Semiconductor storage device

A semiconductor storage device comprising:

• an active region defined by a trench formed in an upper portion of a semiconductor substrate;
• an element isolation insulating film formed in said trench;
• a MOS transistor formed in said active region;
• and
• a capacitor having a lower electrode which is an impurity diffusion layer connected to a source/drain region of said MOS transistor, a dielectric layer formed on a surface of said impurity diffusion layer, and an upper electrode formed on said dielectric layer,
• said element isolation insulating film having a recess which exposes an inner wall of said trench;
• said impurity diffusion layer and said dielectric layer extending from an upper surface of said active region along the inner wall of said trench which is exposed in said recess,
• said upper electrode having a buried portion buried in said recess and having a sidewall formed on a side surface of its portion which is not buried in said recess,
• an outer edge of said buried portion of said upper electrode being located inside an outer edge of said sidewall.