One-Push方法於多角度三維SOI微結構組裝之應用

Abstract

近年來在半導體產業的發展之下，微機電製程技術有許多重大的發展。在眾多領域中對於三維微結構的要求也與日俱增，尤其在光學方面的應用對於三維微結構的角度定位要求相當嚴格。 我們最終目標為設計一微光學資訊儲存平台，因此需要精密的角度定位微結構。為了符合光學鏡面平坦度需求，因此利用SOI (Silicon On Insulator)基版上的單晶矽製造微鏡面，避免其他材質在製程中因為應力而產生翹曲。此外，我們亦將使用SU-8當結構層來製造出平面微結構，由於SU-8有良好的機械特性和低溫製程，可使往後的電路整合更加容易。 本實驗室之前已提出利用單一下壓動作 (One-Push) 即可使微鏡面成功的組裝在90° 的設計，本論文將利用此One-Push 方法，將多個垂直微鏡面結構以一次下壓動作同時組裝起來，以實現批次組裝的概念，符合未來在晶圓級組裝節省時間的需求。本論文並且提出45° 鏡面組裝方式，以便應用在光學資訊平台，同時也探討了利用SU-8光阻來當結構層對於角度定位的影響。最後，本論文也應用垂直微結構來製造角反射器(corner cube reflector)。 本論文已經成功的利用一排探針一次組裝三個微鏡面結構，比起分別組裝的時間減少了46%。同時也利用90° 微鏡面的概念製造出角反射器，並且利用光學方法量測光反射後的角度誤差為1.19° ± 0.4°。對於原始90°結構的誤差問題提出造成誤差的原因以及改善方式，使得角度從89.2 ± 0.3°改善為89.8 ± 0.3°。最後，本論文製造出45° 三維微結構，平均角度為45.9 ± 0.2°，未來可以應用於其他角度的微結構。然而扭力樑的設計有所不當，造成扭力樑回復力太大使結構產生變形，未來仍有改善空間。

Recently, the Micro Electro Mechanical Systems (MEMS) technology has many important developments with the rapid progress in the semiconductor industry. Many applications demand three-dimensional (3-D) structures. Especially in optics, the angular accuracy of the 3-D microstructures is important. In this thesis, silicon on insulator (SOI) wafers with almost zero stress are used to avoid stress-induced curvature for optical applications. SU8 has good mechanical property and low process temperature, making it suitable for another structural layer and integration with circuit. In our previous study, micromirrors were assembled using a novel simple one-push operation. In this thesis, batch assembly of more than one 90° microstructures is demonstrated to reduce the assembly time on the wafer level in the future. An assembly method for 45° structures is proposed to be applied to the optical bench. The angular deviation due to the SU-8 structural layer is also discussed. Finally, the corner cube reflector is fabricated by two 90° out-of-plane microstructure. Three mirrors are lifted up by an array of microprobes to demonstrate batch assembly in this thesis. The assembly time is reduced by 46%, compared to assembling three mirrors individually. A corner cube is fabricated by two 90° micromirrors. The deviation of the corner cube reflector is measured optically, which is 1.19° ± 0.4°. The angular deviation of 90° structure is studied with different flip-up angles of the side latches. The 90° structures are improved from 89.2 ± 0.3° to 89.8 ± 0.3°. The design of the 45° assembly method is verified. The devices are fabricated with an average angle of 45.9±0.2°. The method can be applied to structures with any other angles. Problems encountered during the study, such as the robustness of torsional beams, are discussed for further work.