||In recent years, the rise of the internet of things(IoT) and 5G wireless communication has driven the demand for high-frequency and miniaturized resonator. The traditional mechanical cutting and lapping process has been unable to meet the needs of the gradually miniaturized resonator material. The resonator energy trapping effect is also poor, resulting in frequency stability is also affected, in order to meet the increasingly stringent requirements of the resonator electrical specifications, the wafer fabrication technology will face a transformation.|
In this study, we will discuss the double-sided etching process of quartz microstructure of AT-CUT quartz oscillator. Under the consideration of the complex characteristics of quartz anisotropic materials, we plan to study the mechanism of quartz etching first, in order to observe the influence of the etching rate of quartz and the key factors of the quartz surface morphology, and confirm the process conditions for stable etching.
After completing the study of the quartz etching mechanism, the optimal conditions are used to design through different mask sizes. The photolithography process is combined with the wet etching process, and the single-sided quartz etching is performed on the X-axis and the Z-axis of the quartz, and then the profile of the section is observed and analyzed. According to the definition of the structural features after single-sided quartz etching, the relationship between the etched structural features of different axial directions on single-sided quartz and the size of the reticle is observed and analyzed, and then the X-axis and the Z-axis are doubled observation and analysis of the profile of the quartz after etching. At this stage, the research focuses on the edge structure characteristics after X-axis and Z-axis etching, and compares the results with the single-sided etching research. The edge structure characteristics of the Z-axis after sided etching can be observed. It is unstable and present antisymmetry, and the edge structure of the X axis is stable.
Based on the research results after double-sided quartz etching, the Z-axis development experiment plan is mask shift with the double-sided quartz etching is not penetrated, and the causes and control structures affecting the Z-axis external structural features are analyzed and discussed step by step. The method makes the vibration characteristics of the resonator wafer not affected by the instability of the external structure, and the electrical characteristics of the resonator obtain a stable output.
Keywords：quartz、AT-CUT、wet etching、quartz anisotropic materials
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