| 摘要 |
PURPOSE: A method for fabricating a poly-poly capacitor for use in BiCMOS integrated circuits is neither complicated nor expensive, and utilizes existing polysilicon and masking steps, thereby permitting the integration of the poly-poly capacitor at a low cost. CONSTITUTION: A first polysilicon layer is formed on a portion of an isolation region(12) in a poly-poly capacitor formation region. A first nitride spacer(16) are formed at both sidewalls of the first polysilicon layer. By implanting ions of a first conductivity type into the first polysilicon layer, a lower electrode(22) of the poly-poly capacitor is formed. After forming a second nitride spacer(24), a film stack is formed on the exposed lower electrode(22) by sequentially depositing an oxide layer(32), a second polysilicon layer and a SiGe layer. A doping layer(40) is formed by implanting ions of a second conductivity type into the SiGe layer and the second polysilicon layer. By etching the SiGe layer and the second polysilicon layer, an upper electrode of the poly-poly capacitor is formed. Then, a silicide layer(42) is formed by saliciding all exposed surfaces of the upper electrode.
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