DRAM STRUCTURE WITH EXTENDED TYPE TRENCH AND FABRICATING METHOD THEREOF

摘要

A dynamic random access memory (DRAM) structure with an extended type trench and a fabricating method thereof are provided. The structure comprises an NMOS transistor (6) and a trench capacitor connected with the NMOS transistor (6), wherein the trench capacitor comprises a semiconductor substrate (1), N type SiGe layers and N type Si layers (2) arranged alternately, a trench, a dielectric layer (3) and a polysilicon layer (4); the trench is located in the N type SiGe layers and the N type Si layers (2) arranged alternately and deeply enters into the semiconductor substrate (1), the side cross section of the trench is a comb tooth shape; the N type SiGe layers and the N type Si layers (2) arranged alternately are used as the lower electrode plate of the trench capacitor; the dielectric layer (3) is located on the inner wall surfaces of the trench; the polysilicon layer (4) is filled in the trench and used as the upper electrode plate of the trench capacitor; there is also a P type Si layer (5) formed on the N type SiGe layers and the N type Si layers (2) arranged alternately, and the NMOS transistor (6) is fabricated on the P type Si layer (5). The invention method utilizes the doping and epitaxial technology to alternately grow the N type SiGe layers and the N type Si layers and utilizes selective etching to prepare the sidewall of the comb tooth shape, thereby improving the deep trench type capacitor structure of the DRAM and simplifying production process.