| 摘要 |
PURPOSE:To hold an ion sensing matter stably, by forming an impurity layer from the surface of a film consisting of an inorganic matter by the impurity which reacts on a constituent matter of this film to form an ion exchange site sensitive to specific ions. CONSTITUTION:Drain diffusion region 43 and source diffusion region 44 are formed in semiconductor substance 42 of approximately 200mum thickness, and gate insulating film 45 is formed on the surface of the substance. After that, surface stabilizing film 46 is formed on gate insulating film 45. This surface stabilizing film is formed with the composite consisting of ion permeable inorganic insulating materials such as oxides and nitrides of Si3N4, SiOxNy, Al and Ta by CVD or sputtering. After the film of diffusion source 47 which reacts on the constituent matter of the surface stabilizing film to form an ion exchange site sensitive to specific ions is formed on this surface stabilizing film, gate part 41 is subjected to the heat treatment to diffuse thermally the composite of the diffusion source into the surface stabilizing film, and impurity layer 48 is formed which functions as the ion sensing region. |
