| 摘要 |
An improved method for forming a dynamic random access memory (DRAM) capacitor with increased capacitance is disclosed. The method includes forming a polysilicon layer on a substrate, and forming a silicon nitride layer on the polysilicon layer. A photoresist layer is formed on the polysilicon layer to define a storage node area over the substrate surface. After a portion of the silicon nitride layer is removed using the photoresist layer as a mask, a polymer spacer is formed on the sidewalls of the photoresist layer and the silicon nitride layer. The polysilicon layer is removed using the polymer spacer and the photoresist layer as a mask. After the polymer spacer and the photoresist layer are removed, the polysilicon layer is subject to oxidation by using the silicon nitride layer as a mask, thereby forming a polysilicon-oxide layer on the sidewalls and the surface of the polysilicon not covered by the silicon nitride layer. The silicon nitride layer is stripped, and the polysilicon layer is etched using the polysilicon-oxide layer as a mask to form a trench in the polysilicon. Finally, the polysilicon-oxide layer is removed to form a bottom electrode of the capacitor of the dynamic random access memory.
|
