| 摘要 |
PURPOSE:To enhance the speed of an SOS type FET made in high density by a method wherein an island-shaped semiconductor layer being made the center part thereof thinly is formed on an insulating substrate, and a channel region and parts of source and drain regions are provided in the thin part. CONSTITUTION:A thick island-shaped p type Si layer is formed on the sapphire substrate 11, for example, and recess parts are formed at the channel region 12 and the neighborhood 12A thereof to make the layer to thinly. Then after a gate film 13, a polycrystalline Si gate 14 are formed, n type impurities are implanted in high concentration using the gate 14 as a mask. Accordingly capacitance of the junction of source and drain regions can be reduced, and moreover the resistance values of the source and drain regions can be reduced because of having the thick n<+> type regions 15, 16. Moreover by setting energy of implanting ions as deeper than the region 12A having a thin peak position, concentration of the region 12A can be made as low, and withstand voltage thereof can be enhanced. |
