Geometric Imperfection Characterization and Precise Assembly of Micro Shell Resonators
Yan Shi, Kun Lu, Xiang Xi, Yulie Wu, Dingbang Xiao, Xuezhong Wu
Abstract
Micro glassblowing can be utilized in the fabrication of high-precision micro shell resonator due to its acceptable cost and promising performance. Geometric imperfection characterization and electrode assembly are important but challenging tasks for manufacturing high-quality resonators. This paper characterizes the geometric imperfection of the micro shell resonator and proposes a novel precise assembly process for micro shell resonators with out-of-plane electrodes. The crucial geometric imperfections including thickness imperfection, circularity error and anchor non-planarity of the glassblowing structures are experimentally characterized. The sample resonator exhibits a circularity error below 0.2 % and an anchor non-planarity of 300 nm. The relationship between frequency asymmetry and circularity error is discussed, which can be used to predict the resonator performance. A simplified model is built to analyze the effect of gap deviation on the capacitance variation of the resonator. Finally, a sacrificial layer-free electrode assembly method is proposed, which achieves small (<; 20 μm) capacitance gaps with relatively low tolerance.