Monolithic integrable capacitive humidity sensing method for material characterization of dielectric thin films

A monolithic integrable capacitive humidity sensing method to determine water vapour transmission rates (WVTRs) of dielectric thin films is presented. The capacitive sensor, being used to detect transmission of water vapour, as well as the dielectric thin film to be tested can be processed subsequently with standard semiconductor technology. First measurements yield a reliable value of the well investigated dielectric silicon dioxide (SiO2). A 330 nm thick plasma enhanced chemical vapour deposited film of SiO2 showed a WVTR of ∼1.6∗10-2±0.7∗10-2gm2∗d at 124 °C and a step in surrounding relative humidity from 65% to 85%. The working principle of the sensor, its drawbacks and improvements are discussed and compared with other methods.