| 摘要 |
PURPOSE:To suppress the yield of hot carriers and to avoid a capturing phenomenon of the carriers at an interface between an impurity region with relatively low concentration and a side wall insulating film, by forming source and drain regions by three-layer structure comprising the relatively low-concentration impurity region, an impurity regions having higher concentration and an impurity regions having more higher concentration. CONSTITUTION:Source and drain regions 4 a have a three-layer structure of an N<-> region, 4C, an N<+> region 4D and an N<++> region 4E. The N<->, N<+> and N<++> regions have the impurity concentrations in the order of - 10<12>, - 10<-13>, and - 10<14> pieces/cm<2>, respectively. The N<-> region 4C is embedded beneath a gate electrode 3. The N<+> region 4D and the N<++> region 4E are located beneath a side wall SiO2 film 5. In this constitution, the hot carrier suppressing effect provided in an LDD structure is maintained by the presence of the N<-> region 4C. In the meantime, the disadvantage of carrier capturing in the LDD structure at the interface between the relatively low-concentration impurity region constituting the source and drain and the side wall insulating film can be avoided. |
