CAREER: Piezoelectric Microelectromechanical Systems

9501698 Kim提出将压电、微机电系统（MEMS）技术和集成电路微加工技术相结合，发展压电微机电系统（PMS）。MEMS具有体积小、易于形成大量阵列、可与单芯片上的电路集成等优点，近年来的发展开辟了许多新的应用领域。然而，MEMS的主要活动涉及静电（或热）驱动和电容（或压阻）传感，它们具有一些不适合某些应用的固有特性。PMS扩展了MEMS的应用领域，因为它们具有静电、热、电容或压阻MEMS所不具备的独特和有前途的特性。本研究充分利用了压电驱动和传感技术的优势。特别提出了一种可以探测声源方向的硅基圆顶型压电传声器。为了驱动PMS，提出了以下系统：1)具有波束形成和转向能力的圆顶微型扬声器；2)没有声透镜的聚焦声波束发生器。此外，还提出了用于高频（Ghz）滤波器和振荡器的横向场激发体声波谐振器。由于来自压电薄膜的残余应力一直是PMS的主要性能限制因素，因此我们提出了在溅射沉积压电薄膜过程中利用机械振动能量来提高表面原子迁移率以减少残余应力的新想法（可制造技术）。提出了各种教育活动(1)向学生展示工程是多么令人兴奋；(2)激发学生培养正确的态度（面对技术问题）、正确的分析能力（解决问题）、聪明才智和终身学习的态度；(3)教授学生固态器件领域的具体知识。具体而言，提出了传感器和执行器的新课程。通过提议的大学前教育活动，夏威夷州的普通公众和中学生将更接近工程学。通过高级项目、设计项目和研究项目，学生将与鼓舞人心的教授和行业工程师密切互动。＊＊＊

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. ***