Purpose

Si-based micro electro mechanical systems (MEMS) magnetometer does not require specialized magnetic materials avoiding magnetic hysteresis, ease in fabrication and low power consumption. It can be fabricated using the same processes used for gyroscope and accelerometer fabrication. The paper reports the dicing mechanism for the released MEMS xylophone magnetic sensor fabricated using wafer bonding technology and its characterization in ambient pressure and under vacuum conditions. The purpose of this paper is to dice the wafer bonded Si-magnetometer in a cost-effective way without the use of laser dicing and test it for Lorentz force transduction.

Design/methodology/approach

A xylophone bar MEMS magnetometer using Lorentz force transduction is developed. The fabricated MEMS-based xylophone bars in literature are approximately 500 µm. The present work shows the released structure (L = 592 µm) fabricated by anodic bonding technique using conducting Si as the structural layer and tested for Lorentz force transduction. The microstructures fabricated at the wafer level are released. Dicing these released structures using conventional diamond blade dicing may damage the structures and reduce the yield. To avoid the problem, positive photoresist S1813 was filled before dicing. The dicing of the wafer, filled with photoresist and later removal of photoresist post dicing, is proposed.

Findings

The devices realized are stiction free and straight. The dynamic measurements are done using laser Doppler vibrometer to verify the released structure and test its functionality for Lorentz force transduction. The magnetic field is applied using a permanent magnet and Helmholtz coil. Two sensors with quality factors 70 and 238 are tested with resonant frequency 112.38 kHz and 114.38 kHz, respectively. The sensor D2, with Q as 238, shows a mechanical sensitivity of 500 pm/Gauss and theoretical Brownian noise-limited resolution of 53 nT/vHz.

Originality/value

The methodology and the study will help develop Lorentz force–based MEMS magnetometers such that stiction-free structures are released using wet etch after the mechanical dicing.

中文翻译：

---

MEMS磁力计的开发和切割后湿释放：一种方法

目的

基于硅的微机电系统 (MEMS) 磁力计不需要专门的磁性材料，避免磁滞、易于制造和低功耗。它可以使用与陀螺仪和加速度计制造相同的工艺来制造。该论文报告了使用晶片键合技术制造的已发布 MEMS 木琴磁传感器的切割机制及其在环境压力和真空条件下的特性。本文的目的是在不使用激光切割的情况下以经济高效的方式切割晶圆键合硅磁力计，并对其进行洛伦兹力转换测试。

设计/方法/方法

开发了一种使用洛伦兹力转换的木琴条 MEMS 磁力计。文献中制造的基于 MEMS 的木琴杆大约为 500 µm。目前的工作显示了通过阳极键合技术制造的释放结构 (L = 592 µm)，使用导电 Si 作为结构层，并测试了洛伦兹力转换。在晶圆级制造的微结构被释放。使用传统的金刚石刀片切割这些释放的结构可能会损坏结构并降低产量。为了避免这个问题，在切割前填充了正性光刻胶S1813。建议对晶片进行切割，填充光刻胶，然后在切割后去除光刻胶。

发现

实现的设备是无静摩擦和直的。动态测量是使用激光多普勒振动计完成的，以验证释放的结构并测试其洛伦兹力转换功能。使用永磁体和亥姆霍兹线圈施加磁场。质量因数为 70 和 238 的两个传感器分别以 112.38 kHz 和 114.38 kHz 的谐振频率进行测试。Q 为 238 的传感器 D2 显示出 500 pm/Gauss 的机械灵敏度和 53 nT/vHz 的理论布朗噪声限制分辨率。

原创性/价值

该方法和研究将有助于开发基于洛伦兹力的 MEMS 磁力计，以便在机械切割后使用湿蚀刻释放无静摩擦结构。