Method of fabricating capacitor plate

A method of fabricating a capacitor, comprising the following steps of:

• providing a substrate having a transistor, constituted by at least one diffused region, formed thereon and overlaid by an inter-insulating layer;
• forming a first oxide layer over said substrate;
• sequentially forming a nitride layer and a second oxide layer, both of which constitute a stacked structure, overlying said first oxide layer;
• patterning said stacked structure to form an opening, which exposes a portion of said first oxide layer;
• forming a first polysilicon layer conformably overlying said substrate;
• etching said first polysilicon layer to polysilicon spacers adjacent to the sidewalls of said opening;
• removing said second oxide layer, simultaneously removing a portion of said first oxide layer not covered by said nitride layer as well as said polysilicon spacers to form a contact window thereby exposing a portion of said diffused region;
• conformably forming a second polysilicon layer over said substrate;
• etching back said second polysilicon layer until a portion of said nitride layer is exposed;
• removing said exposed nitride layer, thereby exposing said polysilicon spacers and said second polysilicon layer serve as a bottom plate;
• forming a dielectric layer overlying said bottom plate;
• and
• forming a third polysilicon layer overlying said dielectric layer as an upper plate.