單晶矽微機電深蝕刻製程平台：以電容耦合驅動之梳狀致動器為例

The Fabrication Process of MEMS Device Based on Single Crystal Silicon and Deep Etching — Fabricating a Comb-Drive Actuator Driven by Capacitively-Coupled-Power as an Example

張超閔(Chao-Min Chang)

指導教授 ： 侯帝光 ； 陳榮順

國立清華大學/工學院/奈米工程與微系統研究所/博士(2012年)

https://doi.org/10.6843/NTHU.2012.00267

摘要

近年來，微機電系統（Micro-Electro-Mechanical System，簡稱 MEMS）在消費性電子產品被大量應用。這可歸功於製程技術持續開發，元件設計不斷創新。本研究繼續上述工作，以單晶矽晶圓為基材，配合高深寬比製程技術，設計新式犧牲結構取代原有犧牲層，以此提出一新式微機電製程平台，並開發了一個新式微致動器。
在製程方面，本研究利用深蝕刻技術蝕穿單晶矽晶片，使元件結構厚度或溝渠垂直深度可達矽晶片之全厚度，且有效降低製程複雜度。此外，利用低阻值矽晶片，使元件能從厚度方向進行電流傳遞，易與其它元件進行垂直方向整合。上述優點使微機電元件具備三維整合的可行性，增加元件設計的靈活性。
在平台製程能力的驗證上，本文以梳狀靜電致動器作為研究對象。本研究以上述製程平台製作單晶矽微致動器，並加以測試。初步驗證此製程平台在梳狀靜電致動器製造上之可行性。此外，本研究將元件與印刷電路板相互接合，驗證此製程平台三維整合之可行性。
在元件方面，本研究提出並討論新式驅動機制來驅動梳狀靜電致動器。此梳狀靜電致動器的梳狀手指數量或初始重疊面積是不對稱的。當施加不同大小的電壓於兩邊的定子上，轉子會因為電容耦合效應感應出一個電壓，轉子兩邊將有不同的電位能而使轉子致動。此元件利用上述製程平台製作，比對實驗量測與理論分析結果，顯示電容耦合機制可成功用於致動梳狀致動器。此驅動方式有效解決異質元件電性連接問題，降低異質整合元件設計與驅動上的難度。且可減少製程程序與降低製程成本。

關鍵字

電容耦合

並列摘要

Recently, Micro-Electro-Mechanical Systems (MEMS) have been increasingly used in consumer electrical products, due to their progress in fabrication process and device design. Following the trend, the work further improves the process and design, which use single crystal silicon (SCS) wafers and deep etching process as the substrate and the primary step, respectively. The improvement mainly contains a release method, a fabrication platform and an actuator.
In fabrication, MEMS structures are made of SCS wafers by using deep etching process. A new fabrication platform is proposed. Either structure thickness or trench depth significantly increases, even as large as the wafer thickness. The process is significantly simplified. By using low resistance SCS wafers, electrical current freely flow through the MEMS structures, makes MEMS devices are easier integrated vertically. The foregoing features increase the feasibility of three-dimensional-MEMS. To verify the fabrication platform, a comb-drive actuator was fabricated.
In device development, a new actuation mechanism is proposed to actuate comb-drive actuators. An asymmetric configuration of the finger overlap was used to generate capacitive coupling for the actuation mechanism. When the driving voltages were applied on the stators, a voltage would be induced at the rotor due to the capacitive coupling. Then, an electrostatic force would be exerted onto the rotor due to the voltage differences between the stators and the rotor. The actuator’s static displacement and resonant frequency were theoretically analyzed. The experimental results verified the theoretical analysis. Using this method, the rotor can be fully insulated, i.e. the comb-drive actuators containing heterogeneous structures (e.g. flexible and insulating folded beams) become more practical and promising to provide an impact to MEMS technology.

並列關鍵字

capacitive coupling

參考文獻

[89]C.-M. Chang, S.-Y. Wang, R. Chen, J. A. Yeh and M. T. Hou, “A Comb-Drive Actuator Driven by Capacitively-Coupled-Power,” Sensors, vol. 12, no. 8, pp. 10881-10889, 2012.

[2]L. -S. Fan, Y. -C. Tai and R. S. Muller, “IC-processed electrostatic micromotors,” Sensors and Actuators, vol. 20, no. 1–2, pp. 41-47, 1989.

[3]R. T. Howe and R. S. Muller, “Polycrystalline and amorphous silicon micromechanical beams: annealing and mechanical properties,” Sensors and Actuators, vol. 4, pp. 447-454, 1983.

[4]R. T. Howe, “Surface micromachining for microsensors and microactuators,” Journal of Vacuum Science and Technology, Part B, vol. 6, pp. 1809-1813, 1988.

[5]W. C. Tang, T.-C. H. Nguyen and R. T. Howe, “Laterally driven polysilicon resonant microstructures,” Sensors and actuators, vol. 20, no. 1-2, pp. 25-32, 1989.