| 摘要 |
PURPOSE:To form a stable long life CHEMFET having no possibility relating to the corrosion and insulation of an electrode part at all, by using an SOI base board while taking out a CHEMFET source electrode and a drain electrode from the side of a lower insulating substance base board. CONSTITUTION:A p type SOI base plate comprising the p type silicon single crystal thin film 1 formed on an insulating base plate 2 comprising quartz is used and an n type source region 3 and an n type drain region 4 are formed in the p type silicon thin film 1. Because the thickness of the silicon thin film 1 is 0.5-1mum, the source region 3 and the drain region 4 reach the boundary of the lower insulating base plate 2. An SiO2 insulating film 5, an Si3N4 insulating film 6 and a Ta2O5 film 7 are successively formed on the silicon thin film 1. In the next step, the partial region of the lower insulating base plate directly under the source region 3 and the drain region 4 is perfectly removed so as to reach the insulating base plate and the silicon boundary surface while a source electrode 8 and a drain electrode 9 each comprising a metal are formed to the silicon surfaces of the source part 3 and the drain region 4. A chemical substance responsive layer 10 is form on the insulating film on a gate active silicon region. |
