Method of fabricating deep trench capacitor

摘要

A method of fabricating a trench capacitor includes forming a trench in a substrate; forming a conductive diffusion region in the substrate surrounding a lower portion of the trench; forming a dielectric layer along an inner surface of the trench; and filling the trench with a first doped polysilicon layer. A first recess is formed to expose an upper portion of the inner sidewall of the trench. A collar dielectric layer is formed on the exposed inner sidewall. The first recess is filled with a second doped polysilicon layer. A second recess is formed to expose a part of the upper portion of the inner sidewall. A gap is formed between the exposed inner sidewall and the second doped polysilicon layer, and filled with a doped polysilicon layer converted from an undoped polysilicon layer.