A method of forming a semiconductor structure including a metal-insulator-metal (MIM) capacitor includes: forming a stack structure over a substrate, wherein the stack structure includes a plurality of electrode material layers and a plurality of insulating material layers alternately stacked over the substrate; forming a mask layer on the stack structure; and performing a patterning process on the stack structure, so as to form the MIM capacitor comprising alternately stacked electrodes and insulating layers. Performing the patterning process includes: performing a first etching process to remove a first portion of the stack structure exposed by the mask layer; performing a first trimming process on the mask layer to remove a portion of the mask layer, and a first trimmed mask layer is formed; and performing a second etching process to remove a second portion of the stack structure exposed by the first trimmed mask layer.