閃頻式光干涉動態量測系統之研製

Abstract

干涉顯微技術一般常應用於量測靜態與動態之特性。光干涉技術的優點為快速、非破壞及非接觸性質，且可提供高密度之橫向量測解析能力，且對表面垂直方向具優良之解析度。目前微機電系統(MEMS)已快速朝向商業化，影響其元件動態特性之主要因素在於元件設計及製造，尤其全域式光動態干涉量測技術，對於元件動態特性之檢測與分析工作，將變得相當重要。 本研究將深入探討各種光干涉顯微動態量測方法。同時研製出一套閃頻式光干涉顯微動態量測儀之實驗系統，作全域式動態量測。本研究之量測樣品為AFM探針(或稱微懸臂梁)，量測其共振頻率之模態，同時使用ANSYS有限元素法作理論動態模擬分析。閃頻動態量測之原理，在於促使白光之閃頻動作與微懸臂梁之振動頻率精準地同步，使干涉條紋獲得鎖住，所獲干涉影像之對比度接近靜態量測一樣之品質，同時再配合延遲電路，以進行不同時間之動態模態量測。三維重建技術則是採用垂直掃描法，本系統之動態量測橫向解析及垂直解析，可分別逹到1μm及1nm等級。實驗之動態量測測頻寬已達到1.067MHz，而預期可以逹到2MHz，量測振幅範圍可達數十微米以上。此動態量測系統之成功研製，使國內閃頻式光干涉動態量測技術已超越目前國際之水準。

A dynamic 3-D profilometer with nano-scale measurement resolution was successfully developed using stroboscopic illumination and white-light vertical scanning techniques. Microscopic interferometry is a powerful technique for static and dynamic characterization of micro electromechanical systems (MEMS). The optical interferometry technique is quick, non-destructive, non-contact, and can offer a high density lateral resolution with excellent depth measurement sensitivity. As MEMS devices move rapidly towards commercialization, the issue of accurate dynamic characterization has emerged as a major challenge in their design and fabrication process. In view of this need, previous theory of various optical interferometry systems and technologies for dynamic 3-D surface profilometry were carefully investigated. Furthermore, a microscopic prototype based on white-light stroboscopic interferometry using vertical scanning principle was developed to achieve dynamic full-field profilometry and characterization of MEMS devices. A micro cantilever beam used in AFM was measured to verify the system capability and use ANSYS to make the dynamic simulation analysis of the theory. Using the developed measurement system, the measurement bandwidth can reach a vibration resonant frequency of 1.067 kHz or higher. The MEMS systems or component can be fully characterized with a lateral resolution up to 1 μm and a vertical measurement resolution up to 1 nm, as well as tens micrometers of vertical measurement range can be achieved. Evaluated on the performance of the stroboscopic light and control unit, it confirmed that the dynamic measurement frequency bandwidth of the developed system can reach up to 2MHz or higher.