谐振式MEMS压力传感器的制作及圆片级真空封装

Fabrication and wafer-level vacuum packaging of MEMS resonant pressure sensor

为了提高传感器的品质因数,有效保护谐振器,提出了一种基于绝缘体上硅(SOI)-玻璃阳极键合工艺的谐振式微电子机械系统(MEMS)压力传感器的制作及真空封装方法。该方法采用反应离子深刻蚀技术(DRIE),分别在SOI晶圆的低电阻率器件层和基底层上制作H型谐振梁与压力敏感膜;然后,通过氢氟酸缓冲液腐蚀SOI晶圆的二氧化硅层释放可动结构。最后,利用精密机械加工技术在Pyrex玻璃圆片上制作空腔和电连接通孔,通过硅-玻璃阳极键合实现谐振梁的圆片级真空封装和电连接,成功地将谐振器封装在真空参考腔中。对传感器的性能测试表明:该真空封装方案简单有效,封装气密性良好;传感器在10kPa^110kPa的差分检测灵敏度约为10.66 Hz/hPa,线性相关系数为0.99999 542。

To improve the quality factor of sensors and to protect resonators,the fabrication and waferlevel vacuum packaging methods for a Micro-electro-mechanic System（MEMS）resonant pressure sensor was proposed based on Silicon On Insulator（SOI）-glass anodic bonding technology.Through Deep Reactive Ion Etching（DRIE）process and buffered oxide etched releasing process,H-type resonant beams and pressure diaphragm of the sensor were fabricated on the low resistivity device layer and the substrate layer of SOI wafer,respectively,and a moveable mechanism was release by a SiO2 layer of the SOI wafer corroded by hydrofluoric acid flow.Finally,electrical connection and a cavity for the vibration of beams was implemented on the Pyrex glass piece by fine mechanical machining and the wafer-level vacuum packaging and electric connection of the resonators were achieved with SOIglass anodic bonding.Experimental results demonstrate that the packaging scheme is effective andeasy to achieve with an excellent hermetic sealing,and the sensor has a differential sensitivity of 10.66 Hz/hPa and linear correlation coefficient of 0.999 995in the range of 10kPa to 110kPa.