Abstract: Based on MEMS technology, a design of humidity sensitive
capacitor was described. The capacitor employed sandwich structure,
i.e. polyimide was used as the humidity sensitive material and gold
was used as the electrodes. Capacitor shows a good pass rate of
80{\%}. As can be seen from the measurements, over the testing range
from 15{\%} RH to 95{\%} RH, the maximum linearity error is 1.5{\%}
RH. The sensitivity reaches 0.29pF /{\%} RH. The hysteresis is
small, and the sensor has fast response time of 4~s. Meanwhile,
capacitor shows good temperature coefficient and long-term
stability. The results show that the comprehensive indexes of
humidity capacitor are satisfactory. The capacitor is suitable for
batch fabrication and can be used for high altitude meteorological
observation.

Key words: humidity sensor, humidity sensitive capacitor, polyimide, MEMS