)
Tetsuya Kawanishi, National Institute of Information and Communications Technology (Japan)

Published in SPIE Proceedings Vol. 6376:
Optomechatronic Micro/Nano Devices and Components II
Yoshitada Katagiri, Editor(s)

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