Case 10596/10597

Integrated BST Microwave Tunable Devices Using Buffer Layer Transfer Method and Fabricated on SOI Substrate


High buffer films


Tunable microwave devices, tunable mixers, oscillators, phase shifters and filters

  • Optimize high tenability and low dielectric loss
  • High buffer film fabrication techniques cause residual stress and defects


These inventions propose a method to integrate BST and related films onto Si substrates and to obtain high buffer films without defects. The method uses commercially available SOI wafers with sufficiently thick oxide layers to separate the BST based microwave device structures from the Si substrate, plus a thin, high quality, single crystalline Si top layer capable of initiating the growth of high quality epitaxial BST films on top of it. Defects in epitaxially grown ferroelectric thin films on Si substrates result from a dimensional misfit between the crystal lattices. High buffer films without residual stress and defects are obtained by using the buffer layer transfer technique by wafer bonding and ion cutting.

  • Low surface roughness
  • High quality material

  • Professor Harry L. Tuller(Department of Materials Science and Engineering, MIT)
  • Dr. Ytshak Avrahami (Department of Materials Science and Engineering, MIT)
  • Dr. II-Doo Kim (Department of Materials Science and Engineering, MIT)

Intellectual Property:
  • Case 10596: US Patent 7,579,621 issued on August 25, 2009
  • Case 10597: US Patent 7,479,696 issued on January 20, 2009



Last revised:December 2, 2010

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