Semiconductor device with ring-shaped electrode and method for preparing the same

A semiconductor device, comprising:

• A top electrode disposed over a semiconductor substrate, wherein the top electrode has a ring shape from a top view;
• an insulating layer disposed along an inner sidewall, a bottom surface, and an outer sidewall of the top electrode;
• a bottom electrode structure surrounding the insulating layer, wherein the bottom electrode structure comprises:
• a first bottom electrode layer directly contacting the insulating layer;
• and
• a second bottom electrode layer surrounding the first bottom electrode layer;
• and
• a plurality of insulating portions disposed between the first bottom electrode layer and the second bottom electrode layer.

A method for preparing a semiconductor device, comprising:

• forming a dielectric layer over a semiconductor substrate;
• forming an energy removable layer over the dielectric layer;
• etching the energy removable layer to form a ring-shaped opening exposing the dielectric layer;
• depositing a first bottom electrode layer along an inner sidewall, a bottom surface, and an outer sidewall of the ring-shaped opening;
• depositing an insulating layer over the first bottom electrode layer;
• forming a top electrode in a remaining portion of the ring-shaped opening;
• and
• removing the energy removable layer after the top electrode is formed.