| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for fabricating a deep trench capacitor in which process window can be improved. SOLUTION: A dielectric layer 208 is formed along the inner surface of a deep trench 204 which is then filled with a first doping polysilicon layer 210. The first doping polysilicon layer and the dielectric layer are etched down to a first depth and a first recess 212 is formed above the first doping polysilicon layer thus exposing the upper part of the inner sidewall of the deep trench. A color dielectric layer is formed on the exposed inner sidewall of the deep trench. The first recess is filled with a second doping polysilicon layer 216. The second doping polysilicon layer is etched down to a second depth and a gap is formed above the color dielectric layer between the exposed inner sidewall of the deep trench and the second doping polysilicon layer. The gap is filled with a doping polysilicon layer 220 converted from an undoped polysilicon layer 220. Finally, a pattern mask layer is removed thus forming a drain region 226a adjacent to the doping polysilicon layer. |
