Thermal control in micromachined devices and its application.

摘要

Thermal control is an important issue for Micro-Electro-Mechanical Systems (MEMS) because it is directly related to device reliability during operation. However, few studies have been done about thermal control in MEMS. In this research, the study of heat transfer at the interfaces of micromachined devices and the development of new mechanisms for thermal control are covered.; To study heat transfer at the interfaces of micromachined devices, micromirrors have been used as electrostatic actuators with the substrate. Thermal contact between the micromirrors and the fixed substrate can be induced and controlled by electrostatic actuation, and characterized by pure electrical method. For every device tested, the TCC is higher in vacuum than in air. This is in stark contrast to the behavior of bulk interfaces and may be the result of decreased solid-solid contact area in air caused by the pressure of the interstitial fluid.; At present, thermal detectors are designed and operated with fixed thermal conductance, which limits dynamic range. We have found that adaptive thermal detectors can be operated over a much larger dynamic range by using thermal contact control techniques: first, control of contact points of curved support beams and second, control of contact points of photolithographically defined support beams. Test structures of adaptive thermal detectors based on the first technique have been built and characterized by measuring thermal conductance and responsivity with and without electrostatic actuation. Better performance has been obtained by building a new structure based on the second technique. The performance of the new structure has been compared to commercial microbolometers by measuring thermal conductance, responsivity, and detectivity with noise measurement in an unactuated and an actuated state, respectively.