An Accurate TCAD-Based Model for ISFET Simulation

In this paper, a new model is successfully introduced to describe an ion-sensitive field-effect transistor in a TCAD tool. To model this device accurately, the model should evaluate surface charge density behavior of electrolyte and insulator interface as well as ion concentration according to different pH values. Performance and accuracy of the model have been examined through assessing parameters such as sensitivity and signal-to-noise ratio (SNR). The effect of silicon active layer thickness on the sensitivity and SNR and its maximum condition and relevance to silicon thickness are investigated. Results show that the model can predict the device responses accurately, in accordance with experimental reports. The proposed model reveals that although the top oxide to buried oxide capacitance ratio does not change the SNR; the silicon active layer thickness can affect it efficiently.