Design, Fabrication And Assembly Of 3-D Microstructures

The primary goal of a micro-electro-mechanical system (MEMS) is to integrate electronics, sensors and actuators into a tiny system, which can be easily fabricated and packaged. Currently there is no standard process for manufacturing all the sub-components since a lot of them are made from different materials and fabrication technologies. Therefore, there is a great interest to develop a reliable manufacturing approach that allows for the integration of multiple micro devices on a single chip. This work describes two approaches to achieve this heterogeneous integration: (1) hybrid material integration by introducing new materials into a well-known self-assembly platform (PolyMUMPs) to develop new devices which cannot be achieved by a conventional process. Organic polymer was applied on self-assembled polysilicon microstructures to create new optomechanical devices which can work together with existing micro devices on the same platform. (2) Direct integration of different microcomponents on a common platform by using direct micoassembly. A new active joining mechanism was proposed for this purpose. It can be used for the assembly of microcomponents that are made of different materials, dimensions and shapes.
Both of the two techniques have been successfully demonstrated in this thesis. The microparts have been designed, fabricated, and then assembled into self-aligned 3-D out-of-plane structures. In the first approach, polymer was successfully integrated as the optical interface of a transmission-type thin-film filter with self-assembled microstructures. It overcame the inherent high absorption of optical signals in polysilicon, which has restricted its application only to reflection-type devices. In the second approach, an innovative active lock mechanism is developed. It provides both the mechanical and electrical interconnections between the microparts and the target substrate or subassembly. This technique allows each of the microcomponents to be fabricated optimally using respective processes then assembled together. Several proof-of-concept devices, such as free space filters and multiple micro-manipulators for parallel assembly, have been constructed. The results of this work have provided a new way for heterogeneous integration of 3-D microstructures and have resulted in a number of contributions to the MEMS field.