Method for forming crown-shape capacitor node with tapered etching

Abstract

A crown-shape capacitor node is formed using a tapered etching process to increase the capacitance of the capacitor. A doped polysilicon layer is deposited over a substrate from which the capacitor node is formed. A tapered trench is formed in a doped polysilicon layer using a mask layer. The mask layer is removed and a dielectric layer is deposited over the doped polysilicon layer and filling the tapered trench. The dielectric layer is then etched back, leaving residual portions in the tapered trench. The doped polysilicon layer is then etched using the dielectric material in the tapered trench as an etching mask. The resulting capacitor node has tapered sidewalls, which increases the surface area of the capacitor node, thereby increasing the capacitor's capacitance. The mask layer can be formed so that the tapered etching process forms the capacitor node with either tapered exterior sidewalls or a tapered trench.

Dependencies are inferred from the claim text.