一种高灵敏度硅微机械陀螺的设计与制造

Design and fabrication of high sensitivity silicon micromachined gyroscope

设计与制造了一种高灵敏度的硅微机械陀螺。陀螺用静电来驱动,用连接成惠斯顿电桥的压阻式力敏电阻应变计来检测。主梁、微梁 质量块结构实现了高灵敏度。比较硬的主梁提供了一定的机械强度,并且提供了高共振频率。微梁很细,检测时微梁沿轴向直拉直压。力敏电阻应变计就扩散在微梁上,质量块很小的挠动就能在微梁上产生很大的应力,输出很大的信号。5V条件下,陀螺检测部分的理论灵敏度达到27.45mV/gn。压阻式四端器件用来监测驱动振幅,可以反馈补偿压阻的温度系数。检测模态的Q值达260使陀螺能在大气下工作。陀螺利用普通的n型硅片制造,为了刻蚀高深宽比的结构,使用了深反应离子刻蚀(DRIE)工艺。

A high sensitivity silicon micromachined vibrating gyroscope has been designed and fabricated.The gyroscope is actuated by electrostatic force and detects coriolis forces by four piezoresistors which are connected to form a Wheatstone bridge.High sensitivity is achieved by main beam and micro beam proof mass structure.The main beam,which is rigid,provides high mechanical rigidity and high natural frequency.The micro beams are slim and they will elongate or shorten axially when the gyroscope is tested.The piezoresistors are diffused on micro beams so that very large stress occurs when the proof mass moves slightly.Under 5V dc supply,the sensitivity of the sensing mode is 27.45 mV/g_n theoretically.Piezoresistive four-terminal element is used for monitoring driving amplitude and compensating piezoresistive temperature coefficient by a feedback loop.The Q value of driving mode is as high as 260,so that the gyroscope is capable of working under atmosphere.The gyroscope is fabricated by n type silicon wafer.To obtain high aspect ratio structure,deep reactive ion etching (DRIE) process is employed.