METHOD AND SYSTEM FOR APPLYING ION-SELECTIVE MEMBRANE ON ISFET SURFACE

The present invention provides a method and system for applying ion-selective membrane on Ion-Sensitive Field Effect Transistor (ISFET) surface without involving a mask step. In one embodiment multi-purpose ISFET devices are first prepared at wafer level using a standard Complementary Metal Oxide Semiconductor (CMOS) fabrication process up to Metal I bond pad and ISFET gate window is open for ion sensing purposes. A retaining structure is applied 105 as a protective layer and to define the gate window opening prior to membrane cocktail application 107 by manually pipetting out through a pipette.