Embedded thin-film transistors for signal conditioning in polymer microelectromechnical systems

Microelectromechanical systems are machines on the micron scale that are fabricated using techniques pioneered by the microelectronics industry. Using MEMS technology, many sensors, can be produced at low cost and packaged into small electronic devices. Through the development of polymer MEMS, new frontiers of MEMS technology that can be rapidly prototyped have begun to expand the flexibility of sensor design. However, the sensing elements in these sensors are typically passive and require active electronics for signal conditioning. The current method for solving this problem is to place the active electronic components on the substrate of the MEMS chip or to locate the active components on a secondary chip and connect the passive and active components together by wire bonding. Unfortunately, in many cases, the active components needed may be as simple as a single transistor amplifier, and by separating the two components, an additional ASIC is needed, adding complexity to the packaging. If active electronic sensors can be integrated directly into the MEMS structure itself, then the flexibility of the design and the capability of the polymer MEMS sensor can improve significantly. This thesis presents a novel process for integrating of hydrogenated amorphous silicon thin film transistors into polyimide based MEMS where active devices were fabricated and characterized and proof of concept sensors were designed and measured.