| 摘要 |
PURPOSE:To concentrate the a sensor parts to the point of a substrate and to improve the yield of products by a method wherein insulation between the sensor part and an electrolyte is performed by using a semiconductor insulating film and an intermediate wiring part is performed by using a polysilicon for which impurity is doped. CONSTITUTION:A source area 2 and a drain area 5 are formed at the point part of a silicon substrate 1 by means of diffusion, and an SiO2 film is formed on the whole surface of the substrate 1. Next thereto, an SiO2 film on the required surface of both areas 2 and 5 is removed and thereafter, a polysilicon layer 9 of a stripe or band type is formed toward the rear end of the substrate 1. On this polysilicon layer 9, an SiO2 film is formed and further, an SiN film is formed. Next thereto, the SiN film and SiO2 film of the required part at the surface rear end of the substrate 1 are removed to expose the polysilicon layer and a source electrode S and a drain electrode D are formed, thus, the field effect transistor for ion sensor being constituted. With this, the substrate 1 can be made into a small size and an insulating processing at a wiring part is easily performed. |
