Development and applications of a multi-user polymer MEMS technology

This thesis covers the development and characterization of an all polymer micromachining process designed for multi-user applications. This thesis describes the first MEMS process designed to provide multi-user functionality using polymers as structural and sacrificial layers, and offers new fabrication abilities not previously available with silicon micromachining. The structural material for this MEMS process is the negative tone photoresist SU-8, which is excellent for low temperature permanent applications. This work has developed a very reliable method of producing compliant SU-8 microstructures and has characterized it for a new class of structures and actuators. The use of SU-8 offers many advantages with respect to processing, but also introduces many processing challenges that were solved in this work. The polymer MEMS process developed for this work has a multi-thickness structural layer separated from the substrate by a single sacrificial layer. The sacrificial layer includes dimple features to reduce stiction and allow structures in excess of 5000 X 5000 µm2 to release without problems. The list of working devices fabricated in this process includes low and high aspect ratio compliant mechanisms, micro-optical components, thermal and electrostatic actuators, micro antennas and compliant grippers. The many processing advances introduced through this work include elimination of adhesion failure of polymers during multiple processing steps, alignment of two polymers with similar indices of refraction, development of an anti-stiction substrate with high adhesion anchor areas, characterization of stress gradient in SU-8 with processing conditions, and successful gold wirebonding onto SU-8 devices.