An all-silicon single-wafer micro-g accelerometer with a combined surface and bulk micromachining process
An all-silicon single-wafer micro-g accelerometer with a combined surface and bulk micromachining process
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DOI：
10.1109/84.896777
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发表时间：
2000-12-01
影响因子：
2.7
通讯作者：
Najafi, K
中科院分区：
文献类型：
--
作者：
Yazdi, N;Najafi, K
本文报道了一种全硅全对称z轴微加速度计，它是在一个单一的硅晶片上使用相结合的表面和体加工工艺制造。微加速度计具有高器件灵敏度、低噪声和低/可控阻尼，这些是电容式加速度计实现马克杯和亚马克杯分辨率的关键因素。微制造工艺通过使用整个晶片厚度产生大的检测质量块，并且通过利用薄的牺牲层产生大的感测电容。感测/反馈电极由具有嵌入的25-35 μ m厚的垂直加强件的沉积的2-3 μ m多晶硅层形成。这些电极虽然薄，但通过厚的嵌入式加强件而变得非常坚硬，使得检测质量块的力重新平衡成为可能。多晶硅电极被图案化以产生阻尼孔。微加速度计批量制造，封装和测试成功。具有2 mm x 1 mm检验质量块和全桥支持的器件的实测灵敏度为2 pF/g。一个4 mm x 1 mm悬臂支撑加速度计的测量灵敏度为19.4 pF/g。这些设备在大气中的计算噪声基底分别为0.23 mug/root Hz和0.16 mug/root Hz。
This paper reports an all-silicon fully symmetrical z-axis micro-g accelerometer that is fabricated on a single-silicon wafer using a combined surface and bulk fabrication process. The microaccelerometer has high device sensitivity, low noise, and low/controllable damping that are the key factors for attaining mug and sub-mug resolution in capacitive accelerometers. The microfabrication process produces a large proof mass by using the whole wafer thicknes and a large sense capacitance by utilizing a thin sacrificial layer. The sense/feedback electrodes are formed by a deposited 2-3 mum polysilicon him with embedded 25-35 mum-thick vertical stiffeners. These electrodes, while thin, are made very stiff by the thick embedded stiffeners so that force rebalancing of the proof mass becomes possible. The polysilicon electrodes are patterned to create damping holes. The microaccelerometers are batch-fabricated, packaged, and tested successfully. A device with a 2-mm x 1-mm proof mass and a full bridge support has a measured sensitivity of 2 pF/g. The measured sensitivity of a 4-mm x 1-mm accelerometer with a cantilever support is 19.4 pF/g. The calculated noise floor of these devices at atmosphere are 0.23 mug/root Hz and 0.16 mug/root Hz, respectively.