| 摘要 |
PURPOSE:To make it possible to perform reliably an inter-element isolation by a method wherein a high-concentration and inverse conductivity type semiconductor layer is formed up to the position of a depth, which includes at least first and second impurity diffused regions, of a groove and an insulating film is provided on the lower part of the groove. CONSTITUTION:In a memory cell, an insulating film 54 is formed on the region other than the region on the whole periphery of the upper part of the wall surface of a trench-shaped groove 20 formed in one main surface of a P<--> semiconductor substrate 81. An N<+> impurity diffused region 53 is annularly formed in the one main surface on the periphery of the upper part of the groove 20 and an N<+> source region 22 is continuously connected to this region 53 and is formed in the one main surface. A high-concentration P-type semiconductor layer 80 is formed up to the position of the intermediate depth of the groove 20 in a state that it completely includes these regions 53 and 22. The concentration of this layer 80 is a concentration higher than that of the lower region of the groove 20 and the conductivity type of the layer 80 is an inverse conductivity type to those of the N<+> diffused regions 53 and 22. Thereby, an inter-element isolation is reliably performed and an alpha-ray resistance can be made sufficient. |
