基于掩膜—无掩膜腐蚀的硅微谐振式加速度计关键工艺研究

发布时间：2018-10-24 18:24

【摘要】：硅微机械加速度计是MEMS(Micro Mechanical System)传感器的研究热点之一,具有体积小、成本低、易于批量生产等优点。与其它类型的MEMS加速度传感器相比,硅微机械谐振式加速度传感器测量精度高,输出的是频率信号,可以通过简单的数字电路送入计算机,而不需A/D转换环节,因此,研究谐振式硅微加速度传感器具有重要意义。本文所设计的基于掩膜-无掩膜腐蚀技术的新型硅微谐振式加速度传感器,谐振梁位于衬底上表面,支撑梁的中性面与质量块的重心在同一平面,支撑梁与谐振梁同时成形。相比之前文献中报道的Z轴谐振式加速度传感器,简化了器件结构,降低了封装难度,并且能有有效消除面内加速度引起的交叉轴耦合干扰。为了实现本课题所设计的器件结构,采用掩膜-无掩膜两步腐蚀法腐蚀出位于不同平面的谐振梁和支撑梁,其中谐振梁位于衬底上表面,支撑梁的中性面与质量块的重心在同一平面。并且针对不同腐蚀液及其添加剂做了大量的实验,分析比较了不同腐蚀液及其添加剂对硅片的无掩膜腐蚀腐蚀特性,如硅片表面平整度,腐蚀速率,快腐蚀面与(100)面的腐蚀速率之比r3。经过多组实验发现采用碘过饱和KOH溶液作为无掩膜腐蚀液的硅片具有良好的表面平整度和最小的r3值,而且其r3的离散性最小,具有良好的稳定性和耐久性。简要介绍了谐振器的检测盒激励方式,谐振式硅微加速度传感器的工作原理,对其力学敏感结构进行了理论分析并根据器件的结构设计了一套完整的工艺流程。重点研究了二氧化硅/氮化硅薄膜的制备与残余应力测量以及谐振梁的应力补偿;针对质量块在碘过饱和KOH溶液无掩膜腐蚀过程中会受到的切削,为其设计了补偿图形,并由实验验证可行;对电阻及引线的选取与制备进行了分析与介绍。
[Abstract]:Silicon micromechanical accelerometer is one of the research hotspots in MEMS (Micro Mechanical System) sensor, which has the advantages of small volume, low cost and easy mass production. Compared with other types of MEMS accelerometers, silicon micromechanical resonant accelerometers have high measurement accuracy and output frequency signals, which can be sent to the computer through simple digital circuits without the need for A- / D conversion. It is of great significance to study the resonant silicon micro acceleration sensor. A novel silicon micro-resonant accelerometer based on masking and non-mask corrosion technique is designed in this paper. The resonant beam is located on the surface of the substrate, the neutral surface of the supporting beam is in the same plane as the center of mass of the mass block, and the supporting beam and the resonant beam are formed at the same time. Compared with the Z-axis resonant accelerometer reported in previous literature, it simplifies the device structure, reduces the difficulty of packaging, and can effectively eliminate the cross-axial coupling interference caused by in-plane acceleration. In order to realize the device structure designed in this paper, the resonant beam and the supporting beam located in different planes are corroded by the masking and non-mask two-step corrosion method, in which the resonant beam is located on the surface of the substrate. The neutral plane of the supporting beam is in the same plane as the center of gravity of the mass block. A large number of experiments have been done on different corrosion fluids and their additives. The corrosion characteristics of different corrosion fluids and their additives to silicon wafer without mask have been analyzed and compared, such as the surface smoothness, corrosion rate of silicon wafer. The ratio of the corrosion rate of the fast corrosion surface to the (100) surface is R3. It is found that the silicon wafer with iodine supersaturated KOH solution as non-mask corrosion solution has good surface smoothness and minimum r3 value, and the dispersion of R3 is the least, and it has good stability and durability. This paper briefly introduces the excitation mode of the resonator and the working principle of the resonant silicon micro-acceleration sensor. The mechanical sensitive structure of the resonator is analyzed theoretically and a set of complete technological process is designed according to the structure of the device. The fabrication and residual stress measurement of silicon dioxide / silicon nitride film and the stress compensation of resonant beam are studied emphatically, and the compensation pattern is designed for the mass block which will be cut in iodine supersaturated KOH solution without mask corrosion. The selection and preparation of resistance and lead are analyzed and introduced.
【学位授予单位】：中国计量学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH824.4

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