類LIGA製程應用於靜電式微致動器光開關之研製

Abstract

微機電系統技術中整合光刻術、電鑄及模造成型之深光刻電鑄模造(LIGA)製程，是批量生產高深寬比微元件的最佳方法。標準的LIGA製程使用同步輻射X光為光刻源，可製作次微米精度之微結構，但因其製程成本高、程序複雜、時程長，使得以紫外光、準分子雷射或電漿作為光源的類LIGA製程成為另一種發展趨勢。 本研究目的是利用類LIGA與厚膜製程結合的方式，低成本且快速地開發微光學應用之微反射鏡式光開關元件。本研究所製作之微光開關，依其結構所使用之材料，即微致動器與微反射鏡為結構材料，一是全為SU-8之厚膜製程，另一為UV-LIGA製程鎳電鑄結合SU-8厚膜製程之光開關，採用同一組光罩，兩種不同製程，並成功的製作出以一體成型之微光開關結構，其優點如下：低成本、可降低微反射鏡因組裝所造成的誤差，利用間接驅動方式增加微反射鏡的作動行程，以增進光路切換的適用範圍。 本研究微反射鏡式光開關採用靜電式致動器，鍍金屬膜後，成功地以AC125伏特電壓驅動；微反射鏡對光波長632nm之可光源與光波長1550nm之紅外光源皆有反射效能，其反射效率分別為17.6% 及20.5% 。

LIGA process, which combines x-ray deep lithography, electroforming and micromolding techniques, is a major method for fabricating sub-micro microstructures with very high aspect ratio and batch production. However, standard LIGA whose lithographic source is x-ray synchrotron radiation is high cost, complex procedure and time-consuming. Thus several analogous processes, including UV-LIGA and Laser-LIGA processes, have been developed to overpass the barrier.

In our work, we have developed electrostatic optical switch which was used UV-LIGA and thick film process. Optical switch was used one set of masks for two processes. One was all SU-8 thick film process, another was UV-LIGA combined SU-8 thick film process. We have finished optical switch which was all in one not assembled. Advantages of optical switch are low cost, decrease micro structures assembled tolerances and increase active range of micromirror by being driven indirectly.

In our study, Actuators of optical switch which was sputtered metal are driven by AC 125V. Reflective ratio of micromirror is 17.6% in visible wavelength (632nm) and 20.5% in IR wavelength (1550nm).