Fabrication of Micro Glass Spherical Resonator by Chemical Foaming Process (CFP)

kground and Objectives: The Hemispherical Resonator Gyroscope (HRG) is an inertial sensor that is a good choice for space missions and inertial navigation due to their low noise, low energy consumption, long life, and excellent accuracy and sensitivity. It consists of three main parts: the shell, the excitation and detection system, and the control circuits. In recent years, with using MEMS technology in the construction of HRG, vibrating shells with low volume and low price are made.Methods: The hemispherical shell is the main part and the beating heart of hemispherical resonator gyroscopes and is responsible for sensing. An optimized shell is required to implement the excitation and detection system and operate the gyroscope properly. In this research, the structure of a spherical shell with an environmental base that does not need to release the shell from its environment for its excitation and detection system is selected and the relationships governing this type of shell to improve the parameters of the glass blowing method will be investigated. Also, all sub-processes of this type method of fabrication to optimize the glass-blown spherical shell are implemented.Results: The process of making spherical shell by glass blowing using the chemical foaming process is used to obtain shells with height to radius ratio greater than ۱, and finally, a glass shell with an etched cavity with a radius of ۵۶۲ μm and depth of ۵۲۴ μm created by the CNC process, with height to radius ratio of approximately ۱.۸ Has been achieved. In this method, using direct transfer of calcium carbonate to the etched cavity, before anodic bonding, the glass shell volume has been increased from ۰.۶۰۲ nL to ۱.۰۴ nL.Conclusion: The result is that to achieve a glass shell with a height to radius ratio of more than ۱, in addition to improving the fabrication process, it is necessary to transfer the solid foaming agent to the etched cavity. Finally, in the fabrication of the glass-blown spherical shell, we have used the chemical foaming process (CFP) to obtain shells with a height to radius ratio greater than ۱.

Keywords:

Hemispherical Resonator gyroscope , the Etched Cavity in the Silicon Substrate , Anodic Bonding , Glass Blowing , Height to Radius Ratio of the Shell