Title page for ETD etd-02202009-182950

Type of Document

Master's Thesis

Author

Song, Wenyu

URN

etd-02202009-182950

Title

Two-dimensional Microscanners with T-shaped Hinges and Piezoelectric Actuators

Degree

Master of Science in Electrical Engineering (M.S.E.E.)

Department

Electrical & Computer Engineering

Advisory Committee

Advisor Name	Title
Dooyoung Hah	Committee Chair
Martin Feldman	Committee Member
Theda Daniels-Race	Committee Member

Keywords

actuator
piezoelectric
optical scanner
MEMS

Date of Defense

2009-02-11

Availability

unrestricted

Abstract

For a wide range of application areas such as medical instruments, defense, communication networks, industrial equipment, and consumer electronics, microscanners have been a vibrant research topic. Among various fabrication methodologies, MEMS (microelectromechanical system) stands out for its small size and fast response characteristics. In this thesis, piezoelectric actuation mechanism is selected because of its low voltage and low current properties compared with other mechanisms, which are especially important for the target application of biomedical imaging. Although 1- and 2-dimensional microscanners with piezoelectric actuators have been studied by several other groups, this thesis introduces innovative improvements in design of the piezoelectric MEMS microscanner. A novel T-shaped hinge geometry is proposed, which is flexible in whole six directions and also free from the crosstalk issue found in the earlier designs by other groups.
The piezoelectric actuator of the microscanner is comprised of five layers; a top electrode, a piezoelectric layer (lead zirconate titanate or PZT), a bottom electrode, a dielectric layer, and a mechanical support. The microscanners were analyzed using both analytical formulas and numerical simulations. Based on the analysis, the microscanners were designed and fabricated with four mask levels¯top electrodes, bottom electrodes, bonding pads, and substrate etching windows. During the silicon substrate wet etching process in KOH, ProTEK@ B3 was coated in the front to protect the devices.
Polarization-voltage (P-V) measurement of deposited PZT was performed using RT66B. Actuation of the piezoelectric cantilevers were observed under a microscope by applying voltage.

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