Simulation and fabrication of extended gate ion sensitive field effect transistor for biosensor application

Abstract

In this paper, we present the Extended Gate Ion Sensitive Field Effect Transistor (EGFET) which has a same function as the Ion Sensitive Field Effect Transistor (ISFET). In contrast to the traditional ISFET, the EGFET retains the original metal/polysilicon portion of the gate electrode and the sensing membrane is deposited on the other end extended from the metal/polysilicon gate. This type of ion sensor is suitable for in vivo and in vitro measurement, especially for biosensor applications. Basic concept, fabrication techniques and process/device characterization of EGFET for biosensor development will be discussed in this paper. To support the fabrication process, a simulation study of the process flow using the CoventorWare simulator and the Silvaco Athena process simulator has been done. The results showed good current-voltage characteristics of a multi-finger structure transistor suitable to be used for biosensor transducer.