| 摘要 |
PURPOSE:To avoid the lowering of punch-through voltage accompanying the introduction of a short channel by providing a region having the same conductive type with a substrate and density of impurities higher than the substrate under the source and drain regions of a MOS type transistor and further under a channel region. CONSTITUTION:When N<+> type source regions 22 and 23 are formed diffusely as the MOS type transistor on the P<-> type Si substrate, a P<+> type layer is provided on the substrate 21. Next, on the periphery of this laminate body, by using the P<+> type region as an underlay, a thick filed SiO2 film 27 for sea separating an element is formed, and on the central part of the layer 24 a polycrystalline Si gate electrode 26 is fitted through the intermediary of a gate SiO2 film 25. Then, within the layer 24 exposed on both sides of the electrode, N<+> type source and drain regions 22 and 23 which are shallower than the layer 24 are formed diffusely. Thus, a vacant layer 28a expanding from the region 22 and a vacant layer 28b expanding from the region 23 do not contact with each other since the expansion thereof is controlled, and thereby the lowering of the punch-through voltage can be eliminated without losing the property of high speed of the element. |
