Modeling and Characterization of a Pull-in Free MEMS Microphone
Modeling and Characterization of a Pull-in Free MEMS Microphone
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DOI：
10.1109/jsen.2020.2976527
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发表时间：
2020-06-15
影响因子：
4.3
通讯作者：
Miles, Ronald N.
中科院分区：
文献类型：
--
作者：
Ozdogan, Mehmet;Towfighian, Shahrzad;Miles, Ronald N.
在这项研究中，我们研究了采用基于悬浮的电极配置来设计MEMS传声器的可行性。这种电极方案使电容式MEMS传感器能够在大偏置电压下工作，而不会发生拉入故障。我们的实验和模拟表明，可以在高直流电压下产生健壮的传感器，而这对于大多数基于平行板电极的微尺度器件是不可行的。此外，使用更大的偏置电压将提高MEMS传感器的信噪比，因为它增加了读出电路中相对于噪声的信号。这项研究介绍了一种电容式麦克风的设计、制造和测试，该麦克风由大约2微米厚的高掺杂多晶硅作为膜片制成。它的表面积约为1mm2，并在其三个侧面安装了交叉指状传感电极。在移动电极的正下方，有固定的手指与移动电极保持在相同的电压电位下，并用2亩厚的气隙与它们分开。电子输出是使用电荷放大器获得的。在三种不同的麦克风芯片上获得的测量结果表明，在高达200伏的偏置电压下，完全避免了拉入故障。在200V偏置电压下，初始设计的灵敏度为16.1 mV/pA，带宽为100~4.9 kHz。
In this study, we examine the feasibility of designing a MEMS microphone employing a levitation based electrode configuration. This electrode scheme enables capacitive MEMS sensors that could work for large bias voltages without pull-in failure. Our experiments and simulations indicate that it is possible to create robust sensors properlyworking at high DC voltages, which is not feasible for most of the conventionalparallel plate electrode-basedmicroscale devices. In addition, the use of larger bias voltages will improve signal-to-noise ratios in MEMS sensors because it increases the signal relative to the noise in read-out circuits. This study presents the design, fabrication, and testing of a capacitivemicrophone, which is made of approximately 2 mu m thick highly-doped polysilicon as a diaphragm. It has approximately 1 mm2 surface area and incorporates interdigitated sensing electrodeson three of its sides. Right underneath thesemoving electrodes, there are fixed fingersbeing held at the same voltage potential as themoving electrodes and separated from them with a 2 mu mthick air gap. The electronic output is obtained using a charge amplifier. Measured results obtained on three different microphone chips using bias voltages up to 200 volts indicate that pull-in failure is completely avoided. The sensitivity of this initial design was measured to be 16.1 mV/Pa at 200 V bias voltage, and the bandwidth was from 100 Hz to 4.9 kHz.