| 摘要 |
PURPOSE:To obtain a sensor of which the sensor chip can be brought into direct contact with a solution to be measured, by forming the wiring of a chemical FET sensor, the wiring of MOSFET and a gate electrode, all of which are formed on the same semiconductor substrate, in the oxide film on the surface of the substrate while forming a water resistant film to the surface of the oxide film. CONSTITUTION:An N<+> diffusion layer 2 and a P-diffusion layer 3 are formed on a P type si substrate 1 and only the layer 3 is made thick to form an oxide film while a poly-Si-gate electrode 6 is provided in the left side oxide film 5 as shown in the drawing to form MOSFET and the left side is set to chemical FET. Wirings of both FETs are also formed in the oxide film 5. An Si3N4 film 7 is formed on the oxide film 5 as a water resistant insulating film and a Ta2O5 film 8 is further formed on the film 7. The film 8 is allowed to function as a pH responsive film. By this method, the wirings 4 or the gate electrode is prevented from corrosion because of the presence of the water resistant insulating film 7 even if a sensor chip is immersed in a solution to be measured and the life of the sensor is prolonged. |
