| 摘要 |
PURPOSE:To increase capacitance per planar unit area by a method wherein an impurity region, which serves as a channel stopper, is provided between a capacitor formed on the side of a pillar-shaped protrusion and a source and a drain region. CONSTITUTION:An Si substrate 11 is etched comparatively shallowly through an RIE to form a pillar-shaped protrusion 13. And, as keeping the substrate 11 in this state, As<+> or P<+> ions are implanted into one side of the protrusion 13 from obliquely above to form an n<+>-layer 15, and B<+> ions 16 or the like are implanted into the rest three sides of the protrusion 13 from obliquely above also for the formation of a p<+>-layer 17. Next, the n<+>-layer 15 and the p<+>-layer 17 are covered with an SiO2 film 18 by oxidizing the protrusion 13 or forming a side wall of SiO2 around the protrusion 13. And, a process follows, where the substrate 11 is furthermore etched through an RIE to make the pillar-shaped protrusion 13 higher in level, and ions are implanted into the protrusion 13, which is made higher in level, from obliquely above to form an n<+>-layer 21 on four sides of it this time. In this process, ions are not implanted into the p<+>-layer 17 and the like covered with the SiO2 film 18. |
