Capacitor structures and methods for fabricating the same

A capacitor structure, comprising:

• a first electrode plate disposed on a substrate, wherein the first electrode plate includes a first anti-reflective coating;
• a first capacitor dielectric layer disposed on the first electrode plate;
• a second electrode plate disposed on the first capacitor dielectric layer, wherein a portion of the first electrode plate extends beyond an end of the second electrode plate to form a step, and wherein the second electrode plate includes a second anti-reflective coating, and wherein a thickness of the second anti-reflective coating is less than a thickness of the first anti-reflective coating;
• an inter-metal dielectric layer which covers the second electrode plate, the first capacitor dielectric layer and the first electrode plate;
• a first via which penetrates through the inter-metal dielectric layer to contact the first electrode plate at the portion extending beyond the second electrode plate;
• and
• a second via which penetrates through the inter-metal dielectric layer to contact the second electrode plate.

A method for fabricating a capacitor structure, comprising:

• sequentially forming a first electrode plate material layer, a first dielectric layer, a second electrode plate material layer, a second dielectric layer, a third electrode material layer and a first etching stop layer on a substrate;
• patterning the first etching stop layer, the third electrode material layer and the second dielectric layer to form a patterned first etching stop layer, a third electrode plate and a second capacitor dielectric layer, respectively;
• forming a second etching stop layer over the patterned first etching stop layer and the second electrode plate material layer;
• patterning the second etching stop layer and the second electrode plate material layer to form a patterned second etching stop layer and a second electrode plate respectively, wherein a portion of the second electrode plate extends beyond an end of the third electrode plate to form a step;
• patterning the first dielectric layer and the first electrode plate material layer to form a first capacitor dielectric layer and a first electrode plate respectively, wherein a portion of the first electrode plate extends beyond an end of the second electrode plate to form a step;
• forming an inter-metal dielectric layer to cover the patterned first etching stop layer, the second electrode plate, the first capacitor dielectric layer, the first electrode plate, the patterned second etching stop layer, the third electrode plate, and the second capacitor dielectric layer;
• forming a first opening to penetrate through the inter-metal dielectric layer until the portion of the first electrode plate which extends beyond the second electrode plate is exposed;
• forming a second opening to penetrate through the inter-metal dielectric layer and the patterned second etching stop layer until the portion of the second electrode plate which extends beyond the third electrode plate is exposed;
• and
• forming a first via in the first opening and a second via in the second opening.