| 摘要 |
PURPOSE:To make possible to control the characteristics of an SOS.MOSFET more widely and at high accuracy by forming a semiconductor element on one principal plane of a dielectric substrate and providing an electret plate on the other principal plane side contacting it or separated from it. CONSTITUTION:On a dielectric substrate 1 of sapphire, etc., a p type Si layer 2 is epitaxially grown, and on its central area, a gate metal film 4 is coated via a gate SiO2 film 3. Next, using the film 4 as a mask and diffusing N type impurities into the layer 2 on its both sides, n<+> type source region 5 and drain region 6 are formed, and thus an SOS.MOSFET is formed. Then a thin electret plate 7 consisting of carnauba wax, magnetized zinc, borosilicate glass, etc., is coated on the back face of the substrate 1. By so doing, the threshold voltage of the FET can be controlled by the surface potential and polarity of the thin electret plate 7. |
