| 摘要 |
A method for fabricating a DRAM capacitor is described. First, a semiconductor substrate having a capacitor contact is provided. Next, a first polysilicon layer is formed. Then, an oxide layer and a silicon oxy-nitride layer are sequentially formed over the first polysilicon layer. Next, the silicon oxy-nitride layer, the oxide layer, and the first polysilicon layer are selectively etched to leave a rectangular stack layer. Afterwards, the oxide layer and the first polysilicon layer of the rectangular stack layer are etched from the sidewall direction to leave a double T-shaped stack layer. Then, second polysilicon layer is formed on the upper surface and the sidewall of the double T-shaped stack layer. Next, the second polysilicon layer is selectively removed. The remaining second and first polysilicon layer are used as the bottom electrode. Afterwards, a dielectric layer and an upper electrode are formed on the bottom electrode.
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