| 摘要 |
PURPOSE:To overcome a problem resulting from gate through by extending from the source and drain regions a semiconductor region having the conductivity type reversed from that of source and drain regions to the area under the channel. CONSTITUTION:Boron ion is implanted to the source, drain regions of the bits for rewriting in order to form a semiconductor region 7 of the conductivity type reversed from that of P layer. With the heat treatment, the P type impurity is diffused under the channel region and the reverse, conductivity type semiconductor region 7 is extended under the channel. Phosphorus as an N type impurity is ion-implanted into a drain region to form an N<-> type layer 10. After forming a side wall 11 at the side surface of a polyside gate 2, arsenic as an N type impurity is ion-implanted to form an N<+> type layer 12 and source, drain regions 4, 5. Ion implantation is carried out from the source and drain regions and but it is not carried out in the gate through. Therefore, higher energy ion-implantation is not required, DELTARp becomes small and thereby fluctuation of threshold voltage becomes small and characteristic can be stabilized. |
