INVESTIGATION OF RELATIVE HUMIDITY SENSORS BASED ON POROUS SILICON, POROUS POLYSILICON AND POROUS SILICON CARBIDE

摘要

We are investigating the suitability of porous polysilicon and porous SiC as materials for sensing humidity. The investigation is a continuation of earlier work on porous single crystal silicon, where it was shown that this material could be easily incorporated into a standard process. It was also shown that membrane structures enable the integration of a heating device to 'reset' the system. The best microstructure for humidity sensing was obtained for low doped p-type silicon. The advantage of using polysilicon is that it is possible to tune its response (by doping) so that it has only a very small temperature coefficient of resistance. The advantage of using SiC is that it offers the possibility of a humidity sensor that could withstand very harsh chemical environments.