Wafer-to-wafer transfer process of barium strontium titanate for frequency tuning applications using laser pre-irradiation

Tetuo Samoto, Hideki Hirano, Toshihiro Somekawa, Kousuke Hikichi, Masayuki Fujita, Masayoshi Esashi, Shuji Tanaka

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


This paper describes laser-assisted film transfer technology for barium strontium titanate (BST) deposited on a sapphire substrate. BST is a promising ferroelectric material for varactors, which are required for frequency-tunable RF applications. However, the deposition temperature of BST (600 ∼ 700 °C) is too high for surface acoustic wave (SAW) substrates. In this study, BST grown on a sapphire substrate at 650 °C was transferred at low temperature (140 °C) to a borosilicate glass substrate as well as a LiTaO3 substrate. The transferred BST films were characterized as tunable capacitors. A key process in the BST film transfer technology is the laser pre-irradiation of a buffer Pt layer beneath BST from the backside of the sapphire substrate to weaken the BST-to-Pt adhesion. The mechanism of delamination at the BST/Pt interface is discussed using a simple 1D heat transfer model.

Original languageEnglish
Article number035015
JournalJournal of Micromechanics and Microengineering
Issue number3
Publication statusPublished - 2015 Mar 1


  • barium strontium titanate
  • laser assisted transfer process
  • lithium tantalate
  • metal-insulator-metal variable capacitor
  • wafertowafer bonding

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering


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