Method for making integrated circuit capacitor including anchored plugs

Abstract

A method for making an integrated circuit capacitor includes forming a first dielectric layer adjacent a substrate, forming a first opening in the first dielectric layer, filling the first opening with a conductive material to define a first metal plug, and forming a trench in the first dielectric layer adjacent the first metal plug. An interconnection line lines the first trench and contacts the first metal plug to define anchoring recesses on opposite sides of the first metal plug. The method further includes forming a second dielectric layer on the interconnection line, forming a second opening in the second dielectric layer, and filling the second opening with a conductive metal to define a second metal plug having a body portion and anchor portions extending downward from the body portion for engaging the anchoring recesses to anchor the second metal plug. A second trench is formed in the second dielectric layer adjacent the second metal plug, and is aligned with the first trench. Because the second metal plug is anchored, a depth of the second trench can be greater without the metal plug becoming loose and separating from the underlying interconnection line. The electrodes and dielectric layers of the capacitor are formed so that they line the second trench.