FORMATION OF CONDUCTIVE BURIED LAYER, FORMATION OF TRENCH CAPACITOR AND DYNAMIC RANDOM ACCESS MEMORY DEVICE

摘要

PROBLEM TO BE SOLVED: To make the formation of buried capacitor electrodes, which can be reconciled with the formation of a large-capacity DRAM, possible at low cost and with a high productivity by a method wherein epitaxial layers, which respectively cover a region containing impurities implanted therein and consist of a semiconductor material, are grown and the impurities are diffused in the epitaxial layers. SOLUTION: As an example, a trench capacitor structure is used as an original boundary of an implantation region 20 and the boundary 48 between buried electrodes attained by diffusion. Trenches 4 respectively end in the buried electrodes and the insulation of the trenches from a substrate is obtained by the boundary between the electrodes lower than those to correspond to the respective valleys of dopant profile valleys. Oxide-nitride-oxide sandwich capacitor dielectric materials 52 are respectively formed in the interiors of the trenches 46. Another connection of a dynamic random access memory device can be formed by a metallization, which can form even conductive terminals of transistors 58 and 58' which are used for controlling an access to a cell.