硅微陀螺仪器件级真空封装技术研究

为进一步提高硅微陀螺仪的品质因数及其稳定性，研究了硅微陀螺仪器件级真空封装的高真空获取技术和真空保持技术。首先，以硅微陀螺仪动力学方程为基础，分析了硅微陀螺仪的误差信号与品质因数之间的关系，并采用稀薄气体动力学分析具有高品质因数陀螺仪的空气阻尼。根据早期真空封装陀螺仪的品质因数跟踪测试曲线，分析了品质因数下降原因。采用程序升温脱附职谱分析法（TPD-MS）分析陶瓷管壳和金属盖板的放气特性，并选用了合理的吸气剂。最后，改进了器件级真空封装流程。测试结果表明，采用改进的器件级真空封装的陀螺仪品质因数最高可达162660，约为早期真空封装陀螺仪品质因数的14倍，且在一年内的变化小于0.05%。

Device level vacuum packaging technologies of MEMS gyroscopes

The high vacuum level and vacuum maintenance of device-level Vacuum packaging for silicon microgyroscopes are studied in order to increase the quality factor and its stability. First, the relationship between error signals and quality factor is analysed based on the dynamics equations of silicon microgyroscopes. The air damping of gyroscopes with high quality factor is analysed using rarefied gas dynamics theory. According the early continual test results of quality factor of vacuum packaged gyroscope, the reasons of vacuum level degrade are given. Temperature programmed desorption-mass spectrometry (TPD-MS) is used to measure the contents of the evolution gases for the ceramic packages and the lid. According to the contents of trapped gases, the reasonable getter is chosen to absorb the gases and keep the vacuum level of the cavity. Finally, the device-level vacuum packaging process is improved. The test results show that the quality factor of gyroscope packaged with new device-level vacuum packaging process is about 162660, which is about fourteen times of quality factor of previous vacuum packaged silicon microgyroscopes, and the change of quality factor is less than 0.05% within one year.