靜電式微振鏡元件製作之探討

Abstract

本論文主旨在探討靜電式微振鏡元件之製作。運用特殊之(111)正向異方蝕刻矽微加工技術，製作出微間距浮板結構。浮板的組成是以富矽氮化矽為主要結構，於其表面加以一金屬電極層。當於金屬電極與矽基板間加一電位差，浮板因受到靜電力作用而產生機械式的形變，如此即可達到元件振動之目的。本研究中元件的工作模式隨浮板形狀與金屬電極設計不同而異，大致可區分為兩種：一為平移式微振鏡元件，一為扭轉式微振鏡元件。實際完成之元件前者量測的結果，加以100伏特的電壓，垂直平移約1.9微米。後者加以相同電壓，則元件扭轉角度約 ±2度，並量得元件之第一共振頻率在16.5仟赫茲。最後對於製程上所遇到的問題及改進的方法加以探討分析。

In this thesis, we study on the fabrication of an electrostatic vibrational micromirror. Based on Si (111) front-side anisotropic etching technique of micromachining, we can fabricate a floating membrane of shallow gap. The membrane consists of the major structural layer of silicon rich nitride and the electrode layer of metals. When a potential difference is applied to the metal-electrode and the substrate, mechanical deformation such as displacement and tilt of the membrane results from the creating of an electrostatic force, and then the device vibrates. According to the difference of the shapes of membrane and metal-electrode, we can divide the fabricated devices into two operating modes, vertically vibrational micromirror and torsionally vibrational micromirror. In optical measurement, the former has a 1.9μm vertical displacement as a 100Volt voltage is applied. The latter has a tilt of either +2 degrees or –2 degrees as the same voltage is applied, and we obtain its first resonance frequency at about 16.5KHz. At last, we discuss what problems we experience and how to improve in fabrication process.