A Fully Packaged CMOS Interdigital Capacitive Humidity Sensor With Polysilicon Heaters
A Fully Packaged CMOS Interdigital Capacitive Humidity Sensor With Polysilicon Heaters
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DOI：
10.1109/jsen.2011.2154325
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发表时间：
2011-11-01
影响因子：
4.3
通讯作者：
Huang, Qing-An
中科院分区：
文献类型：
--
作者：
Zhao, Cheng-Long;Qin, Ming;Huang, Qing-An
本文提出了一种全封装CMOS叉指电容式湿度传感器。该传感器采用工业标准CMOS工艺和MEMS后处理步骤制作。利用聚酰亚胺良好的线性度作为传感材料。为了扩大叉指电极之间的凹陷的深度，多晶硅加热器被放置在Al电极下方，并且叉指电极之间的钝化也被部分蚀刻。结果，可以在Al电极之间沉积较厚的聚酰亚胺，从而可以提高传感器的灵敏度。在铝电极和聚酰亚胺之间采用了抗蚀钝化处理，保证了传感器的可靠性。为了实用化，对传感器进行了全封装，并采用多晶硅加热器，大大改善了传感器的迟滞和恢复时间。封装后的湿度传感器在整个测试范围内具有良好的线性度和重复性。
This paper presents a fully packaged CMOS interdigital capacitive humidity sensor with polysilicon heaters. The sensor was fabricated with the industrial standard CMOS process and the MEMS postprocessing step. Polyimide was used as the sensing material for its good linearity. To enlarge the depth of the recesses between the interdigital electrodes, the polysilicon heater was placed under the Al electrode and also the passivation between the interdigital electrodes was partly etched. As a result, thicker polyimide can be deposited between the Al electrodes and thus the sensitivity of the sensor can be improved. The etching resistant passivation between Al electrodes and polyimide was used to ensure the reliability of the sensor. To put it into practical use, the sensor was fully packaged, and by using the polysilicon heaters, both the hysteresis and the recovery time of the sensor could be greatly improved. The packaged humidity sensor was measured to show a good linearity and repeatability over the whole testing range.