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Detailed Program
Paper Number : PI-P01
Time Frame : 12:00~13:30
Presentation Date : Thursday, 27, November
Session Name : Piezoelectric Device & Application
Session Chair 1# : -
Session Chair 2# : -
Fabrication of Piezoelectric Micromachined Ultrasonic Transducer (pMUT) Using Aerosol Deposition Method
Mr. Joontaek Jung
Daegu Gyeongbuk Institute of Science and Technology
Sol-gel method is widely adapted for the fabrication of piezoelectric micromachined ultrasonic transducer (pMUT) to deposit piezoelectric thin-film, mostly lead zirconate titanate (PZT). However, sol-gel process requires enormous time and efforts for solution preparation and film deposition. Also, the thickness of PZT layer deposited by sol-gel method is limited to few microns in a wafer scale, which may limit the actuation power of the pMUT. To overcome these shortcomings, aerosol deposition (AD) method is introduced to deposit PZT layer for pMUT. This paper presents the fabrication process using aerosol deposition method of pMUT and characterizes the performance of device. The fabrication process for aerosol deposition was conducted at room temperature with high deposition rate of ~5 µm/min. The fabrication process starts from the 5 µm PECVD SiO2 deposition process on the 6 inch Si wafer, which works as an insulating and etching stop layer for deep reactive ion etching (DRIE) process. Titanium and Platinum was deposited as an adhesion layer and bottom electrode, respectively. SU-8 2010 photoresist was used for lift-off process for AD PZT patterning. Platinum was deposited as a top electrode and patterned using SU-8. After patterning, annealing was processed at 650 degree Celsius during 1 hour for grain growth. Aluminum masking and back DRIE process was done for the last fabrication step. The fabricated 7 x 7 pMUT array is shown in figure 1. The performance of the device was represented by its hysteresis curve and impedance peaks. pMUT using AD PZT is expected to present comparable coupling coefficient with the sol-gel based pMUT while enormously reducing the fabrication efforts. The advantages and difficulties of pMUT using AD method are discussed.
Acknowledgements : This work was supported by a Ministry of Science, ICT and Future Planning of Korea grant funded by the Korea government (No. PNK3771) and Office of Naval Research.