A two axes scanning SOI MEMS micromirror for endoscopic bioimaging
A two axes scanning SOI MEMS micromirror for endoscopic bioimaging
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DOI：
10.1088/0960-1317/18/2/025001
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发表时间：
2008-02-01
影响因子：
2.3
通讯作者：
Sheppard, C. J. R.
中科院分区：
文献类型：
--
作者：
Singh, J.;Teo, J. H. S.;Sheppard, C. J. R.
设计和开发了一种新的绝缘体上硅(SOI)MEMS工艺，实现了两轴热驱动单晶硅微镜器件，该器件由一个镜板、四个弯曲弹簧和四个热驱动器组成。镜板具有与SOI器件层相同的厚度，即4微米。SOI层被选择性地减薄到2微米，以制造弯曲弹簧和热致动器。SOI层的减薄对于降低(控制)弹簧和致动器的弯曲刚性，从而在低热功率下获得更大的倾角是必不可少的。开发的单晶片工艺是基于干法反应离子刻蚀的与CMOS兼容的化学工艺。最小芯片尺寸设计为1 mm x 1 mm，镜片直径为400微米。其他芯片设计包括镜片直径在200~500微米范围内。本文还对镜片曲率、热驱动机理和实验结果进行了研究。在小于2V的工作电压下测得的最大偏转角为17度，镜片的曲率半径在20~50 mm范围内。该微镜是为用于体内光学相干层析成像的微型导管光学探头而研制的。较小的探针横截面尺寸和较高的分辨率对于研究体内难以接触的病理是必不可少的。这需要紧凑的微镜芯片和足够大的镜片(通常类似于500微米或更大)，这是本文研究的关键动机。
A novel silicon on insulator (SOI) MEMS process has been designed and developed to realize a two axes thermally actuated single crystal silicon micromirror device, which consists of a mirror plate, four flexural springs and four thermal actuators. The mirror plate has the same thickness as a SOI device layer i.e. 4 mu m. The SOI layer is selectively thinned down to 2 mu m for fabricating flexural springs and thermal actuators. The thinning of the SOI layer is essential to lower ( control) the flexural rigidity of the springs and the actuators and thus to achieve a higher tilt angle at low thermal power. The developed single wafer process is based on dry reactive ion etching CMOS compatible chemistries. The minimum chip size design of 1 mm x 1 mm has a 400 mu m diameter mirror plate. Other chip designs include the mirror diameters in the range from 200 to 500 mu m. This paper also presents a study on the mirror plate curvature, thermal actuation mechanism and the experimental results. The measured maximum angular deflection achieved was 17 degrees at an operating applied voltage of less than 2 V, and the radius of curvature of the mirror plate was in the range from 20 to 50 mm. The micromirror was developed for a miniature catheter optical probe for optical coherence tomography in vivo imaging. A low cross-sectional size of the probe and higher resolution are essential for investigating inaccessible pathologies in vivo. This required a compact micromirror chip and yet sufficiently large mirror plate ( typically similar to 500 mu m or more), this trade-off was the key motivation for the research presented in this paper.