Advances in microfabrication technologies has changed the way society functions, giving rise to the microelectronics and the digital age we live in. Microresonators are a popular micro electro mechanical system (MEMS) used in many applications such as gyroscopes, oscillators and many micro sensors. They are structures that vibrate upon the application of a force at its resonant frequency. Their performance is characterized by a non-dimensional parameter known as the quality factor which is defined as the ratio of the input energy to the energy lost over one period of vibration. Among all the loss mechanisms, air damping, which is caused by constant collisions between air molecules and the resonator, dominates when the resonator vibrates in air or even in a low vacuum environment. For ma...[ Read more ]

Advances in microfabrication technologies has changed the way society functions, giving rise to the microelectronics and the digital age we live in. Microresonators are a popular micro electro mechanical system (MEMS) used in many applications such as gyroscopes, oscillators and many micro sensors. They are structures that vibrate upon the application of a force at its resonant frequency. Their performance is characterized by a non-dimensional parameter known as the quality factor which is defined as the ratio of the input energy to the energy lost over one period of vibration. Among all the loss mechanisms, air damping, which is caused by constant collisions between air molecules and the resonator, dominates when the resonator vibrates in air or even in a low vacuum environment. For many applications, damping is a hindrance which people try to mitigate by operating in a high vacuum or by changing the structural design. For others, such as pressure sensing based on air damping, enhanced damping is however desirable as it could potentially increase the sensing range. Regardless of the objective, it is an area where research could be beneficial.

In this thesis air damping in microresonators is explored and the impact of using a different shape such as a curved one instead of the standard parallel plate is studied. A 3D Monte Carlo simulation is performed to simulate the damping in the curved and straight structures following which a practical design is created to experimentally validate the effect suggested by the simulations. The devices are fabricated and tested both optically and electronically. A two-node driving and detection scheme is used owing to its simplicity and the signal output is used to obtain the quality factor of the various resonators fabricated.

Preliminary results suggest that curved structures do indeed enhance the damping when compared to parallel plates that have the same number molecules entering the squeeze film domain. The difference can be as high as twice that of its equivalent straight structures, indicating the curved plates could be a viable design for damping enhancement.