与CMOS兼容的MEMS气压传感器工艺实现与性能分析

摘要

采用CMOS标准工艺,同时采用三种典型MEMS后处理关键工艺,重点通过对牺牲层释放工艺进行研究,制作实现了一种新型CMOS兼容的电容式气压传感器.在该传感器结构中,作为牺牲层的是在CMOS工艺中形成的掺硼氧化硅.通过释放使电容上电极悬空从而感应气压变化.释放过程采用氢氟酸HF、氟化铵、甘油和水的混合溶液.由于释放孔大小和释放孔间距的设计十分关键,通过实验验证优化了4 μm×4 μm的释放孔更适用于此传感器结构,并对此结构进行了性能分析与实验测试.结果表明,该气压传感器结构合理,工艺成功,重点解决了MEMS后处理中的牺牲层释放工艺与CMOS标准工艺的兼容问题,为利用CMOS标准工艺进行MEMS传感器的研制做出了有益的尝试.%By studying the release process of MEMS sacrificial layer, a novel CMOS compatible capacitive barometric pressure sensor was fabricated by the standard CMOS process and three typical post-MEMS processes. The sacrificial layer of the sensor structure is boron-doped silicon oxide formed in the CMOS process. By releasing the sacrificial layer, the top electrode of the sensor is impending in order to sense the changes of air pressure. Releasing process uses a mixed solution of hydrofluoric acid HF, ammonium fluoride, glycerin and water. Because the dimension and the space of release holes are critical for the releasing process, the structure with 4 μm square release holes is more suitable for the sensor by experiments. Finally, the corresponding performance analysis and experimental test were carried out based on the sensor structure. The results show that the pressure sensor has reasonable structure and successful process. It solves the problem that the releasing process of MEMS sacrificial layer is not compatible with CMOS standard process in post-MEMS processes, which has made a beneficial attempt for the development of MEMS sensors using CMOS standard process.