| 摘要 |
PURPOSE:To reduce a leakage current which flows through a transfer transistor by a method wherein a plurality of wiring layers which connect the tips of pillar-shape protrusions along a required direction are so provided as to be isolated from gate electrode to constitute a storage device. CONSTITUTION:A mask pattern of photoresist is formed on a P<->type Si substrate 1 surface and trenches 3 are formed by RIE. With this process, a plurality of pillar-shape protrusions 4 are formed on the substrate 1 surface in island shapes. Then 1st gate oxide film 6 is formed over the whole surface by heat oxidation. After that, 1st polycrystalline Si layer 5 is made to grow. Trenches 7 are dug from the top surfaces of the pillar-shape protrusions 4 by RIE. Then, after 2nd gate oxide film 8 is formed, donors are implanted by ion implantation to form S/D regions 9. After that, 2nd polycrystalline Si layer 10 is made to grow and apertures are drilled in the Si layer 10 at the center parts of the protrusions 4. After a layer insulating film 11 is formed, apertures for bit line contacts are drilled in the film 11 and Al wirings are applied to form the bit lines 12. With this constitution, quantity of charges which leak from a trench capacitor through a transfer transistor can be significantly reduced. |
