| 摘要 |
A method for preparing a trench capacitor structure first forms at least one trench in a substrate, and forms a buried bottom electrode on the lower outer surface of the trench. A dielectric layer is formed to cover an inner sidewall of the trench, and a plurality of deposition processes are then performed to form several polysilicon layers in the trench, wherein a process of introducing a gas containing dopants into the trench is performed at an interval of these deposition processes to diffuse the dopants into the polysilicon layers. Afterward, a planarization process and an anisotropic dry etching process are performed to remove a portion of the polysilicon layers from the top portion of the trench to form a top electrode in the lower portion of the trench. A collar insulation layer is then formed on the upper sidewall of the trench, and the collar insulation layer is used as an implanting mask to perform an implanting process to implant the dopants into the top electrode.
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