High sensitivity capacitive humidity sensor with a novel polyimide design fabricated by mems technology

Ji Hong Kim, Sung Min Hong, Jang Sub Lee, Byung Moo Moon, Kunnyun Kim

Research output: Chapter in Book/Report/Conference proceedingConference contribution

29 Citations (Scopus)

Abstract

High sensitivity capacitive humidity sensor based on novel designed PI with cavity structure fabricated by MEMS technology is presented in this paper. The humidity sensor consists of a substrate with a cavity, a bottom electrode, a sensing layer, and a comb-shaped top electrode with branches. The cavity structure of the substrate was formed to protect the sensing material and improve reliability. PI was employed for the sensing layer due to its low hysteresis, good linearity, high sensitivity and high resistance to most chemicals. The comb-shaped top electrode was designed to have 50% fill factor with branches and the coated PI was etched by using O2 plasma asher in accordance with the top electrode passivation. This structure could improve the sensitivity and the response time of the humidity sensor due to larger area of contact between the PI and vapor, and shorter pathway of vapor absorption. The humidity sensor was fabricated on a 4 inch silicon wafer by MEMS technology. The humidity sensor with the etched PI showed a high sensitivity of 350 fF/%RH and the response time of 40sec from room humidity condition to 900/oRH. These are more improved results compared with values before PI etching, which are sensitivity of 303 fF/%RH and response time of 122 sec. Further characterizations were carried out to measure the hysteresis and the stability. The humidity sensor showed the hysteresis of 1.3% and maintained stable capacitance values with maximum 0.17% error rate, that are enough values to be used as a reliable humidity sensor in various applications.

Original languageEnglish
Title of host publication4th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2009
Pages703-706
Number of pages4
DOIs
Publication statusPublished - 2009
Event4th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2009 - Shenzhen, China
Duration: 2009 Jan 52009 Jan 8

Publication series

Name4th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2009

Other

Other4th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2009
CountryChina
CityShenzhen
Period09/1/509/1/8

Keywords

  • Capacitive humidity sensor
  • Humidity sensor
  • MEMS
  • Polyimide

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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  • Cite this

    Kim, J. H., Hong, S. M., Lee, J. S., Moon, B. M., & Kim, K. (2009). High sensitivity capacitive humidity sensor with a novel polyimide design fabricated by mems technology. In 4th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2009 (pp. 703-706). [5068676] (4th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2009). https://doi.org/10.1109/NEMS.2009.5068676