Capacitive humidity sensor using a polyimide sensing film

Author

Laconte, J. ; Wilmart, V. ; Raskin, J.P. ; Flandre, D.

Author_Institution

Res. Center in Micro, Univ. Catholique de Louvain, Belgium

fYear

2003

fDate

5-7 May 2003

Firstpage

223

Lastpage

228

Abstract

This paper investigates novel isolation and patterning schemes to increase the sensitivity of a capacitive humidity sensor based on a polyimide sensitive layer. We obtained an optimum sensitivity of 23% using aluminum interdigitated electrodes with fingers of 1 μm width separated by 1 μm, deposited on a first insulating polyimide layer and covered by two more polyimide layers whose upper one features a regular array of holes to increase the active surface area. A mathematical model was developed to optimize its sensitivity regarding water absorption factor, electrodes design and ratio between active and parasitic capacitances. Its process was optimized to be fully compatible with usual CMOS-IC processes in order to finally be able to fabricate a humidity smart sensor.

Keywords

CMOS integrated circuits; capacitive sensors; humidity sensors; polymer films; 1 micron; CMOS-IC process; aluminum interdigitated electrodes; capacitive humidity sensor; electrodes design; humidity smart sensor; insulating polyimide layer; mathematical model; parasitic capacitance; polyimide sensing film; sensitivity; water absorption factor; Absorption; Aluminum; Capacitive sensors; Design optimization; Electrodes; Fingers; Humidity; Insulation; Mathematical model; Polyimides;

fLanguage

English

Publisher

ieee

Conference_Titel

Design, Test, Integration and Packaging of MEMS/MOEMS 2003. Symposium on

Print_ISBN

0-7803-7066-X

Type

conf

DOI

10.1109/DTIP.2003.1287041

Filename

1287041