Title page for etd-0731106-100342


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URN etd-0731106-100342
Author Chi-ching Liu
Author's Email Address No Public.
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Department Electrical Engineering
Year 2005
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title The Study of ZnO Piezoelectric Thin Film Prepared by Two-Step Sputtering for FBAR Application
Date of Defense 2006-07-18
Page Count 124
Keyword
  • FBAR
  • ZnO
  • Abstract In this study, a two-step deposition method using RF
    reactive magnetron sputtering is proposed to obtain high quality Piezoelectric ZnO thin films for film bulk acoustic resonators (FBARs). The titanium (Ti) seeding layer and platinum (Pt) bottom electrode were deposited by a dual gun DC sputtering system. The properties of thin film are investigated using the scanning electron
    microscope (SEM), Atomic force microscope (AFM) and the
    four-point probe method. The results show that the Pt bottom electrode deposited on the Ti seeding layer has lots of favorable characteristics, such as the crystallite size smaller than 10 nm, a surface roughness of 0.69 nm and a sheet resistance of 0.26 Ω/□. The bottom electrode with the low resistance and the low surface roughness contribute markedly to the performances of the FBAR device.
    The Ttwo-step deposition method was adopted for ZnO thin
    film deposition, The 1st step deposition is focused on lowering the surface roughness of ZnO seeding layer films. The c-axis preferred orientation of ZnO film This is accompanied by the 2nd step deposition where the sputtering parameters O2 concentration arewere controlled to enhance the c-axis preferred growth of ZnO films. The AFM image shows that the surface roughness of the ZnO film is drastically reduced. It is also observed by monitoring the XRD spectra that the films deposited by two-step method reveal the high c-axis preferred orientation.
    Finally, the frequency response of ZnO-FBAR device using the two-step sputtering method shows the excellent performance at center frequency of 1.804GHz with the return loss of nearly 60dB and the electro-mechanical coupling coefficient of 3.2%.
    Advisory Committee
  • Chao-ming Fu - chair
  • Rumg-sheng Guo - co-chair
  • Chien-chuan Cheng - co-chair
  • Ying-chung Chen - advisor
  • Files
  • etd-0731106-100342.pdf
  • indicate access worldwide
    Date of Submission 2006-07-31

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