SUBMERGED STORAGE PLATE MEMORY CELL

PURPOSE: To provide a transistor storage cell which is highly immune to noises, without needing an epitaxial layer by facing the surface of a polycrystalline Si core formed in a trench, perpendicular to a substrate surface in a p-type region formed round the trench through a dielectric layer. CONSTITUTION: A capacitor is formed in a cylindrical trench 11 approximately vertical to the plane of a semiconductor substrate surface. The vapor phase diffusion is applied to form a p+-region 13 contg. B at a high concn. in the trench 11. The reign 13 forms one electrode plate of the capacitor, while a polycrystalline Si core 14 in the trench 11 forms the other electrode plate. The core 14 is isolated from the region 13 through a thin dielectric layer 15 of Si dioxide or mixture of Si nitride and Si dioxide. Charge storage occurs in the core 14 at a deep part 19 of the trench. This structure eliminates need for the use of an epitaxial layer and reduces the cost of a MOS semiconductor device, using the trench-type storage capacitor.