Microtechnologies for pH ISFET chemical sensors

A review of different microtechnologies for the fabrication of pH ion sensitive field effect transistor (ISFET) sensors is presented. Integrated ISFETs are of interest due to the advantages of low price, fast response and small dimensions that they present compared to ISE electrodes. ISFETs can be also applied to the detection of different ions, using the proper sensitive membranes. A lot of work has been done during the last few decades to obtain commercial devices, and many technologies and structures can be found in the literature. In this paper, both front-side and back-side contacted devices are studied, in order to determine the compatibility of different processes, devices and materials with standard CMOS technologies, which seems to be a goal for present and future applications. (C) 1997 Elsevier Science Ltd.