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Micromachined capacitive silicon bulk acoustic wave gyroscopes.

机译：微加工电容式硅体声波陀螺仪。

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摘要

Gyroscopes are angular velocity sensors that are used for measuring rate or angle of rotation. The application domain of silicon microgyroscopes is quickly expanding from automotive to aerospace and consumer electronics industries. Examples include anti-skid and safety systems in cars, inertial measurement units (IMUs), image stabilization in digital cameras, and smart user interfaces in handheld devices. As potential high volume consumer applications for micromachined gyroscopes continue to emerge, design and manufacturing techniques that improve the performance, reliability and shock survivability of gyroscope while providing multi-axial functionality become increasingly important.;Today, state-of-the-art silicon micromachined vibratory gyroscopes can achieve high performance with low operational frequency (3--30kHz) at the cost of large form factor, high operating voltages and very low pressure package environment. Additionally, temperature compensation is required to guarantee stable performance over temperature. These all add up to make the finished product elaborate and costly. In this dissertation, capacitive bulk acoustic wave (BAW) silicon disk gyroscopes are introduced as a new class of micromachined vibratory gyroscope to investigate the operation of Coriolis-based gyroscopes at high frequency and further meet consumer electronics market demands. Capacitive BAW gyroscopes, operating at high frequency of 1--10MHz, are stationary devices with vibration amplitudes less than 20nm, resulting in high operational bandwidth and high shock tolerance, which are generally unavailable in low frequency gyroscopes. BAW gyroscopes require low operating voltages, which simplifies the interface circuit design and implementation in low-voltage CMOS technologies. They also demonstrate appropriate thermally-stable performance in air, which eliminates the need for vacuum packaging and temperature compensation, resulting in superior reliability and reduced cost.;This dissertation presents the design, implementation and characterization of z-axis capacitive BAW disk gyroscopes in (100) and (111) single crystal silicon. A revised high aspect-ratio poly- and single crystalline silicon (HARPSS) process was utilized to implement these devices in thick silicon-on-insulator (SOI) substrates (35--60microm) with very small capacitive gap sizes (∼200 nm). The prototype devices show ultra-high quality factors ( Q) in excess of 200,000 and large bandwidth of 15--30Hz under very high-Q mode-matched condition. The measured rate sensitivity for a 6MHz-disk gyroscope with Qmatched-mode of 235,000 was 270microV/°/sec in (100) silicon.;Another major contribution of this dissertation is to optimize the design and implementation of BAW disk gyroscopes for self-matched mode operation. Operating a vibratory gyroscope in matched mode is a straightforward way to improve performance parameters. But, it is very challenging to achieve without applying large voltages, which are difficult to generate with CMOS electronics. In this work, self-matched mode operation was