[KSCI] Korea Science Citation Index Service

A Highly Sensitive Humidity Sensor Using a Modified Polyimide Film

Kim, Yong-Ho (School of Mechanical Engineering, Yonsei University)
Lee, Joon-Young (School of Mechanical Engineering, Yonsei University)
Kim, Yong-Jun (School of Mechanical Engineering, Yonsei University)
Kim, Jung-Hyun (Department of Chemical Engineering, Yonsei University)

Publication Information

JSTS:Journal of Semiconductor Technology and Science / v.4, no.2, 2004 , pp. 128-132 More about this Journal

Abstract

This paper presents the design, fabrication sequence and measurement results of a highly sensitive capacitive-type humidity sensor using a polyimide film without hydrophobic elements. The structure of the humidity sensor is MIM (metalinsulator-metal). For a high sensitivity, a modified aromatic polyimides as a moisture absorbing layer has been synthesized instead of using general polyimides containing hydrophobic elements. The polyimide film was obtained by synthesizing and thermally polymerizing polyamic acid composed of m-pyromellitic dianhydride, phenelenediamine and dimethylacetamide. Characteristics of fabricated sensors which include sensitivity, hysteresis and stability have been measured. The measurement result shows the percent normalized capacitance change of 0.37/%RH over a range from 10 to 90%RH, hysteresis of 0.77% over the same %RH range and maximum drift of 0.25% at 50%RH. The result shows that the developed humidity sensor can be applied to evaluate a hermeticity of various sensors and actuator systems as well as micro packages.

Keywords

Capacitive humidity sensor; modifiedaromatic polyimide films; hydrophobic;

Citations & Related Records

Reference

1	J.O Simpson and A.K. St.Clair, 'Fundamental insight on developing low dielectric constant polyimides,' NASA Tech. Report, no.294, 1997
2	Y.T. Cheng, W.T Hsu, L. Lin, Nguyen and K. Najafi, 'Vacuum packaging technology using localized aluminum/silicon-to-glass bonding,' 14th IEEE Int. Conf. on MEMS, pp.18-21, 2001 DOI
3	Chong. H. Ahn, Yong J. Kim and Mark G. Allen, 'A planar variable reluctance magnetic micromotor with fully integrated stator and coils,' J. MEMS, vol.2, no. 4, pp.165-173, 1993 DOI ScienceOn
4	H. Han, H. Chung, C.C. Gryte, T.J. Shin and M. Ree, 'Effects of precursor origins on water sorption behaviors of various aromatic polyimides in thin films,' Polym., vol. 40, pp.2681-2685, 1999 DOI ScienceOn
5	M. Dokmeci and K. Najafi, 'A high-sensitivity polyimide capacitive relative humidity sensor for monitoring anodically bonded hermetic micropackages,' J. MEMS, vol.10, iss. 2, pp.197-204, 2001 DOI ScienceOn
6	Y.Y. Qui, C. Azeredo-Leme, L.R. Alcacer and J.E. Franca, 'A CMOS humidity sensor with on-chip calibration,' Sen. Act. A, vol. 92, pp.80-87, 2001 DOI ScienceOn
7	C. Laville and C. Pellet, 'Comparison of three humidity sensors for a pulmonary function diagnosis microsystem,' IEEE J. Sensors, vol. 2, no.2, pp.96-101, 2002 DOI ScienceOn
8	G. Maier, 'Low dielectric constant polymers for microelectronics,' Prog. Polym. Sci., vol. 26, pp.3-65, 2001 DOI ScienceOn
9	Yong-Jun Kim and Mark. G. Allen, 'Surface micromachined solenoid inductors for high frequency applications,' IEEE Trans. CPMT., vol. 21, no. 1, pp.26-33, 1998 DOI ScienceOn