Low temperature bonding of LiNbO3 waveguide chips to Si substrates in air

Ryo Takigawa, Eiji Higurashi, Tadatomo Suga, Satoshi Shinada, Tetsuya Kawanishi

Research output: Contribution to journalConference articlepeer-review


This paper describes the low-temperature bonding of a lithium niobate (LiNbO3) waveguide chip to a silicon (Si) substrate for integrated optical systems. The bonding was achieved by introducing the surface activation by plasma irradiation into the flip-chip bonding process. After the surfaces of the Au thin films (thickness: 100 nm) of the LiNbO3 chip and the Si substrate were cleaned using an Ar radio frequency (RF) plasma, Au-Au bonding was carried out only by contact in ambient air with applied static pressure. The bonded chips fractured at bonding temperature higher than 150°C because of the coefficient of thermal expansion (CTE) mismatch. The LiNbO3 chips were successfully bonded to the Si substrates at relatively low temperature (100°C). The die-shear strength of the LiNbO3 chip was estimated to be more than 12 kg (3.8 MPa), the upper limit of our shear testing equipment.

Original languageEnglish
Article number605012
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2005
Externally publishedYes
EventOptomechatronic Micro/Nano Devices and Components - Sappora, Japan
Duration: Dec 5 2005Dec 7 2005

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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