DRAM cell with a cradle-type capacitor

摘要

An efficient method for manufacturing a cradle-shape capacitor for use as part of a DRAM cell in a silicon integrated circuit is described. The effective area of the capacitor plates is increased by providing a trench along the center of the capacitor which has the form of a polysilicon rectangular prism. The trench is formed by locating a heavily doped layer of silicon oxide on the surface and then heating the structure to a degree sufficient to cause significant outdiffusion of dopant from the silicon oxide into the polysilicon. A selective etching procedure is then used to remove only the area into which dopant has diffused, thereby creating the aforementioned trench.