| 摘要 |
PURPOSE:To remove a leak current and a decrease in breakdown strength while transistors channel parts and element isolation regions do not come in contact with each other, by forming a transistor of each memory cell into a ring shape in which a contact hole of bit lines is surrounded and forming an element isolation region on the periphery of this transistor. CONSTITUTION:Measure-shaped groove parts 12 are formed as shown in oblique lines on a silicon substrate 11 and memory cells are formed inside their parts. A thick oxidizing film 13 for element isolation is formed to isolate respective memory cells on the bottom of grooved parts 12. A thin oxidizing film 16 is formed on side walls 14 of the groove parts 12 and a flat part of the silicon substrate 11. Electrodes 17 for capacitors are formed into such a shape that their lower parts extend to the inside of the grooves 12 and their upper parts extend to the edge parts of the grooves 12. A capacitor of each memory cell is composed of the electrode 17, the thin oxidizing film 16, and the silicon substrate 11. Surface areas of capacitors are increased by utilizing the side walls of the groove parts 12 as capacitors for charge accumulation. |
