Patent ID: 7405122

Claim:
A method for forming a capacitor, comprising: providing a substrate; forming a material layer on the substrate; forming a first mask layer on the material layer; forming a second mask layer on the first mask layer; patterning the second mask layer to form a first opening therein, wherein the first opening is provided in a predetermined region for formation of a capacitor; forming a plurality of hemispherical grain structures on a sidewall of the patterned second mask layer in the first opening; etching the first mask layer by using the hemispherical grain structures and the patterned second mask layer as a mask, thereby forming a patterned first mask layer having a pattern and with a second opening therein; transferring the pattern of the patterned first mask layer to the material layer to form a patterned material layer with a third opening therein; forming a bottom electrode material layer on a sidewall of the patterned material layer in the third opening; removing the patterned material layer; and forming a capacitor dielectric layer and a top electrode layer on the bottom electrode material layer to form the capacitor.