DRAM technology of buried plate formation of bottle-shaped deep trench

摘要

An improved method for forming a buried plate in a bottle-shaped deep trench capacitor. The method includes the steps of: (a) forming a deep trench into a semiconductive substrate; (b) filling the deep trench with a first dielectric material to a first predetermined depth; (c) forming a silicon nitride sidewall spacer in the deep trench above the dielectric layer; (d) removing the first dielectric layer, leaving the portion of the substrate below the sidewall spacer to be exposed; (e) using the sidewall spacer as a mask, causing the exposed portion of the substrate to be oxidized, then removing the oxidized substrate; (f) forming an arsenic-ion-dope conformal layer around the side walls of the deep trench, including the sidewall spacer; (g) heating the substrate to cause the arsenic ions to diffuse into the substrate in the deep trench not covered by the sidewall spacer; and (h) removing the entire arsenic-ion-doped layer. This method(can also be advantageously applied to the fabrication of buried plates for conventional deep trench capacitors.