摘要
文章首次报道了一种基于面积可变电容结构的微机械加速度传感器。质量块呈栅状结构,由悬臂梁支撑。两组交叉放置的定电极位于质量块的正下方。在惯性力的作用下,质量块呈平行于衬底水平移动,引起由质量块的栅与定电极的叉指构成的差分电容变化。通过测量差分电容的变化,可以得到加速度信号的大小。理论分析表明加速度响应信号随面积呈线性变化,而与质量块及定电极的间距无关。加速度传感器的制作采用了基于金属电镀的准LIGA技术,设计量程为20m/s2。测量结果表明,加速度传感器量程为20m/s2,灵敏度为581mV/(m·s-2),非线性为4%FS。讨论了器件线性度不够理想的原因。
In this paper,a newly developed accelerometer based on the principle of area changeable capacitance is presented at the first time.The movable mass is designed as many bars connected together and suspended by elastic beams.Two comb shaped fixed electrodes with their fingers side by side are alternately placed under the mass.The mass moves in the direction parallel with the substrate plane under the effect of acceleration.The movable mass and fixed electrodes compose a differential capacitor unit.It is concluded by theoretical analysis that the signal of the acceleration is only proportionally related to the area between movable mass and fixed electrodes but not related to the gap between them.The parasitic capacitance C P between the mass and fixed electrodes and C B induced by boundary effect both lower the sensitivity of the accelerometer by about 20%,and lead to a vertical effect on accelerometer that could be ignored if compared with the sensitivity.The quasi LIGA technology with Ni as structure layer and Cu as sacrificial layer is used to fabricate the sensor chips.The fixed electrodes are fabricated on a glass substrate.A Cu sacrificial layer used to determine the gap between the mass and fixed electrodes is then electroplated with the fixed electrodes layer.Finally,the movable Ni mass is also electroplated with the Cu layer and is released after selective etch of the Cu layer.After packaging in IC ceramic die under atmosphere,the accelerometer is put on avibrator to be tested under a frequency of 25 Hz.The output signal is connected to the interface circuit with electric wires.The experimental results show that the accelerometer has typical sensitivity of 58 1 mV/(m·s -2 ) and non linearity of 4%FS in operating range of 20 m/s 2.The obtained non linearity is not ideal and the reason is discussed based on experimental conditions. [
出处
《中国工程科学》
2000年第2期36-40,共5页
Strategic Study of CAE
基金
国家攀登计划B微电子机械系统 (MEMS)资助项目!(8537)
