利用輻射狀垂直梳型致動器驅動二維掃描微鏡片之特性分析

Abstract

近年來光學微機電在許多領域的地位逐漸重要，像是光纖通訊，顯示科技和生醫影像都有其大量的研究。本文利用輻射狀的垂直梳型靜電致動器結合十字結構的彈簧來驅動一個二維轉動的微鏡面。所有的驅動結構皆位於微面下方，而且沒有外環的構造(gimbal structure)，這樣的設計提升了元件的填充因子(fill factor)，使其適合應用在微鏡面陣列方面。本元件是由Sandia SUMMiT-V的製程的製造，其中包含了五層由多晶矽沉積而成的結構層(structural layers)。元件的設計包含了許多參數：三種不同彈簧結構以及移動梳型手指(movable comb finger)和固定梳型手指(fixed comb finger)之間的間隔等變數。元件的特性與參數彼此之間的關係將會被討論。

Microelectromechanical System (MEMS) scanners have been extensively studied in recent years due to their compactness and capability of optical beam steering, which can be applied to various applications such as optical fiber communication, biological imaging, and display technologies. In this thesis, a two-axis MEMS scanner driven by radial vertical combdrive actuators has been demonstrated. A cross-bar spring structure is designed to obtain two rotational degrees of freedom (DOFs), enabling the dual-axis rotation without gimbal structure. Both the vertical comdrive actuators and the torsion springs are hidden underneath the mirror to achieve a small form factor. The device is fabricated by a five-layer polysilicon surface micromachining process (SUMMiT-V). Three types of spring designs were evaluated with modal analysis using ANSYS and the resonant frequencies is measured as 7 kHz /12 kHz for x-axis / y-axis rotation. Moreover, devices with different parameter values are characterized and discussed. For one of the devices, the measured mechanical rotation angles of ±6.68° at 43 V and ±2.16° at 65.5 V for rotation about x- and y-axis, respectively.