In our previous work (Lazarus and Fedder 2011 J. Micromech. Microeng. 21 0650281), we demonstrated a CMOS-MEMS capacitive humidity sensor with a 72% improvement in sensitivity over the highest previously integrated on a CMOS die. This paper explores a series of methods for creating a faster and more manufacturable high-sensitivity capacitive humidity sensor. These techniques include adding oxide pillars to hold the plates apart, spin coating polymer to allow sensors to be fabricated more cheaply, adding a polysilicon heater and etching away excess polymer in the release holes. In most cases a tradeoff was found between sensitivity and other factors such as response time or robustness. A robust high-speed sensor was designed with a sensitivity of 0.21% change in capacitance per per cent relative humidity, while dropping the response time constant from 70 to 4s. Although less sensitive than our design, the sensor remains 17% more sensitive than the most sensitive interdigitated designs successfully integrated with CMOS. © 2012 IOP Publishing Ltd.
CITATION STYLE
Lazarus, N., & Fedder, G. K. (2012). Designing a robust high-speed CMOS-MEMS capacitive humidity sensor. Journal of Micromechanics and Microengineering, 22(8). https://doi.org/10.1088/0960-1317/22/8/085021
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