PZT壓電微致動器之製程與鐵電特性研究

Abstract

PZT薄膜所具有優越之壓電特性在微機電系統之感測器與致動器中扮演重要的角色。在本文以Sol-gel法製作PZT壓電薄膜並結合以微細加工技術製成之微懸臂樑與微懸膜製作出PZT壓電微致動器並建立其一套製作流程系統。其中PZT薄膜成長於白金之電極上，並發現各種介於Si3N4或SiO2之白金附著金屬層會影響PZT薄膜之顯微結構與結晶相結構。此外觀察微懸臂樑之偏折量來分析各層薄膜間產生的殘留應變量，進而調整各層薄膜的厚度來改善微懸臂樑之平整狀況。製作出疊層之PZT微致動器，以有限元素模擬分析單層與疊層之PZT微懸臂樑與微懸膜，並探討單層及疊層結構對於微動器性能上產生之差異。製作完成之微致動動器，利用都普勒干涉儀進行壓電效應之靜態與動態量測，證實微動器能成功運作。

The superior piezoelectric properties of ferroelectric materials make it suitable for micro-actuators applications. In this work, sol-gel process was used to deposit the PZT film on a 4” Si wafer by multiple spin-coating. By using micromaching technology, the fabrication process of a piezoelectric micro-actuator based on PZT-film micro-diaphram and cantilever-type structure has been developed. It was found that the adhesion metal in between Pt and Si3N4 or SiO2 has strong influence on phase crystallization and microstructure evolution of PZT films. The deflection of micro-cantilever beam was also evaluated in order to analyze the residual strain and flat effect of PZT beam by changing the layer thickness of Pt/PZT/Pt/Ta/ Si3N4 /Si structure. In addition, the fabrication process and physical characteristics of bi-layer PZT film structure was also developed. Finite element (FEM) simulation was further performed to discuss the difference between single layer and bi-layer PZT-film structure. The piezoelectric response of the PZT-based micro-actuator at static and resonant condition is measured by the Doppler interferometer that further demonstrates that it (PZT-film actuator) works properly.