Atomic diffusion bonding using oxide underlayers for optical applications

G. Yonezawa, Y. Takahashi, Y. Sato, S. Abe, M. Uomoto, T. Shimatsu

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Atomic diffusion bonding of quartz glass wafers using thin Ti films, with SiO2 underlayers on wafer surfaces, provides 100% light transmittance at the bonded interface along with strong bonding energy, after post-bonded low-temperature annealing. Cross-section images obtained using transmission electron microscopy show that the bonded interface after annealing at 350 °C consists of amorphous structure including nanocrystalline grains. Structural analysis using electron energy loss spectroscopy shows that post-bonded annealing enhances oxidation of Ti with oxygen dissociated from SiO2 underlayers, and that Ti oxides form close to TiO2 or Ti4O7. This oxidation provides 100% light transmittance with high bonding strength attributable to the annealing. Moreover, we applied this technique for bonding glass and sapphire wafers using SiO2-Nb2O5 underlayers, demonstrating that 100% light transmittance and control of refractive index matching are achieved simultaneously at the bonded interface.

Original languageEnglish
Article numberSBBC03
JournalJapanese journal of applied physics
Issue numberSB
Publication statusPublished - 2020 Feb 1

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)


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