CAREER: Piezoelectric Microelectromechanical Systems

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9501698 Kim It is proposed to develop Piezoelectric Microelectromechanical Systems (PMS) through combining piezoelectricity, microelectromechanical-systems (MEMS) technology and IC-microfabrication technology. Recent development of MEMS has opened up many new applications due to their small size, easiness of forming large number of arrays, integrability with circuits on a single chip, etc. However, major activities in MEMS have involved electrostatic (or thermal) actuation and capacitive (or piezoresistive) sensing that have some inherent characteristics unsuitable in some applications. PMS expand the application areas of MEMS due to their unique and promising features that are not offered by electrostatic, thermal, capacitive, or piezoresistive MEMS. The proposed research takes full advantages offered by piezoelectric actuation and sensing. Specifically proposed for sensing PMS are dome-shaped piezoelectric microphones on silicon that can detect the direction of sound source as well. For actuating PMS, the following systems are proposed: 1) dome-shaped microspeakers with beam forming and steering capability and 2) focused acoustic beam generators without acoustic lens. Also proposed are lateral-field-excited bulk-acoustic-wave resonators for high-frequency (Ghz) filters and oscillators. Since the residual stresses coming from piezoelectric thin film has been the major performance limiting factor for PMS, it is proposed to develop (into manufacturable technology) our novel idea of using mechanical-vibrational energy to increase surface-adatom mobility during sputter-deposition of piezoelectric thin film for residual-stress reduction. Various educational activities are proposed (1)to show the students how exciting an engineering is; (2)to inspire the students to develop right attitude (toward technical problems), proper analytical skills (to solve the problems) ingenuity and life-long-learning attitude; and (3)to teach the students the specific knowledge in the area of solid-stat e devices. Specifically, new courses on sensors and actuators are proposed. Through the proposed pre-college educational activities the general public and secondary-school students in the State at Hawaii will be drawn closer to engineering. Through senior projects, design projects and research projects the students will closely interact with an inspiring professor and engineers in industry. ***