A HEATED MEMBRANE FOR A CAPACITIVE GAS SENSOR

Interdigital capacitors covered with a gas-sensitive layer are suitable for the integration of gas sensors with microelectronic technologies. They can be temperature stabilized by mounting them on a heated membrane. Usually one faces the problem of significant temperature gradients across the membrane for large-area sensors. In this work a heater arrangement capable of maintaining an almost even temperature distribution on the heated membrane is presented. An analytical approach and finite-element simulations are used to estimate heating power distribution for a square-shaped membrane. A test chip was designed and fabricated. The fabrication process is fully compatible with standard bipolar processing.