Ferroelectric capacitors with metal oxide for inhibiting fatigue and methods of forming the same

A method of forming a semiconductor device, the method comprising the steps of:

• forming a MOS transistor on a substrate;
• forming an interlayer insulating layer on the substrate and the MOS transistor;
• forming a contact plug penetrating the interlayer insulating layer and electrically connected with a source region of the MOS transistor;
• forming a stack type lower electrode on the interlayer insulating layer and that is electrically connected with the contact plug;
• oxidizing the lower electrode to form a metal oxide film on an upper surface and sidewall surfaces of the lower electrode;
• forming a ferroelectric film on the metal oxide film while providing oxygen to the metal oxide film;
• and
• forming an upper electrode on the ferroelectric film.

A ferroelectric capacitor comprising:

• a lower electrode on a substrate, the lower electrode comprising a metal film in which a surface portion of the metal film is oxidized as a metal oxide film;
• a ferroelectric film on the metal oxide film and the substrate;
• and
• an upper electrode on the ferroelectric film.

A semiconductor device comprising:

• a MOS transistor on a substrate;
• an interlayer insulating layer on the substrate and the MOS transistor;
• a contact plug that penetrates the interlayer insulating layer and is electrically connected with a source region of the MOS transistor;
• a stack type lower electrode on the interlayer insulating layer and electrically connected with the contact plug, the lower electrode comprising a metal film in which an upper surface and sidewall surface portions of the metal film are oxidized as a metal oxide film;
• a ferroelectric film on the metal oxide film and the interlayer insulating layer;
• and
• an upper electrode on the ferroelectric film.