| 摘要 |
PURPOSE:To eliminate a boron implantation overlapping part of a trench sidewall, and improve reliability, by preventing ion implantation in the upper part of a sidewall, by utilizing an eaves type mask of insulating film formed at the time of opening a trench of a trench type cell capacitance part of MOS type DRAM. CONSTITUTION:A P<+> layer 3 is formed at an aperture part of a nitride film 2 on a semiconductor substrate 1; a field oxide film 4 is formed and the film 2 is eliminated; an N<+> layer 5 is formed at a desired part; then photoresist 6 is spread and a specified aperture part is formed; a trench 7 is formed by ion etching. At this time, eaves of the resist is formed at a trench aperture part by controlling reaction gas. When B<+> ions are subjected to oblique rotation implantation in a sidewall, the ions are not implanted in the sidewall upper part, and the layer 3 does not overlap with the layer 8, thereby preventing the local residue of crystal defect. After the resist 6 is eliminated and an N<+> layer 9 and a high dielectric layer 10 are formed, a polysilicon electrode 11 and the like are formed in order, and a cell of MOS type DRAM is obtained. |
