Recent advances in micro electromechanical system (“MEMS”) technology has resulted in the successful commercialization of high-performance sensors and actuators in a variety of applications, including motion sensing, wireless communication, energy harvesting, and healthcare. Micro assembly processes are generally employed for producing complex micro sensors and actuators. However, micro assembly processes have notable limitations. For example, the throughput of micro assembly processes is lower than that of batch fabrication approaches. Additionally, the alignment accuracy of micro assembly processes is inferior for the production of high performance capacitive sensors and actuators.
Further, it is preferable that objects to be aligned have alignment marks and are observable under a microscope during assembly. However, in many cases, alignment marks cannot be patterned onto the objects because of the microfabrication processed used. Additionally, objects to be aligned are commonly covered by other objects during microfabrication causing the objects to be unobservable during assembly. Jigs are used to align objects that are difficult to see under a microscope. However, the jigs must be accurately aligned with the objects and using conventional alignment tools it can be difficult to achieve high alignment accuracy.
Further, the micro assembled devices can have large variances in nominal capacitances across devices, as well as poor uniformity in capacitance values between electrodes in a single device, because of the low reliability of the fabrication processes of the individual components. For example, the inaccurate alignment and low capacitance uniformity negatively impacts the functionality of micro-shell rate-integrating gyroscopes. Micro shell rate-integrating gyroscopes comprise a micro scale shell resonator anchored on a substrate having multiple electrodes for capacitively actuating and sensing the vibrating pattern of the shell resonator.
Ideally high-performance micro-shell rate-integrating gyroscopes have (1) perfect leveling of the micro-shell resonator to the substrate; (2) small controllable gaps, for example less than 5 μm, between the micro-shell resonator and the electrodes of the substrate; (3) large controllable gap sizes in other regions, excluding that between the micro-shell resonator and the electrodes of the substrate; and (4) uniform gaps between the micro-shell resonator and all surrounding electrodes. Contemporary microfabrication processes are generally unable to produce device having all of these properties. Thus, there is a continued need for micro assembly processes allowing for the creation of high-performance micro-shell rate-integrating gyroscopes having these features.
This section provides background information related to the present disclosure which is not necessarily prior art.