| 摘要 |
PURPOSE: To provide a high density dynamic random access memory(DRAM) by providing an access transistor in a self-aligned and shallow trench, vertically arranged on a storage capacitor in a deep-trench structure. CONSTITUTION: A wafer having a semiconductor substrate 10 and an epitaxial layer 12 on the substrate has a vertical transistor 14, arranged in a shallow trench 100, laminated and self-aligned on the capacitor in a deep trench 16. The laminated vertical transistor 14 has a channel 18 of which one part positions on a horizontal plane and one part positions along the side wall of the shallow trench, and drains 20 and 21 of the access transistor have a thinly- doped diffused drain structure and are connected to a bit line element 22. At the bottom of this vertical transistor 14, a source 24 of the transistor 14 positioned at the upper part of center of the trench capacitor is aligned and connected to a polycrystalline silicon 28 inside the trench capacitor. Thus, a high-density DRAM can be provided. |
