Fabrication and analysis of MEMS resonator
Date Issued
2007
Date
2007
Author(s)
Lin, Ming-Feng
DOI
zh-TW
Abstract
In this thesis, the Film Bulk Acoustic Resonator (FBAR) has been fabricated by stacking various layers of Al/ZnO/Al/Si3N4 on a silicon substrate (100). The low-stress silicon nitride films were deposited on both side of the substrate by Low-pressure chemical vapor deposition (LPCVD). The upper Si3N4 layer served as a support membrane for the FBAR cantilever, while the bottom layer acted as an etching mask and selectively etched in a KOH (potassium hydroxide) wet etching process to create a cavity under the piezoelectric-active area. The piezoelectric zinc oxide (ZnO) thin film was deposited by reactive RF magnetron sputtering. The bottom and top electrodes are deposited by using thermal evaporation. The underside of the residual silicon was then removed using reactive ion etching (RIE) etching process to create a cavity under the piezoelectric-active area to form a crystal/air interface beneath the resonator.
The ZnO film was investigated using x-ray diffractometer (XRD) and scanning electron microscopy (SEM) techniques. The ZnO film showed strongly preferred orientation towards the c-axis, well-textured columnar structure.
The FBAR device piezoelectric-active area was 200×200 μm2 which consisted the ZnO film, low-stress Si3N4 membrane, top and bottom Al electrodes with thicknesses of 1.54μm, 0.2μm, 0.1μm, and 0.1μm, respectively. Simulated resonant frequency is 1.86GHz, and measured one is 1.27GHz. The experimental results provided a valuable reference for the future development of FBAR.
Subjects
薄膜體聲波共振器
氧化鋅
射頻磁控濺鍍法
氫氧化鉀
反應式離子蝕刻
FBAR
zinc oxide
RF magnetron sputtering
KOH
RIE
Type
thesis
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