Electrostatic MEMS Actuators using Gray-scale Technology
| dc.contributor.advisor | Ghodssi, Reza | en_US |
| dc.contributor.author | Morgan, Brian Carl | en_US |
| dc.contributor.department | Electrical Engineering | en_US |
| dc.contributor.publisher | Digital Repository at the University of Maryland | en_US |
| dc.contributor.publisher | University of Maryland (College Park, Md.) | en_US |
| dc.date.accessioned | 2006-09-12T06:08:17Z | |
| dc.date.available | 2006-09-12T06:08:17Z | |
| dc.date.issued | 2006-08-30 | en_US |
| dc.description.abstract | The majority of fabrication techniques used in micro-electro-mechanical systems (MEMS) are planar technologies, which severely limits the structures available during device design. In contrast, the emerging gray-scale technology is an attractive option for batch fabricating 3-D structures in silicon using a single lithography and etching step. While gray-scale technology is extremely versatile, limited research has been done regarding the integration of this technology with other MEMS processes and devices. This work begins with the development of a fundamental empirical model for predicting and designing complex 3-D photoresist structures using a pixilated gray-scale technique. A characterization of the subsequent transfer of such 3-D structures into silicon using deep reactive ion etching (DRIE) is also provided. Two advanced gray-scale techniques are then introduced: First, a double exposure technique was developed to exponentially increase the number of available gray-levels; improving the vertical resolution in photoresist. Second, a design method dubbed compensated aspect ratio dependent etching (CARDE) was created to anticipate feature dependent etch rates observed during gray-scale pattern transfer using deep reactive ion etching (DRIE). The developed gray-scale techniques were used to integrate variable-height components into the actuation mechanism of electrostatic MEMS devices for the first time. In static comb-drives, devices with 3-D comb-fingers were able to demonstrate >34% improvement in displacement resolution by tailoring their force-engagement characteristics. Lower driving voltages were achieved by reducing suspension heights to decrease spring constants (from 7.7N/m to 2.3N/m) without effecting comb-drive force. Variable-height comb-fingers also enabled the development of compact, voltage-controlled electrostatic springs for tuning MEMS resonators. Devices in the low-kHz range demonstrated resonant frequency tuning >17.1% and electrostatic spring constants up to 1.19 N/m (@70V). This experience of integrating 3-D structures within electrostatic actuators culminated in the development of a novel 2-axis optical fiber alignment system using 3-D actuators. Coupled in-plane motion of electrostatic actuators with integrated 3-D wedges was used to deflect an optical fiber both horizontally and vertically. Devices demonstrated switching speeds <1ms, actuation ranges >35&#956;m (in both directions), and alignment resolution <1.25&#956;m. Auto-alignment to fixed indium-phosphide waveguides with <1.6&#956;m resolution in <10 seconds was achieved by optimizing search algorithms. | en_US |
| dc.format.extent | 6408012 bytes | |
| dc.format.mimetype | application/pdf | |
| dc.identifier.uri | http://hdl.handle.net/1903/3944 | |
| dc.language.iso | en_US | |
| dc.subject.pqcontrolled | Engineering, Electronics and Electrical | en_US |
| dc.subject.pquncontrolled | Optical Fiber Alignment | en_US |
| dc.subject.pquncontrolled | Gray-scale Technology | en_US |
| dc.subject.pquncontrolled | 3-D fabrication | en_US |
| dc.subject.pquncontrolled | comb-drives | en_US |
| dc.subject.pquncontrolled | silicon DRIE | en_US |
| dc.title | Electrostatic MEMS Actuators using Gray-scale Technology | en_US |
| dc.type | Dissertation | en_US |
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