Development of PZT Microcantilever Type Actuators by Mechanical–Chemical Machining Method

• Main Authors: Quan-Lin Zhuang, 莊坤霖
• Other Authors: 吳嘉哲
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/52597437970484870740

碩士 === 國立中興大學 === 機械工程學系所 === 96 === In the reported literature fabrication process of PZT micro sensors and actuators were minute and complicated. For example, PZT suspended microstructures could be fabricated by sacrificial layers. Even though sacrificial etching is the standard semiconductor process, it is not suitable to fabricate PZT sensors and actuators for two reasons. First, sintering process of PZT layers should be heated at 650℃, and underneath photoresist could not sustain. Also, etching of PZT layers are extremely difficult because the etch rates of Pb, Zr, and Ti of PZT are quite different. In pervious works, wet etching, gas phase etching, RIE, and focus ion beam are reported to pattern PZT films. However, those methods have drawbacks such as poor etch uniformity and profile and expensive equipment and operational cost. Compared to the other methods, the micro- mechanical cutting provides the better flexibility to simplify, stabilize and economize the fabrication process. This purpose of this thesis was to use micro-mechanical cutting to fabricate PZT thin-film cantilever-base actuators. Specifically, two goals have been achieved. The first goal is to demonstrate the feasibility of using PZT thin films to actuate cantilever beams. PZT films are fabricated by sol-gel process. The resulting thickness is around 1~2μm. Fabricated thin films are used in the cantilever-based actuator whose dimension is 60mm × 10mm × 0.25mm. Experimental result shows that first resonance frequency of actuator is 115Hz and tip displacement of cantilever is up to 21.6μm. The second part is to fabricate PZT microcantilever by micro- mechanical cutting and back side etching called mechanical- chemical-machining-method（MCMM）. Since silicon wafer is hard and brittle material, this thesis also use ultrasonic vibration assistance tool to improve machining quality. Instead of making the drill vibrate by the ultrasonic actuator, a new design of PZT-driving ultrasonic workpiece wafer holder is used to ensure the high quality, high efficiency and longer life for micro tools in milling the silicon wafer. Experimental result demonstrates the ultrasonic workpiece holder could enhance the quality and efficiency in micro-mechanical machining. After finishing micro-mechanical cutting in the front side of silicon wafer, back side chemical etch is used to release cantilever from the substrate. Micro cantilever with dimension 1mm × 0.2mm ×0.03mm.