CAPACITIVE HUMIDITY SENSORS IN SACMOS TECHNOLOGY WITH MOISTURE ABSORBING PHOTOSENSITIVE POLYIMIDE

We present integrated capacitive humidity sensors fabricated with the industrial SACMOS (self-aligned contact CMOS) technology. The devices are based on different interdigitated microelectrodes. Some of these include a new, photosensitive as well as humidity-sensitive, polyimide layer which offers the advantage of easy patterning and processing. The capacitances and phase angles of the sensors have been measured as a function of the relative humidity (RH) of the ambient air for different polyimide thicknesses, temperatures and frequencies in an environmental chamber. Their fast response to humidity is linear over a wide range of RH. Good reproducibility over the prototype batch is obtained.