High-k dielectrics for use as ISFET gate oxides

Two binary oxides, Ta/sub 2/O/sub 5/ and HfO/sub 2/, were investigated for use as the pH-sensitive gate oxide of ion-sensitive field-effect transistors (ISFETs). Both materials have been extensively studied as high-k materials for advanced CMOS technologies. They are both deposited by CVD methods, which enable batch processing of several wafers at the same time. After deposition, these materials are thermally annealed, during which step the oxide properties are optimized for use as ISFET gate oxide. The performance of the ISFETs is evaluated by characterization of several parameters including the pH-sensitivity, drift and light sensitivity.