provided by enhanced design of the perforations of the disk structure. In addition, the operating frequencies of the secondary elliptic modes were high enough to marginalize air damping losses. At the same time, the high operating frequency offers a very large device bandwidth of ∼ 400Hz when these devices are operated in air. The rate sensitivity of the optimized device in air was measured to be 65microV/°/sec for a 7.3MHz device with Q matched-mode of 15,000. In addition, these most advanced devices were characterized over a typical consumer electronics temperature range. It was observed that the modes remained matched and the measured Q and scale factor demonstrate the high performance stability of BAW gyroscopes even at elevated temperatures.;To complete this thesis, a gyroscope with planar-axis sensitivity (x-axis) is developed as an extension of the z-axis BAW gyroscope design. The x-axis gyroscope uses out-of-plane modes of a silicon disk structure. A rate sensitivity of 73microV/°/sec around the x-axis was measured for this device with a Qmatched-mode of 17,000 in (100) silicon. A multi-axis single-proof-mass gyroscope was introduced to measure the rotation rate around the x or y-axis and the z-axis by operating in in-plane and out-of plane modes. Like the single-axis devices, these gyroscopes were also optimized to achieve self-matched mode operation. The optimized multi-axis gyroscope exhibits matched in-plane mode and out-of-plane modes.;In conclusion, the experimental results establish the suitability of BAW gyroscopes for consumer electronic applications.
机译：陀螺仪是角速度传感器，用于测量速率或旋转角度。硅微陀螺仪的应用领域正在迅速从汽车扩展到航空航天和消费电子行业。示例包括汽车中的防滑和安全系统，惯性测量单元（IMU），数码相机中的图像稳定以及手持设备中的智能用户界面。随着微机械陀螺仪潜在的大批量消费应用不断涌现，设计和制造技术在提高多轴陀螺仪功能的同时，提高了陀螺仪的性能，可靠性和耐冲击性变得越来越重要。当今，最先进的硅微机械加工振动陀螺仪可以以较低的工作频率（3--30kHz）实现高性能，但要以大尺寸，高工作电压和非常低压的封装环境为代价。此外，需要温度补偿以保证整个温度范围内的稳定性能。这些都使成品精巧而昂贵。本文介绍了电容体声波硅圆盘陀螺仪作为一类新型的微机械振动陀螺仪，以研究基于科里奥利的陀螺仪在高频下的运行情况，进一步满足消费电子市场的需求。电容式BAW陀螺仪工作在1--10MHz的高频下，是振动幅度小于20nm的固定设备，因此具有较高的工作带宽和较高的耐震性，这在低频陀螺仪中通常是不可用的。 BAW陀螺仪要求低工作电压，这简化了低压CMOS技术中的接口电路设计和实现。他们还展示了在空气中适当的热稳定性能，从而消除了真空包装和温度补偿的需求，从而实现了卓越的可靠性并降低了成本。本论文提出了z轴电容式BAW盘式陀螺仪在（ 100）和（111）单晶硅。修订后的高纵横比多晶硅和单晶硅（HARPSS）工艺用于在具有很小电容间隙尺寸（〜200 nm）的厚绝缘体上硅（SOI）衬底（35--60μm）中实现这些器件。原型器件在非常高Q模式匹配的条件下显示出超过200,000的超高品质因数（Q）和15--30Hz的大带宽。在（100）硅中，Qmatched模式为235,000的6MHz磁盘陀螺仪的测得速率灵敏度为270microV /°/ sec。模式操作。以匹配模式操作振动陀螺仪是改善性能参数的直接方法。但是，在不施加大电压的情况下实现这一点非常具有挑战性，而这是CMOS电子设备难以产生的。在这项工作中，通过对磁盘结构穿孔的增强设计来提供自匹配模式操作。另外，次级椭圆模式的工作频率足够高，以使空气阻尼损失边缘化。同时，当这些设备在空中运行时，高工作频率提供了约400Hz的非常大的设备带宽。对于Q匹配模式为15,000的7.3MHz器件，优化后的器件在空气中的速率灵敏度测得为65microV /°/ sec。此外，这些最先进的器件在典型的消费电子温度范围内得到了表征。观察到模式保持匹配，并且所测得的Q和比例因子证明了BAW陀螺仪即使在高温下也具有较高的性能稳定性。为了完成本论文，研制了具有平面轴灵敏度（x轴）的陀螺仪。 Z轴BAW陀螺仪设计的扩展。 X轴陀螺仪使用硅盘结构的平面外模式。对于在（100）硅中具有17,000的Qmatched-mode的该设备，在x轴周围测得的速率灵敏度为73microV /°/ sec。引入了多轴单质量质量陀螺仪，通过在平面内和平面外模式下进行操作来测量围绕x轴或y轴和z轴的旋转速率。像单轴设备一样，这些陀螺仪也进行了优化以实现自匹配模式操作。优化的多轴陀螺仪具有匹配的面内模式和面外模式。总之，实验结果证明了BAW陀螺仪适用于消费电子应用。

著录项

  • 作者

    Johari, Houri.;

  • 作者单位

    Georgia Institute of Technology.;

  • 授予单位 Georgia Institute of Technology.;
  • 学科 Engineering Electronics and Electrical.;Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 201 p.
  • 总页数 201
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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