基于量子巨隧道磁阻效应的高精度MEMS加速度计研究

The micro accelerometer, which is applied to the new areas such as micro satellite and miniature autonomous system, is difficult to meet the increasing precision demand. The high precision accelerometer, which is applied to the traditional area such as microgravity measurement, the guidance of tactical and strategic weapons, is facing increasingly stringent constraints in size, weight and power consumption. The existing accelerometer product can’t meet these described demands. This project will research a high-precision MEMS accelerometer based on quantum giant tunnel magnetoresistance effect. It is expected to break through the current detection limit of MEMS accelerometer. This device has huge potential to achieve the inertial level performance, with the good characteristics of MEMS device in small volume, light weight, low power consumption and so on. The main research contents of this project including: (1) Researches on the mechanism of quantum giant tunnel magnetoresistance effect and influencing factors; (2)Researches on the accelerometer structure topology; (3) Researches on high-precision signal detection and control technology; (4)Researches on the layout design and processing technology of the accelerometer. The main innovations including: (1) The high sensitivity of giant tunnel magnetoresistance effect will be adopted to realize the acceleration signal detection, which improves the acceleration measurement precision and avoids the defect that nm level gap is difficult to achieve in traditional tunneling accelerometer; (2) Micro hydraulic amplifier will be integrated in MEMS accelerometer to amplify displacement for the first time，which overcomes the disadvantage that the range and detection sensitivity limit are not compatible in the traditional tunnel accelerometer. Through the project research, the micro-structure chip and principle prototype of high-precision tunnel magnetoresistance effect accelerometer are implemented. The successful development of this high-precision micro-accelerometer has important theoretical and practical significance for meeting the urgent needs of domestic aerospace, defense equipment and high-end industrial products.

应用于微纳卫星、微型自主系统等新兴领域的微型加速度计难以满足日益增长的精度需求;同时应用于微重力测量、战术战略武器制导等传统领域的高精度加速计也面临日益苛刻的体积、重量、功耗等约束; 目前加速度计很难满足以上需求。项目研究一种基于量子巨隧道磁阻效应的高精度MEMS加速度计，有望突破MEMS加速度计的检测极限，该器件具有实现惯性级性能的巨大潜力,同时兼具小体积、轻重量、低功耗等MEMS器件的特质。该项目主要研究内容:量子巨隧道磁阻效应机理及影响因素研究;加速度计结构拓扑研究;高精度信号检测和控制技术研究;版图设计和加工工艺研究。主要创新:(1)采用高灵敏度的巨隧道磁阻效应实现加速度信号检测,提高了加速度测量精度,避开了传统隧道效应加速度计nm级间隙难以实现的缺陷;(2)首次在MEMS加速度计中集成微型液压放大器进行位移放大,克服传统隧道式加速度计量程和检测极限灵敏度不能兼顾的缺点。通过项目研究，设计实现了高精度隧道磁阻效应加速度计微结构芯片和原理样机。该高精度加速度研制成功对满足国内航空航天和国防装备等迫切需求，具有重要的理论价值和现实意义。

应用于微纳卫星、微型自主系统等新兴领域的微型加速度计难以满足日益增长的精度需求;同时应用于微重力测量、战术战略武器制导等传统领域的高精度加速计也面临日益苛刻的体积、重量、功耗等约束; 目前加速度计很难满足以上需求。针对上述需求，在对量子巨隧道磁阻传感器原理进行研究的基础上，项目研究一种基于量子巨隧道磁阻效应的高精度MEMS加速度计。项目提出和设计了三个不同的高精度巨隧道磁阻效应加速度计结构，分别为基于微杠杆的平动式隧道磁阻式加速度计结构、扭摆式隧道磁阻式加速度计结构、基于静电力反馈的水平运动隧道磁阻式加速度计结构。针对三个高精度巨隧道磁阻效应加速度计结构，分别进行了理论分析和有限元仿真优化，以确定结构设计的可行性。针对三种主要的隧道磁阻效应加速度计结构和力矩反馈器差异，提出了三种隧道磁阻式加速度计的测控系统，分别设计了隧道磁阻式加速度计核心电路模块和闭环控制系统， 并进行了系统仿真。仿真结果表明隧道磁阻式加速度计的测控系统实现了加速度信号检测，验证系统设计的正确性。根据现有多种MEMS芯片加工工艺，采用DDSOG工艺来实现巨隧道磁阻效应加速度计的加工，完成了基于微杠杆的平动式隧道磁阻式加速度计、扭摆式隧道磁阻式加速度计和基于静电力反馈的水平运动隧道磁阻式加速度计的版图设计、加工、微组装和封装，完成了隧道磁阻式加速度计的控制系统和信号检测电路，实现了基于微杠杆的平动式隧道磁阻式加速度计、扭摆式隧道磁阻式加速度计和基于静电力反馈的水平运动隧道磁阻式加速度计样机，验证了结构原理的正确性。接着搭建了实验平台，对隧道磁阻式加速度计在不同间隙和不同永磁薄膜尺寸下的结构特性和加速度计样机性能进行测试，测试结果表明样机性能达到指标要求。